gps, glonass, galileo, and beidou for mobile devices from...

GPS, GLONASS, Galileo, and BeiDou for Mobile Devices

From Instant to Precise Positioning

Get up to speed on all existing GNSS with this practical guide. Covering everythingfrom GPS, GLONASS, Galileo, and BeiDou orbits and signals to multi-GNSS receiverdesign, AGPS, network RTK systems, and VRS, you will understand the completeglobal range of mobile positioning systems. Step-by-step algorithms and practicalmethods provide the tools you need to develop current mobile systems, whilst coverageof cutting-edge techniques, such as the instant positioning method, gives you a headstart in unlocking the potential of future mobile positioning. Whether you are anengineer or a business manager working in the mobile device industry, a student or aresearcher, this is your ideal guide to GNSS.

Ivan G. Petrovski leads the development of GNSS applications at iP-Solutions, Japan.He has over 25 years’ worth of research and development experience in the GNSS field,and has previously led GNSS-related R&D for DX Antenna, GNSS Technologies Inc.,and the Institute of Advanced Satellite Positioning at TUMSAT. He has academicexperience working as an associate professor with MAI and as a guest professor withTUMSAT. As an engineer he has developed RTK software, the algorithms and softwarefor indoor and outdoor positioning with pseudolites, in addition to instant positioningalgorithms, real-time GNSS software receivers, and the GNSS DIF recorder and RFsignal simulator.

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Cambridge University Press978-1-107-03584-3 - GPS, GLONASS, Galileo, and BeiDou for Mobile DevicesIvan G. PetrovskiFrontmatterMore information

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GPS, GLONASS, Galileo,and BeiDou for Mobile Devices

I VAN G. PETROVSKIiP-Solutions, Tokyo






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It furthers the University’s mission by disseminating knowledge in the pursuit ofeducation, learning and research at the highest international levels of excellence.

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Library of Congress Cataloging in Publication dataPetrovski, Ivan G., 1962–GPS, GLONASS, Galileo, and BeiDou for mobile devices : from instant to precise positioning / Ivan G.Petrovski, iP-Solutions, Tokyo.

pages cmISBN 978-1-107-03584-3 (Hardback)1. GPS receivers–Design and construction. 2. Mobile communication systems.3. Global Positioning System. 4. Galileo satellite navigation system.5. Artificial satellites in navigation. I. Title.TK6565.D5P45 2014910.285–dc23 2013032821

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Contents

Foreword by Glen Gibbons page xiiiAbout this book xixAcknowledgments xxList of abbreviations and acronyms xxiList of definitions xxv

Part I GNSS: orbits, signals, and methods

1 GNSS ground and space segments 3

1.1 Ground segment and coordinate reference frames 31.2 Space segment and time references 10

1.2.1 GPS time and calendar time 101.2.2 Other GNSS time scales 111.2.3 Onboard clock error 11

1.3 Satellite motion description using Keplerian parameters 131.4 Algorithm for satellite position calculation using standard Keplerian

parameters 171.5 Theoretical background for the spherical harmonics of the Earth’s

geopotential 201.6 Algorithm for transformation of GLONASS almanac parameters into

standard Keplerian parameters 221.7 Medium Earth GNSS orbits 261.8 GEO and HEO for SBAS 29

1.8.1 GEO 291.8.2 HEO 30

1.9 Algorithm for GPS, Galileo, and BeiDou for satellite position calculationusing ephemeris in the form of osculating elements 32

1.10 Algorithm for GLONASS satellite position calculation using ephemeridesin the form of Cartesian vectors 35

1.11 Algorithm for GLONASS satellite position calculation accountingfor lunar and solar gravitational perturbations 36

References 37

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2 GPS, GLONASS, Galileo, and BeiDou signals 39

2.1 GNSS signals 392.1.1 GNSS signals in general 39

2.1.1.1 CDMA method 392.1.1.2 GNSS signal structure 422.1.1.3 GNSS spread codes: past, present, and future 42

2.1.1.3.1 Shift register and memory codes 422.1.1.3.2 Strange attractor codes 45

2.1.1.4 BOC modulation 462.1.1.5 Data 472.1.1.6 Tiered code 482.1.1.7 Pilot channel 49

2.1.2 GPS L1 signals 492.1.2.1 GPS L1 C/A signal 492.1.2.2 GPS L1C signal 51

2.1.3 GLONASS L1 signals 532.1.4 Galileo signal 562.1.5 BeiDou signal 57

2.2 GNSS signal propagation error models 582.2.1 Effects of signal propagation through the atmosphere on GNSS 582.2.2 Algorithms for tropospheric delay calculation 60

2.2.2.1 Black and Eisner model 602.2.2.2 Saastamoinen tropospheric delay model 612.2.2.3 Niell mapping function 61

2.2.3 Algorithms for ionospheric delay calculation 622.2.3.1 Single-layer ionosphere model 632.2.3.2 Ionospheric error compensation in GPS and BeiDou

receivers 652.2.3.3 Ionospheric error compensation in GLONASS receivers 672.2.3.4 Ionospheric error compensation in Galileo receivers 672.2.3.5 Ionospheric error corrections from GEO/HEO satellites 68

2.2.4 Ionospheric error compensation in multi-frequencyGNSS receivers 69

2.3 GNSS data 722.3.1 GPS and BeiDou navigation messages 722.3.2 Galileo navigation message 732.3.3 Algorithm for constructing GPS/BeiDou/Galileo pseudorange

measurements 752.3.3.1 GPS time mark 752.3.3.2 BeiDou time mark 752.3.3.3 Galileo time mark 762.3.3.4 Pseudorange construction algorithm 76

2.3.4 GLONASS navigation message contents and structure 77

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2.3.5 Subframe of a GLONASS navigation message 802.3.5.1 Algorithm for reading GLONASS subframe 802.3.5.2 Subframes containing immediate information 81

2.3.5.2.1 Subframe 1 812.3.5.2.2 Subframe 2 812.3.5.2.3 Subframe 3 812.3.5.2.4 Subframe 4 822.3.5.2.5 Subframe 5 82

2.4 What’s in a sat’s name? 822.4.1 Models 842.4.2 Signals 842.4.3 Geometry 842.4.4 Clock 85

References 86

3 Standalone positioning with GNSS 88

3.1 Application of pseudorange observables 883.1.1 Code phase measurements 883.1.2 Carrier phase measurements 903.1.3 Pseudorange equations 913.1.4 Satellite coordinates 933.1.5 Minimum number of satellites for positioning 95

3.2 Navigation solution algorithms 983.2.1 Least-squares estimation (LSE) solution 983.2.2 Analytical solution 1013.2.3 Kalman-filter solution 1023.2.4 Brute-force solution 104

3.3 Multi-system positioning 1043.3.1 Generalized equations 1043.3.2 Time-shift calculation using navigation message data 105

3.4 Error budget for GNSS observables 1053.4.1 Error budget contents 1053.4.2 Geometrical factors 1063.4.3 Multipath 108

References 109

4 Referenced positioning with GNSS 110

4.1 Requirements for code and carrier differential positioning 1104.2 Spatial correlations in error budget 112

4.2.1 Decorrelation of satellite orbital errors 1124.2.2 Decorrelation of tropospheric errors 1134.2.3 Decorrelation of ionospheric errors 113

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4.3 Observables 1134.3.1 Single-difference observables 1134.3.2 Double-difference observables 1144.3.3 GLONASS inter-frequency bias 1164.3.4 Triple-difference observables 1164.3.5 Double-difference equations for multi-systems 117

4.4 Real-time kinematic method 1184.4.1 Code and carrier phase difference equations 1184.4.2 RTK positioning algorithm 120

4.4.2.1 Float solution 1214.4.2.2 Integer solution 1224.4.2.3 Validation 123

4.4.3 Network RTK method 1234.4.3.1 Network of reference stations 1234.4.3.2 Control center 124

References 126

Part II From conventional to software GNSS receivers and back

5 Generic GNSS receivers 131

5.1 GNSS receiver overview 1315.1.1 Digest of GNSS receiver operation 1315.1.2 Receiver specification 135

5.1.2.1 Specification parameters 1355.1.2.1.1 Accuracy 1355.1.2.1.2 Sensitivity 1375.1.2.1.3 Systems and frequencies 1385.1.2.1.4 Time to first fix 1385.1.2.1.5 Interface 139

5.1.2.2 Spec specifics for main application fields 1405.1.2.2.1 Geodetic applications 1405.1.2.2.2 Geophysical applications 1405.1.2.2.3 Aviation applications 1415.1.2.2.4 Mobile applications 141

5.1.2.3 Evaluation of parameters 1425.1.3 GNSS receiver design 142

5.1.3.1 Hardware and generic receivers 1425.1.3.1.1 Receiver functional model 1425.1.3.1.2 Receiver structural model 143

5.2 Receiver components 1445.2.1 Correlators 144

5.2.1.1 Signal acquisition 1445.2.1.2 Massive parallel correlation 148

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5.2.1.3 Coherent signal integration 1495.2.1.4 Frequency resolution 150

5.2.2 Receiver channel functions 1515.2.2.1 Tracking loop theory 1515.2.2.2 Tracking loop implementation 157

5.2.2.2.1 PLL-aided DLL 1575.2.2.2.2 Coherent tracking with 20 ms coherency interval 1595.2.2.2.3 Coherent tracking with 1 s coherency interval 161

5.2.2.3 Lock detectors 1625.2.2.4 Bit synchronization 1635.2.2.5 Measurements 164

5.3 GPS/GLONASS receiver 165References 167

6 Receiver implementation on a general processor 169

6.1 Development of the “software approach” 1696.2 Software receiver design 171

6.2.1 Baseband processor implementation 1716.2.2 Acquisition implementation 173

6.3 Advantages of software receivers 1746.3.1 Software receiver advantages for mobile applications 174

6.3.1.1 Potential reduction of required hardware 1746.3.1.2 Upgradeability 1756.3.1.3 Bug fixing 1756.3.1.4 Reduction of new product development cycle 1756.3.1.5 Adaptability to new signals 1756.3.1.6 Change of receiver type 1776.3.1.7 Third-party product involvement 177

6.3.2 Software receiver advantages for high-end applications 1776.3.2.1 Flexibility 1776.3.2.2 Access to baseband processor 1776.3.2.3 RF signal post-processing 178

6.4 Real-time implementation 1786.4.1 Concurrency 1786.4.2 Bottlenecks in GNSS signal processing 1806.4.3 Algorithmic methods used to speed up processing 181

6.4.3.1 Early-minus-late discriminator 1816.4.3.2 Signal decimation 182

6.4.4 Hardware-dependent methods 1826.4.5 Software methods 184

6.4.5.1 “Bitwise processing – a paradigm for deriving parallelalgorithms” 184

6.4.5.2 Pre-calculation of replicas 185

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6.5 Applications of high-end real-time software receivers 1856.5.1 Instant positioning 1866.5.2 Ionosphere monitoring 1866.5.3 Ultra-tightly coupled integration with INS 1876.5.4 Application in education 187

References 187

7 Common approach and common components 190

7.1 Common approach for receiver design 1907.2 Mobile antennas 1927.3 TCXO and bandwidth 1957.4 Front end 199

7.4.1 Down-converter 1997.4.2 Analog-to-digital converter 201

7.5 Navigation processor 203References 204

Part III Mobile positioning at present and in the future

8 Positioning with data link: from AGPS to RTK 207

8.1 Merging mobile and geodetic technologies 2078.2 Application of external information in the baseband processor 209

8.2.1 Doppler assistance in acquisition 2108.2.2 Code phase assistance in acquisition 2148.2.3 Doppler assistance in tracking 2148.2.4 Navigation data assistance 216

8.3 Application of external information in the navigation processor 2178.3.1 TTFF improvement: snapshot positioning 2178.3.2 Accuracy improvement: RTK positioning 220

8.3.2.1 The catch: antennas 2208.3.2.2 Network RTK implementation: virtual reference station

RTK system 2218.4 External information content 225

8.4.1 Group 1: assistance data 2258.4.2 Group 2: additional parameters 2268.4.3 Group 3: differential corrections 227

8.5 Pseudolites 2278.5.1 Pseudolite applications 2278.5.2 Indoor positioning with carrier phase 2328.5.3 Repeaters 233

References 235

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9 Positioning without data link: from BGPS to PPP 238

9.1 Advantages of positioning without a data link 2389.2 BGPS: instant positioning without network 241

9.2.1 Advantages of BGPS 2419.2.1.1 Instant positioning 2419.2.1.2 Power savings 2419.2.1.3 Less interruption during cellular operation 2429.2.1.4 High sensitivity 242

9.2.2 History of the approach 2429.2.3 BGPS in a nutshell 2439.2.4 Formalization 2459.2.5 Algorithm criteria 2509.2.6 Required a-priori information 2529.2.7 Time resolution in real time 253

9.2.7.1 Task example 2539.2.7.2 Heuristic approach to search strategy 254

9.2.8 Preliminary position estimation methods 2549.2.9 Instant positioning implementation in a device 255

9.3 Precise positioning without reference station 2589.3.1 From a network to the global network 258

9.3.1.1 Global correction information for mobile devices 2589.3.1.2 Free global corrections 2599.3.1.3 Orbit prediction 259

9.3.2 Embedded algorithms 2639.3.2.1 Satellite ephemeris interpolation procedure inside

mobile device 2639.3.2.2 Precise error models 2649.3.2.3 Filtering 2659.3.2.4 The catch 266

9.4 Applications 2679.4.1 Fleet management 2689.4.2 Bird tracking 2699.4.3 Positioning with pilot signals 270

References 272

10 Trends, opportunities, and prospects 274

10.1 From Cold War competition to a business model 27410.2 Would you go for a “multi-mighty” receiver? 27510.3 From SDR to SDR we go 27810.4 SA off, AGPS on, mass market open 28110.5 Convergence of mobile and geodetic applications 283

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10.6 Synergy of the Internet and GNSS 28410.6.1 Integration of a mobile device into the Internet 28410.6.2 The Internet as correction provider 28510.6.3 The Internet as data link 28510.6.4 Improvement in GLONASS accuracy 285

10.7 Towards a new GNSS paradigm 28610.7.1 Online updates and upgrades 28710.7.2 Programmable personality change 28710.7.3 Full set of online corrections 28710.7.4 Application of cloud computing technology 28810.7.5 Third-party tools and services 28810.7.6 One for all and all for one 28810.7.7 Offline operation 289

10.7.7.1 Network position calculation 28910.7.7.2 AGPS 28910.7.7.3 BGPS 289

References 289

Part IV Testing mobile devices

11 Testing equipment and procedures 293

11.1 Testing equipment 29311.1.1 Multi-channel simulator 29311.1.2 RPS: record and playback systems 295

11.2 Device life cycle 29711.2.1 Research and development 29811.2.2 Design 29811.2.3 Certification 29911.2.4 Production 29911.2.5 Consumer testing 300

11.3 Test examples 30111.3.1 General tests 30111.3.2 AGPS tests 30211.3.3 Multi-GNSS test specifics 304

11.4 Case study: new paradigm SDR simulator 305References 310

Index 311

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Foreword by Glen Gibbons

The Law of Unintended Consequences – case in point: the mandate for enhanced 911(E911) services for mobile devices.

In 1996, the Federal Communications Commission (FCC), a US regulatory agencywith broad powers over telecom providers and services, issued its first report, order, andnotice of proposed rule-making (NPRM) regarding E911. The FCC action sought torequire wireless telephone companies to be able to report automatically the location ofan emergency caller.

This initiative proposed to bring to the rapidly expanding wireless space a require-ment previously established for wireline providers. Unlike telephones at fixed locations,the whereabouts of a mobile phone was not readily known in emergencies, often noteven to the callers themselves.

In issuing the NPRM, however, the Global Positioning System – let alone otherGNSS systems – was not on the minds of the FCC commissioners. Indeed, if FCC staffand officials were aware of GPS in 1996, which had only reached full operationalcapability the year before, it was probably as the precise timing technology providingsynchronization to wireline and some wireless networks.

No, in 1996, the FCC assumed that the positioning solutions for E911 would arisefrom within the networks themselves, using such techniques as angle of arrival (AOA),time of arrival (TOA), and time difference of arrival (TDOA).

This is where the unintended consequences enter in, and why the AOA ofDr. Petrovski’s latest book – GPS, GLONASS, Galileo, and BeiDou for Mobile Devices:From Instant to Precise Positioning – is a particularly resonant and relevant pointof entry.

With E911, the FCC was focused on helping first responders (e.g. police, ambulance,and fire department personnel) reach people in need quickly. The agency probablyassumed that, as with many other regulatory mandates, the telecom industry wouldresist or at least seek to delay the imposition of the new rules. In fact, the full accuracyand reporting conditions of E911 only took effect in December 2012, nearly 16 yearsafter the original FCC report and order.

For our purposes, however, we can leave the prolonged story of E911’s implementa-tion, filled as it is with bureaucratic woes and bewildering discoveries about the natureof emergency services’ communications infrastructure and processes. Long before E911arrived, a much more remarkable thing happened: GNSS capabilities began appearingvoluntarily on almost every cell phone sold into the US market. Moreover, GNSS has

xiii






spread to many other mobile devices, such as cameras and notepad computers, notintended primarily for communications.

What happened?Well, to answer that question we need to return briefly to 1996 and consider the state

of the GPS industry – GPS being the only practically accessible GNSS technology at thetime. By the mid 1990s, GPS had become well accepted within certain professional andcommercial sectors: surveying and mapping (including geographic informationsystems), along with the previously mentioned timing applications, and – in the wakeof the first Persian Gulf war – the military community.

What GNSS did not have in 1996 was a mass market. In large part, this situationstemmed from the US policy of “Selective Availability” or SA – an effort to maintain anadvantage for US and allied military forces. This measure imposed a timing dither onthe open GPS C/A code signal that degraded the real-time positioning accuracy to “noworse than” 100 meters 95 percent of the time, typically in the range of 60 to 70 meters.

Aside from a few fisherman and recreational boaters, who were happy to usesomething that would provide them with a better accuracy than the quarter-mile or sothen possible with Loran-C, nothing approaching a consumer market had emerged yetfor GPS. (Marine users’ counterparts in general aviation also found that a GPS receiver –even one that cost thousands of dollars – was still a lot cheaper and a lot more accuratethan other types of navigation aids.)

At the time, visionaries and pioneers in a newly named, but underpopulated, world oflocation-based services (LBS) were looking to the automotive industry for the platformthat would lift GPS into the popular imagination. For Americans, cars are the quintes-sential consumer product. With millions of them sold every year, automobiles seemedthe ideal vehicle (no pun intended) for carrying GPS into a mass market.

In addition to SA, however, a couple of things turned out to be wrong with thatparadigm. First, the complex network of interlocking hardware and software vendorsand LBS providers had not sorted themselves out sufficiently to have found a successfulbusiness model. Second, demand for navigation systems among car owners, who do 90percent of their driving on familiar local routes, remained unencouraging – it sufferedfrom the “So what?” factor. And, more importantly, the US auto industry with a typicalseven-year design cycle and price sensitivities, was distinctly uninterested in a largelyuntested technology that would add hundreds of dollars to the price of a new car.

The FCC’s E911 mandate, however, changed that calculus. Mobile phone manufac-turers, who had a much shorter design cycle, began thinking about how they might meetthe federal mandate with a handset-based solution, rather than a network-based one.And they began looking more closely at the opportunity to build in money-makingapplications that took advantage of the regulatory mandate for location – a classiclemons-into-lemonade scenario.

By the time Selective Availability was removed in 2000, a substantial and ultimatelyirresistible momentum had begun for adding GNSS capabilities to mobile devices. Fast-forward to the recent Lightsquared controversy in which the massive installed base ofGNSS receivers – driven largely by GPS in mobile phones – created a major obstacle torollout of a high-powered wireless broadband system in frequencies adjacent to GNSS.

xiv Foreword by Glen Gibbons






Thus, mobile phones had popularized GNSS with a speed and widespread adoption thatvehicle telematics could not.

One further aside: the popularization of affordable, precise location brought about byGNSS has actually fed back and rejuvenated interest in other positioning technologies.Because, as we well know, GNSS does not work everywhere that people live, work, andplay, but now that they have experienced its utility and even come to depend on it,people want the capability everywhere and all the time.

So, product developers and service providers have redoubled their efforts to find toolsand methods to provide ubiquitous positioning – not merely among the network-basedsolutions mentioned earlier, but also in exploiting such things as WiFi, magnetic fields,inertial sensors, signals of opportunity, and even echoes. Sometimes alone, but moreoften in combination with GNSS in mobile devices.

So, about this book. . . .First off, it could not be more timely. GPS, of course, is well established – there are

easily more than a billion receivers in operation around the world, both as standalonetools in the hands of, for example, geocachers or integrated into other devices andsystems.

At the same time, after 16 years of decline, restoration, and modernization, Russia’sGLONASS system has returned to full operation and appears to be here to stay, despiterecent troubles in its space program. Europe’s Galileo, finally escaping a long series ofpolitical misadventures and technical travails, is on the threshold of a rapid build-out ofthe constellation – with a public interface control document (ICD) and Galileo-capablereceivers already available.

China’s GNSS program, BeiDou (actually, BeiDou-2, reflecting the second phase ofa satnav program that began in 2000) has shown the fastest evolution – launching itssecond-generation program with a 2007 launch and following up over the next fiveyears placing another 15 spacecraft into orbit, including two dual-satellite launches.That led to the declaration of regional service and the publication of a B1 civil signalICD in December 2012.

With these systemic developments and the worldwide adoption of GNSS by allcategories of users in mind, I believe that we have arrived at one of those axial agesof technology: a turning point at which a door opens into a world of myriad possibil-ities, in which familiar endeavors take on new forms and entirely novel ways of workingand living appear.

Dr. Petrovski’s discussion begins, as so many previous publications rightfully have,with the GNSS infrastructures themselves: the ground control and monitoring segment,the satellite constellations, and the signals. Dr. Petrovski continues by taking up thedesign of GNSS receivers, both hardware and software, before leading the reader into theapplication realm of mobile positioning – as my preface to these remarks should makeclear, what I consider the pivotal development of GNSS for the general population.

As he has done in previous works, Dr. Petrovski brings his long-established expertisein the GNSS field to bear. The scope of the text’s discussion is wide ranging butdetailed, thorough without losing perspective and a sense of proportion, sober andinformed yet piquant at points, reflecting the personality of the author. In the

xvForeword by Glen Gibbons






penultimate Chapter 10, “Trends, opportunities, and prospects,” Dr. Petrovski wraps uphis examination of GNSS with a thoughtful reflection on prospects for advancingreceiver technology in the future. The final chapter of the book – on testing mobiledevices – is essentially a practical “how-to” appendix for which the preceding discussionhas well prepared the reader.

Let me now step away from the contents of Dr. Petrovski’s book again. I must leaveto others with far more expertise in the engineering and scientific disciplines the task ofassessing, interpreting, and communicating the lessons provided within its covers.

Instead, I want to place this publishing project in a wider context, to highlight thebook’s purpose against a backdrop of social and historical factors that have informedGNSS technology even as it has altered some of our most quotidian human activities.

Such matters are easy to underestimate or overlook, because GPS had barely reachedthe public consciousness before it began to disappear back into the context of daily life,increasingly invisible within its applications and the unconscious expectations of loca-tion users – like light switches or water faucets, noticeable only by its absence.

In human affairs, we may describe some things as game-changing events, or water-shed moments, or even sea changes. But such characterizations are inadequate todescribe the pervasive and far-flung effects of GNSS. The changes brought about bythis still-young technology are more on the scale of plate tectonics or gravity. And thisis not mere hyperbole, not when we are speaking of a technology that is used to measurethe wobble in the Earth’s rotation itself.

Indeed, had it not been appropriated by the environmental sciences, we would speakof GNSS in terms of global change to capture its true dimensions. Because, since theadvent of GNSS, the world has changed – and it almost certainly is not changing back.

Of course, the intersection of GNSS with the routines of average citizens does nothave the weightiness of its applications in geodesy, weather monitoring, or spacecraftnavigation. Rather, for almost all of us, GNSS manifests itself on a human, evenmundane, scale. Nonetheless, we can no more think of people abandoning theirlocation-based applications – traffic guidance, photo-georeferencing, rendesvouzing,friend finding, ATM finding, cinema finding, whatever finding – than we can imaginethem giving up the Internet or social media.

So, what are some of the hallmarks of this technology that has so transformed theworld? Let me suggest just a few.

GNSS are incremental and cumulative For all of their transformative effects, GNSSbuild on earlier endeavors, discoveries, and achievements. In fact, it was in the context ofGNSS that I first heard the expression, “We stand on the shoulders of giants.” Thus,Galileo and BeiDou have largely recapitulated GPS and GLONASS while bringing theirown advances and novel contributions. The Soviet Union’s GLONASS almost certainlyreflected a security-related response to GPS, only using a different orbital configurationand adding an FDMA element to the spreading-code design of GPS’s CDMA.

But the lineage of cause and effect, of research and practice, goes back much further.Most immediately, GPS built on earlier Defense Department initiatives, including theNavy’s TRANSIT (Doppler) system and Timation program, the Air Force 621BProject, the Army’s SECOR satellites, and OMEGA.

xvi Foreword by Glen Gibbons






Looking further back, however, the Earth’s first artificial moon, Sputnik, sent aloft bythe Soviet Union in 1957, inspired researchers at Johns Hopkins Applied Physics Lab touse the satellite’s radio signal to determine its orbital location by means of Dopplermeasurements. And soon they speculated that the reverse was possible: to determine areceiver’s position on the ground if the satellite’s orbital location was known. That, inturn, led to efforts to replicate in space the radionavigation capabilities seen in suchterrestrial systems as Loran and DECCA.

If we broaden the bandwidth on our scan of history for GNSS antecedents, however,we will ultimately assemble a pantheon of pioneers in physics, astronomy, math, andengineering – from Einstein, to Kepler and Newton, Tycho Brahe, Copernicus, and onback to Archimedes and Euclid.

GNSS clearly is a “disruptive” technology, a term much in vogue. In the words ofthat familiar repository of knowledge, Wikipedia, “A disruptive innovation is aninnovation that helps create a new market and value network, and eventually goes onto disrupt an existing market and value network (over a few years or decades),displacing an earlier technology.”

Oddly enough, Wikipedia does not yet include GNSS in its list of these innovations –where such inventions as telephones, automobiles, and personal computers appear – butGNSS certainly fits the bill.

Moreover, GNSS has put a previously inconceivable capability into the hands ofmillions. Before GPS, positioning was not a term of art known to the general public.Yes, people were familiar with such concepts as navigation, with mapping, withsurveying. But these were understood to be in the bailiwick of professionals, of peoplewho trained for years with expensive, specialized equipment, and not a matter ofconcern for the rest of us.

How that view has changed! The quotation from Ralph Waldo Emerson on page xixwith which Dr. Petrovski introduces this book is as true today for GNSS as it was for thedisruptive technologies of the nineteenth century.

A GNSS is a strategic national or regional asset Undertaking a GNSS reflects therelative weight and aspirations of nations around the world. In the bipolar world of the1970s, that meant the United States and the Soviet Union. In the twenty-first century,Europe and China have joined the club, with India and Japan adding regional satnavsystems. These roles have been enshrined by membership in the UN-sanctioned Inter-national Committee on GNSS.

Consider this: as Europe was exploring the possibility of developing its own GNSS, itposed a variety of benefits – commercial opportunities, a boost to the manufacturingeconomy, education and employment of high-tech professionals, a civil alternative to“military” systems such as GPS and GLONASS. But the real argument that persistedthrough the years of studies, debates, and indecision, and ultimately persuaded theEuropean Union to launch Galileo, was the desire for political sovereignty and controlover a critical infrastructure.

GNSS are complexly global and universal By this, I do not mean the obviousphysical reach of the system infrastructures themselves. Here, “global” refers to thescale and “universal” to the degree of penetration that GNSS technology has already

xviiForeword by Glen Gibbons






achieved into so many areas that cross national and ethnic boundaries: transportation,communications, economics, politics, sociology, law, and on and on.

For example, a truly global technology like GNSS intrinsically points toward a globalmarket. And along with such an expansive geography of business comes a panoply ofrelated activities: intellectual property rights, trade issues (subsidies, “dumping,” taxes,and tariffs), compatibility and interoperability of technologies, international rule-settingand adjudication of disputes, and so forth. In the meantime, location-based advertisinghas emerged as one of the fastest-growing revenue streams associated with mobiledevices.

Another example: Use of GNSS by law enforcement agencies has become a conten-tious issue in many countries, having already reached the US Supreme Court. At thesame time, concern about its potential misuse by private individuals is rising. In fact, byone measure we might even say that a technology has truly “arrived” when it beginsbeing put to undesirable uses. That appears to be the situation with GNSS, where we seesuch misapplications of the technology as virtual stalking, warrantless surveillance, roadtoll avoidance, deceiving truck dispatchers, and manipulating stock markets.

At the same time, GNSS-inspired position/location has become part of the commonground of human experience. It has entered into our language and our mental maps –our sense of where we come from, where we are, where we are going. GNSS andassociated technologies orient us to the world and its inhabitants around us – bothknown and unknown.

So, thank you Ivan for giving us new insights and access into use of the remarkabletechnology and tool of GNSS.

xviii Foreword by Glen Gibbons






About this book

As far as GNSS is concerned there are four main areas: mobile applications, geodesy,geophysical applications, and INS-aided navigation. This book covers the first topic,and the last two topics are covered in the book written together with Dr. Toshiaki Tsujiiand published by Cambridge University Press, Digital Satellite Navigation andGeophysics.

This book is different from Digital Satellite Navigation and Geophysics in one otherrespect. In this book I take a pragmatic approach, providing algorithms and methods, incomparison with an holistic approach in Digital Satellite Navigation and Geophysics,where we tried to explain how GNSS is related to other manifestations of the physicalworld and physical science, and to the nature of things.

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Acknowledgments

I would like to thank colleagues and friends without whom this work wouldn’t bepossible: Dr. Toshiaki Tsujii from JAXA, Mr. Ken Satoh from Amtechs Corporation.Prof. Harumasa Hojo and Prof. Emeritus Akio Yasuda from Tokyo University ofMarine Science and Technology, Mr. Andrew Addy from Spirent Communications,and Dr. Takuji Ebinuma from Tokyo University.

I would also like to thank Mr. H. Torimoto from GNSS Technologies Inc. for hissupport during the years I was working with him.

I would like to thank my wife Tanya for her support and for encouraging me to sharemy knowledge and experience in this book.

Figures 8.3 and 9.1 were created by Natalia I. Petrovskaia, BA (Cantab), MPhil(Cantab), PhD (Cantab).

Credits for cover image and Figure 2.29: ESA– J. Huart; for Figure 10.1: ESA–S. Corvaja.

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Abbreviations and acronyms

ADC analog-to-digital converterAGPS (AGNSS) assisted GPS (GNSS)AMP accelerated massive parallelismAPI application programming interfaceARAMIS™ adaptive receiver applied for monitoring of ionospheric

scintillationASC audio sub-channelASIC application-specific integrated circuitsBDT BeiDou Navigation Satellite System timeBOC binary offset carrierbps bits per secondBPSK binary phase shift keyingC/A coarse/acquisitionCDGPS (CDGNSS) carrier differential GPS (GNSS)CDMA code division multiple accessCEP circular error probableCGCS2000 China geodetic coordinate system 2000CODE Center for Orbit Determination in EuropeCPLD complex programmable logic deviceCPU central processing unitCUDA computer unified device architectureDFF D-type flip-flopDFT digital Fourier transformDGPS (DGNSS) differential GPS (GNSS)DIF digitized intermediate frequencyDLL delay-locked loopDOP dilution of precisionECEF Earth-centered, Earth-fixedECI Earth-centered inertialECO Earth-centered orbitalEGNOS European Geostationary Navigation Overlay ServiceEMC electromagnetic compatibilityEOP Earth orientation parameters

xxi






FCC Federal Communications CommissionFDMA frequency division multiple accessFFT fast Fourier transformFIFO First In First OutFLL frequency-locked loopFPGA field-programmable gate arrayFTF fundamental time frameGATE Galileo test and development environmentGEO geostationary Earth orbitGIS geographic information systemGLONASS Global Navigation Satellite SystemGMT Greenwich Mean TimeGNSS Global Navigation Satellite SystemsGPS Global Positioning SystemGPU graphic processing unitGSI Geographical Survey Institute (Japan)GST Galileo system timeGUI graphical user interfaceHEO highly elliptical orbitHIO highly inclined orbitICAO International Civil Aviation OrganizationICD Interface Control DocumentICRF International Celestial Reference FrameIERS International Earth Rotation and Reference Frames ServiceIF intermediate frequencyIGP ionospheric grid pointIGS International GNSS ServiceIGSO inclined geosynchronous satellite orbitIMES indoor messaging systemINS inertial navigation systemIONEX ionosphere exchange formatIP intellectual propertyIPP ionospheric pierce pointISC inter-signal correctionITRF International Terrestrial Reference FrameITU International Telecommunication UnionJAXA Japanese Aerospace Exploration AgencyJPL Jet Propulsion LaboratoryLAAS local area augmentation systemLEO low Earth orbitLNA low-noise amplifierLO local oscillatorLOS line-of-sight (between a receiver and a satellite)LSE least-squares estimation

xxii List of abbreviations and acronyms






LTO long-term orbitL2C GPS civil signal on L2 frequency of L-bandLUT lookup tableMEO medium Earth orbitMODIP modified dip latitudeMps megasamples per secondMSAS Multi-functional Satellite Augmentation SystemNAV navigationNCO numerically controlled oscillatorOCXO oven-controlled crystal oscillatorOEM original equipment manufacturerPDF probability density functionPLL phase-locked loopPPP precise point positioningPRN pseudorandom noiseQPSK quadrature phase shift keyingQZSS Quasi-Zenith Satellite SystemRAIM receiver autonomous integrity monitoringRF radio frequencyRHCP right-hand circularly polarizedRINEX Receiver Independent Exchange FormatRMS root mean squareRPS record and playback systemRTCM Radio Technical Commission for Maritime ServicesRTK real-time kinematicRTOS real-time operating systemsSA selective availabilitySARP Standards and Recommended PracticesSAW surface acoustic waveSBAS space-based augmentation systemSDCM system of differential correction and monitoringSDR software-defined radioSEP spherical error probableSIMD single instruction on multiple dataSMA sub-miniature version ASNR signal-to-noise ratioSoL safety of lifeSOW seconds of weekSP standard precisionSV space vehicleSVID space vehicle identification numberSVN space vehicle numberTCXO temperature-compensated crystal oscillatorTEC total electron content

xxiiiList of abbreviations and acronyms






TOT time of transmissionTOW time of weekTTA time to alertTTFF time to first fix2DRMS twice distance RMSURA user range accuracy (GPS)UTC Coordinated Universal TimeVCXO voltage-controlled crystal oscillatorVLBI Very Long Baseline InterferenceVRS virtual reference stationWAAS Wide Area Augmentation SystemWGS-84 World Geodetic System 1984

xxiv List of abbreviations and acronyms






Definitions

Code phase measurements Ambiguous code phase measurements are measured byreceiver baseband processor. These measurements do notrequire any information to be decoded from navigationmessage.

Observables Observables are formed using receiver rawmeasurements in various combinations. Pseudorangeobservables are just pseudoranges.

Pseudoranges orpseudorange observables

Pseudoranges are created from code phase measurementsproperly aligned with each other (removing time skew)and made unambiguous using time mark either fromnavigation message or external sources.

Receiver measurements Receiver measurements usually refer to antennacoordinate measurements, when observables areprocessed in the receiver navigation processor.

Receiver raw measurements Receiver code phase and carrier phase rawmeasurements are unambiguous pseudoranges andambiguous carrier phase measurements.

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