University of Southern Queensland Faculty of Engineering & Surveying Telemetry and Communication Systems for Irrigation Management A dissertation submitted by Alison McCarthy in fulfilment of the requirements of ENG4111/2 Research Project towards the degree of Bachelor of Mechatronic Engineering Submitted: November, 2006 Abstract The development of wireless communication systems for agricultural and irrigation ap- plications has enabled farm managers to access real-time data from in-field sensors to improve on-farm operations. Recent research into wireless sensor networks for agri- culture has focussed on reducing the power consumption and manual configuration of the nodes by the end-user, while commercial wireless sensor networks use short-range transceivers such as Zigbee or long-range transceivers such as UHF citizen band radio. However, the research wireless sensor networks often experienced reduced reliability under field conditions. Therefore, this project aims to design a telemetry system with a focus on reliability under field conditions. UHF citizen band radio was investigated as a candidate wireless transmission medium over which audio tones, modulated with serial data, were transmitted. The modulation technique used was frequency modulation, and was implemented using integrated circuit modems. A wireless network was designed with: a polling medium access method; star topology; error handling using repetition and cyclic redundancy codes; and robust protocol. The developed telemetry system was tested under field conditions, such as in the pres- ence of crop canopy and irrigation water, and near power lines which potentially cause noise in telemetry signals. Data delivery rates of 100% were achieved using 0.5 W radios transmitting at 1200 baud for 2 km, which satisfied all the telemetry system requirements. UHF citizen band radio is a reliable, long distance transmission medium for wireless sensor networks. The feasibility of a wireless sensor network using UHF citizen band radios and medium access methods including polling for on-farm use has ii been demonstrated. Further research on the use of UHF citizen band radios in wireless sensor networks may potentially allow higher data rates and rival data rate capacities of short-range transceiver networks. University of Southern Queensland Faculty of Engineering and Surveying ENG4111/2 Research Project Limitations of Use The Council of the University of Southern Queensland, its Faculty of Engineering and Surveying, and the staff of the University of Southern Queensland, do not accept any responsibility for the truth, accuracy or completeness of material contained within or associated with this dissertation. Persons using all or any part of this material do so at their own risk, and not at the risk of the Council of the University of Southern Queensland, its Faculty of Engineering and Surveying or the staff of the University of Southern Queensland. This dissertation reports an educational exercise and has no purpose or validity beyond this exercise. The sole purpose of the course pair entitled “Research Project” is to contribute to the overall education within the student’s chosen degree program. This document, the associated hardware, software, drawings, and other material set out in the associated appendices should not be used for any other purpose: if they are so used, it is entirely at the risk of the user. Prof G Baker Dean Faculty of Engineering and Surveying Certification of Dissertation I certify that the ideas, designs and experimental work, results, analyses and conclusions set out in this dissertation are entirely my own effort, except where otherwise indicated and acknowledged. I further certify that the work is original and has not been previously submitted for assessment in any other course or institution, except where specifically stated. Alison McCarthy 0050009145 Signature Date Acknowledgments My family for their support throughout my project and program. My project supervisors, Mark Phythian, Professor John Billingsley and Erik Schmidt for their assistance and guidance. Nigel Hopson and Lindsay Evans in Jondaryan and Ray Griffith in Dalby for providing field trial sites. Alison McCarthy University of Southern Queensland November 2006 Contents Abstract i Acknowledgments v List of Figures xvi List of Tables xxi Chapter 1 Introduction 1 1.1 Broad Aims and Specific Objectives .................... 2 1.2 Overview of the Dissertation ........................ 3 Chapter 2 Background 4 2.1 Telemetry in Irrigation in Australia ..................... 4 2.2 Furrow Irrigation ............................... 4 2.3 IrrimateTM Surface Irrigation System .................... 5 2.4 Other Advance Rate Sensors ........................ 7 2.4.1 Capacitance Sensors ......................... 7 CONTENTS vii 2.4.2 Two-point Measurement of Advance Rate ............. 7 2.4.3 Agricultural Sensors ......................... 8 Chapter 3 Literature Review 9 3.1 Wireless Technologies for On-farm Sensor Networks ............ 9 3.1.1 Short-range Transceivers ....................... 10 3.1.2 Citizen Band Radio ......................... 11 3.1.3 Amateur Radio ............................ 12 3.1.4 Cellular Mobile Telecommunications ................ 13 3.1.5 Infrared, Visible-light and Acoustic Devices ............ 13 3.1.6 Comparison of Wireless Technologies’ Specifications ....... 14 3.2 Research Prototype Wireless Sensor Networks ............... 15 3.2.1 Literature Review of In-field Performance of Research Prototype Wireless Sensor Networks ...................... 15 3.2.2 Comparison of Research Wireless Sensor Networks ........ 17 3.3 Commercial Wireless Sensor Networks ................... 18 3.3.1 Literature Review of Specifications of Commercial Wireless Sen- sor Networks ............................. 18 3.3.2 Comparison of Commercial Wireless Sensor Networks ...... 19 3.4 Conclusions .................................. 19 Chapter 4 Conceptual Investigations 21 CONTENTS viii 4.1 Wireless Technologies for New Telemetry System ............. 21 4.1.1 UHF Citizen Band Data Transmission ............... 21 4.1.2 Integrating Short-range Transceivers with Citizen Band Radio . 22 4.1.3 Wireless Technology Chosen ..................... 23 4.2 Feasibility of Citizen Band for Telemetry System ............. 23 4.2.1 Voice Modulation ........................... 24 4.2.2 Tone Modulation ........................... 26 4.3 Conclusions .................................. 27 Chapter 5 Data Modulation and Demodulation 29 5.1 Software-based Decoding at Base Station ................. 30 5.1.1 Software in Delphi .......................... 31 5.1.2 Software in Matlab .......................... 32 5.1.3 PICAXE Circuit to Transmit Signals for Software-Based Decoding 32 5.1.4 Conclusions on Software-based Decoding at Base Station .... 34 5.2 Hardware-based Decoding at Base Station ................. 34 5.3 Choosing a Modulation Technique ..................... 34 5.3.1 On-off Keying ............................. 35 5.3.2 Amplitude-shift Keying ....................... 35 5.3.3 Audio Phase-shift Keying ...................... 36 5.3.4 Audio Frequency-shift Keying .................... 37 CONTENTS ix 5.3.5 Multiplexing ............................. 37 5.3.6 Chosen Modulation Technique ................... 38 5.4 Evaluation of Frequency Shift-keying Modems ............... 38 5.4.1 TCM3105 ............................... 39 5.4.2 FX614 ................................. 40 5.4.3 XR2206 and XR2211 ......................... 41 5.5 Conclusions .................................. 42 Chapter 6 Design of Network Protocol 43 6.1 Network Topologies .............................. 43 6.1.1 Ring, Bus, Mesh and Star Network Topologies .......... 44 6.1.2 Network Topology Chosen ...................... 45 6.2 Medium Access Methods ........................... 45 6.2.1 Random Access Methods ...................... 46 6.2.2 Scheduled Access Methods ..................... 47 6.2.3 Medium Access Method Chosen for System ............ 47 6.3 Error Handling ................................ 48 6.3.1 Acknowledgements and Non-acknowledgements .......... 48 6.3.2 Parity Bit Schemes .......................... 48 6.3.3 Checksum ............................... 49 6.3.4 Cyclic Redundancy Schemes ..................... 49 CONTENTS x 6.3.5 Repetition Codes ........................... 50 6.3.6 Implementation of Error Handling Scheme ............. 50 6.4 Asynchronous/Synchronous Transmission ................. 51 6.5 Format of Data ................................ 51 6.5.1 Data Compression .......................... 51 6.5.2 Designed Communications Protocol for Telemetry System .... 52 6.6 Implementation of Network Protocol .................... 53 6.6.1 Design of Circuit to Implement Network Protocol ......... 53 6.6.2 Overview of Base Station and In-field Node PICAXE Software . 56 6.7 Construction of Interfacing Circuit ..................... 59 6.7.1 PICAXE Microcontrollers Chosen ................. 59 6.7.2 Circuit Schematic of Interfacing Circuit .............. 59 6.8 Workshop Evaluation of Interfacing Circuit ................ 60 6.8.1 Testing the Network Protocol .................... 60 6.9 Development of Graphical User Interface .................. 61 6.10 Comparison of Designed Protocol with OSI Model ............ 64 6.11 Conclusions .................................. 65 Chapter 7 Construction of Nodes for Field Evaluations 66 7.1 UHF Citizen Band Radios .......................... 66 7.1.1 Extending Communication Range ................. 69 CONTENTS xi 7.1.2 Interference from Other