Gnss 101 – Era of Integration

Home , GNSS applications, RINEX, World Geodetic System

2/4/2020

GNSS 101 – ERA OF INTEGRATION

Wisconsin Society of Land Surveyors Conference

Wisconsin Dells, 2020

PRESENTATION OUTLINE

A general overview of GNSS today GPS USA • Physical Layer

• Data Layer Global GLONASS RUSSIA Navigation • Application Layers Satellite BEIDOU • Integrations Systems CHINA

• Other Interesting GNSS Applications GALILEO EU

BEFORE WE GET STARTED

A few abbreviations to learn

ANTCAL Antenna Calibration Format GDOP Geometric diluation of precision PPS Precision positioning service ANTEX Antenna Exchange Format GEO Geostationary Earth orbit PRN Pseudo-random noise

ARP Antenna Reference Point GLONASS Global'naya Navigatsionnaya Sputnikova Sistema QZSS Quasi-Zenith Satellite System

AS Anti-Spoofing GNSS Global Navigation Satellite System RAIM Receiver Autonomous Integrity Monitoring ATOM Adaptive Transmission of Optimized Messages GPS Global Positioning System RINEX Receiver Independent Exchange

AUSPOS Australian Positioning Service GRS Geodetic Reference System RMS Root Mean Square

BDS Beidou Satellite System HDOP Horizontal dilution of precision RTCA Radio Technical Commission for Aeronautics

BINEX Binary Exchange Format IGS International GNSS Service RTCM Radio Technical Commission for Maritime Services

BKG Bundesamt für Kartographie und Geodäsie IGSO Inclined geo-synchronous orbit RTK Real-time kinematic

BPSK Binary phase-shift keying IOV In-orbit validation RTX Satellite and IP delivered corrections by Trimble

CDMA Code division multiple access IRNSS Indian Regional Navigation Satellite System SA Selective Availability

CEP Circular Error Probable ITRF International Terrestrial Reference Frame SAASM Selective Availability Anti-Spoofing Module CMR Compacted Measurement Record LLH Latitude Longitude Height SBAS Satellite-based augmentation system

COM Center of Mass MEO Medium Earth orbit SDCM System for Differential Corrections and Monitoring

CORS Continuously Operating Reference Station MGEX Multi-GNSS Experiment SINEX Solution Independent Exchange

DGNSS Differential GNSS MSAS Multi-Function Satellite Augmentation System SPS Standard Positioning Service

DGPS Differential GPS NAD North American Datum SSR State Space Representation DIP Direct Internet Protocol NGS National Geodetic Survey SVN Satellite vehicle number ECEF Earth-centered Earth-fixed NMEA National Marine Electronics Association TDOP Time dilution of precision

EGNOS European Geostationary Navigation Overlay Service NRCAN National Resources Canada TEC Total electron count

EPSG European Petroleum Survey Group NSAS Nigerian Satellite Augmentation System UHF Ultra-high frequency

ESA European Space Agency NTRIP Network Transport of RTK via Internet Protocol UNAVCO University NAVSTAR Consortium

ESRI Environmental Systems Research Institute OPUS Online Positioning User Service UTM Universal Transverse Mercator FDMA Frequency division multiple access PCV Phase Center Variation VDOP Vertical dilution of precision FOC Full operational capability PDOP Position dilution of precision VHF Very-high frequency GAGAN GPS-aided GEO Augmented Navigation PNT Positioning, navigation and timing WAAS Wide Area Augmentation System GATBP Geoscience Australia Test Bed Project PPP Precise point positioning WGS World Geodetic System 3

1 2/4/2020

BEFORE WE GET STARTED

Abbreviations reorganized

Positioning Space Messaging Systems Organizational Communications Mathematics Domain Component ANTCAL AS ATOM BDSBAS BKG BPSK CEP ANTEX SA CMR EGNOS CORS CDMA RMS ARP FOC RTX GAGAN EPSG DIP GDOP ECEF GEO DGNSS GLONASS ESA FDMA HDOP LLH IGSO DGPS GNSS ESRI NTRIP PDOP PCV MEO NMEA GPS GATBP RAIM TDOP PNT IOV PPP IRNSS IGS SAASM VDOP PRN PPS BINEX MSAS MGEX UHF COM SVN SPS RINEX NSAS NGS VHF GRS TEC SINEX QZSS NRCAN NAD SBAS OPUS UTM SDCM SSR WGS WAAS UNAVCO

PHYSICAL LAYER Physical properties of GNSS

PHYSICAL LAYER

What is GNSS? • Ground Segment • Space Component •Users

2 2/4/2020

PHYSICAL LAYER

GNSS Players • Global Services • SBAS Regional Services • GPS ~ 30 satellites • WAAS – USA ~ 3 satellites • GLONASS ~ 23 satellites • EGNOS – EU ~ 3 satellites • GALILEO ~ 22 satellites • BDSBAS – China ~ 3 satellites • BEIDOU ~ 35 satellites • MSAS – Japan ~ 2 satellites • Orbital Regional Services • GAGAN – India ~ 2 satellites • QZSS – Japan ~ 4 satellites • SDCM – Russia ~ 3 satellites • IRNSS – India ~ 8 satellites

At least 138 navigation satellites in space

PHYSICAL LAYER

GNSS Update • GPS III* • SV01 and SV02 in space • SV03, SV04 and SV05 awaiting launch • SV07, SV08 and SV09 are on the assembly line

SV06 undergoing testing and validation in vacuum chamber

PHYSICAL LAYER

GNSS Status • Beidou • 49 satellites | 24 are BDS III • Inter-satellite link capabilities • New generation rubidium and hydrogen maser clocks • 27 satellites in Medium Earth Orbit • 5 satellites in Geostationary Orbit • 3 satellites are inclined Geostationary Orbit

3 2/4/2020

PHYSICAL LAYER

GNSS Status • Galileo designed as a 24 satellite constellation in 3 circular MEO orbits • Open Service signals currently available • Search and Rescue Service currently available • When fully operational, three additional services will be available • Public Regulated (Government) • Safety of Life • Commercial (Professional)

PHYSICAL LAYER

GNSS Status • Glonass launched its most recent "M" class satellite December 11, 2019 from the Plesetsk cosmodrome. A January 2020 launch is also planned • Glonass and Beidou sign agreement to cooperate on the "Peaceful use of GNSS BDS and Glonass" • Glonass focuses on users by maintaining continuous services and stable performance

PHYSICAL LAYER

Frequency Summary

Frequencies in MegaHertz

1176.450 1207.140 1227.600 1246.000 1278.750 1561.098 1575.420 1602.000

GPS L5 L2 L1

GLO L2 L1

GAL E5a E5b E6 E1

BDS E5 E2

QZSS L5 L2 L1

SBAS L1

4 2/4/2020

PHYSICAL LAYER

Radio Signal Characteristics

GPS L5 GPS L2 GPS L1

PHYSICAL LAYER

Mission Planning as a learning tool • Allows visualization of the physical layer • https://www.gnssplanningonline.com/#/maps

PHYSICAL LAYER

Mission Planning as a learning tool • Allows visualization of the physical layer • Wisconsin Dells, Wisconsin | January 29th, 2020 @ 12:20 PM

5 2/4/2020

PHYSICAL LAYER

Mission Planning as a learning tool • Allows visualization of the physical layer • Sentosa Island, Singapore | January 29th, 2020 @ 12:20 PM

PHYSICAL LAYER

Expanding User Segment

• GNSS assisted approaches for airplanes (LPV) is

replacing the single-legged ILS landing method

• Autonomy explosion – planes, trains, automobiles,

drone deliveries, automated tasks, safety of life

• Accurate positioning via GNSS is now an

assumption worldwide – global infrastructure

PHYSICAL LAYER

GNSS Receivers and Satellite Tracking Technology • GPS and Glonass are not perceived to be good enough - BDS and Galileo are expected • Combined signals from multiple constellations and frequencies are called X-Signals • The International GNSS Service (IGS) is conducting a pilot project called MGEX (Multi-GNSS Experiment) to study the X-Signals

6 2/4/2020

PHYSICAL LAYER

GNSS antennas vary Magellan 111406 L1 Offset – 6.01 cm (2.37”) • PCV = Phase Center Variation • ARP = Antenna Reference Point Spectra Epoch 35 L1 Offset – 9.97 cm (3.93”) 90° 90°

Phase Center Phase Center

0° 0° Spectra SP60 Antenna Reference Point Antenna Reference Point L1 Offset – 5.05 cm (1.99”) Phase Meter Phase Meter +π +π

0.f λ 0.f λ -π -π Elevation Elevation Ashtech 111661 (Imaginary) Ideal Antenna Real Antenna Pattern L1 Offset – 5.72 cm (2.25”)

PHYSICAL LAYER

Leap Seconds – IERS • Precise Time is TAI (International Atomic Time) • GNSS uses TAI • Imprecise Time is known as UT1 • Varies due to long-term slowdown in the Earth's rotation • Normal clocks use some offset of UTC time which is referenced to TAI • Leap seconds are announced by the IERS to align UT1 and UTC • The GPS epoch began at midnight, January 6, 1980 • At that time, TAI – UTC = -19 seconds • Today, TAI – UTC = -37 seconds • Thus, GPS time is offset from UTC by 18 seconds ((TAI – UTC) + 19)

1972 1980 1990 2000 2010 2020 20

PHYSICAL LAYER

GPS Week Number Roll-Over (WNRO) • The GPS epoch began at midnight on the cusp between January 5 & 6, 1980 • GPS uses a 10-binary counter to represent the week number • Every 19.7 years, this counter reaches its limit and rolls back to zero • April 6, 2019 was the second WNRO event in the GPS epoch

7 2/4/2020

PHYSICAL LAYER

Sky Occlusion – GNSS Needs Sky • At least 4 visible satellites are required to compute a 3D position

PHYSICAL LAYER

Clock Technologies and Timing • NASA Deep Space Clocks • The first GPS-like clock designed for deep space • Will allow spacecraft to navigate themselves versus relying on directions from Earth • The mercury-ion clock loses one second every 10 million years

https://m.phys.org/news/2019-08-nasa-deep-space-atomic-clock.html 23

PHYSICAL LAYER

Spoofing and Jamming • "Protect yourself from Interference with the Spirent GSS900 Series" • "U.S. officials warn of Iranian threats to commercial vessels including GPS interference" * • "Modeling jammed and spoofed signals to protect critical systems" – Orolia Defense Systems • Jamming and spoofing are becoming more prevalent, not just for the military but also for consumers – Cast Navigation, LLC • Protecting PNT | Anti-jam receivers protect data, mitigate navigation warfare threats – GPSWorld cover story, December 2019 • As the threat of jamming and spoofing increases, the receiver industry will have to develop counter measures and mitigation strategies – Cyrelle Gernot, Syntony GNSS

*https://nypost.com/2019/08/07/us-officials-warn-of-iranian-threats-to-commercial-vessels-including-gps-interference/

8 2/4/2020

PHYSICAL LAYER

Spoofing and Jamming – What is GPS doing to protect users? • Excerpts from GPSWorld December 2019 editorial by Dana Goward • European standards for resilient receivers have been published and acquisition of an interference detection network is underway • Russia is improving its terrestrial Loran/Chayka PNT system for military use and has promised to make the upgraded service available to civilians • China …testing PNT satellites in low earth orbit to provide more powerful and reliable signals than available from current GNSS • The U.S. DoD has been very active protecting its own with GPS M-code signals…Yet, DoD…says it has no intention of sharing any new PNT systems with civilians "Putting someone in charge is key to reversing America's civil PNT decline"

https://editions.mydigitalpublication.com/publication/?i=638464#{"issue_id":638464,"publication_id":"59713","page":6}

PHYSICAL LAYER

Spoofing and Jamming – • "The threats of interference, jamming and spoofing are real and serious" Professor David Last, Consultant Engineer & Expert Witness https://mycoordinates.org/the-threats-of-interference-jamming-and-spoofing-are-real-and-serious/

• Iran is reportedly jamming ship GPS navigation systems to get them to wander into Iranian waters* • **…vessels reporting their locations as being on land at airports far from where the ships were operating offshore

*https://www.businessinsider.com/iran-is-jamming-ship-gps-navigation-systems-to-seize-them-2019-8 **https://www.maritime-executive.com/article/gps-spoofing-patterns-discovered

DATA LAYER Utilizing the Signals from Space

9 2/4/2020

DATA LAYER

RTCM SC104 (Radio Technical Commission for Maritime services - Special Committee 104) • Recommended Standards for Differential GNSS Service • Working Groups of SC104 include… • Beidou •QZSS • Coordinate Transformation •RINEX • Glonass • State Space Representation •NMEA • Version 3 •NTRIP

DATA LAYER

RTCM SC134 (Radio Technical Commission For Maritime services - Special Committee 134) • Recommended Standards for High Accuracy, GNSS Based Applications • Autonomy standards • Rail and Marine navigation are the primary drivers • Automotive autonomy is much further away

DATA LAYER

RTCM SC135 (Radio Technical Commission For Maritime services - Special Committee 135) • Recommended Standards for Real-Time GNSS Applications • Question: How many in this audience have ever had problems with the radio layer of their RTK system? • SC135 has the mission to solve the problems with this layer • Forward Error Correction, Whitening, 4- Level FSK, duty cycles, scheduling, interleaving, framing, baud rates, channel spacing

10 2/4/2020

DATA LAYER

NMEA GGA - essential fix data which provide 3D location and accuracy data.

• Data output standard for GNSS fed $GPGGA,123519,4807.038,N,01131.000,E,1,08,0.9,545.4,M,46.9,M,,*47

Where: hardware and applications GGA Global Positioning System Fix Data 123519 Fix taken at 12:35:19 UTC 4807.038,N Latitude 48 deg 07.038' N • Laser range finders, ground 01131.000,E Longitude 11 deg 31.000' E 1 Fix quality: 0 = invalid 1 = GPS fix (SPS) penetrating radar, fathometers, 2 = DGPS fix 3 = PPS fix 4 = Real Time Kinematic photogrammetry 5 = Float RTK 6 = estimated (dead reckoning) (2.3 feature) • Many software packages rely on 7 = Manual input mode 8 = Simulation mode 08 Number of satellites being tracked NMEA for their position information 0.9 Horizontal dilution of position 545.4,M Altitude, Meters, above mean sea level 46.9,M Height of geoid (mean sea level) above WGS84 • Most widely used NMEA message ellipsoid (empty field) time in seconds since last DGPS update (empty field) DGPS station ID number is GGA *47 the checksum data, always begins with *

DATA LAYER

RINEX – Receiver INdependent data EXchange format • The common language of GNSS static raw data • Managed/Developed primarily by the IGS and secondarily by RTCM SC104 • Current version is 3.0.4 • The standard has issues… • Implementations between companies do not always match – used for kinematic data – OPUS is picky – a lot of versions in use

DATA LAYER

PPP – Precise Point Positioning • No more base stations? • Commercial services available today via satellite link • The drive for autonomous everything could change this model • Accuracy down to the size of a softball anywhere on the planet • Delivered datum versus target datum • 15 parameter transformation

11 2/4/2020

DATA LAYER

RTK Throughputs Dilemma • Is more better? • Delivering all of the available data at 1 Hertz with current radio technology is not practical • What scheduling technique should be used? • Corrections, reference antenna and position, coordinate system information • What correction format should be used? • Antenna offsets - ADVNULLANTENNA

DATA LAYER

CORS and Networks • Estimate over 5,000 CORS globally • Many provide RTK data streams via IP •NTRIP (Network Transfer of Rtk data via Internet Protocol) managed by SC104 • Delivery method used by most GNSS networks providing real-time RTK data • Most recent version is 2.0 • Very, very few implementations of V2.0 • Version 1 is "good enough"

APPLICATION LAYERS Capturing and Managing the Data

12 2/4/2020

APPLICATION LAYERS

Coordinate Systems • An overlay to the raw GNSS measurements • In addition to north, east and height, a modern coordinate also has a date • GNSS datums are complex • Many networks still require a transformation to be performed • Grid and Ground, Mapping plane, Mapping plane ground

APPLICATION LAYERS

Field Software • Hundreds of vertical markets utilizing GNSS data through application software • Within the surveying industry… • Prepared for time-dependencies? • Migration from Windows CE to Windows 10 or • Migration from Windows CE to Android • Are the terms Fixed and Float enough? • RTCM proposal contains 9 graduations

APPLICATION LAYERS

Office Software

Open • Proprietary data transfers between field and Proprietary Source Software office software provides the most fidelity Software • Standards based data exchanges will License fee Charge No charge generally work, but with some loss of data

• RINEX for example Commercial Community Maintenance support support and Support • DXF and XML are not standardized available available

• 3D – Emerging trend for interoperable Access, Source code No access modification access datasets regardless of the sensor that was possible used to collect the data

13 2/4/2020

APPLICATION LAYERS

Statistics: PPM, RMS, DOP • Accuracy versus Precision • Vertical specification is usually 1.5 to 2 times the horizontal specification • DOP is used to compute RMS • PPM – There is a distance dependent error (between base and rover) • Specifications are written for ideal conditions • Multipath, quality/availability of corrections, number of satellites, geometry, etc. will affect performance

INTEGRATIONS Putting it all together

INTEGRATIONS

MEMS • MicroElectronicMechanical System • A miniature machine that has mechanical and electronic components • Can be a small as a micron • Used in many vertical markets and devices • In the Surveying industry, MEMS are used as rough leveling devices in GNSS receivers and total stations

14 2/4/2020

INTEGRATIONS

IMU - INS

• IMU – Inertial Measurement Unit

• An inertial measurement unit is an electronic device that measures

and reports a body's specific force, angular rate, and sometimes the

orientation of the body, using a combination of accelerometers,

gyroscopes, and sometimes magnetometers • INS – Inertial Navigation System

• A navigation device that uses a computer, motion sensors and

rotation sensors to continuously calculate by the position, the

orientation, and the velocity of a moving object without the need for

external references

INTEGRATIONS

Photogrammetry

• The science of making measurements from

photographs

• PPS and Event Marker are GNSS impulses

used to trigger a photogrammetric camera

while placing an event marker into the data

for post-processing the data

INTEGRATIONS

Point Clouds •LIDAR –LIght Detection And Ranging • Rotating lasers collect millions of spatially related X,Y,Z coordinates that can be stitched together • Emerging market segment for surveying

15 2/4/2020

INTEGRATIONS

Odometry

• The use of data from motion

sensors to estimate the change

in position over time

• Another tool in the tool-belt

• Used extensively in rail

• Default in automobiles

INTEGRATIONS

UAV – Unmanned Aerial Vehicle - Drones • Copter or fixed-wing • GNSS + Photogrammetry • Lasers are still too heavy

INTEGRATIONS

Combination of sensors • Trimble's "MobileMapping" MX9… • IMU/INS for trajectory estimation • Odometry for trajectory estimation • GNSS for positioning and heading • Laser scanners for LIDAR data • Six cameras for panoramic photogrammetry • Software brings (terabytes of) data together in the office

16 2/4/2020

OTHER INTERESTING GNSS APPLICATIONS It's everywhere