United Arab Emirates University Scholarworks@UAEU
Theses Electronic Theses and Dissertations
12-2007 Using GIS to Optimize the Design and Implementation of the RTK Reference Network in Abu Dhabi Mustafa Abdulla Mohammed Almusawa
Follow this and additional works at: https://scholarworks.uaeu.ac.ae/all_theses Part of the Digital Communications and Networking Commons
Recommended Citation Mohammed Almusawa, Mustafa Abdulla, "Using GIS to Optimize the Design and Implementation of the RTK Reference Network in Abu Dhabi" (2007). Theses. 524. https://scholarworks.uaeu.ac.ae/all_theses/524
This Thesis is brought to you for free and open access by the Electronic Theses and Dissertations at Scholarworks@UAEU. It has been accepted for inclusion in Theses by an authorized administrator of Scholarworks@UAEU. For more information, please contact [email protected]. United Arab Emirates University Deanship of Graduate Studies
Using GIS to Optimize the Design and
Implementation of the RTK Reference
Network in Abu Dhabi
By
Mustafa Abdulla Mohammed Almusawa
A Thesis submitted to the Deanship of Graduate Studies UAE University in partial fulfilment of the Requirelnents for the Degree of Master of Science in Remote Sensing and GIS
December 2007 Using GIS to Optimize the Design and
Implementation of the RTK Reference Network in
Abu Dhabi
By
Mustafa Abdulla Mohammed Almusawa
A Thesis submitted to the Deanship of Graduate Studies UAE University
in partial fulfilment of the Requirements for the Degree of Master of Science in Remote Sensing and GIS
Supervising Committee:
Supervisor: Dr. Ahmed Mahmoud EI-Mowafy Associate Professor Civil and Environmental Engineering Departlnent College of Engineering United Arab Elnirates University
Co-Supervisor: Dr. Salem Mohammed Ghaleb Issa Assistant Professor Departn1ent of Geology College of Sciences United Arab Emirates University
December 2007 II
The Thesis of Mu tafa A. Almu awa for the Degree of Ma ter of cience in Remote en ing and Gl i approved.
...... E amining Committee Member, Dr. Ahmed EI Mowafy
......
Examining Committee Member Dr. Hussein Harah heh
··· · ··4 ;0.� · · · · · · · ···· · · · · · ··· ············· · ········ ····...... Examining Committee Member, Dr. Nazmi Saleous
.....� ...... �. � ...... Director of the Program, Dr. Nazmi aleous
...... , ...... - ...... Assistant Chief Academic Officer for Graduate Studies,.. . Professor Ben Bennani
United Arab Emirates University
2007/2008 III
ACKNOWLEDGEMENTS
I would like to e pre my incere gratitude to my upervisor, Dr. Ahmed EI-Mowafy fo r hI gr at up port and guidance throughout my graduate studie . His continuous advice and encouragement were extremely appreciated. My co-supervisor, Dr. Salem Issa i also thanked fo r hi comment improving my work in thi thesis. r would like to thank
Engineer Giridhar Redd Kolan, GIS instructor fo r his technical upport and advice in
u ing the GIS tool . Abu Dhabi Municipality i al 0 thanked fo r providing GIS data and infonnation that \ as needed fo r this research. Special thank is due to the Municipality
GI consultant, Mike Cheremshyn kyi, who gave me usefulfe edback and comments.
Finally, I ould like to thank my parent , wife and children who gave me a lot of encouragement and pro ided an excellent working environment at home which allowed me to ucceed in writing this thesis. I could not have done it without the above mentioned
upport. IV
ABSTRACT
everal challenging application and con truction works demand real-time measurements fi r po ltioning at the centimeter-Ie el accuracy. Thi positioning accuracy can be obtained by U ing a Global Positioning ystem (GP ) roving unit and employing a ingle reference tation (base- tation) or through util izing the service of mUltiple reference
tation fo nning a Real-Time Kinematics (RTK) Reference etwork.
The limitation of the ingle reference approach is that measurement errors are distance dependent and good accuracy can be only obtained when di tances are Ie s than 10 kms.
In addition, thi method requires a nearby Geodetic Control Point (GCP). Recently, RTK reference nenA/orks are widely estabh hed in modem cities all over the world. The popularity of RTK reference nenvorks is due to the benefit of providing real-time accurate and con i tent GPS data 0 er a wide geographical area u ing a single GPS rover
\ Ithout the need to be referred to a nearby GCP.
De igning and implementing an RTK reference network is a challenging task. The
ystem performance and co t are highly related to the distance between stations nature of building hosting the reference tations as well a type and methods of communications.
Thus. a moderntool uch a the Geographic Information Systems (GIS) that can integrate geographic information and several types of heterogeneous data can be used to effectively optimize the design and implementation of the RTK reference network.
Thi re earch discusses the use of GIS as an advanced tool to study efficient approaches fo r designing and operating the Global avigation Satellite System (G SS) RTK v reference net\: ork in the mirate of bu Dhabi, United Arab Emirates. GI functionality i mainly u ed fo r manipulating, analyzing, evaluating and pre enting the results of diffe rent de ign and implementation approache .
The malll de ign a pect that are con idered include: reference tation location , their di tnbution and eparating di tance , tation ite election and the communication method . Recommendation concerning the selection of the most appropriate options fo r de igning and operating the sy tem are given.
a re'ult of the tudy, to en ure preci Ion and reliability it is proven that station di tribution and election can be be t ba ed on service demand while maintaining the user buffe r of a radiu of 35-50 km from the neare t reference station.
Finally, some of the applications that can be integrated with the RTK reference network. are explored and analyzed. Focus i made on the integration with Machine Control &
Automation due to the benefitsof pro iding increased production and efficiency to many pha e of the construction projects. VI
LIST OF ABBRIV ATIONS
OM Abu Dhabi Municipality
D L ynchronou Digital ub criber Line
DG P Diffe r ntial Global Positioning ystem
DM Department of Municipal Affairs
D Department of Defen e 0
DVR Dubai Virtual Reference Sy tem
FKP The GenTIan Abbre iation of "Area Correction Parameterization"
FM Frequency Modulation
GBA Ground Based Augmentation Systems
GCP Geodetic Control Points
GLO ASS GLObal'naya NAvigat ionnaya Sputnikovaya Sistema (Russian)
G S Global avigation Satellite Sy tems
GPRS General Pocket Radio System
GPS Global Po itioning System
IDW Inver e Distance Weighed
ISS InternetService Supplier
LA Local Area Network
CC Network Computer Center
TRIP Networked Tran p0l1 of RTCM ia Internet Protocol
PDA Per onal Data Assistant
RF Radio Frequency 11
RT M Radio Technical Commi ion fo r Maritime
RTK Real Time Kinematic
BA atellite Ba ed Augmentation ystem
DI patial Data Infra tructure
TETRA Terre trial Trunked Radio
U E United rab Emirates
UHF Ultra High Frequency
UTM Univer al Transverse Mercator
HF ery High Frequency
R Virtual Reference Station
WADGP Wide Area Differential Global Positioning Sy tern
W Wide Area etwork
WG 4 World Geodetic Sy tern 1984 Vll1
TABLE OF CONTENTS
AC KNO\VLEDGEMENTS ...... iii
ABSTRACT ...... iv
LIST OF ABB.RIVATIONS ...... vi
T BLE OF CONTENTS ...... viii
1. CHAPTER 1 INTRODUCTION ...... I
1.1. Background ...... 1
1.2. Thesi Objecti es ...... 4
1.3. Thesis Outline ...... 5
2. CHAPTER 2 AN OVE RVIEW OF GIS ...... 8
2.1. Definition of GIS ...... 8
2.2. GI Component ...... 9
2.�.1. Hard\vare ...... 9
2.2.2. Software...... 10
2.2.3. Data ...... 13
2.2.4. People ...... 14
2.3. GIS Analy is Tools ...... 16
2.3.1. Quelies ...... 16
2.3.2. Buffe ring ...... 17
2.3.3. Polygon Overlay ...... 18
2.3.4. Ra ter Interpolation ...... 18
3. CHAPTER 3 AN OVERVIEW OF THE GPS TECHNIQU ES ...... 20
3.1. Fundamentals of GPS ...... 20
3.2. Po t- mission and Real-Time Positioning ...... 25 3.3. RTK from Single Point Positioning ...... 26
3.4. Wide Area DGPS (WAD GPS) Techniques ...... 26 3.4.1. Satellite Based Augmentation Service (SBAS) ...... 28
3.4.2. Ground Based Augmentation Service(GB AS) ...... 30
3.5. RTK Positioning Using Single Reference Station ...... 32
3.6. RTK Positioning Using Multi Reference Stations (RTK Reference Networks) ...... 32
3.7. Summary of GPS Positioning Techniques ...... 35
4. CHAPTER 4 RTK POSITION ING AND ACCURACY REQUIREMENTS IN
ABU DHABI ...... 36 4. 1. Real-time Positioning from Augmentation Systems in Abu Dhabi ...... 37
4. 1.l. Positional Accuracy of the SBAS and GBAS Systems ...... 37
4.2. RTK Positioning ...... 39
4.2. 1. RTK Positioning Using a Single Reference Station ...... 39 IX
4.2.2. RTK Po itioning ing Multiple Reference Station ...... 39
4.3. Po itional Accuracy Requirements in bu Dhabi ...... 41 4.4. etwork Reference Datum ...... 43 4.5. Importance of RTK etwork in bu Dhabi fo r Supporting Spatial Data
Infra tructure ...... 47 5. CHAPTER 5 USING GIS FOR THE DESIGN OF THE RTK STATIONS
DISTRIBUTION ...... 49
5.1. eparating Di tance between Stations ...... 49
.2. e of GIS fo r election of Reference Station Distribution ...... 51
5.2.1. Methodology to Select the Be t Di tribution Approach using GIS ...... 51
5.2.2. Di tribution Options ...... 51
5.2.3. Di tribution Evaluation Criteria...... 52
5.2..1.U e of GIS Tool in Selecting Stations Distribution ...... 52
5.3. U e of G[ to Examine Re ults of the Distribution Options ...... 53
5.3.1. General Analy i Strategy ...... 53
5.3.2. Acquired and Created Data ...... 54
5.3.3. Station Di tribution Based On 35 km User Buffe r ...... 57
5.3.4. Station Distribution Ba ed on 50 km User Buffe r ...... 60
5.3.5. Station Distribution Sa ed On Service Demand ...... 62
5.3.6. Benefits of GIS as a Tool to De ign the RTK Reference etwork ...... 63
5.4. Evaluation and Compari on of Station Distribution Options ...... 64
6. CHAPTER 6 SITE SELECTION OF THE REFE RENCE STATIONS...... 70
6.1. Site Selection Criteria ...... 70
6. 1.1. Building Type Cliteria ...... 71
6.1 .2. Building Stability Criterion ...... 71
6.1 .3. Sky Visibil ity Criterion ...... 73
6.2. Adopted Methodology in Using GIS to Select the Optimal Sites ...... 76
6.3. Case Study Example - One Site in Abu Dhabi Island ...... 80
6.3. 1. Using GIS in Examining Stability of Buildings ...... 80
6.3.2. U ing GIS in Examining Type of Buildings ...... 81
6.3.3. Using GIS Tools to Velify the Building's Good Satellite Visibility ...... 83
6.3.4. 3D Investigation and Presentation Using ArcScene ...... 85
7. CHAPTER 7 COMMUNICATION NETWORK DESIGN ...... 88
7.1. Communication between the Reference Stations and the Center ...... 88
7.1.1. Corporate Wide Area etwork (WAN) ...... 89
7.1.2. Government WAN Network ...... 89
7. 1.3. Local Telecommunication Services ...... 90
7. 1 .4. Corporate Radio Frequency Network ...... 91
7.2. Using GIS in Communication Infrastructure Assessment ...... 92
7.2. 1. Studying Abu Dhabi RTK Network Conm1Unication Methods ...... 93
7.2.2. Analysis Approach fo r Examining the RF Communication ...... 96
7.2.3. Results and Conclusions ...... 97
7.2.4. Selection of Repeaters Locations and Antenna's Heights ...... 99 x
7.3. Communication Method between Control enter and U er ...... 103
7.4. U ing GIS to amine the VHF Broadcasting in bu Dhabi ...... 107
7.4. 1. Required Infonnation fo r HF Broadcasting ...... 108
7.4.2. Implementing Geo patial Proce and GIS naly i ...... ItO 8. CHAPTER 8 ADVA CED RTK ETWORK BASED GIS APPLICATIONS 112
.1. Remotely Monitored and Controlled Machine Automation ...... 112
9. CH PTER 9 CONCLU ION ...... 120
ARA BIC U�ll\lARY ...... 132 XI
LIST OF FIGURES
Fig. 1.1 United Arab Emirates Map ...... 3
Fig. 2. 1 GIS components ...... 9
Fig. 2.2 bu Dhabi Municipality new upgraded GIS architecture ...... 12
Fig. 2.3 GIS User ...... '" ...... 15
Fig. 2.4 n example of the buffe r and 0 erlay (intersect) tool ...... 17
Fig. 3.1 GP egments ...... 21
Fig. 3.2 BAS ervice Exemple : Onmi STAR SBAS service ...... 30
Fig. 3.3 Marine beacon station ...... 31
Fig. 3.4 RTK Reference etwork architecture (Source: Lieca Geosystems) ...... 34
Fig. 4.1 Beacon reference stations and testing point ...... 38
Fig. 4.2 Proposed di tribution of the multi reference station in Abu Dhabi ...... 41
Fig. 4.3 Mapping Accuracy requirement in Abu Dhabi ...... 42
Fig. 4.4 rea-categories classification (Source: Abu Dhabi Municipality)...... 43
Fig. 4.5 Typical SDr Architecture ...... 48
Fig. 5.1 Station Di tribution based on user buffe r of 35 km without overlap ...... 58
Fig. 5.2 tation distribution based on user buffe r of 35 km with overlap ...... 60
Fig. 5.3 Stations di tribution based on user buffe r of 50 km without overlap ...... 61
Fig. 5.4 tations di tribution based on user buffe r of 50 km with overlap ...... 62
Fig. 5.5 tation distribution Based on Service demand ...... 63
Fig. 5.6 Station di tribution options with their weighing fa ctors ...... 67
Fig. 5.7 Di tance between stations ...... 69
Fig. 6. 1 Building drift ...... 73
Fig. 6.2 Ma k angle of the reference station's antenna ...... 75
Fig. 6.3 Logical Flow Chart fo r Site Selection ...... 77 Fig. 6.4 Spatial Analysis Model (Using ESRI Model Builder 9. 1) ...... 79
Fig. 6.5 Buildings in Abu Dhabi of heights less than 50 meter ...... 81
Fig. 6.6 Govemment buildings in Abu Dhabi ...... 82
Fig. 6.7 Example of the Govemment buildings that are open to Sky .. , ...... 84 Fig. 6. Openness to ky presentation in 3D ...... 86
Fig. 6.9 Selected site as seen from diffe rent angles to velify its visibility to satellites ... 87
Fig. 7. 1 Reference stations cOlmectivity ...... 94
Fig. 7.2 Line of sight status fo r RF connections ...... 99 Fig. 7.3 Examining the line of sight between stations according to the observer and target heights from ground ...... 100
Fig. 7.4 Final RF communication network: Stations and repeaters ...... 103
Fig. 7.5 Satellite communication geographical coverage by Thuraya ...... 106
Fig. 7.6 Design view of Sky Tower in Abu Dhabi . (Source TEN Real Estate) ...... 108
Fig. 7.7 Visible and invisible line of sights from the Sky Tower Building ...... 111 Fig. 8.1 Proposed RTK reference network & SCADA integration ...... 115 Fig. 8.2 Flow chart fo r the RTK Network & SCADNGIS Logic control...... 117 Fig. 8.3 The architecture of the proposed integrated system of RTK Network & SCADNGIS fo r machine automation ...... 119 XII
LIST OF TABLES
Table 2. 1 Key package of ome of the main GIS oftware vendor ...... 11 . Table 3. 1 Compari on bet\: een B and GBA ...... 28 . . . . Tabl 3.2 RTK GP po itioning technique and equipment cia sification ...... 35 . Table 4. 1 Beacon tation in UAE. ource: Trimble, 2007) ...... 37 ( Table .t.2 ccuracy Mea urement of Omni TAR and Beacon Services ...... 39
Table 4.3 ompari on between diffe rent options fo r choosing a Reference Datum ...... 47
Table .1 U ed data fo r the analysi of the tation distribution ...... 55 . . Table 5.2 Refer nce tation Di tribution Option ...... 66 . Table 5.3 Oi tance ben een tations ...... 68
Table 6. 1 umber of bui Iding according to their type ...... 85 . Compari on between diffe rent types of communication media ...... 92 Table 7. 1 .. . cquired and created data fo r the a sessment of RF locations ...... 96 Table 7.2 . ntenna height fo r the RF tations and their repeaters ...... 102 Table 7.3 . . Comparison between the broadcasting media options ...... 107 Table 7.4 . . U ed data fo r the Sky Tower broadca ting ignal analysis ...... 110 Table 7.5 . . CHAPTER 1
INTRODUCTION
1.1. Background
Over the la th:o decade , the Global Positioning Sy tem (GPS) has become a significant tool fo r ci ilian na igation and po itioning. The need fo r positioning and recording the coordinate in the fieldha become a crucial requirement fo r all of the daily activities in civil on truction surveying and utility service . It i estimated that over 80% of data proce ed by local go ernments have a patial component (Longley el at., 200 1). Spatial data i con tructed and built ba ed on a well defined coordinate y tern. Today, new and challenging application and con truction works demand real-time positional accuracy at
ub meter and centimeter-level. Sub-meter po itioning accuracy can be achieved by using the Deferential GPS (OGPS) technique, employing code (phase smoothed) measurements, utilizing either a dedicated single reference station or a ateilite or ground ba ed correctional ervice.
Centimeter-level positioning accuracy can be achieved usmg a GPS rovmg unit referenced to a single reference station (ba e station) and utilizing code and phase mea urements. However, the limitation of this setup is that the distance dependent error wi be ignificant when the baseline exceeds 10 as wel l as the dependence on the II krn availability of the nearby Gep. Instead of relying on a single reference station, many 2 modem citle nowaday e tabli h GPS multi reference tation that can be u ed fo r post ml ion or real-time po itioning. The e network are widely known a Real Time
Kinematic (RTK) reference networks. The wide pread of thi type of network is due to th ir benefit of not only pro iding real-time high quality accurate and con i tent GPS po itioning at an economical co t 0 er a wide geographical area, but also they help in increa ing the urveying producti ity, reducing capital equipment co t and their ease of u e. The need to get accurate po itioning in real-time becomes of great impoliance either in the na igational field or in the geodetic surveys. However, designing and implementing an RTK reference network is a challenging task. The system ha pecific con train a far a the di tance between station , nature of building ho ting the reference
tations a well a type and methods of communication .
The GI ha the capabilitie fo r transforming the original patial data in order to be able to an wer pecificqu erie and pro ide analy is capabilities that will be able to operate on the spatial a pect or the topology of the geographic data. Hence, it can be used as an advanced tool to optimize the design and implementation of the RTK reference network.
Abu DhabI, the capital city of the United Arab Emirates (UAE), (see Figure 1.1) is becoming one of the mo t fa st developing cities in the world. The rapid development of the city is driven and oriented by the vision of the governmentto make the city enjoying better life with perfect balance (Barney, 2007). The biggest challenge with quick urban development in Abu Dhabi i to maintain the balance as fa r as environmental, traffic, infrastructure as well as social and economical aspects are concerned. Optimizing the 3
Geo patial data infra tructure i one of the key fa tor to allow the government to make the nght trategic pia rulingdeci ion . patial data po itional accuracy generated through
urveying equipment and ystem i one of the most critical fa ctor affecting the quality of the patial Data Infra tructure Hence, improving ( 01). tandards, practices and tools that a ure patJaI data location accuracy i a trend that goe in line with the government
trateg to expedite fi r t cia re ult toward a su tainable development in today's challenging and competiti e world. Thus, the local authority in the Emirate of Abu
Dhabi, in United Arab Emirate ha recently realized the need fo r establi hing a regional
RTK reference net:\ ork and decided to have it operational before the end of year 2007.
This re earch in e tigate the u e of GIS a an advanced tool to optimize the design and implementation proce s of the newly under construction Abu Dhabi RTK reference network.
, - +
-
'- ... -.
-
legend uAf --
Fig. 1. 1 United Arab Emirates Map 4
1.2. Thesis Objectives
De igning and implementing RTK reference networks i a challenging task due to the com pie. ity of the tem component . The di tance eparating reference tations, network configuration, communication between the computing center and the user and net\\'ork algorithm are the main de ign parameters to be considered fo r the RTK reference net\vork (El-Mowafy,2005 ).
Thi re earch work focu e on m estigating the capability of GIS as an advanced tool to h Ip optimizing the de ign and implementation of the RTK reference network. The thesis ha the fo llowing research objectives:
rnve tigate the role of RTK reference networks in achieving the positioning accuracy • requirement of the patial and GIS data - A case tudy of Abu Dhabi will be
di cus ed.
In estigate the use of GIS to analyze and evaluate the design approaches of the RTK • reference network system. A case tudy is elected as the newly under-construction
network of Abu Dhabi. Emphasis will be on main parameters such as: reference
tations location and their eparating distances, reference tation' ite selection, and
the communication methods between stations, rovers and the center.
Recommendations will be drawn fo r the most uitable design approaches.
Investigate and examine the deployment of GIS functionality and analy is tools to • analyze and evaluate the operation approaches of the RTK network such as erving
the corrections via broadcasted wireless ignals, and integration of the network with 5
GI -ba ed application . Recommendation will be pro ided fo r the optimal de ign of
broadca ting the RTK reference network correctional ignal.
In e tigate, e plore and evaluate ome advanced GIS-ba ed application that can • b nefitfr om RTK ref! renee network such a volume machine automation.
1.3. Thesis Outline
The challenge in designing and implementing the RTK reference networks and the need fo r eft! ctive tool such a GIS to optimize the design define the objectives of this re earch. Thi the i tructured in uch a \i ay as to address each of its objectives in detail a fo llow :
Chapter one gives an introduction to the thesis background, objectives and it outline.
The background explores the ignificance of GPS fo r civilian navigation and daily activitie in civil con tructions, surveying and utility ervices. The need fo r real-time mea urement at centimeter-level po itional accuracy fo r the new and challenging applications is highlighted. RTK reference network popularity and its benefits of pro iding real-time accurate positioning over a wide geographical area i highlighted as an al ternative surveying olution fo r the traditional RTK positioning with a single reference station. The latter method has the limitation of experiencing large errors when mea uring over distances that are more than 10 Km from the base station. The chapter i concluded with details of thesis objectives and its outline.
Chapter two gives an overview of the GIS system and it analysis tools. GIS definition and concepts are explored. The components of GIS (hardware, software, data and users) 6 and theIr role are explained. The analy i tool that are u ed in this re earch uch a buffenng, 0 erlaying, ra ter interpolation, contour calculation, model builder and line of
'ite are de'cribed.
In chapter three the concept , practice and po itioning technique of GPS are mtr duced. A hi toric background about the GPS and its objective are given. Segments that fo rm the GPS are explained. The main two types of GPS observations, code and pha e, are de cribed. The main positioning techniques, post mis ion and RTK are c mpared. Different type of RTK po itioning techniques are explained and compared.
The e technique include the u e of Ground or Satellite Based Augmentation Systems
(GBA , SB S), the u e of a single reference tation, and the use of RTK multiple reference tation (network ).
Chapter fo ur di cu e the currently used RTK positioning techniques in Abu Dhabi and the po itional accuracy requirements of the spatial data. Available GBAS Beacon service and SBAS OlnniSTAR services in Abu Dhabi are described and tested. RTK positioning u ing ingle and multiple reference stations are compared. The chapter concludes with highlighting the importance of the role of RTK Reference etwork in the Abu Dhabi
Spatial Infra tructure.
In chapter five, the 1I e of GIS to study and evaluate the design aspects of reference station locations and their separating distance is examined. Adopted methodology fo r 7 de loping the di tnbution option and their e aluation criteria is discu ed. The mo t
uitable de ign approach i propo ed ba ed on GIS in e tigation.
In chapter ix, the capability of GT tools to elect the optimal ite fo r the RTK reference network station that ati f preset criteria i inve tigated. Investigating, evaluating and
lecting the be t building fo r each reference site i conducted using ArcGIS tools such as
election b attlibute, analy i model builder and 3D presentation. A generic model is developed using ArcGIS model builder to run a serie of automated querie governed by the above mentioned criteria against a unique set of data input fo r each site.
In chapter even exam1I11l1g, analyzing and selecting the best approaches fo r telecommunication infra tructure of the RTK Reference etwork using GIS tools is di cu ed.
Chapter eight highlight the potential benefits of integrating GIS with the RTK reference network to enhance ome of the vital field construction application. Field Machine
Automation is investigated as an example of uch integration.
The thesis is concluded with a summary of the research findings. Recommendations fo r enhancing the Abu Dhabi RTK reference network are given. CHAPTER 2
AN OVERVIEW OF GIS
Geographic lnfonnation y tems (GIS) are increasingly being integrated into the IT infra tructure of major organizations in govemment a well as the pri ate ector. It is
0 e'timated that 0 er 0 0 of data proce ed by local go ernmenthave a spatial component
(Longley el al., 200 1), and would benefit from the capabilities of GIS. Thi chapter provide a hort introduction to ba ic concepts of the GIS. Definition of the system and it components are brieflydi cu sed. ext, the GIS analytical tools that are u ed in this
the 1 are addres ed.
2.1. Definition of GIS
Diffe rent GIS definitions of GIS can be fo und in a large number of articles, books and web resource. GIS is defined as 'a set of tools fo r collecting, storing, retrieving at will, transfomling and displaying patial data from the real world fo r particular et of purpose ' (Burrough , 1986). Another definition i "Systems designed to store and manipulate data, which relate to locations on the Earth's surface" (Taylor and Blewitt,
2006). A more deta iled GIS definition can be given as "a collection of computer hardware, software, and geographic data fo r capturing, managing, analyzing, and di playing all fo rms of geographically referenced infonnation."(ESRl, 2007). 9
2.2. Gl Component
The maIO omponent of GI are hardware, oftware, data and people as hown in Figure
Thi ection de crib 2.1. e GI components and their role in fo rming the GIS ystem.
.. . ".., �� Haraware"' Ii...l" I
-'
' Datal
Fig. 2.1 GIS components
2.2. 1. Hardware
The GIS hardware component i centered on the computer platform and has peripheral
device related to its input and output. These include, data collection and input devices
uch a GPS and scanners as well as devices fo r toring and proces ing data such as
erver , workstations desktops, laptops, networking devises, together with output devices
uch as monitors, printers and plotters. 1 0
2.2.2. oftware
GI oftware manages the processe of accessing, editing, analyzing and pre enting the data in it patial fo rm a geo-referenced data (spatially adj u ted) as well as non spatial linked attribute . oftware include the computer operating system, Adopted Relational
Databa e Management y tem (RDBMS), GIS applications and GIS web applications. In general, Gf ofn are organize and control data management, geo-possessing tools and u er interface. Main GI oftware package can be classified into six groups based on their functionality and type, including: databa e erver professional, desktop, hand held,
\'iewer component and Internet. There are many commercial oftwarepack ages available in the market. Table 2. 1 hows the key packages of ome of the main GIS software vendor (Longley al., et 200 I). II
AutoDisk ESR Intergraph Maplnfo GE Small World Database Vision ArcSDE Oracle Spatial Ware Small World server Spatial
Professional AutoCAD Arclnfo GeoMedia Maplnfo Small World Pro Professional
Desktop World ArcView GeoMedia Maplnfo Spatial Professional Inte lligence
Internet Map ArcGIS WebMap MapXtreme lAS Guide Server/ArclMS
Table 2.1 Key packages of some of the main GIS software vendors
vendor except Intergraph have their own proprietary database erver that works a a II middleware to optimize geospatial data management and processing as well as interfacing with Oracle databa e which in mo t cases is used as the backend enterprise databa e. A profe ional package usually has an advanced functionality that satisfies the expert u er , GIS data management and editing teams. A desktop package is meant to sati fy the nonnal GIS u ers with minimum GIS functionality. The Internet erver package i the package that provide GIS service through the Internet where the client need only a typical Internet brow er. Google Earth( www .googleearth.com) and Map24
pular GIS web ervices. ( \vww.map24.com) free services are two examples of the most po
The popularity of those ser vices i due to the ability to access a huge amount of
continuously updated high resolution image with a global coverage overplayed with rich
vector data without the need to buy any software or data. 12
Looking at the overvIew of the system ar chitecture of Abu Dhabi Municipality new upgraded GI architecrure is given here a an e ample of a typical enterprises GIS
y tem a hown in Figure 2.2, the ystem con ist of three main tiers: data, application
ervice and client tier (Abu Dhabi Municipality 2007).
PSS DBE Svstem Architecture Design - Overview
AppHcatJonsMonday-A r'"utoO.sk �ay 2007 Maplnfo -
- � - ______'\ Desktop & ....
... .Qtt\., A.ppllc.t:lons- - - - - , o.l.k1opIlc.aUons App - ESRt �:::CI (J - (J u:=- Cl 1 � 1 ....�� "'_'"""" '� X' �-. 1 I __ 1oGQI. ...1 .... -- 1 IOQ'U CIOI.," DJQ,to a.::lOI U I 1 MN 1 t r------, ...... 1 flI<..-. ... _. a.t 1I PSS o.� 6r0W'Nt' 1 : \ ��·O C.onnKt 10 0ncI_ $pIIII" PSSOfSE bIM AtcGN I I ______i' ______0..- �'tory ,"AMdonlY"'" j ------I @. ®,...... ®.... ' :I ------,
- --______, r� -4t.s,.,car, .tt .. """.,. or Mt"\I'efS - WebS-V,cft :;0 NoM The Wow ,.,...... orwd .....-b� be �,..Utd sIng!. web mutt.I &. ...� tJ� _b6Mip� 560 IlpacheT.;lI'T'ICaI 60 I �\\'MSYGS FV� SQII o..a Ora:::Ie a-t!) W-.bSMwItM F'SS � e..DWWf� �" CAerl9!
,.... --�------;:--::'=L.:..::.C; Data ne,
ClldlOM:.t.n. tOGR2 (New.... A.tx.OIat» lIPdIl'.edErtwac! 1 Or'-I I "' can!Jl!' I: �lJl.:..-.or S""" Sa_Anal ,.....,. � ,Ora::Je r-Sa:.Ir Fli...... vd 0':f1et$II.! �. � I ac:cH'I«t .,..lharwdfoi<'t!I'Y ______.!>�.�I! Q� s! ...!'2. _'!.EJ______G 2 �l;�[��_i�)I J
Fig. 2.2 Abu Dhabi Municipality new upgraded GIS architecture
Data tier is based on Oracle version 109 enterprise where the spatial data is managed and stored. It provides the functionality to supp0l1 data editing, topology rules, geo-coding, spatial analytical functions and coordinate system transfonnation. The application servIces are based on MapXtreme web server from Maplnfo on top of the Microsoft
Internet Information Server and data retrieving from Oracle. It provides the enterprise 13 data brO\ er ervlce through Web Map ervlce (WM ) and Web Feature ervlce
(v F ). The client tier i the u er interface to view brow e and query the patial data.
CI ient can be ba ed on the tandard Internet browsers or one of the standard G IS desktop viewer . Maplnfo and utode k Map 3D client can access oracle database directly, where the editing oftware ha been selected to be Autode k Map 3D ince it would be the tool of the contractor who i contracted out to maintain the database after pro ject con truction. Autode k package being a CAD based oftware is usually used fo r ed iting and digitizing due it rich drm: ing and engineering functionality.
2.2.3. Data
Data m GIS is the ab tractions of reality organized in digital fo rms (Longley et (1/., 200 l).
It give the information about the shape, locations and attributes of the real objects eXlstll1g in reality but coded in the computer. GIS data consist of two main components:
patial and non-spatial data (Longley et al., 200 1). Spatial data is used to manipulate and vi ualize the real object modeled in the computer (Taylor and Blewitt, 2006). Most of the new GIS software packages store both types of data in one database. Usually, GIS data is organized in diffe rent themes or layers. Each layer represents a specificfe ature class such as road edges, buildings or parcels (Taylor and Blewitt, 2006).
In GIS, data is held in raster or vector type fo rmat according to the used data model. GIS
molding means abstracting and simplifying geographic reality in GIS (Longley et aZ.,
2001). The abstraction and simplification increases gradually as it is presented in the 14 conceptual, logical and phy ical data modeling. Ra ter data i about fe ature and their attribute related to the pi el of the image . Vector data exist a fe ature with their attributes. The feature are repre ented a point, line or polygon representing the spatial infonnation \ here their a ociated attributes contain the non-spatial data.
GI data collection i one of the mo t important and expen ive proce e while con tructing or maintaining Gf . The data can be collected from heterogeneou sources including: a field survey, paper map , existing structured databases, satellite imagery or aerial photograph .
2.2.4. People
The GI i designed, programmed, managed, maintained and used by people. The needed
GI kill fo r people ary according to their role and use of GIS. Most of the GIS indu trie hire people who have kills in system analysi , programming, software design, and sale staff with a background of computer science, geography and others (Longley ef al., 2001). The people working in finns that provide GIS education and training need to have the theoretical and practical experience in the disciplines of GIS, Geodesy and
Remote Sen ing. Specificexperience in the relevant software used in the lab, i.e. ESRI,
Intergraph, ERDAS or similar software packages is needed fo r the trainer in order to be able to provide the required knowledge about the used GIS software.
People in charge of managing the GIS system are fe w in number but should be highly qualified and have practical experience in working with GIS. There job is to manage, 15 maintalO the GI hardware, ofu: are, application and data. Relevant experience about the
pecIfic u ed oftware package uch as Oracle, E Rl, Maplnfo and other i definitely required. Expert u er \: ho are making complex spatial analysi , queries and thematic mapplOg are mo t likely engineer with rele ant bu ine s experience and have GIS educational background and long working experience in patial data and its analy is.
The majority of the GI u er are the general viewers. They need to be trained on the relevant u ed GIS package (Longley et af., 200 Traditionally, the re lationship between I). number of users and GI needed kill is inversely proportional. Figure 2.3 shows this relation hip.
Many Low Users Skills
Needed Number Internet Viewers Skills of users Desktop Users Professional Users Educators and Trainers GIS teams GIS industry High Skills
Roles and usage ty pe
Fig. 2.3 GIS Users 16
2.3. GIS Analy i Tool
patial analy i i defined a the proce by which u eful infonnation is derived from raw data. [t add a alue to the Gl data after applying a et oftr ansfonnation, manipulation and method to the data (Longley ef ai., 200 ew infonnatio I). n can be derived when
patial operation are applied to the GIS data. Thi section discus es the analy is tools that are u ed in thi re earch fo r optimal designing of RTK reference networks. The tools include querie , buffering, polygon 0 erlay, and spatial interpolation. ArcGIS 9.2
oftware i u ed to analyze the data fo r the case tudy of optimizing the de ign of Abu
Dhabi RTK Reference etwork. ArcGIS Spatial Analyst extension i used particularly in the analytical operation fo r the raster cell-based data.
2.3.1. Queries
Querying i about the retrieval of infonnation from a databa e using a language with well defined yntax and emantics. QuelY language allows users to retrieve data based on logical arithmetic operator . In GIS, attribute querie extract feature from an input fe ature cia or input feature layer, and stores them in a new output fe ature class based on
Structured Query Language (SQL) expression. SQL is the language of querying tables and relational databases (Longley et ai., 1999).
Model Builder is an application in ArcGIS 111 which models are created, edited and managed. Workflow can be automated by tringing processes together in the model 17
diagram that will e ecute the geo-proce ing and query operation In equence when the model i ,ecuted.
2.3.2. Buffering
Buffi r tool create buffe r polygon to a pecified di tance around the input fe ature. An optional di olve can be performed to remo e 0 erlapping buffe r. Figure 2.4 illustrates an example of the buffer and overlay (inter ect) tools. In this example, a river is buffe red to
1000 meter' creating a polygon layer to the river buffe r. "Intersect" tool of the overlay anal is tool i u ed to combine the low land and the river buffe r creating a new polygon definingthe low land that intersects with the river buffe r.
- PJ Layers - It.I RIV_ EZ_in 0 1 - It.I Elev _zones - It.I RIVer
- 0 Rrver_ buf C
Fig. 2.4 An example of the buffe r and overlay (intersect) tools.
(Source: UAEU MSc. Program) 1
2.3.3. Polyoon Overlay
In the overlay operation, two or more thematic layers are integrated through analytical
operation in order to generate a new layer. When u ing the pol ygon overlaying
operatIOn , a ne polygon i created based on the intersection of two polygon layer . The
value a igned to ach point in the created polygon is a function of the independent
value' a ociate with that location on two or more existing overlays (Longley et at.,
1999).
2.3.4. Raster Interpolation
Interpolation is defined a predicting value fo r cell in a raster fo rmat from a limited number of ample data point . For example, instead of vi iting each site of the study area
and mea uring the height elected mea ured sample and predicted height values can be a \gned to all other locations. Interpolating a surface from points can be done by u ing diffe rent techniques. In thi research, ra ter interpolation using the Inverse Distance
Weighted (IDW) technique i used. In IDW, the cell value is estimated by a eraging the
values of sample data point in the vicinity of each cell (McCoy and Johnson, 2002). The
interpolation to raster i used to create the elevation model fo r the Emirate of Abu Dhabi
from the et of points that have height values. Additional information from the
interpolated raster can be derived such as contours, angle of slope, aspect, hillshade,
view hed and cut & fill. In the research, the contours and the viewshed are derived from
the interpolated raster data. 19
ont ur are poly-line that connect point of equal alues such as ele ation . Area of the
ame height can be fo und u ing contour . Elevation value fo r pecific location and the overall graduation of the land al 0 can be examined u ing the contour .
Cell in an input ra ter that can be een from one or more ob ervation points or lines can be identified using View hed. Thi helps to know how isible objects might be (McCoy
and John on, 2002). In this research, the viewshed is u ed to find the well-exposed places
fo r the commun ication tower of the repeaters of the RTK reference station . The line of
ight tool in the raster interpolation analy is tool uses an input poly-line fe ature class
along with a ra ter urface to determine visibility between two point , which can be
defined a the 'from' and 'to' points. It produces output line fe ature class that contains
line and target vi ibility information. 20
CHAPTER 3
AN OVERVIEW OF THE GPS TECHNIQUES
3.1. Fundamentals of CPS
urrently, there are two operating Global avigation Satellite Systems (G SS), the
mencan avigation _ignal liming �nd Ranging (NA VSTAR) system and the Russian
GLObal'naya NAvigat ionnaya Sputnikovaya Si tema (GLO ASS) system. A VSTAR
widely known as the Global Positioning Sy tem (Red Sword Corporation 2007).
nother G S planned fo r the future is Europe's "Galileo". GPS is a satellite positioning
y tem developed by the U Department of Defense (DoD) fo r real time navigation fo ur decade ago. The key objecti es of the GPS is to provide worldwide, all weather, continuou radio signals to u er to detem1ine position, velocity and time throughout the world (Taylor and Blewitt, 2006).
There are three segment fo nning the GPS (See Figure 3.1):
pace Segment, which includes 27, con olidated atellites orbiting the earth (24 • active and 4 pares). There are always more than fo ur visible satellites in the sky
anywhere on the planet. The satellites send continuous radio signals to user .
Control Segment: The control segment consists of five monitoring stations that • monitor the satellites and one processing center in Colorado Spring which ends
correctional data through three stations to keep the satellite in their right positions. 21
U r egment: The u er segment include mea urement hardware and software (GPS • receiver ) fo r data collection and proce ing. The recei er need simultaneou Iy to
look onto at lea t fO llr atellite to be able to detennine it 3D po ition on the ground
any time and an " here on Earth or in the space around the Earth. GPS receivers can
be cla ified into two main categorie : hand held receiver and geodetic grade
recei ers. The hand held recei ers u e only code mea urement (or phase-smoothed
code mea urement ), and usually work in a ingle point positioning mode. They are
u unlly u ed in coar e na igation and produce low positioning accuracy m- (1 lOm).The geodetic-grade recelVers use both code and phase measurements. They
work in relative mode and are u ed in surveying with high precision (em accuracy).
Space Segment �
User Segment
ontrolSe
Fig. 3.1 GPS Segments.
(www.geog.ubc.ca/courses/geog376/notes/GPS/gps 06.ppt) 22
Ob ervation by GP are mainly offe red through two malO type , code and pha e
ob ervation . U ing c de ob ervation techniques, positioning accuracy at the sub-meter to meter Ie el can be achi ed, wherea pha e mea urements can give accuracy in the millimeter or centimeter range. To detennine the unknown coordinates of a point, code or pha e mea urement from at lea t fo ur at ellite are collected and processed using a
ingle recei er. CIA Code - the standard (Course/Acquisition) GPS code i used in most
GIS operations. Or bital, atmospheric, satellite and receiver clock error , and receiver noise governs the accuracy of GPS single point po itioning. This can be shown from the
code ob ervation equation, which can be fo nnulated as fo llows (Hofmann-Wellenhof et
al.. _001):
P (3.1) = P + dp + C (dt - dT) + dio1l + d'rop + &1111111 + &(P)
Where:
P - Code (Pseudorange) observation
fe rence between the _ the dif p Receiver-to- atellite range, representing in vector space
the receiver in the known position of the satel lite (R ) and the unknown position of ( r ) fo nn = - II R r II dp - Orbital error
C - Speed of light dt, dT - Receiver and satellite clock errors 23
lono pheric and tropo pheric error dion, dtrop -
Emult - Multipath noi e
Recei er noi e and remaining errors E(P) -
Two radio carrier wave ignal are transmitted by GP , known as L 1 and L2. Proce sing u 'uall u e the Ll frequency of 1575.42 MHz in the Ultra High frequency (UHF) band.
The pha e ob ervation equation can be given as:
Where:
pha e range - l/>: - ( A. Measured pha e True range p: - wa e length A: - carrier phase ambiguity N: - Speed of light c: - Receiver clock error dT: - dt: - atellite clock error diono: - range error due to the iono pheric error dtropo : - range error due to the Tropospheric error e( From Eq. (1) and (2) it can be concluded that po itional accuracy is affected by e eral , urce of error , including: atellite orbital and clock error , atmo pheric error , recei er clock error, mUltipath and recei er noi e error. The cheapest handheld GPS recei er IS affi cted by all ource of elTor and provide an accuracy of 1 - 10 meters. To mitigate mea urement error , the user should either work in a relative mode or apply a fo rm of mea urement corrections. Methods of sending measured correction to the users uch a Differential GP (DGPS) can increa e the accuracy to the sub-meter and centimeter level. Diffe rential cOITection can al 0 be app lied on-line in the field, which i u ually refereed a Real Time Kinematic (RTK) positioning. It can be also performed after data collection using a post processing technique. The principle of diffe rential GPS i ba ed on u ing two receivers. One receiver i placed at accurately and previou Iy urveyed point of known coordinates, usually called the base station. The other GPS receiver i commonly called "the rover"' and i used to determine the required unknown po ition. Diffe rential GPS (OOPS) is used whenever sub-meter and centimeter accuracy i required. Sub-meter accuracy can be obtained by using code mea urements wherea cm po itioning requires u ing carrier phase measurements (Elliote, 1996). Handheld GPS receIvers Il1 a ingle positioning mode use code measurement mostly smoothed by phase measurement. They are usually used in coarse navigation achieving 1-10 meter accuracy. The price of such devices is in the range of fe w hundreds of Dirhams. The geodetic grade receivers use code and phase measurements typically in a relative mode. They are relatively expensive due to the fact that they use better and 25 c mplex hardv are to acquire and tore pha e mea urement. They u ually give higher accuracy ( ub-meter to centimeter level) qualifying the device to be u ed in preci e engineering, mapping and urve ing. For more detail , see (Terry, 200 1). 3.2. Po t- mission and Real-Time Positioning G P mea ur ment accuracy without correction would be in the range of 1-10 meters. 10 mo t of the application other than coarse navigation, this accuracy is not ufficient. To achi \e meter or centimeter accuracy, DGPS corrections are required. The corrections can be u ed in real time or po t proce ing. In real time proce sing, usually known as RTK po itioning, GP receivers equipped with correctional signal receivers applies the correction in tantaneously a oon as the signal is received. Po t proce ed corrections i made after collecting the data from the field and then later apply the corrections using a computer software to compute the unknown position using corrections received from the reference station. RTK positioning usually is less accurate than po t proces ing because the ob ervation time while collecting the satellite data used in computation of point coordinates is limited, resulting in a reduced redundancy of data ( atirapod and Hominiam, 2006). Real-time precise positioning is even possible when the GPS receiver is in motion and makes the u e of GPS-RTK feasible fo r many time-critical applications such as engineering surveying, GPS-guided earthworks/excavations, machine control and other 26 high preCI lon na igation application (Rizo , 2003). Type of RTK technique are reviewed in the e fo llowing ection . Tho e technique include ingle point po itioning, Wide rea DGP ugmentation ervice both Ground ba ed or Satellite ba ed (GBAS and B , re pecti ely), u ing a ingle reference tation, or multiple reference tations. 3.3. RTK from Single Point Positioning The ingle point po itioning technique mainly use code measurements, or pha e- moothed code mea urement (Ten)" 200 1). Handlleld receivers are the common types of receiver that u e thi technique and are usually used in coarse navigation. They are affected by all source of elTors such as fa ulty clocks, ephemeri ariation, receiver fuzzine , multipart. Vehicle navigation, fo r example, a a stand alone user using tandard po itioning ervlce cannot achieve real time accuracy of about I-10 m (Hofmann-Wellenhof et al. 200 1). 3.4. Wide Area DGPS (WAD G PS) Techniques W ADGPS uses a network of reference stations and covers a larger area that calmot be co ered by a single reference station. The W ADGPS networks include one master tation, which collect the range correction from the monitor stations; process this data to form the correction , which are next tran mitted to the user community (Mueller, 1994, ellite Based and Mueller et al. , 1994). WADGPS can be appbed in two fO nDS, Sat Augmentation Service (SBAS) or Ground Based Augmentation Service (GBAS). SBAS 27 and GB ha e an objecti e to pro ide enhanced accuracy, integrity, availability and continuity of en/ice capabilitie fo r any underlying navigation satellite y tern (GPS, GLO A and Galileo) ( A A, 2007). atellite Ba ed Augmentation Service (SBA ) pro\ ide national or global Real Time Kinematic (RTK) correctional service to ac hieve ub-meter po itioning accuracy. Ground Ba ed Augmentation Service (GBAS) provides cOITectional ervice to allow u er to mea ure with ub-meter positional accuracy in natIonal and regional coverage (Euler et ai., 2004). Both B and GBAS utilize Ll ignals modulated with CIA code. They eliminate 'atellite related error and reduce atmospheric errors to achieve 1-5 meter accuracy in RTK. which is good enough for medium accuracy urveying work and navigation. B and GBAS diffe r in orne a pect such a their coverage area and running co t as illu trated in Table 3. l. 2 SBAS GBAS amped Item Running co t ( Sub cription) Ye No E ample Omni Star , W AAS Beacon Service Services Geographical Co erage Global ational Type of Recei er SBAS Enabled GP GPS Receiver connected to Receiver RF Receiver Table 3.1 Compa rison between SBAS and GBAS 3.4.1. Satellite Based Augmentation Service (SBAS) B y tern is u ed to improve the performances of GPS with the objective to make it more accurate if no dedicated reference station exists within a large distance. This is achieved by providing ignal of a et of correction from Geostationary Satellite that improve the position and time calculation performed by the user receiver. Currently, there are everal SBAS that can provide this type of corrections including: EG OS in Europe, W AAS in U.S.A., MSAS in Japan, and Biduah in China. The popular OmniSTAR service owned by Fugro surveying company is an example of a commercial worldwide SBAS service. The service provide an international correctional ignal fo r the subscriber to improve their GPS positional accuracy. The service system control consi t of 70 reference stations distributed around the globe, and 3 network 29 center utilizing Geo tationalY atellite to broadca t the correction over large area . Man Ornni T R enabled G P recei ers can recei e the correction data in a standard fo rmat Radio Technical Commi ion fo r Maritime (RTCM-104). The result i a real-time correction fo r the u er' GP mea urement . The "Commercial" GPS receiver can achieve horizontal accuracy of les than (0.5 to 1.5 meter). Vertical accuracy will be 2 to 2.5 time greater than the horizontal accuracy (Fugru World Wide, 2005). The service ub cription co t i appro imately 800 per year. Figure 3.1 illustrates the components of the Omni TAR sy tern a an example of BAS; it shows equence of correction proce a fo llow : 1- GP atellites broadca t the positioning signal. 2- OmniST AR reference tations around the globe continuou ly receive and observe the GPS signals. 3- Ob erved data from the tations is ent from all reference stations through a global Wide Area etwork (WA ) to the central calculation center. 4- The center uploads the corrections to a geostationary satellites distributed around the globe. 5- Geo tationary satellites receive the corrections. 6- The geo tationary atellite broadcast the corrections encoded through a carner ignals. 7- Sub cribed user receIve the correction signals with OmniSTAR enabled GPS receivers to decode the correction, which will be used to improve the accuracy. The receiver has to be compatible with a module to receive the corrections. Most commercial receivers contain this module. 30 The ab ve mentioned proce illu trated in Figure 3.2. . -- - - - ...... To �II I /", "� 1- Fig. 3.2 SBAS Service Exemple : Omni STAR SBAS service 3.4.2. Ground Based Augmentation Service (GBAS) GBAS i a sy tern of atellite and ground stations that supports augmentation through the u e of terrestrial radio me ages and provides GPS ignal correction , giving the u ers better po itioning accuracy. The GPS information collected by the ground reference tation that are located in known locations are fo rward to a master station via a terrestrial comm unications network. The rna ter stations collect information from the reference tation and, through a eries of algorithms, correct the information received to account fo r tandard GPS error . The corrected message, now known a a diffe rential message, is then broadcast through the ground stations. These messages contain information that 31 allow GP recei er to remo e error tn the GP ignaJ allowing fo r a ignificant t ncrea e 10 location accuracy and reliability. The GBAS correction data typically provide 1 to 5-meter accuracy in real time (Fore t ervice Technology and Development Program, 2004). Marine bea on tation , a hown in Figure 3.3, are an example of GBAS, where they broadca t their correction me sage ia a Very High Frequency (VHF) radio data link from a ground-ba ed tran mitter to user receivers (Australian Maritime Safety Authority, 2007) GPS Satellites •.� L Fig. 3.3 Marine beacon stations Beacon reference station service broadca ts DGPS corrections through mari ne beacon stations most likely along the sea coast line (Euler et al., 2002).The purchase of a OGPS beacon receiver is the only cost of this kind of service. There i no running cost to use the service. This receiver is then coupled with the GPS receiver via a three-wire connection or blue tooth connection which relays the corrections in a standard serial data fo rmat 32 called Radio Technical ommi ion fo r Maritime (RTCM pecified commi ion -104). ith a beacon recei er, GP mea urement error can be reduce to 1 to 5 meter . When a eraged over a period of time, accuracy can improve (Johnny Apleseed GP Comp any, 2 00). 3.5. RTK Positioning Using Single Reference Station RTK po itioning using ingle reference station i a diffe rential positioning technique that u e known coordinates of a reference tation occupied by one receiver to determine c ordinate of unknown points i ited by a [0 er recei er. The reference tation coordinate and mea urement are tran mitted to the rover via data link to proces the data in real time. Very High Frequency (VHF) and Ultra High Frequency (UHF) are u ually u ed fo r di tance Ie than 15 km. The RTK u es two radios, a transmitter at the reference tation and a recei er at the rover. A licen e from the local authorities is usually required to transmit high power radio to transmit correction over distances longer than 20 Kilometers. Radios repeater can be used to extend distance fo r radios. Single frequency receivers only) can be used fo r RTK as well as dual frequency ones (LI (L1 and Dual frequency receivers are preferred fo r long ba e-to-rover di tances due to L2). the fact that fa ter acqui ition of correct ambiguity can be obtained (El-Mowafy,2002 ). 3.6. RTK Positioning Using Multi Reference Stations (RTK Reference Networks) One main disadvantage of the single base RTK approach is that the maximum distance between reference and rover receiver must not exceed 15 kilometers in order to be able to 33 rapidly and reliably r olve the carrier phase ambiguitie . Thu , RTK po itioning , tended fr e om a ingle ba e to a multi-ba e technique (Euler et ai., 2001) and (Raquet and Lachapelle, 200 RTK Reference I). Network approaches ideally provide po itioning ind ...." ith error ependent of the rover po ition \ ithin the network as well as it cover the de ired area 'Ii ith fe \ er reference tations compared with the single reference tation approach (Raquet, 1998). The tudie of RTK Reference etwork aim to develop a centimeter accuracy RTK y tern operating over di tances up to tens of kilometers. The e timated di tance between reference tations can be in the order of 50- 1 00km. In addition, the ro er need to operate within the region defined by the reference station network ( antana and Tottwr trom, 2002). RTK Reference etwork process data from multiple reference recei er that are connected to rna ter control stations, which will provide cOlTection information to u ers, in real-time or in po t-mission. The RTK Reference ernork has a data management system and data communication ystems. There are two type of data communication y tern: (a) communication between the rna ter control center and reference tations, and (b) communication between the master control center and users (Rizo and Han, 2002). An RTK Reference etwork y tern mainly consists of three basic segments. These are: ai., data collection, data manipulation and broadcast elements (Cruddace et 2002), see Figure 3.4. These elements can be summarized as fo llows: stations are continuously operating and \- Data Collection Segment: Reference permanently tran mitting the GNSS observations to the etwork Control Center (NeC) via direct data links. Thi link could be via lea ed line , W A or the Internet. 34 2- Data Manip ulation egment & elTor calculation at the CC: The center i equipped with erver loaded with the computational oftware that manipulate the erTor and dis emin ate the correction to the roving u er (El-Mowafy et al., 2003). 3- Data broadca ting egment: everal method can be u ed to tran fe r network information to th u er. Medium could be GSM, General Pocket Radio Sy tern (GPRS) or HF. orneof the mo t widely used computational methods used fo r estimating the correction include: rea Correction Parameterization method (FKP, in German). • irtual Reference Station (VRS). • Ma ter Auxiliary Correction (MAX). • Detail of these methods can be fo und in (Raquet, \996) and (Wubbena et (II., 1996). However, their description i out ide the cope ofthi thesis. Multi Reference RTK Network Architecture Data Collection Manipulation Data from reference al control broadcasting D stations o center o roving users 10 Fig. 3.4 RTK Reference Network architecture (Source: Lieca Geosystems) 35 3.7. ummary of GPS Positioning Techniques RTK GP po itioning technique and equipment can be cia sified according to their po itioning accurac into three categorie : meter-level, sub-meter and centimeter level . The mea ured po itional accuracy Ie el depend on the purpose of the urveying works. Hence, the proper type of urveying equipments and method hould be adopted accordingly. Table 3.2 summarize the compari on between the three categories as fa r a g ographical coverage, accuracy, and cost. An example fo r each type i also given. �leter-level Sub meter Centimeter Receh er and Single S.B.A.S G.B.A.S Single MultIple en ice t) pe Po Itionlllg Reference Reference Ob ef\ ation StatIon tatlon Geogra p hica I GLobaL Global National Within 10 KM Regional COHrage Horizontal 1-10 m Les than 1 Le than 1 < 5 cm <5 cm Accurac meIer meter Example Hand-held and Omni Star, Beacon Service Commercial Dubai Multi PDA GPS WAA RTK frequency Reference receIvers receIvers Stations RTK Dlrect Needs receiver, Needs receiver Uses RF, �eed receIver, modem and and modem Limited to 10 modem and ub cnption Km, needs 2 subscription radio devices Capital cost Low Medium Medium High High Table 3.2 RTK GPS positioning techniques and equipment classification 36 CHAPTER 4 RTK POSIT IONING AND ACCURACY REQUIREMENTS IN ABU DHABI There ar a few technique of RTK DGPS that are currently used in Abu Dhabi. SBAS ba ed Omni TAR and GBA ba ed beacon ervices are widely u ed fo r marine un e ing providing correction data positioning with sub-meter accuracy. RTK ingle reference tation i commonly u ed fo r urveying work that require centimeter level ac uracy. Multi reference tation ervice that allows positioning with centimeter level accuracy in a wide geographical area with a ingle GPS receiver (rover) i only available at the areas near the border of Dubai Emirate. Dubai Municipality has established its RTK Reference etwork con isting of five tation in 200 1 (Almrzooqi el (Ii., 2005). Abu Dhabi Municipality has commenced a project to establish the RTK Reference etwork to co er the Emirate of Abu Dhabi. The project started in Ma rch 2007 and expected to be completed in 8 months. Thi chapter explores the RTK po itioning technique that are currently used in Abu Dhabi and describes the accuracy requirements fo r surveying works. 37 4.1. Real-time Positioning from Augmentation Systems in Abu Dhabi There are two operating beacon tation located in the territory of the UAE. One in Abu Dhabi and the second i located in Ra's I Khaimah. The detailed information about the e tation i gi en in Table 4. 1. Abu Dhabi Station Ra's AI Khaimah Station Position: 24°6'N, 52°56'E 25°59'N, 56°4'E Frequency (kHz) 314 292 Nominal Range (km ) 460 460 Table 4.1 Beacon stations in UAE. (Source: Trimble, 2007) .t.1.1. Positional Accuracy of the SBAS and GBAS Systems A fieldte t to examine the po itioning accuracy of the beacon correctional services as a GBAS sy tern, and positioning accuracy from mea urement using OmniSTAR as an SBAS y tem wa carried out in Abu Dhabi in March 2007. Trimble Pro XRS receiver was used in the test. The device has an antenna that can recei e both beacon correction signal and OmniST AR. A known Geodetic Control Point (GCP) of known coordinate was selected inside Abu Dhabi Island to be the reference fo r comparison, where its known po ition was compared with the output position from the receiver after observing fo r a fe w minutes. The GCP is located 150 km away from the beacon station as illustrated in Figure 4.1. 3 Fig. 4.1 Beacon reference stations and testing point (Image source: Coogle Earth) The po ition and estimated elTors from the SBAS (OmniSTAR) and GBAS (Beacon) method are ummarized in the Table �.2. The projected coordinate system util ized the ahrawan 1967 datum, u ing Universal Tran erse Mercator (UTM) Zone 40 projection. The beacon recei ed frequency is 314 KHz. The signal to Noise Ration SNR recorded from the testing wa (l8 db). Results show that the GBAS y tern gave better po itioning accuracy. However, both ystems gave accuracy at the sub-meter level. 39 Item GCP III Trimble Trimble Pro Error in using Error in using order Pro XR Omni TAR Beacon Coordinate Omni TAR Beacon (meter) (Meter) E ( lJTM) 234799.04 234798. 12 234798.4 1 .92 .63 l'.(lJTM) 27 1 0900.56 271 0900.79 2710900.03 -.23 .53 Error (meter) .94 .82 Table 4.2 ccuracy Measurement of OmniSTAR and Beacon Services. 4.2. RTK Positioning RTK po itioning can be can-ied out using either a ingle reference station or usmg multiple reference tations. 4.2.1. RTK Positioning Using a Single Reference Station Many urveyors and civil engineer in Abu Dhabi use the single reference station DGPS on daily ba e . They rely on the exi ting GCPs obtained from the Municipality. In most po t of the case , RTK mode is used to determine position in the field.Some of them use 5 cm. processing. The recorded accuracy in most projects range from 1 cm to 4.2.2. RTK Positioning Using Multiple Reference Stations 40 Currentl , Dubai irtual Reference y tern (DVR ) i the only multiple RTK reference tation tern \: orking in the UAE. The econd coming ystem i planned to be operational in Abu Dhabi before the end of 2007. It is planned to integrate both sy terns to gl\e the u ers eamle ervice with more coverage area. Fortunately, both sy terns are manufactured by the arne upplier "Lieca Geo y terns" such that it i expected that the integration proce of the two y terns would be Ie challenging. Th multiple reference tation projects was launched by the Department of Municipal !Tair In bu Dhabi COMA) to erve the entire Emirate of Abu Dhabi, \ ith an objective of providing real-time mea urernent correction with accuracy better than 5 cm. The net\ ork i planned to con i t of 20 stations distributed with a proposed average di tance between �tation of 70 krn. The control center would be in Abu Dhabi Municipality. It is expected to u e different type of communication medium and methods fo r data linking between the reference tation and the control center, a well as between the center and the u ers. Figure 4.2 illu trates the proposed RTK Reference Network layout in Abu Dhabi by the upplier. Option I is to build the RTK network with partial converge of the emirate of Abu Dhabi whereas the second option is to build the system with fu ll coverage of the emirate area. 41 I o - Dubai tation - Option 2 Fig. 4.2 Proposed distribution of the multi reference station in Abu Dhabi 4.3. Positional Accuracy Requirements in Abu Dhabi In practice, there are a variety of application and fieldworks that reqUire GPS mea urement with location accuracy at the centimeter level. Surveyors have to comply with tandards and accuracy requirements of their local authorities. These requirements may vary according to their local conditions. For in tance, Ordnance Survey in UK require , fo r internal data collection activities, a horizontal position accuracy of Scm to 12cm ( tandard deviation) fo r it GPS coordinated point , at 1:12 50 cale (Cruddace, et al., 2002). Figure 4.3 illustrates an overview of the positional accuracy requirements fo r mapping in Abu Dhabi according to the As-built regulation manual of Abu Dhabi Municipality (Abu Dhabi Municipality, 2007). 42 20 em 40 em 1 meter Fig. 4.3 Mapping Accuracy requirement in Abu Dhabi (Source: Abu Dhabi Municipality) According to the A � Built regulation manual of Abu Dhabi Municipality (ADM As Built, 2007), accuracy ranges in the Emirate of Abu Dhabi i classified into 4 categories, which are illu trated in Figure 4.4. These categories can be summarised as: 1. City (Abu Dhabi City) defined by developed areas and areas of special importance. The required po itional accuracy should be better than (1-20 cm) in order to be u ed fo r mapping purpo e with a scale of 1:10 00. 2. Town hip villages, ettlements, industrial areas and defined development areas. The required positional accuracy should be better than 40 cm in order to be used fo r mapping purpo es with a scale of 1 :2500. 43 3. Fann land, cattered populated area, area with scattered building . The required po itional accuracy hould be better than 1.5 meter in order to be used fo r mapping purpo e with a cale of 1:10 ,000. 4. De ert, and dunes mountain area and other not populated area. The required po itional accuracy should be better than 15 meters in order to be used fo r mapping purpo es \ ith a cale maller than 1:10 000. Standardfor As�uilt Documenta tion Fundamental Geographic Data (FGD) Vector and Image Data FGD-D Satellite Image w/major map features pas. Acc. ( 15m Medium Scale Map Content FGD-C u II Pos. Acc. 1.5m Orth U hoto �r ( FGD-B � Detailed Map Content Pos. Ace. ( 0.45m Orth�photo II FGD-A Very Detailed Map Content Pos. Acc. ( O.20m 1 : 10,000 Farmland Fig. 4.4 Area-categories classification (Source: Abu Dhabi Municipality) Network Reference Datum 4.4. One of the biggest challenging tasks when constructing the RTK Reference Network is selecting the suitable reference coordinate system. Points of concern include: 44 ompliance with the exi ting coordinate y tern. • alculating the e act Orthometric height of the reference stations. • cquiring the preci e Geoid model in order to be able to serve the u er with true • rthometric height on the fly. Thi is needed to con ert ellipsoidal heights determined from the GP to the orthometric heights that are referenced to the Mean ea Level. This relation can be fo rmulated a (Hofmann-Wellenhof et al., 200 1) and (Ro enthal, 2005): H = h-N (4.1) \V here H orthometric height h ellip oidal height geoidal height (undulation) Compliance with the international reference sy tern. • eed fo r the future u e. • Compatibility with the existing data which is available with the local authorities. • Determining transfonnation parameters between diffe rent coordinate systems. • For Abu Dhabi, there are three propo ed options fo r electing the coordinate reference y tern of the RTK Reference Network: the old datum, the currently used datum and the new datum. The old reference system is based on ahrawan datum using Clark 1880 ellipsoid, fo llowing the old national reference, which was created by the Military Surveying Department (MSD). MSD has the mandate to create and manage the horizontal and vertical reference system at the UAE national level. Abu Dhabi old base- 45 map and the geodet ic control network that wa created in 2001, wa ba ed on orne of first order o control point in ahrawan datum. Many local planning and utility authoritie ha e built their patial data in reference to the old base map. Currently, the new geodetic control network and the new ba e-map are based on the new MSD network whIch i ba ed on World Geodetic System 19 4 (WGS84) and International Terrestrial Reference Frame (ITRF2000) reference frame. The RTK Reference etwork will be ba ed on WGS 4 and ITRF2005 reference frame. The three coordinate reference options are compared with re pect to the impact on compliant with international reference coordinate frames, con istency with the old and the e isting geodetic network, compliant with the old and the e i ting patial data and the user needs. Looking at the compliance with the new international reference frame, ITRF 2005, using ahrawan datum a uggested in option 1, will have the worst compliance with new international reference. This i due to that points were determined in the old system using traditional methods, which has Ie s accuracy compared with GPS. Proper transformation i al 0 required. In the econd option, using WGS84-ITRF2000 is relatively compliant with the international reference frame. Few centimeters can be observed a a difference between IRTF2000 with the ITRF2005. The new reference system WGS84-ITRF2005 will have the maximum compatibility with the international reference frame. The existing geodetic ground network and spatial data is based on WGS84-1TRF2000. option !, ahrawan, will have the worst compatibility with ITRF2000 due to its poor accuracy, and coordinate transfonnation should be applied to re-project the data. Options 2, ITRF2000, will have the maximum compliance with the current reference. Option 46 three, ITRF2005, will have a diffe rence of fe w centimeters with LTRF2000 here it can be negligible fo r many application . Looking at the compliance with the old geodetic ground network and with the old patial data, option Nahrawn, will have t, the maximum compliance ',: ilh the old geodetic network and with the old data since it has the same reference. Option2, ITRF2000, will not be compliant with the old data and with the old geodetic netvv'ork due to the diffe rence and due to the need to apply coordinate tran fo rmation. Option3, lTRF2005, will have the worst compliance with the old data and geodetic network. The summary of the abo e discus ed comparison is given in Table 4.3. A weighing factor fo r the degree of compliance i given ranging from I to 5, where 1 represents the wor t compliance and 5 represent the be t compliance, it can be concluded that building up the Abu Dhabi RTK Reference etwork based on WGS84-1TRF2000 or WGS84- lTRF2005 are the be t options. 47 Compliance Consistency Compliance Need for Compliance with Compliance Total with the with the with the future the old spatial with the old weight International existing existing data GCP Reference geodetic spatial data Network network Old datum I I 2 I 1 4 to (Clark I 0- Nahru\\ un) EXlstmg 3 5 5 3 5 3 24 \\ G 4 (lTRF 2000 ) '\,e\\ \\'GS84 5 4 4 5 5 2 25 ( ITRF 200 - ) • J Helf?hts. 1. \er:- Loll' . Very High - , Table 4.3 Comparison between diffe rent options fo r choo ing a Reference Datum 4.5. Imp ortance of RTK Network in Abu Dhabi fo r Supporting Spatial Data Infrastructure Spatial Data Infra tructure (SDI) is defined as "the technology, policies, standards, human re ources, and related activities necessary to acquire, process, distribute, use, maintain, and pre erve patial data" (US Federal Government, 2002). SDr is usually consisting of centrally managed fundamental data based on the common ba e-maps, geodetic network and commonly used data. RTK Reference Network services, being utilized by all agencies, can be considered as one of the main components of the infrastructure of spatial data. Figure 4.5 shows a typical SDI structure where the RTK 4 Reference etwork can be con idered a a part of the core of the commonly u ed data and ervice . The principle of Dl is to keep the data clo e to the ource. Each de entralized data provider from the main entitie i re ponsible fo r creating maintaining and haling hi 0\ n data to the central common data browser hosted, most likely, by the city GI centre. Elec1nc;t) Conv>on data bfows.;<' Fig. 4.5 Typical SDI Architecture 49 CHAPTER S USING GIS FOR TH E DESIGN OF THE RTK STATIONS DISTRIBUTION [n thi the i , the mam fo ur de ign element of the RTK reference network will be im'e tigated, including: tation di tribution, eparating di tance between station , site election of tation , and communication between station and control center and the u er with control center. The use of GIS to rudy and evaluate the above mentioned de ign a pect of the RTK reference network are in estigated. This chapter investigates the design element related to distribution of the reference stations and the eparating di tance between them. 5.1. Separating Distance between Stations The di tance between the reference stations i one of the most critical elements in the de ign of an RTK reference network due to its impact on the system functionality and co t. Although increasing the number of stations will usually increa e the ystem accuracy and reliability, it come with the tradeoff of high establishment coast. In practice, fo r the roving u ers wi hing to achieve high positional accuracy, e.g. better than 5 cm, they have to be located within a certain distance from the nearest reference station ( Petrovski et al. , 2001) and (Wtibbena et ai., 2001A and 20018). 50 Recently, e eral studie and re earches have been conducted to inve tigate and figure out the relation hip between the di tance of the roving u er from the nearest reference tati n and the achieved accuracy. Thi distance ha a major impact on selecting the 'eparating di tance between the reference tations. El-Mowafy (2005) has concluded that "To achie\ e a fa t and reliable integer ambiguity resolution, it i recommended to select average ba eline length between reference tation of 50-70 km, with a maximum value of 100 km". Thi mean that the distance between the user and the nearest reference 'tation can be elected as 25-50 km. Seeber (2000) mentioned that it has been proven recently in an operational reference tation network in Germany that it is po sible to achieve em po sitional accuracy er a di tance as large as 30 to 50 Santana and I 0 Km. Tottwr trom (2002) mentioned that it is possible to make VRS RTK measurements with good accuracy - even at the di tance of 40-45 km from the nearest physical reference tation. Based on the above references, it could be as umed in this research that the expected typical range of the distance between the roving user and the nearest station might be between two neighboring stations from 35 to 50 km. In thi case, the separating distance can be double that alue. Hence thi can be used as a guideline to design the separating distance between the reference stations with an objective of keeping the user in the above mentioned range from the nearest reference station. 51 U e of GIS fo r 5.2. election of Reference Stations Distribution The can G I be u ed a an ad anced tool to help in el ecting the best station di tribution approach. Thi ection di cu e the adopted methodology to elect the best distribution approach u ing Gl a well a analyzing and evaluating the tation distribution options. The u e of G I geo patial functionalities (buffe ring and overlaying) to distribute the reference tation i addre d. 5.2.1. Methodology to Select the Best Distribution Approach using GIS In thi' re earch, the adopted methodology m usmg the GIS as an ad anced tool fo r electing tation di tribution consi t of two teps. Fir t, fe w options are proposed fo r the tation di tributions ba ed on propo ed baseline lengths. A et of criteria are identified fo r evaluating the option . ext, diffe rent options are te ted again t preset criteria to elect the be t approach. weight i gi en fo r each option related to each criterion. The election of the best option i based on finding the di tribution that has the maximum overall weight. 5.2.2. Distributions Options Diffe rent approaches are propo ed using GIS to aid designing the network to achieve the optimal eparating distance between the reference stations which would lead up to the mo t co t effecti e setl!p. The fo llowing approaches are sugge ted to di tribute the reference tations, where a radius refers to the di tance between the user and the neare t reference station. An overlap refers to the overlap between circles formed from the tested radius, with their centers are taken as the reference stations. 52 l. Maintaining a radiu Ie than 35 km with no 0 erlap. 2. Maintaining a radiu Ie than 35 km with overlap. 3. Maintaining a radiu Ie than 50 km with no overlap. 4. Maintaining a radiu Ie than 50 km with overlap. Oi'tributing the tation according to demand of ervice 5.2.3. Distribution Evaluation Criteria The evaluation criteria ba ed on \ hich the tested di tribution of the reference tations can be compared are: co t of e tabli hing the system, y tern reliability, and degree of ati fying ervice demand and user needs. The cost of the system is directly proportional to the number of reference tations to be established in the network. This includes capital and running co t . However, the more station in the ystem, the more robu t, redundant and reliable the ystem would be, due to the hort di tance between tations. Reliability include y tern availability and integrity. If one station goes out of order or malfunction, the roving user should till be covered by another buffe r domain from the nearest reference tation. User need and demand fo r network ervice include assuring centimeter level accuracy and high reliability and availability. This is highly needed in the built up area . 5.2.4. Use of GIS Tools in Selecting Stations Distribution The use of GIS geospatial functionality to distribute the reference stations based on the above mentioned options is es ential. Two main GIS functionalities are used in this 53 exercI e, bufti ring and overlaying. The buffe ring i u ed to draw the 35 and KM SO buffe r around the location of each proposed reference tation. This help in locating the tation fo r the option I to 4 within the project area while editing the data to maintain the reqUIred coverage with or without the overlapping option. The overlaying functionality i u ed along with buffe ring to help locating the stations fo r option 5. erlaying the tations using layer of the built up areas representing the user demand of er\ ice help in locating the stations in a balanced order. 5.3. Use of GIS to Examine Results of the Distribution Options Thi ection discusse the general analysis trategy assessing the design of locating and di tributing the reference tation . Distribution options are developed, evaluated and compared. The section concludes with selecting the be t distribution option according to the analy i result of each option tested again t a preset evaluation criteria. 5.3.1. General Analysis Strategy The general procedure that was used to evaluate the distribution options tarts with creating a point fe ature representing the reference tations layer. A circular buffe r to a distance equal to 35 km or 50 km, according to the tested option, is created fo rming the user range around each reference station. Next, the reference stations with their as ociated buffe rs are distributed over the project area (Emirate of Abu Dhabi) with or without the overlapping according to the tested option. The distributed reference stations with their buffe rs are overplayed on top of the built up areas to examine compliance with 54 area co erage of the u er demand fo r the RTK Reference network erv'ice. Finally. each di tribution option i analyzed con idering the fo llowing fa ctors: number of reference tation . y tem reliability and ati faction of users need fo r the service. Weights fo r each of the e fa ctor are calculaled fo r each option, and te ted against preset criteria to select the b t di tribution option. The election i ba ed on finding the distribution that has the ma. imum overall weight. 5.3.2. Acquired and Created Data everal fundamental type of data were u ed in thi study when considering distribution of reference station and selecting their locations. The e data include: geo-referenced image from the Indian Remote Sen ing (IRS) Satellite of 5 meter • pixel re olution covering the entire project area (Emirate of Abu Dhabi), obtained from bu Dhabi Municipality (ADM). This image is used a the background fo r the project layout. The UAE boarder with neighboring countries expressed in a shape file fo rmat, • (polygon vector data), obtained from ESRl tutorial data. This data is also used as an additional background fo r the project area layout. Built up areas within cities of the Emirate of Abu Dhabi in a shape fi le fo rmat • (polygon vector data), obtained from Abu Dhabi Municipality ba e map which ha a cale 1 :2,500. This data is used to define the built up areas that are representing for the u er the highest areas of need and demand fo r the RTK Reference network servIce. 55 Built up area in the urban cities in the Emirate of Abu Dhabi in a hape filefo nnat • (polygon vector data), obtained from Abu Dhabi Municipality ba e-map of scale I: Thi data i u ed to define the urban built up areas that represent area of LO,OOO . medium u er need and demand fo r the RTK Reference network service. Table 5.1 de cribe the data u ed fo r the analysi . Layer Name Data Data Data Used fo r type fo rmat source UAE Image Raster Geo lRS Background of the project Tiff 5 meter area resolution UAE Boarder Polygon Sbape ESRI Background of the project area Built up areas at Polygon Shape ADM Shows the areas of 1 :2,500 map scale maximum demand and need oftbe RTK network service rban built up area Polygon Shape ADM Show the areas of medium at demand and need of the 1:10 ,000 map cale R TK network service Table 5.1 Used data for the analysis of the station distribution Buffe rs of reference stations and distance between them are created fo r each di tribution option in the fo llowing data fi les: Point fe atures in a shape file fo nnat, representing the reference station . • 56 Polygon fe ature, in a hape file fo rmat repre enting the buffe r around each reference • tation. Line fe ature repre enting the di tance between adjacent reference tations fo r each • opti 11 . 57 5.3.3. tation Distribution Ba ed On 35 km User Buffe r For all di tnbution option , the GI wa u ed to examine thi option with the fo llowing tep : The 1a r of the project area of coverage was fir t added which was defined as • "Emirate of bu Dhabi Territory". A p int fe ature ,. a next created representing the reference station . • buffe r polygon wa ne t generated to a 35 km di tance around the reference • tation . ButTe red tation were distributed equally to cover the entire coverage area. Two • buffering zone \ ere created. The first i without any overlap and the econd with an overlap of 300 0 between circles representing the coverage area of adjacent reference tation to cover the entire area. Figure 5.1 illustrates the distribution of the stations and their eparating distances fo r the fir t option, tation distribution based on 35 km buffe r without any overlap. 5 Scale 1 1 500.000 Fig. 5.1 Station Distribution based on user buffe r of 35 krn without overlap dopting the di tance eparation ba ed on the u er buffe r of 35 km without coverage overlap a hown in Figure 5. L end up with 14 reference tations fo r the network. This ha an advantage of a relati ely low cost in e tablishing the network. Howe er, this option has a drawback of not covering the entire user area by the buffering zones, as bown from the regions between the coverage circle that were not covered. In addition, poor reliability and service demand atisfaction would be expected in thi ca e. This is area al 0 hown from Figure 5. L as the stations were not properly located at the built up that require demand of centimeter accuracy. The second option of tation di tribution is also based on maintaining the roving user within 35 km radius, but with an 30% overall overlap with adjacent reference stations, on 59 a\ erage. Thi option analyzed u mg the arne tep detailed above. Figure 5.2 illu trate th re ult of the propo ed di tribution and the eparation di tance between the reference tation in this ca e. hown in Figure 5.2, thi di tribution option ends up with 25 reference tation fo r the neh ork. Hence it provide the maximum y tern reliability and ervice co erage due to the high number of utilized station . However, it ha the max imum co t of sy tern e tabli hrnent a well. The number of the reference station that were located in the built up areas is not ufficient. Denser station were needed fo r the built up area to cover in tances of malfunctioning of one or more of the reference tation . Hence, the level of user needs and service demand compliance can be con idered a medium. 60 Fig. 5.2 Stations distribution based on user buffer of 35 km with overlap 5.3.4. Station Distribution Based on 50 km User Buffer Another proposed approach fo r station distribution i ba ed on maintaining a u er buffe r of 50 km from the nearest reference station. Utilizing the GIS to examine thi option without overlapping the stations buffe r, the results are illustrated in Figure 5.3. As shown from the fi gure, this option end up with using only 7 station . The biggest advantage of this option is that it will bring the project cost to a minimum due to the small number of station u ed. Howe er, the system reliability becomes very poor. If one station fa ils, the ervlce will significantly degrade, and may become unreliable fo r a very large geographical area. Another drawback fo r this option is that many areas were not covered 61 b, the 50 km buffe r; henc , . the u er need and the ervlce d emand compliant criterion would al 0 be ery poor. 1.1.500,000 Fig. 5.3 Stations distribution based on user buffe r of 50 km without overlap Examining the tation di tribution based on a 50 km user buffe r with an overall overlap of 300 0 on average bet\veen adjacent reference stations utilizing the GIS functionality is iUu trated in Figure 5.4. In thi ca e, there would be 1 I reference stations. Thi has an advantage of a relatively low cost of system establishment. However, thi option has a drawback of not covering the entire user area, with poor reliability and service demand sati fa ction. As shown from Figure 5.4, the stations are not properly located at the built up area with high demand of centimeter acc uracy as discussed earlier. In addition, network reliability and coverage fo r the service demand and user needs are still poor. 62 Scale 1-1.500.000 Fig. SA Stations distribution based on user buffer of 50 km with overlap 5.3.5. Station Distribution Based On Service Demand The la t propo ed option fo r di tributing the reference stations is to select locations of the stations according to the service demand and user need . Service demand is con idered to be high at the built up areas in Abu Dhabi where the need fo r preci e surveying is high due to the extensive amount of con truction works. Thus, the service will be more needed and mis ion critical in the cities and township areas. As discussed in the previous section, the target accuracy of the base map and the GIS as built data can reach up to the 40 cm level. Applying the GIS functionality of overlaying the accuracy domain layers allows fo r di tributing the stations and their buffe r (while in the editing mode) in the most appropriate locations. The resulting created layout map is illustrated in Figure 5.5. This approach leads to ending up with 20 stations in the network. Although the project cost 63 " ill be relati ely high compared with the previou di tribution option , but the y tern reliability at the area with maximum ervice dema.nd . an d duser f nee 0 ervlce (the regIon , B and C in the figure) will be very high. Fig. 5.5 Station distribution Based on Service demand 5.3.6. Benefitsof GIS as a Tool to Design the RTK Reference Network The GIS helps in identifying the number of stations needed fo r each option. Using the buffe r function in the GlS allow the ystem de igner to di tribute the station properly. Thi is important due to e eral factors. For instance, the number of stations needed fo r the network is inversely proportional to the selected separating distance. It is fe asible to increase the number of stations in the built up areas to increase system reliability and enhance the accuracy even with compromising the number of stations in the desert, where the need of the network service is low. Once the average distance between tations is defined, the next step is to determine the reasonable location of each station to maintain 64 that eparating di tance. Hence, the GI become one of the best tools to help defining the approximate tation location due it' functionality of di tance mea urement and buffering. Thi help to di tribute the stations while vi ualizing and measuring the dl tanee to the neighbor tation . otably, GIS becomes an excellent tool not only to de ign the tation distribution, but al 0 helps examining the a ailability and reliability of the RTK net\. ork ervice in the built up areas. 5.4. Evaluation and Comparison of Station Distribution Options RTK Reference net\.vork y ternco t and reliability i directly proportional to the number of reference tation in the network. Comparing the reference stations distribution options ba ed on the contribution of each option to the system cost and reliability can be ummarized a fo llow : Reference tation distribution based on maintaining a radius less than 35 krn with no overlap, and distribution based on maintaining a radius less than 50 krn with overlap, as well as distributing the tations according to user demand of service, ended up with 14 reference tations fo r the net\.vork. This makes the system cost and reliability relatively low. Reference tation di tribution based on maintaining a radius les than 35 krn with overlap ended up with 24 reference stations fo r the network, which make the sy tern cost and reliability very high. Reference station dish-ibution based on maintaining a radiu less than 50 krn without overlap ended up with 7 reference stations fo r the network, resulting in very low cost, but also with low reliability, which are competing factor . Distributing 65 the tation according to demand of ervice ha the maximum compliance with the degree of ati fying the u er' need and demand fo r the net\: ork service. The ummary of the above discus ed comparison between the above di cu sed stations di tribution option are ho\ n in Table 5.2. Applying weights to the degree of compliance \ ith e aluation criteria related to co t, reliability and u er needs atisfaction can be given in a range from I to 5 fo r a better quantification a sessment. In weighing 1 repre ent the wor t compliance and 5 represent the be t compliance. From the table, it is shown that distributing the tation ba ed on 50 km has the lowest weight, where station di tribution while maintaining 35 km buffe r has a medium weight, whereas and the di tribution ba ed on service demand ha the maximum weight. It can be concluded that ion according to demand of ervice is the best option. di tributinbo the tat � 66 Option Number of Co t Reliability Satisfying Total tation User Need Points 35 km buffe r 14 3 2 2 7 Overlapped 1 4 3 8 35 km buffe r 50 Km buffe r 4 1 1 6 Overlapped 1 1 3 2 6 50 KM buffe Service 20 2 3 4 9 Demand Bad Good ( Evaluation weights: 1 = Minimum, 4= Maximum) Table 5.2 Reference Stations Distributions Options A compan on between the reference stations distribution options and their weighs derived from the above table i represented in a bar chart as illustrated in Figure 5.6. 67 � r------� 25 20 0 36 Km·NoOverlap 035 Km·Overlapped 15 10 5 o -' Number of Cost Factor rellebllrty User Need Overall Stations F actor factor Factor Fig. 5.6 Statio n distribution option with their weighing factors Due to the fact that the distance bel:\veen tation i an important factor in the RTK Reference network design, ba ed on the abo e di cus ion, it is recommended to elect a\ erage ba eline lengths ranging between 50 and 70 km between adjacent reference station a long as it ati fy the user ervice demand. This is required to achieve fa st and reliable integer ambiguity resolution (EI-Mowafy, 2005). The tatistic of distances between stations fo r the examined distribution derived from the analy is of different option i given in Table 5.3. 6 Km-No 35 35 Km - 50 Km-No 50 Km- On Overlap Overlap Overlap Overlap Demand Max Distance 76 105 122 145 126 Average Distance 70 64 100 89 67 Minimum Distance 65 46 93 67 36 Table 5.3 Distance between tations To have a better view fo r the tati tics of distances between stations fo r the examined di tribution derived from option analy i tati tic , the results of the di tances between tation are repre ented in a bar chart and are illustrated in Figure 5.7. The average di tance between tation in Abu Dhabi's network is about 100 km. Thus, it can be concluded that the ro ing users would be alway in the approximate range of 50 km from the neare t reference station. 69 160 140 120 100 o Max Distance 80 • Average Distance 60 o MInimum Distance 40 20 o 35 K�No 35 Km 50 K�No 50K� 01 Dernad CNerlap CNerlap CNerlap CNerlap Fig. 5.7 Distance between stations 70 CHAPTER 6 SITE SELECTION OF THE REFERENCE STATIONS Reference tation should be installed in carefullysele cted ites that would satisfy pre et ite election criteria. These criteria include that the building containing the r f r nce station hard\ are and oftware hould be ecured, powered, has acce to communication, table and open to sky. In this chapter, the capability of GIS tool to help electing the optimal ites that ati fy the above criteria is investigated. ArcGIS tools uch a election by attribute, analysis model builder and 3D presentation are u ed to help inye tigating, evaluating and electing the best building fo r each reference site. A generic model i developed u ing ArcGIS model builder to run a serie of automated queries governedby the above mentioned criteria against a unique set of data input fo r each ite. 6.1. Site Selection Criteria The location and type of the building ho ting a reference tations can not be randomly elected. It has to be based on specific criteria that would meet the requirements of the be t functionality of reference stations. Ordinance survey in UK adopted site selection criteria that requires the selected site a to be secure, suitable fo r good GPS observations al., (clear horizon etc.), as well as having access to communication (Cruddace ef 2002). 71 In thi re earch, the propo ed ite election cri teria require that the building containing th reference tation houJd be table, owned by the government, powered, have acce to communication, open to ky and will not be demoli hed in the near fe ature. The cri teria ha e orne a pect related to the building type and orne aspects related to fa ctors affecting the bUIlding. Building related fa ctor include building stability, lifetime and u age. The a pect atlecting the building include urrounding buildings, location within the net\, ork grid, and availability of power, communication, and security. 6.1.1. Building Type Criteria It i preferred that the building containing a reference tation to be a go emment building. Thi is due to the fa ct that such a building will be most likely secure, powered, ha acce to telecommunication and built in a good structural status. For the Abu Dhabi case, the municipal center owned by the municipality would be the most preferred sites due to the easy proce of getting the licen e and appro al of using the building and easy ite acces ince the municipality owns and runs the RTK reference network. 6. 1.2. Building Stability Criterion One important criterion in selecting a reference tation fo r positioning activitie is that the building on which the reference station is fixed hould have the maximum level of stability. This means that its vibration or movement with time should not exceed a certain level that would change the coordinates of the reference station to the Ie el that could lead to inaccurate network olution, and consequently wrong determination of the rover (u er) position. The reference station antenna hould be firmly mounted on top of the 72 building and hould be very table without any movement. The building tability i directly proportional to the building height a well a the relation to the nature of oil on which the building exi t. tudying the recommended maximum drift of a building, Segui (2003) concluded that erviceability limitations on bui lding drift under " ind or earth quick load r quire that the drift should not exceed where H is the building H/SOO, height in meter . imilarly, mith (1996) ugge ted that the drift value should not exceed (H :00). Howe er, Simiu (1996) recommended that the allowed drift should not exceed ( H, 600). Hence, ince most tudies recommend the fo rmer figure, the relationship between the building height and its maximum allowed movement a illustrated in Figure 6. 1 can be fo rmulated in general a : (6.1) cr < LlSOO lding height and denotes the maximum allowed displacement. \I here Li the bui (0) 73 o D D D o 0 o 0 D 0 D 0 Fig. 6.1 Building drift In thi re earch, it i a sumed that the maximum building drift should not exceed 10 em, uch that point po itioning at the same level can be achieved from the network olution (in the worst case). Hence, from equation (6.1), it can be concluded that the maximum high of the building that would be used fo r the reference station should not exceed 50 meter . 6. 1 .3. Sky Visibility Criterion The selected buildings fo r the reference stations should be open to the sky to be able acquire signals from a maximum as possible of atellites all the time. Thus, any ob truction should be located as fa r as possible from the reference station antenna. This means that the antenna of the reference station must have relatively clear visibility above 74 the horizon without any ob truction v ithin an arbitrary angle, defined a the rna k angle. This rna k angle ca n be taken a 5-10 degrees. The relation between the building containing the referenc tation and a neighboring building can be fo rmulated a : h = D * tan( e) (6.2) Where h: i the diffe rence in height between the building hosting the reference station and a neighboring building. i the ddance between the two buildings. 0: 8: the mask angle Eq. (6.2) can be depicted in Figure 6.2. 75 5 - 10 degrees D o 0 0 0 CJ 0 0 0 DO CJO OD D D DO D D Fig. 6.2 Mask angle of the reference station's antenna hown in Figure 6.2. and ub tituting in equation 6.2 with a S-degres mask angle give : (6.2) A an example, let u as ume h is 5 meter, representing the approximate height of one additional floor fo r the urrounding building, and a uming that the two buildings have the arne elevation fo r their base. Hence, (D) which represents the di tance between the reference tation site and the surrounding building would be approximately 50 meter . For such a distance, it can also be concluded that SUITounding buildings that might block the ateilite vi ibi lity fo r the reference tation antenna are those buildings that have heights more than 55 meters. 76 dopted Met 6.2. hodology in Using GI to Select the Optimal Sites Mo t of the above mentioned criteria are patially related, hence, the GIS would play an important role to collect, tore and analyze the data of the propo ed ites and e amine the compliance of the e ite with the above criteria in order to select the optimal ite fo r each reference tation. In order to do that, a serie of GIS patial and attribute querie are implemented to the exi ting building layer to elect the area covering each site. This layer con ist f the geometry and attribute of all building that are located in the area of the tudy urrounding the candidate ite. The quenes are ba ed on the selection criteria di u ed in the prevlOu ection including building containing the reference tation hould be table, owned by the government, powered, have access to communication open to k:y and will not be demo Ii hed in the near fe ature. For each criterion, one query \\ a fo rmulated. Running each query will lead to fi ltering out the buildings that do not ati fy each criterion, ingling out the proper building. The equence and logical order of the querie i illustrated in Figure 6.3. The logical chart defining the logic and the equence of teps and proces e i realized through a model developed using ArcGIS oftware package. Structured Query Language (SQL) is used in the GIS to build the earch process throughout the databa e. 77 Butldln y o Yes. Fig. 6.3 Logical Flow Chart fo r Site Selection 7 The fo lio\) ing QL querie wer e developed: 1- To elect the building that are governmental, ecured, powered and lower than 50 met r in height ( ee Eq. 6.1), the query wa fo rmulated a fo llow : elect * From Building = ( \V here "TYPE" 'gov' AND "POWERED" = 'yes' AND " ECURED" = ' . es' A D "NEW" = 'yes' AND "HEIGHT" <50) 2- To elect the building that are open to ky, three steps were fo llowed: Fir t, building that are higher than 55 meters are elected (see Eq. 6.2). Tho e buildings are the building that are higher with at least one floor than the desired buildings, which \.vere "elected in the pre IOU step. Buildings that are higher than 55 meters were selected through the fo llowing query: (Select * From Building Where "HEIGHT" > 55) Second, a buffer of 50 meters from the selected buildings that are higher than 55 meters wa created. Finally, a patial query was u ed to define the buildings that are not inter ecting with the above created buffe r. A spatial analysis model based on the series of queries as described in Figure 6.3 was developed u ing ESRI Model Builder 9. 1 as shown in Figure 6.4 to help automating the process of the running the queries in a batch mode .The model is employed fo r evaluation of each site to help selecting the best location fo r each reference station. Each selected 79 ite fo r any reference tation in the network hould comply " ith all ite election criteria. The mod I i g neric uch that it can be u ed fo r all ites. For each specific ite, the model output wa related to the input data to the model. The model tarts with recei ing the input la er which i in thi ca e the building layer. ext, it run the query to elect building that are governmental, ecured, powered and lower than 50 meters in height. Then. it run a quer to elect the buildings that are higher than 55 meters in height, wh r the re ult i u ed to create a buffe r of 50 meters around each building. Finally, the filtered government building that are 50 meter away fromthe building , that are higher than � meter , are selected. ------" selKU Model EiI VIeW Wl1do\v � � �� +J :: 0:: :: �I _ lE ' I\Ll ..!... Select the powered and secured government � buildings that have heIght ofL-r------V less than 50 meters � �dings that are 50 meters away SE & from any buildings more than 55 & Secured meters Select the Make A Buildings that spatIal have height buffer of more than 55 50 meters meters Fig. 6.4 Spatial Analysis Model (Using ESRl Model Builder 9.1) o 6.3. Ca e tudy Example - One Site in Abu Dhabi Island The , ite of a propo ed ref erence tation to be located in Abu Dhabi I land i u ed a an e ample to te t the abo e methodology and the developed patial analysi model that was di cu "ed in the pre iou ection. Data of the e i ting buildings in bu Dhabi Island obtained from bu Dhabi Municipality were u ed. The data is given in ESRI shape fo nnat populated with rich attributes related to each building, including its name. type, ubtype and height. Each proces of the patial analy is model is discussed, explained and pr ented in the fo llowing ub-section. 6.3. 1. Using GIS in Examining Stability of Buildings A di cu sed in the previou ection the building tability is proportional to the building height. The assumption made i that the reference station cannot be installed in a building with height taller than 50 meter to avoid a alue of building vibration and movement that can cau e large po itioning errors 1 0 em). Extraction of the government building that (> have heights less than "0 meters i carried out through using the GIS functionality of election by attribute in Arc iew as in the fo llowing query: SELECT * FROM Buildings WHERE "HEIGH" < 50 The result of this query fo r Abu Dhabi Island is illustrated in Figure 6.5. Out of 30,850 building in Abu Dhabi Island, 30507 are cia sified as buildings with height less than 50 meter , which are marked in Figure 6.5 and thus were included in the next tep. The remaining 343 building were e c1uded. A ". "' . .... Legend .... ; ...�� , i.� . 4 ' ••� • i. _ Butld.ng Less Than 50 meter 1 100,000 Fig. 6.5 Buildings in Abu Dhabi of heights less than 50 meters 6.3.2. Using GIS in Examining Type of Buildings Extraction of the governmentbui lding fo r the above case study of Abu Dhabi Island wa performed by u ing the GIS functionality of selection by attribute in ArcView software as fo llow : 2 ELECT * FROM Building WHERE "TYPE" = 'go\" The re ult of thi query i illu trated in Figure 6.6. Out of 30,507 building with height Ie than 50 meter elected from the fir t query, 215 are cla ified as go emment which are marked in Figure .6. . .� . ... . . -.., '. I \ , , .' •. • ' . • . .. . ' . ' ...... j. .. . . '. . "'- Legend • .,., Government Buildtngs _ • 1 100,000 Dhabi Fig, 6.6 Government buildings in Abu 3 6.3.3. ing GI Tool to Verify the Building Good Satellite Visibility order In to elect the ite that are open to ky and have good atellite vi ibility, a patial anal i wa carried out fo r the urrounding building of the candidate sites. As di cus ed arlier, it \ a concluded that the de ired ite fo r the reference station hould be at lea t 50 meter awa from an urrounding building that i higher than 55 meter . Thi mean that the building which i ho ting the reference station must have relati ely clear \ i ibility above the horizon without any ob truction higher than an arbitrary angle, defined as the ma k angle reference. Thi mask angle can be taken a 5-10 degrees. In order to maintain a minimum of 5 degrees rna k angle of atellite visibility, the fo llowing tep were fo llowed to fm d a building with uch geometry: 1. A query by attribute to elect buildings that are higher than 55 meters i fo rmulated u ing the building layer. Thi can be fo m1ulated a : SELECT * FROM Buildings WHERE "HEIGH" > 55. 2. A buffe r of 50 meter i selected around the buildings that are higher than 55 meters. 3. patial selection of the go ernment buildings that intersect with the buffe r of any building higher than 55 meter is performed. 4. An inverse selection is made to select the building that do not intersect with the buffer. These include the buildings that are 50 meters away from the surrounding higher buildings. Tho e are the buildings that are meeting the criteria of government buildings that are lower than 50 meters and are open to sky. A sample of the result 4 howing th govemm nt building that are open to ky (Blue color) and the building that are not open to ky (Red Color) i illu trated in Figure 6.7. Legend Roadedge GovButldongs Open SI Gt S5m • 13,000 Fig. 6.7 Example of the Government buildings that are open to Sky After performing the serie of equential queries as described above, it was fo und that out of the 30805 buildings in Abu Dhabi Island that pass the first criterion, only 282 buildings are higher than 55 meter. It is also fo und that only 3 government building are not open to kyo Finally, the number of candidate building that have a height less than 50 meters and are open to ky are 212. The obtained results are summarized in the table 6. 1. 5 Total number of building in Abu Dhabi 1 land (Source ADM) Higher Tban 55 meter No. of building lower than 50 meter - 30159 282 Government Government Government Open to Sky ot Open to ky 215 3 212 Table 6.1 Number of buildings according to their type 6.3.4. 3D Investigation and Presentation Using ArcScene ite clearance to sky can also be investigated by analyzing tbe relation between building height u ing ArcScene oftware module by examining the urrounding buildings and displaying re ults in a 3D fo nn. Figure 6.8 illustrates the results of verifying the uitability and openness to sky of building in tbe example of Abu Dbabi Island using ArcScene. The fo llowing teps were used to come up with the 3D presentation: A building layer was added to ArcMap. • Symbology of each building was categorized by the unique value of its height. The • result wa coloring the building according to their heights. Categorized buildings were next copied and pa ted in ArcScene. • Building polygons were turned into 3D blocks. The buildings were extruded by their • heights. 6 In order to ee the diffe r nce in height between the Municipality building and the • urrounding building , a rectangular polygon plate of 50 meter width wa created and extruded by the height of the municipality building, which i 38 meter, a 500;0 tran parency of the plate layer \: a u ed to help in vi ualizing the buildings that are borter than the Municipality building. hown in Figure 6. \: hich illu trate the above example, it can be concluded that the GP receiver in thi ite will have good atellite vi ibility since the building is not urrounded by taller building that can block atellite signals according to the pre et criterion . ...... ,. J!lg • -... ._ � .. .. "t .. • ,:, I . .... 111:1 .... - � � 14 !4 �.!:: ,.. . � � • "- Ilr ,. .!.. ..!.. .. Fig. 6.8 Openness to sky presentation in 3D 7 The ite can al 0 be een from diffe rent angle to verify it vi ibility to satellites a hown in Figure 6.9. Fig. 6.9 Selected site as seen from diffe rent angles to verify its visibility to satellites CHAPTER 7 COMMUNICAT ION NETWORK DESIGN The communication medium is one of the most important sy tern components of the RTK reference network. Thus, election of the be t communication medium i an important de ign a pect. It i generally recommended that each reference tation hould be connected through a direct link with a minimum of 256 kb/ to the sy tern control center. However, the medium election fo r each site would be ba ed on its availability and according to the cost benefitanalysis model. Thi model would examine the performance, the re liability the capital and running cost . On the other hand, the roving users will be onnected to the center through a wireless link. Thi link could be the Global System Mobile (GSM), the General Pocket Radio Sy tern (GPRS), a Radio frequency (RF), or through the satellite communication. In thi ection, the u e of GIS to examine, analyze and elect the best approache fo r telecommunication infra tructure between reference tation and ystem control center and between it and users is di cussed. 7.1. Communication between the Reference Stations and the Center The reference station need to be permanently connected through a data link to the network center located at the operating organization premises. The currently available options of connecting the stations to the center might include Corporate Wide Area 9 em ork ( ), go ernment fiber backbone, er ice provider lea ed line , and Radio Frequency (RF) tran mi ion. 7.1.1. Corporate Wide Area Network (WAN) The corporate wide area network u ed can be the private network owned by the firm operating the RTK reference network. Since the RTK in most of the countries is generall operated by the local Authorities, fo r example Ordinance Survey in UK, uch organization u ually own a wide area network connecting their regional offices. The RTK network can utilize a minimum bandwidth of 256 kb/ to link each tation to the center, thu , it would not be a challenge to make a provision fo r this requirement with today' modern communication network . The main advantage of this option i its quick deployment of linking the tations ith minimal installation and running co t. [t would be obviou to u e thi link wherever applicable fo r any reference station ite. It might ha\e the di advantage of having a limited coverage and it might not reach the sites located in buildings that are not owned by the operating organization. 7. 1.2. Government WAN Network Many cities have a government owned WA linked by fiber optics. U ually, this link type mainly connects important government buildings. Typically, it has a very big bandwidth. The advantages of using this type of networks are it free running co t and high reliability. However, the geographical coverage and usage availability have to be investigated. Some citie are equipped with a government network that i based on 90 "Terre trial Trunked Radio (TETRA) " ith different partie involved. TETRA i an open digItal trunked radio tandard defined by the European Telecommunication tandardization Ln titute (ET 1) to meet the need of the mo t demanding professional mobile radio u er . It i de cribed a "Pri ate network fo r own bu ine s communications fo r oice, data and telephony calls on etwork 1 with I Radio" (Motorola, 2007). 7.1 .3. Local Telecommunication Services Currently, local telecomm unication pn ate compallle provide a variety of paid data linking services. The ervice might include leased lines, RF and Internet based solutions. Each type of link has a pecific functional specification, reliability tatus, pricing frame\ ork and geographical coverage. Asynchronou Digital Sub criber Line (ADSL) data-link service can be utilized as a good example. In Abu Dhabi, the local telecommunication service provider has a wide coverage area of high speed data link. The bandwidth of thi ervice reaches up to 1 Mb/ . The geographical coverage extends to all built-up areas. From practice, it has been proven that the ervice is very reliable. It ha one time installation fee and rea onable fixed monthly charge on the average. 91 7.1 .4. Corporate Radio Frequency Network Building a dedicated RF network fo r communication between the reference tation fo r tran mi ion of the network corrections can be con idered a one of the communication medium options. The disad antage are it require getting an approval fo r a dedicated radio frequency - ery High Frequency (VHF ) or Ultra High Frequency (UHF), \ hich rna take a long time, and ignificant in estment i required in building up towers, buying communication equipment and funding operation and maintenance expense . Choosing thi option can be driven by two main factor . One i to reduce the running cost, and the econd i to provide the link wherever other option are not applicable. The major advantage of this option would be in sa ing the communication running charges of cOlmecting the tation . The capital cost and finding free carrier frequencie are the ignificant di advantages of thi option. Each of the above di cu sed communication media fo r connecting the reference stations to the control center has ad antage and disadvantage as far a geographical coverage of ervice availability, required capital cost fo r establishing the ystem, running co t of u ing the service, and ervice reliability. A comparative ummary of the advantages and disadvantages between diffe rent methods is given in Table 7.1. A weighing fa ctor is given fo r each aspect, ranging from 1 to 5, where 1 represents the lowest weight and 5 represents the highest weight. From the comparison given in table 7. 1, it can be concluded that connecting the reference stations to the center using the government line network, wherever available, is the first best option. Using the service provider land 92 connecti ity is the econd preferred optio n, wherea USln2: the RF connectivity 1 a � rea onable option fo r the tation that are not reached by either government network or ervice provjder land-line connectivity. Geographical Capital Cost Running Reliability Coverage Cost Corporate WAN 2 5 1 4 Goyernment 4 1 I 5 etwork Service Pro ider 1 1 3 2 (RF) Service provider - 3 1 3 4 Land Line Corporate RF 1 5 1 2 Government 1 1 1 5 TETRA Internet 2 2 3 3 Weights: I - Very Low, 2- Fair, 3- good, 4- ery good, S - Excellent Table 7.1 Comparison between diffe rent types of communication media 7.2. Using GIS in Communication Infrastructure Assessment The GIS can serve a an important tool to help carrying out the needed assessment fo r the selection of the appropriate type of communication infrastructure between the reference stations and the computing center. GIS is useful in such assessment due to the involvement of a large extent of geographical area as well a the relationship to the 93 lerraln of the project area. To util ize the 01 in tudying the available connecting option , data related to the e i ting communication infra tructure and ervice a well as the terrain data would be needed. 7.2.1. Studying Abu Dhabi RTK Network Communication Methods di cu ed earlier, bu Dhabi RTK reference network can be designed u mg approximately 20 reference tation . By investigating diffe rent options, it was fo und that 15 'tation can be connecte d u ing the available corporate Abu Dhabi Municipality ( DM) W a illu trated in Figure 7.1. Hence, examining the applicable ways of connecting the remaining reference tation to the computing center and proposing recommendation fo r the be t method based on a systematic process of analy is and evaluation are needed. By investigating possible communication methods fo r the propo ed reference station location , it was fo und that five tations lack the ground-based connection and better to be connected using the wireless Radio frequency (RF) method. GIS i propo ed here to examine the po sibility of connecting the e five ites to the nehvork and select the mo t co t effective approach. This can be performed as in the fo llowing teps: site to the nearest connected ites IS The line of j oa ht from each unco nnected • examined using the OIS line of sight tool. The terrain surface of the project area is created based on the heights of the Geodetic • Control Points (OCP). Thi data is obtained from Abu Dhabi Municipality. The shortest direct connection is elected with a clear line of sight per each tation. • 94 For ite lacking the line of ight to the nearest connected reference • station, a ystem of r peater i propo ed. GIS analysis i used to locate the repeaters in the be t cost effecti e way. � + egendUn Connected Station • Connected stations ADM_WAN UAE Scale 1:1,500,000 Fig. 7.1 Reference stations connectivity To examine the line of sight fo r possible RF locations, the fo llowing GIS data, analysis and pre entation are utilized. Data of the UAE border is needed to define the project area. This data was obtained • from ESRl tutorial materials in the fo rm of polygon layer in a shape file fo rmat. Data of the Geodetic Control Points is required to make use of its height information • to interpolate the raster elevation surface. This data was obtai ned from Abu Dhabi 95 Municipality in the fo nn of point feature layer in a hape file fo rmat. Two layer were created and derived from the GCP data: a raster layer of an interpolated urface, which repre ent the ele ation model of the project area, and a contour line layer that repre ent the telTain elevation . Data of the reference tation i required to identifythe location of each station. This • data i obtained from bu Dhabi Municipality in the form of point fe ature layer in a hape fi le fo nnat. Table 7.2 ummarizes the acquired and created data. 96 Layer Feature Format Source U ed attributes / Role T. pe UAE Boarder Polygon Shape ESRI Background Geodetic Control Point Shape ADM Height, a source to derive Point DTM and contours Reference Stations Point Shape DM Name, identifystation locations ADM \V AN Line Shape ADM Distance, indicating existing connections Elevation Raster GRID Created Elevation model a a source of generating Contour GCP Contour Line Shape Created Elevation, indicating elevation height RF Line Shape Digitized Distance, indicating RF connections Table 7.2 Acquired and created data fo r the assessment of RF locations 7.2.2. Analysis Approach for Examining the RF Communication To examine the best RF communication method between the fi ve sites that require this type of connections and the remaining station of the network, the fo llowing steps were carried out: Layer of input data were added in the ArcMap software. These layers include: UAE • Boarder, Geodetic Control Point (GCP) and reference tations. 97 mg the 3D naly t e ten ion, a ra ter ur face wa created by interpolation, • appJ tng the lnver e Di tance Weighed (l DW) method u ing the height attribute of the GCP a their Z alue . ing the 3D anal t e ten ion, contour were created u ing the urface analysi tool • from the created ra t r data produced in the previou tep. Interpolated ra ter data is added a a urface that reflect the terrain heights with the created contours in reMap. The contour fe atures were labeled with the height attribute. U ing 3D analy t exten ion in ArcGIS, line of ights were generated from each of • the unconnected five reference stations (considered a an observer) to the nearest reference tation (con idered a a target). The line of ight between the ob erver and target points deteImines vi ibility (between "from" and " to" points). The output were analyzed and c1as ified according to the visibil ity statu . Invisible • ite were inve tigated fo r further studying and analy is in order to figure out the best approach fo r be t location of repeater tations and required heights of transmitters and receivers antennae. 7.2.3. Results and Conclusions Figure 7. 1 show the avai lable W A connections between tations and Abu Dhabi propo ed RTK reference network. As shown in the Figure, the RF connection fo r data transfer i needed fo r 5 stations that are out of the Municipality WAN. RF connections can be established using communication equipment (Transceivers) that transmit mutual electromagnetic waves in a Very High Frequency (VHF) or Ultra High Frequency (UHF). The VHF and UHF waves propagate in the peed of light reaching the target 9 area in the line of ight. To e tabli h an RF connection between two tation , the two tation hould be able to e each other without any ob tacIe intercepting the line of , ight. To link the tation that have no clear line of ight, a repeater system is proposed in a location that can be een by both tation . The repeater i a communication sy tern that work a a minor to reflect the RF ignal . It con i t of a receiver and a transmitter working in a duplex mode. [n thi exerci e the GI wa mainly utilized to olve two main issues. Fir t, it i used fo r examining the line of sight fo r each tation, and as es ing findingthe optimal location to etup the repeaters. The cond GIS function i to examine the line of sight fo r each tation by using a tool that creates line of ights in 3D Analy t Extension u ing ArcGIS. Thi \: a performed ba ed on the elevation surface layer that was created from data of the GCP . The vi ibility from each of the tested five tations to their neighboring reference tations were examined by tudying line of sights between them. Results are shown in Figure 7.2, where the color of the lines determines vi ibility between point . The bre· n color repre ents good visibility, \ hereas red color indicates invisibility. 99 JD Analyst .., • TOf9OC M.w+.. .,....'·40'... f1U1W't lU,. iIOUUI 1JJ """ I�...,. _ 'U J'II&UM ''' I ....)'' ______ ��� , '__ ___==___ Fig. 7.2 Line of ight status fo r RF connections hown from the Figure 7.2. the only tation that has complete isibility is tation 3. This mean that dir ct RF cOlmection can be established only fo r tation 3. Thus all of the remaining fo ur reference tation need a repeater sy tern to be installed in proper place within the network to pro ide the required connectivity. 7.2.4. Selection of Repeaters Locations and Antenna's Heights The GIS patial 3D analy t extension was utilized to help findingthe optimal location of the repeater in the network. The fo llowing procedure was developed to achieve this task: First, the raster urface, which was generated from the GCPs repre enting the • elevation model, i added to ArcMap software including all reference tations that are connected with DMA WA and the stations that need to have RF connection. A group of vectors denoting line of sights were generated from the unconnected • tation with a gradual increase of the observer offset height and target height 100 r pre enting the ant nna height . The e ector "ere u ed to examine the e tent of the vi ibilit y from the tation to the n ighboring station a illu trated in the Figure 7.3. 2 Set oplJons below as deSired. then click the observer pOint and the target pOint on the map Observeroff set Z units Target offset ZUnits Fig. 7.3 Examining the line of sight between stations according to the observer and target heights from ground The same exerci e for generation vectors denoting line of sights was perfonned to • generate vectors from the connected reference station toward the unconnected sites. The offset from ground repre enting the antenna height was also changed gradually at the ob erver and target point . The gradual increa e of antem1a heights i incremented by fe w meter while • in pecting the meeting point of vi ibil ity defining the possible repeater location. The above tep were repeated using a trial and error approach. The possible locations • of the repeater stations were examined while inspecting the line of ight from both ide and changing the antennas heights. Finally, the optimal repeater location can be selected. 101 For the te ted five tation , utilizing GIS functionality and too l , a di cu ed in the abo\ e procedure , helped in figuring out the optimal location of the repeater station , the needed h ight fo r the communication tower repeater tations, and the neare t neighboring tation that i connected with the network. As an example, it wa fo und that the required height of antennae wa 10 meter fo r the te ted station number 1, the repeater needed a length of 3 meters and 10 meter was required fo r the neighboring tation, \vhich i corU1ected to the network. The results of the calculated antenna height based on the above carried out patial analy is are summarized in Table 7.3. 102 Station Station ntenna Repeater Antenna Network tation number Height (m) Height antenna height (m) (m) [ [0 3 10 2. [0 10 15 3 3 3 3 4 30 25 30 15 10 10 Table 7.3 Antenna height fo r the RF station and their repeaters The repeater location and the connecting path derived from this tudy are shown in Figure 7 A. Thi conclude that there is a need fo r e tablishing 3 repeater system . The height of the antenna mounted in tructured towers fo r the tation and the repeater ystem varie from 3 to 30 meters to ensure clear line of sight between the tations and the repeater . From the above discussion, it can be concluded that the GIS 3D analy is tool represents extremely powerful tool to support the optimal deci ion to properly locate the repeaters. GIS 3D analy i tool ha tbe fo llowing benefits: It help in defining theexact number of needed repeater sy terns. • y tern . It helps in defining precisely the optimal locations of the needed repeater • and at the It helps in defining the needed height of each antenna at the stations • repeater . 103 Thi would mak GI a ver . y u eful tool to upport declo Ion rnak' Il1g 1 eading to optimal co t effective 'olution • • R4IP«. ... • _...... Rf StMOOl,. _11ft WAH CotKourSurt.c:e1 _ ADM_WAH 100 Fig. 7.4 Final RF communication network: Stations and repeaters 7.3. Communication Methods between Control Center and Users In real-time po itioning u ing the G SS RTK reference network service, u er employ GPS receivers that are equipped with wirele modems to receive the mea urement correctional signal from the etwork Control Center ( CC). The wireles link could be a GPRS Internet connection a Dial up "'lith GSM modem, VHF, UHF, Frequency Modulation (FM) or Satellite communication. The type of used medium depends on the local environment of each country. For instance, in UK, approximately 20% of the total 10-+ u age of the network i carried out via GSM. The remaining 800"0 i achieved via VHF ( ruddace et at., 2002). The characteri tic of each type of the above communication method can be summarized a fo llO\\ GPR : In thi cn e, the roving user needs a geodetic-grade GPS receiver equipped • v. ith GPRS modem. ubscription with the local Internet Service Supplier (ISS) is required to be able to acce the Internet to receive the correction service through the etv. orked Tran port of RTCM via an internet Protocol (NTRIP). TRIP upports wireless Internet acce through mobile IP networks like GPRS and GSM. The ad\ antage of this option i the 10\ running cost since the charges are estimated a per the ize of the data tran fe rred during tbe un/eying ession. Thi makes it an economical option con idering that the amount of tran fe rred data is u ually mall. However, the peed of linking and data transfer would depend on the data traffic condition of the ervice provider. This type of communication passe the data in a duplex mode. This means that the sy tern i composed of two connected parties or device which can communicate with one another in both directions. Dial up with GSM modem: In this case, the roving u er needs a geodetic-grade GPS • receiver equipped with compatible GSM modem. The user call the center in a dial up mode. Independency of the service provider as fa r a link speed and availability might be an advantage, however the running charges when using GSM modem might be higher than GPRS due to the fact that calling charges is based on the duration of the 105 call, \\!hich may take the whole period of the urveYlllg se Ion. Thi type of communication also pa e the data in a duplex mode. VHF: In thi mode, the correction data can be broadcasted In one or two ways • communication u ing wirele VHF tran ceiver and repeater network . The roving u er In thi ca e need an RF data modem. The main di advantage of thi option is the limIted geographical coverage due to need fo r a clear line of sight. The high capital co ts that might be needed to build up communication towers repre ents another di ad antage. However, the biggest advantage of this option is the free running costs a no calling charge are needed. An e ample of uch system is the 2m-band VHF delivery ystem being used with excellent result in Germany. This type of communication pas es the data in a simplex mode. This means that the ystem is compo ed of two connected partie or device that can communicate in one direction. In thi ca e, the data i ent only from the broadcasting station to the roving u er. Satellite communication: In this case, the rovmg user is connected through the • Internet or dials up to the network processing center to receive the corrections from the center through a satellite based service. This service works in a imilar principle as the GSM dial up or GPRS through the Internet by dial up access to the service provider. The satellite-based system 'Thuraya' is one example of such service providers. It provides access to the Internet in its dual mode handset. Thuraya ubscribers can brow e the Internet anytime and anywhere within its coverage area. The coverage area of this Satellite service in the Middle East region is illu trated in 106 FIgure 7.5 (Thuraya, 2006). Thi type of communic ation a1 0 pa e the data in a dupl x mode. - - - Fig. 7.5 Satellite communication geographical coverage by Thuraya The ad antage of this option i its global coverage giving unlimited geographic access to the ervice within the regional RTK reference network, which makes it advantageous fo r remote areas. However, the drawback is the high cost of the equipment and running cost of calling charge . The ummary of the compari on between diffe rent medium options that can be used fo r broadcasting the network mea urement correction signal as fa r as range of coverage, reliability, capital costs and running charges are given in Table 7.4. [t can be concluded 107 that u ing GPR a a communication medium i the best option that ati fies the optimal benefit a fa r a range of coverage, reliability, capital co t and running charge Geographical Charging Capital �umber of Running Coverage Ba is Co t Concurrent Users Cost by u ers �TRIP : GSl\I, 0 CPR GSt\I Dial up 'Jational time Low Few Medium Satellite Global Time and Med Few High communication data \,HF-U HF Limited Subscription High Many Mintmal Broadcasting Fl\l Limited Subscnption Low Many Minimal Broadca ting Table 704 Comparison between the broadcasting media options 7.4. Using GIS to Examine the VHF Broadcasting in Abu Dhabi Studying the fea ibility fo r u ing the VHF communication fo r broadcasting the RTK reference network information in Abu Dhabi seem from diffe rent aspects an important option for future need . It is uggested in this research to mount the broadcasting tation that at the highs points in Abu Dhabi. One of pos ible locations would be the Sky Tower y Tower will will be established in Al Ream Island. According to (Cribs, 2007), the Sk letion date of the have 83 stories, with approximate height of 379 meters. The comp in Figure 7.6. The project is cheduled fo r May 2009. The Sky Tower location is shown tely determined as it is area of co erage, inside and outside the city, should be accura 10 con Idered a on of the main fa ct or fo r e aluation of the ervice potential. The GI i th proper tool to identify the required area of co erage. Fig. 7.6 Design view of Sky Tower in Abu Dhabi . (Source TEN Real Estate) 704.1. Required Information fo r VHF Broadcasting Ln order to tudy the fe asibility of u ing the Sky Tower fo r broadca ting the measurement correction from the RTK reference network, the fo llowing GIS data, analy is and presentation are required: Data of the UAE border is needed to define the project area. This data i obtained • from ESRI tutorial materials in the fo rm of a polygon Layer in a hape file fo rmat. 109 Data of the Geodetic Control Point i required to make u e of it height value to • interpolate the ra ter elevation urface. This data i obtained from Abu Dhabi Municipality in the fo rm of a point fe ature layer in a shape file fo rmat. T\\ 0 layer were created and deri ed from the GCP data: a raster layer of an • interpolated urfa ce that represent the ele ation model of the project area, and a layer including contour line , repre enting the terrain elevation level . Data of the reference station i required to identify the location of each station. This • data i obtained from Abu Dhabi Municipality in the fo rm of a point fe ature layer in a hape ti le fo rmat. Table 7.5 ummarizes the acquired and created data. Layer Feature Type Format Source Used attributes / Role UAE Boarder Polygon Shape ESRI Background Geodetic Control Point Shape ADM Height, a source to derive Points ra ter surface mode I Elevation Raster GRID Created Elevation model as a source of Contouring Contour Line Shape Created Elevation, indicating elevation heights Building Polygon Shape ADM Height, representing obstacles Building spot Points Shape Created Height to generate raster heights surface model 110 Table 7.5 U ed data fo r the ky Tower broadca ting ignal analy i 7.4.2. Implementing Geospatial Process and GI Analysis To e amme the po ibility of u mg the ky Tower fo r the broadca ting of the mea�urement correction from the RTK reference network via VHF signal , the fo llo\ ing tep were carried out: A terrain model fo r all of the Emirate of Abu Dhabi is created based on heights of the • Gep . ra ter ele ation ervice model i generated using ArcG[S 3D analysi . • A point fe ature i created at the Sky Tower location in Al Reem I land in Abu Dhabi. • The height attribute a igned to it \Va set a 380 meter . U ing ArcView 3D analy t extension, a ra ter urfa ce model is generated from the • GCP layer, mentioned above, to reflectthe topographic changes. U ing the line of ight functionality, visible and invisible places are identified to • determine the po sible areas of coverage. Thi task is illustrated in Figure7.7. From the Figure 7.7 it can be concluded that the majority of the areas within the Emirate of Abu Dhabi are visible from the Sky Tower, which guarantees that the broadcasting ignal will be received. This exerci e show that without GIS in such study, it would be hard to achieve such important conclusion. Thu GIS facilitates achie ing important 111 conclu Ion with minimal effort and in a peedy manner. The traditional normal approach " ould be a tediou and time con uming altemati e. Visible - Invisible -�------���--�--� • A Legond• SkyTo",o, ctou(J _ 1 18021�12· 32 7:)64().121 UAE 32 7364().122 • 292589 29258901 .9580187138 64 95 801871381 · '27 64 127 40495087 158 96" 434 J().I9586 961 143!t · 190 5173282 1!>S i 1 1.800,000 Fig. 7.7 Visible and invisible line of sights from the Sky Tower Building 112 CHAPTER 8 ADVANCED RTK NETWORK BASED GIS APPLICATIONS The RTK reference network pro ide real time po itioning at the centimeter level fo r a \\ id geographical coverage, which gives a chance fo r many re earch institutes and olution pro iders to de elop a variety of new GI applications and enhance current ones. Thi ection explore orne of the ad anced GIS application that are based on u ing the RTK reference network . Machine automation olution that integrates RTK reference network v.:ith upervi ory Control and Data Acqui ition (SCADA) is a good example that help improving field\ ork in several areas. In thi chapter, the use of RTK reference network , with machine automation and SCADA ystems is presented. Remotely monitored and controlled field machine application is explored a an example to in\e tigate and study the concepts and fe asibility of integrating RTK reference network ervice \ ith GI and SCADA. Some other applications that are based on RTK reference network and can benefitfr om GIS techniques include mapping, volume calculation, cut g. & fill.dredg ing, machine automation and land levelin 8.1. Remotely Monitored and Controlled Machine Automation Integrating RTK reference network with SCADA can enhance location-based applications with additional functionalities and capabilities. Ha ing real-time accurate 113 po itioning p information a a newly introduced field input to the SCADA ystem gl e a lot of opportunitie to develop many solutions fo r planning, designing, con tructing and monitoring field operation that require precise po itioning. Figure .1 dIu trate a de eloped architecture a a propo ed example of uch integration. n automated machine uch a a field tractor that can be automatically operated, unmanned and fullyre motely monitored and controlled is presented. The machine would be controlled by the analogue and digital outputs from a Remote Tenninal Unit (RTU). It j propo ed that the RTU will have preloaded Programmable Logic Control (PLC) oftware that activate the outputs according to the field input from the machine primary 'en ors, as well the real-time accurate coordinates fe d from the GPS roving unit receiving mea urement corrections from the RTK reference network. The field operation , events, log and alann can be fully remotely monitored through the SCADA system. For the DAD y tern programming oftware standards uch as lEC 1 L31-3 is proposed to be u ed. lEC l13 1-3 is the intemational tandard fo r programmable controller programming language . As such, it specifies the yntax, semantics and display fo r the PLC programming language . An open standard communication protocol such as Oi tributed et\ ork Protocol (D P) i also sugge ted. D Pi a set of standard and interoperable communication protocol used between companies in process automation ystems. These open tandards and interoperable platfonns will allow the system design to be implemented in any of the industrial proven commercial SCADA systems away from any proprietary platform or vender pecific solution. The functionality and process automation of the proposed integrated system can be described in the fo llowing step : 114 l- The roving GP which i mounted in the fieldma chine receive the correction from the RTK reference network. The ro ing GP hould be enabled with a GPR modem and proper ub cription to the RTK reference network in order to be able to receive the correction . The GP receiver continuou Iy fe eds the RTU with the real-time po itioning information (x, y and z coordinates) repre enting the exact location of the machine in the field. 2- The RTU controls the field machine based on a preloaded automat ion process program that produce the controlling outputs based on a et of variable inputs from the primary sen or as well as the input of the variable po ition information which is produced from the GP receiver. 3- When the machine change its status and location, the RTU receives the new signals from the input including the new positioning information. Thi process loop keeps running according to the oft PLC program, which is pre-loaded in the RTU to govern the automated fieldproce s. 4- The RTU is connected through a modem to a remote monitoring and control center equipped with SCADA monitoring and controlling hardware and software. The SCADA system will be integrated with the GIS through an interface where the mimic are truly geo-referenced maps representing the reality of the fieldin a full3D mode. The fieldautom ated process is fu lly monitored and controlled in a remote mode. Report alarms, trends and historical records can be retrieved and archived at the SCADA centre. can be planned 5- Field construction works such as cut & fill, land leveling or dredging at the backend office u ing GIS and utilizing an accurate planning and base-map data. 1 1 - o tern will e tract the 3D accurate coordinate of the fi eld point from Gl and get it impeded in the oft PLC program, which can be downloaded remotely to the fieldRT . 6- Real time data from the GP and tbe primary en or can be sent remotely from the fieldthr ough the RTU to the CADA s tern to update the GIS map with real time information. Thi would help monitoring the actual field progre ed work again t the planned one. The de eloped integration architecture propo al is shown in Figure 8.1. RTK Supervisory Control andNetwork Data Acquisition SYlitem ( SCADA) <0� GO ¢=> c� c.."tlN' J l ONP Protocol . .. O Rofo nco SIMI"". '-"'.. -'\.cC-) PRS - - -- - Intemel l Gl-7'� -- ___ Intamll4 ______-- IEC - � j:RS� � �_� '--..'--://"S 1131-3 1 � GPS Rover �Modem;; ••.. •.) c::. ______Remote -� �- '''''1��1 r .. T2·rm coordi_ 1 x. Y Z I ( . r-3 ) Doootal An�ogue & """Iogue�---- o.rtpu: .. ModIlno Input. ModI .... Contro4- -Moving Senaon ----- _ ____I -- - F,gOU _____ l Mac ---- ;:7 ITII]'- - --' SCADA Measurement and control Equipment In the field moving object RTK Networ c=J F'Ig .. 8 1 Proposed RTK reference network & SCADA integration 116 The logical equence of the oft PLC proces program of the RTU i illu trated in Figure .2 a a flowcb art. The program tart with in:itializing and te ting the y tern availability and bealtb tatu . It read tbe current po itioning information of tbe macbine as well a th tatu of the input from primary en ors. It execute the RTU proces program while monitoring any alarm or malfunction signals fo r an emergency stop. The RTU event , log and alam1 are ent to the remote CADA center. 117 Read Coordinates. pnmary sensors Input. remotly ". • downloaded new programes & Execute RTU Program j .. Read output feedback Read RTU Inputs I Yes Report by exceptJon to SCAOA & GIS .. � o � Yes Send events, reports and Report to SCADA trends to SCADA & Display triggered ? in GIS f No Update inputs & outputs readings Update RTU Programm �" I • Updat coordinates 1--- Readings Fig. 8.2 Flow chart fo r the RTK Network & SCADAIG IS Logic control II n th r propo ed cenario of field machine automation integrating the RTK reference net\\ ork wi th C 0 to allow a field operating excavating machine to preci 'ely excavate according to pre et accurate plans. The architecture of the proposed mtegrated y tem i illu trated in Figure 8.3. The proposed ystem present a cost effective olution to automate a proces of land leveling and exca ation that i carried out in the field by u ing a group of excavator . Applying the same proposed design fo r automating the fieldmac hine that was discu ed earlier; each exca ator will be equipped \\ ith a roving GP recei er which i equipped with a wireless Local Area et\vork (L ) modem to enable receiving the RTK reference network corrections through the router, which i installed in site. The router is connected to the RTK reference net\vork through an ADL Internet link. The excavator is also equipped with a pre-programmed RTU which i connected to the SCADA y tern. To achie e the optimal running cost when utilizing the RTK reference net\: ork service, an Internet enabled wireless LA propo ed on ite to be used as a medium fo r re cei ing the RTK reference network correction . With this arrangement, the running cost of communication charges will be only limited to the monthly payment of the ubscription to the InternetADSL ervice. 119 _lion D ot_ - SCADA Fig. 8.3 The architecture of the proposed integrated system of RTK Network & SCADA/GlS fo r machine automation 120 CHAPTER 9 CONCLUSIONS Today , ne,,\ and hallenging application and construction works demand real-time po itioning accuracy at ub meter and centimeter-Ie el. The traditional technique of using a ingle reference tation (ba e-station) and a GPS roving unit to achieve centimeter accuracy has a limitation where the di tance dependent error will be significant when the ba eline exceeds km as well a the dependence on the availability of the nearby GCP. 10 In tead of relying on a ingle reference tation, many modem cities nowaday establish GP multi reference tations that can be u ed fo r post mission or real-time positioning, which are widely u ed a Real Time Kinematic (RTK) reference network . Thi i due to the benefit of thi type of networks of not only providing real-time high quality accurate and con i tent GPS positioning at an economical price over a wide geographical area, but al 0 increa ing the surveying productivity, reducing capital equipment costs and it ea e of use. RTK reference networks service , being util ized by all agencie , can be con idered as one of the main components of the infrastructure of spatial data. Gl can be used as an advanced tool to optimize the design and implementation of the RTK reference networks. In this research, it has been concluded that the u e of GIS can help in optimizing the design and implementation process of the newly, under construction, Abu Dhabi RTK reference network. The main considered design parameters 121 fo r the RTK reference network included: the di tance eparating reference tation , type and location of ite ho ting the reference station , the communication between reference 'tation and the y tern center, and between the computing center and the user . fi eld te t wa performed to examine the po itioning accuracy from the available augmentation y tern in Abu Dhabi. Te ting the beacon measurement correctional en,ice a a GBAS y tern, and po itioning accuracy u ing OrnniSTAR a BAS system \\ a carried out in March 2007. Re ults showed that the GBAS y tern gave better po itioning accuracy. Howe er, both ystems gave accuracy at sub-meter level. For bu Dhabi, there are three option fo r selecting a coordinate reference ystem fo r the R TK reference network: the coordinate system of the old datum, which is based on ahra\ an datum u ing Clark 18 0 ellip oid, the currently used ITRF2000 coordinate y tern. which i ba ed on WGS84 Datum, and the new [TRF2005 coordinate y tern reference which i al 0 ba ed on WGS84 Datum, but in a different measuring epoch. It wa concluded that building the Abu Dhabi RTK on either the [TRF2000 or lTRF2005 WGS84 coordinate system reference is the best option. This is due to the fact that this would be the be t approach when con idering the overall compliance with international reference coordinates frame , consistency with the old and the existing geodetic network, compliance with the old and the existing spatial data and the user needs. Few approaches were suggested fo r distributing the reference stations in Abu Dhabi. Tho e include: maintaining a distance between the user and the nearest reference tation of 35 krn with/without overlap of the coverage area, maintaining a distance between the 122 u 'er and the neare t reference tation of km 50 \. ithlwithout overlap of the coverage area, and di tributing the tation according to the demand of service. It was concluded that fo r bu Dhabi RTK reference network, di tributing the stations according to demand of ervice i the be t option due it greate t compliance with cost of establishing the ystem, 'y t m reliability, and degree of ati fying ervice demand and userneed . [n general, reference tation hould be installed in buildings that are secured, powered, have acce to communication, table and open to kyo It was pro en in this re earch that GI tool can help electing the optimal sites that satisfythe above criteria. ArcGIS tool uch a ejection by attribute, analysis model builder and 3D presentation were used to help investigating, evaluating and electing the be t building fo r each reference site. A generic analy is model wa developed using ArcGIS model builder to run a eries of automated querie go\ emed by the above mentioned criteria against a unique et of data input fo r each site. ArcScene oftware module was very useful tool to examine the unounding building fo r sky vi ibility and displaying results in a 3D fo rmat. It has been proven in thi research that the GIS is a powerful tool to examine and analyze diffe rent approaches of the telecommunication infrastructure fo r the RTK reference network, and next elect the best one based on the optimal compliance with performance, reliability, capital and running costs of the network. The options of permanently connecting the stations to the center might include: Corporate Wide Area Network (WA ), govemment fiber backbone, service provider leased line and Radio Frequency (RF). It was concluded that connecting the reference stations of Abu Dhabi network 123 tern to the cente r u ing the go emment network wherever available the fl f t preferred option. U ing the ervice provider land line connectivity i the econd be t option, wherea u ing the RF connectivity represent a rea onable option fo r the station that are not reached by either the go errunent network or service pro ider land line connectIvity. GI \Va in trumental when utilizing the spatial 3D analyst extension in order to help fi nding the optimal location of the repeaters in the case-study of Abu Dhabi net\vork fo r the area where RF communication medium wa required. GIS 3D analysis tool repre ent extremely powerful tool to support the optimal deci ion to properly locate the repeater due to the fa ct that it enabled fa cilitating defining the exact number of needed repeater y tern , defining precisely the optimal location of the needed repeater systems and detining the needed height of each antenna at the tation and at the repeater . The rovmg users can be connected to the center through one of several options of wireles links including: Global System Mobile (GSM) General Pocket Radio System (GPRS), or Radio frequency (RF) and Internet satellite communication. It was concluded that u ing GPRS a a communication medium in Abu Dhabi is the best option due to the fact that it ati fies the optimal benefits as fa r as range of coverage, reliability, capital co ts and running charges. U ing the VHF communication for broadcasting the RTK reference network information in Abu Dhabi is an important option for future need . It wa suggested in this research to 124 mount the broadca ting tation at a high point in Abu Dhabi. This would include the ky Tower building that will be tabli hed in AI Ream [ land in 2009. It was concluded by u ing the G[ tool that the majority of the area of intere t are vi ible from the ky Tower, which guarantee that the broadcasting signal will be successfully received. Integrating RTK reference net\ ork ervice with GIS and advanced applications such a C ADA give a chance to enhance the current location-based ap plications and field machin automation \i ith additional functionalitie and capabilities. To achieve the optimal running co t when utilizing the RTK reference network ervice, an Internet enabled wirele LA is proposed on site to be used as a medium fo r receiving the RTK reference network corrections. With this arrangement, the running cost of communication charge will be only limited to the monthly payment of the ubscription to the Internet ADSL service . References bu Dhabi Municipality 2007. Bullit! Regulatioll. Department of Municipal ffair , bu Dhabi, AE Imrzo qi, Y., Fa hir, H. and Babker, T. 2005. Es tablishment of Dubai Virtl/al Referellce YSTem (DVRS) National GPS-RTK NetH'ork. Conference "From Pharaoh to Geoinfonnatic ",Cair o, Egypt pril 16-21, 2005 th u tralian Maritime afety Authority, DGPS, Acce sed on 18 October 2007 from http: www.am a.gov.au/Shipping SafetylNavigation Safety/Differential Global Postiti onmg Sy tem General lnfonnation! Barney,G. 2007. The Riche t city ill the world. 1 sue o. 172, Fortune, March 19, 2007. th Crib Central. The sA:} To wer - The gate Di trict. Acce se on 16 June, 2007 from http://www.crib central.com/fearured property detail.asp?projectid=268 Cruddace, P. Wi! on, t, Greave , M. Euler, H-J, Keenan, R. and Wtiebbena, G. 2002. The long road to eSTablishing a national network RTK solution. In: Proceedings, FIG XXll lntemational Congre , Washington, D.C. USA, APlil 19-26. 2002. Elliote, D. 1996. Understandillg GPS Principles and Applications. Artech House Pub!i her. orwood, MA USA. pp. 101-107. EI-Mowafy, A. 2002. Performance Analysis of the RTK Te chniques in Urban Ern'irolllnellf. Technical Papers 48, The Australian Surveyor. Deakin, Australia. Vol. 45 o. 1. EI-Mowafy, A., Fashir, H. Al Marzooqi, Y., Al Habbai, A. and Babiker, T. 2003. Te sting of the DVRS Natiollal GPS-RTK Netl-I'ork. In: Proceedings of the 8th ISU Lnternational Sympo iUITI, Stra bourg, France, 25-28 May, 2003. 126 EI-Mo\ afy, . 2005. Analysis of the Design Parameters of Multi- Reference Station RTK CPS etworks, un/eyingand Land Infomlation cience. Gaithersburg, D U A. 01. 65, o. 1,2005, pp. 17-26 Euler H.-J., Keenan, R. Zebhau er, B., and Wilbbena, G. 2001. Study of a simplified approach in utili-;.illg illfonnaTion frolll penl1aJzellt referellce station arrays. In: Proceeding of GP -2001. Salt Lake City, USA. 11-14 September, 200 1 10 Euler H.-J., Keenan, C, Zebhauser, B. and Wubbena, G. 2002. Reference station nel1l'Orks: A conceptual study using their injornlCltioll Ivith the current and next generation of RTCM llIe ·sages. In: Proceeding of the European avigation Conference, the 6th International GN S symposium, G SS-2002, Copenhagen, 27-30 May, 2002. Euler H-J, Seeger S, Zelzer Takac F, and Zebhauser B. 2004. Improvement of 0, Positiollin � Peli onJ1([llce Using Standardi-;.ed Nel1l'ork RTK Me sages. Proceeding of TM, San Diego, C , January 26-28, 2004. 10 Fore t ervice Technology and Development Program, Comparing Four Methods of Correcting GPS Data: DGPS, WAAS, L-8wzd. and Postprocessing July 2004 , Accesses on June 1 "\ 2007 from: http://www.fs .fe d.us/database/gps/pubslhtmlpubs/htm047 1 2307/ Fugru World Wide. About Ol1lniStar World Wide DGPS Service 2005. Acce sed on June 1 "1, 2007 from http://w\vw.ornnistar.com/about.html Hofmann-Wellenhof, B., Lichtenegger, H . and Collins, 1. 2001, GPS Th eory alld Practice. Springer-Verlag Y USA. pp. 20-22, 136- 1 39, 223, 348. "1 Johnny Apleseed GPS company, Th e theory alld practice oj GPS, Acces ed on June 1 , 2007 from 'http://'A,'WW.ja-gps.com.au/whatisgps.html. 127 Longley P., Goodchild M., Maguire D., Rhind D., 1999, Geographic bzjomwtion \'stems iley We tu x England. pp. 1 4, 404, 488, 1002, lOt9. Longley P., oodchild M., Maguire D., Rhind D., 200 I, Geographic Infon/wtion Systems and cience Wiley We t us ex England. pp. 80, 169-171, 184- 1 89, 282. Me 0 ,J., John on K., 2002, Usillg ArcGIS Spatial Analvst, ESRl, CA. USA. t Motorola. Glo ary of Term , ece ed on 8 h June 2007, fr om http://www.motorola.com/governmentandenterprise/contentdir/en GB/Files/Productlnfor mation ETRA Glossary.pdf Mueller, T. 1994. "Wide Area Differential CPS", GPS World, Santa Ana California, US . Innovation, June, 1994. Muller, T., Bie ter, M., Loomi , P, 1994. Pelfonllance comparison of candidate U.S. eoa t Cuard WA DGPS network architecture. In: Proceeding 0 the ational technical Meetll1g of the in titute of avigation, San Diego, California, USA. January 24-26 t ASA, CPS augmentatioll & Other network Accessed on I June, 2007 from http: fgpshome.sse.na a.go v/content.a px?s==aug Petrov ki, I., Kawaguchi, S., Torimoto, H., Fujii, K., Ebine, K. Sasano, K., Cannon, M. E. and Lac hapelle, G. 200 L, "Practical Issues of Vi rtual Reference Station 5t Implel1lentalioll for Nationwide RTK Network", Proceeding of G SS 200 I, The h G SS InternationalSymp o ium- Satellite avigation: Objectives and Strategie , Seville, Spain, 8-11 May. Raquet, J. 1996. Multiple Reference GPS Receiver Multipatlz Mitigation Te chnique. In nd Proceedings of the 52 Annual Meeting of the In titute of Navigation, pp. 68 1-690. Cambridge, Mas achusetts, USA 1996. 12 Raquet, 1. 199 . Development of a Methodfor Kinematic GP Carrier-Phase Ambiguity Resolutio/l Using Multiple Reference Receivers. PhD The i , published a Report o. 20 1 J 6, Department of Geomatics Engineering, The Uni ersity of Calgary. Canada. Raquet, 1., and Lachapelle, G. 2001. RTK positioning with multiple reference stations. GP World. anta na California, USA. 12(4) pp. 48-53. th Red \: ord orporation Hmv GP alld GNSS works, Acces ed on 28 September 2007 fromhtt p://www.redsword.comlGPS/apps/ge nerallhow.htm. Rizo . c., Han, . 2002. Reference Station Network Based RTK Systems - Concepts and Progress. The Uni ersity of ew outh Wale , Sydney NSW 2052 USTRALIA, chool of urveying and patial Information ystem . Rizos, C. 2003. Netll'ork RTK Research and Illlplel1lelltation- A Geodetic Penpectil'e, The Univer ity of ew South Wale , Sydney SW 2052 AUSTRALIA, School of urveying and Spatial Infolmation Sy tems. Ro enthal, G. 2005. Th e Modenzi;.atiol1 Of TIle State of Berlin Geodetic Reference Svstelll Reali;.ation, International Symposium in Geodesy, Sofia, Bulgaria , ovember 03-04, 2005. Santana. J. and Tottwr trom, S. 2002, all Testing of RTK-Nenvork Virtual Concept, FIG XXII International Congres , Wa hington, D.C. USA, Apri1 19-26 2002 Satirapod. C. and Hominiam, P. 2006. GPS Precise Point Po 'itiolling Software fo r Ground Control Point E tablishl7lent in Remote Sensing Applications. Journal of Surveying Engineering, Y, USA Volume 132, Issue 1, pp. 11-14 (February 2006). Seeber, G. 2000. Real-Time Satellite Po itiolling on the Centimeter Level in the 21s[ Century using Pennallent Reference Stations, ordic Geodetic Sunmmer School, Fe ik, orway, 30.08.2000 129 egui, W. 2003. "LRFD teel Design, edition," Thorn 3rd on Brooks/Cole Belmont, CA U imiu E. and canlan R. H. 1996. "Wind Ef fects on tmctllres - Fllndalllellfais and Applications to De\'igll, edition," John yd Wiley & Son , Hoboken J USA. l111th J. . 1996, "Stmcrural Steel Design - LRFD Approach, edition," John 2nd Wiley & on ,Hoboken, J U Taylor, G. and Blewitt, G. , 2006 Intelligent Positioning, John Wiley & Son , L TO. Hoboken, J USA Terry, K. 2001, Integrating GIS and thee Global Positioning System, ESRl, USA. pp. 3, 13-1 . th Thuraya, 2006, 'Direct Dial Up ' access to Imel7let, Acce ed on 16 June 2007 from ( http://w\vw.thuraya .cofTh contentJdirect-dial-up.htmI. Wtibbena, G., Bagge, A., Seeber, G., Boder, V. and Hankemeier, P., Reducing 1996, Distance Depelldam Errors for Real-Time Precise DGPS Applications by Establishing Reference Station Networks. In Proceedings of the 9th International Technical Meeting of the atellite Division of the Institute of avigation GPS-96), pp. 1845-1852. (10 Kan a City, Missouri, 1996. ION GPS-97, Kansas City, Missouri, September 1997 10 Wtibbena, G., Bagge, A. and Schmitz, M. 200 1A. RTK networks based Oil Geo++® GNSMART- Concepts, implementation, and reslIlts. In: Proceedings of the International Technical Meeting, ION GPS-OI, Salt Lake City, September 1 1-14, 2001. Wtibbena, G., Bagge, A. and Schmitz M. 2001B. Network-Based Te chniques fo r RTK pan In titute Applications. In: Proceedings, GPS Jl 2001 Sympo iurn,GPS Society, Ja of avigation, Tokyo, Japan, overnber 14-16, 200 l. 130 �I.? �WI �I yJI jL...:,) � �� ("\.b.j � �h. (":!.lil � Y �..fo.JI �..;bll . . � - I _ ' . �I �\.S.:i 0-".5}'i 1 .l.:Jl.J.J .J I I � .) � � � �..;-.JI L...... JI w�1 ("Lhi J..,\.S:i.l (."S':9"j,,,aJI �I �1.J.l!\ c fo.J ��I � ("I�\' 4...i).ia � \ � o �\.Jj I..?) � .l9.J .�IH wla�1 �.J �I..;-.JI.J o� 1,...,\.oQ� J..,�.J:. \.S:il1 I� l.J� �1.J.l!\ �.J'�4-l\ �I ��I �ls �YI .,;bjl w4kc \ �",....w-, �I Jlac.l � � .jC �YI �\..;-.J\.J o� � w� �.J y-",hiJ .�\ .J�I � 0"."..J... �Y �.J�\..c. 4jj.J O�� �I.J� I 131 l...A �I ;.,� �yJI -, �)I.J w'W4.JI LY> 19 �tS..JI �.w\ .for �-' :i..:;JkA.JJ....1.S:i .J .�\.:ij 'O.. 1.iS LY> �-'� f'JA' ·,ill t9)1 � Lt.....: �! li� � � w�L....JI �.b.:i.J �I"p �L....JI wl..h:....Jl e::jy wl)� �I ��.J ..;JI.J �kA :i,.j).i.JI �\.:ij 0Sly �..J.A � .. (":lp\ t-" � �� �yll-, wl)�ll � J:b..:i o wi ).. :i,.j}.iA-' J:h:i � ��.J I.J 'O .. �I .l.<> )�)l �jyl\ ? .)...p.. JSJ � � 1 � hli w\..b...JI e:: )y Cl:W...... )l l.. u� 1 .:.k . < � :i,.j . .:..'I lo·L ·I i WI...J.ASA . L� . ..JLi.JI .J �I . . < w I .1.:.. w -'j l I I I " �I ' .J <.,? < r..,r�:W I r-. < , �� I...S"'. . 0� � � • w I I I ufo ..) �� � Lb....J '-4"; M ul � � �4-.J J,...;::..Si ..J�I � 'OLL....JI . < . ::"UWI • �• 'u. ...:u..J• � �t.=..< \ J<'=I� loS � �. (1\ � :G�< . � .J li.Jli. .J 'u....< �.C I . 4...5 \.:.: . : ' ( :iJ � :Uk! 'Obi U' .,...... (. u �. .. ': 11 .J 'I wl.. ·L .'I . 1.:.. ; f'I� 'u ')WI .A.J'u. .J y-a '-.? . i t.,? :W< I�·:.. · � � . � . �..?-'-· '1 �\.:ij � "�.J .:i...:..yi.J I �4-JI LY> 'O� 'O..J� ��I }..<>!Y\ wi)... ;') J�I ��l � J-! ).AJ l I hi A...... I..J� �1y..;JI wl.....�1 wl.Jj! �y lJS....: .�� 0�1.iS.J 4.c.Y" .J 4j�� tull �i Lb....JI wbfo:i...... , IJ�1 d�i �.J-!i 'O..JloJ � �L....J\ w � f'\..hJ (,?'.I9'ill'A\1 � � LY> �WI �lyJI �.b.:i f'Lb.i j�) � �� JL...) ,hjL...-' -' li;b � J)l:.. Y I w� I ..,hJ.J 0:!-"\ :"-; ,, 'A ll w\..b...J\ � f'\..hi t-" i.Sy.. 'i I :i.....J:..i I J...1.S.:i > �w y, � 1..J�1 fo.J .�L....JI jjpl w\� .J:ljl) I w�-,-" � �)lll �I �-' f'1 l :iJl...aj :i...... , c �lb.J �I LY> �L....JI j�..JYI w\..j4! �I j� '-4"; 0.i..;h uc � \:.1.".J.l JiJ �W\ I-, ..J.J �.J-!i O..Jl..) �i �)\jl (":l)1 Oy,...?- � o�� Cjii.J ' \.:i <.,?tS..... cy W) � � � 4.J1 1..Jj � ..�-' .(f' u� CLW...-.:l I � '-- --!oIJ l�,JI �L...... ,I.).ll1 O.l� �I�I �\..4�1 J .)�'JI �\..4 � .lly LP �Uj;l AJ\.....,)1 61� ��I � I Ji..a�1 � � ");,11." �J4q"'l1 � �I�I �\..4�1 � f'1�1 o�1 �..;aJ1�1.J \..4�1 AJJ.l- �.;.:i� :.!A411 el ' �J�I � -Ul1� • (,.iJi1, '44 \.;1 �.;JI �'JI f' A...u.u.I ,,) � �I I .J ��I� ��I � �I..,...JI � .l..c=.i ,,,) 1 o�1 �yJl wl),.o'll�L;.. - ��I � � ('yW I �� b)�1�I �I � � �li:. � �L...... l 2 o�1 �yJI wl.JL.o'l1 �L;.. o�1 ��I �1.Jl4'i1 �4- �I �L....I.J.ll1 oJ� .. · , . .! ... .. j . � ( .!J t� 3,, \ . ... \ ..,\ � . A\ t\ A t .. 1\ �t:-� \ " ...14.lj, \ .' � � ';9 II .J to �\\.I � � '-I\.A�. � � I I � �} 4...a.ll..a ;U�J 1.--�)":lI..lJI w�IJ.ll1 o.J� o�1 �yJl WljA)'1 �l;.. � l.P )�;J\ rYe� �WI �Jj � J�I w� J�;; �I�\ w��1 �.J 2007 �j