Server-side GPS and Assisted-GPS in Java (Artech House Gnss Technologies and Applications)

261 Pages·2009·2.18 MB·English

by  Neil Harper

Server-Side GPS and
Assisted-GPS in Java™
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Server-Side GPS and
Assisted-GPS in Java™
Neil Harper
artechhouse.com
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ISBN-13: 978-1-60783-985-9
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10 9 8 7 6 5 4 3 2 1
To my wife, Tracey,
our children, Kate, Emma, and Adam,
and my parents, Barry and Brigit,
who have made this, and everything else, possible.

Contents
Preface xiii
Acknowledgments xvii
CHAPTER 1
Introduction 1
1.1 Overview 1
1.2 Terminology 2
1.3 Global Navigation Satellites Systems (GNSS) 2
1.4 GNSS Augmentations 3
1.5 GPS from a High Level 3
1.6 Assisted-GNSS from a High Level 5
1.7 A-GNSS Protocols and Standards 9
1.8 Why Is an Accurate Location Required? 10
1.9 Location Market 11
1.9.1 E9-1-1 11
1.9.2 Location-Based Services 11
1.9.3 Lawful Intercept Services 12
1.10 Java and Software Design for A-GNSS Applications 12
1.10.1 Coding in Java 13
1.11 Organization of This Book 14
References 14
CHAPTER 2
Coding for GNSS and the Coordinate Reference Frame 17
2.1 Coordinate Reference Frame 17
2.2 World Geodetic System 1984 18
2.3 Source Code Structure and Management 22
2.4 WGS 84 Implementation 23
2.5 Unit Testing 27
2.6 Debugging 29
2.7 Performance Testing and Benchmarking 29
2.8 Code Coverage Analysis 30
2.9 Configuration Management 32
References 32
vii
viii Contents
CHAPTER 3
GPS 35
3.1 GPS Constellation and Segments 35
3.2 GPS Services 36
3.3 Satellites 36
3.4 Ranging Codes 36
3.5 PRN Codes 37
3.6 GPS C/A Code 37
3.7 GPS L1 Signal 38
3.8 GPS L2 Signal 38
3.9 GPS Time 39
3.10 Broadcast Information Navigation Message Structure (NAV) 39
3.11 Decoding and Storing the Navigation Model 46
3.11.1 Storing the Raw NAV Data 46
3.11.2 Running the Classes to Store the Raw Data 47
3.11.3 Other Sources of Raw NAV Data 49
3.11.4 Decoding the NAV Data into Useful Information 49
3.11.5 RINEX as a Data Source for the Navigation Message 50
3.11.6 Implementation of Methods Using the NAV Model 51
3.12 GPS Signal Acquisition 54
3.13 Receiver Positioning 54
3.13.1 Uncertainty and Confidence 56
3.14 Factors Affecting Location Accuracy 58
3.15 Geometry and Dilution of Precision 59
3.16 Differential-GPS 59
3.17 Software Projects 60
References 62
CHAPTER 4
Assisted-GPS and Assistance Data 63
4.1 The Assistance Model 63
4.2 GNSS Reference Server (GRS) 65
4.2.1 GPS Reference Receiver Configuration for a GRS 66
4.2.2 GRS Interface 69
4.2.3 Open Source GNSS Reference Server (OSGRS) 70
4.3 Location Server (LS) 72
4.4 Location-Based Application (LBA) 73
4.5 Emergency Services Messaging Entity 75
4.6 The Handset 76
4.7 Assistance Data Types 76
4.7.1 Reference Time 77
4.7.2 Reference Location 79
4.7.3 Navigation Model 79
4.7.4 Ionosphere Model 79
4.7.5 UTC Model 80
4.7.6 Acquisition Assistance 81
4.7.7 Real-Time Integrity 86
Contents ix
4.7.8 Almanac 86
4.7.9 DGPS Corrections 86
4.8 Assistance Data Type Sizes 87
References 88
CHAPTER 5
Assisted-GPS Location Within a Network 91
5.1 Location Architectures 91
5.2 A-GPS Protocols and Messaging 92
5.3 RRLP 92
5.3.1 RRLP Procedures 93
5.3.2 RRLP Messages 94
5.3.3 RRLP Encoding and ASN.1 Packed Encoding Rules 95
5.3.4 RRLP Implementation 104
5.3.5 Testing the RRLP Classes 110
5.3.6 Communication Across Sockets with RRLP 110
5.4 PCAP and RRC 114
5.4.1 PCAP Procedures 115
5.4.2 PCAP Messages and Encoding 117
5.5 Software Projects 117
References 118
CHAPTER 6
Position Calculation 121
6.1 Position Calculation and Handset-Assisted A-GPS 121
6.2 The Accuracy and Yield Trade-Off 122
6.3 Positioning Using GPS Code Phase Measurements 123
6.3.1 Data Preparation 126
6.3.2 Worked Example 127
6.3.3 Satellite Health 129
6.3.4 Calculate the Location of Each Satellite 130
6.3.5 Satellite Clock Correction 130
6.3.6 Group Delay Differential 132
6.3.7 Geometric Range Correction 132
6.3.8 Substituting in a Pseudomeasurement 134
6.3.9 Pruning Bad Satellite Measurements 134
6.3.10 Pruning Low Elevation Satellites 134
6.3.11 Pruning Weak Measurements 136
6.3.12 Ionosphere Correction 136
6.3.13 Troposphere Correction 137
6.3.14 Position Calculation 138
6.3.15 Uncertainty 143
6.3.16 Quality Measures 145
6.4 Doppler-Based Position Calculation 146
6.5 Hybrid Position Calculation 149
6.6 Software Projects 149
References 150