CONTENTS

Page

CHAPTER 1:  SYSTEM OVERVIEW..............................................................................................1 1

1.1

General Description .........................................................................................................1 1

1.2

System Overview.............................................................................................................1 2

1.2.1

Space Segment..................................................................................................1 2

1.2.2

Control Segment ...............................................................................................1 3

1.2.3

User Segment....................................................................................................1 5

1.3

GPS Services ...................................................................................................................1 5

1.3.1

Precise Positioning Service................................................................................1 5

1.3.2

Standard Positioning Service.............................................................................1 6

1.4

GPS Theory of Operation................................................................................................1 6

1.4.1

GPS Satellite Signals.........................................................................................1 7

1.4.1.1

C/A Code..........................................................................................1 7

1.4.1.2

P(Y) Code ........................................................................................1 7

1.4.1.3

Navigation Message..........................................................................1 7

1.4.1.4

Satellite Signal Modulation  ..............................................................1 8

1.4.2

GPS Receiver Operation ...................................................................................1 9

1.4.2.1

Satellite Selection............................................................................1 10

1.4.2.2

Satellite Signal Acquisition..............................................................1 11

1.4.2.3

Down Conversion...........................................................................1 12

1.4.2.4

Code Tracking ................................................................................1 13

1.4.2.5

Carrier Tracking and Data Detection..............................................1 13

1.4.2.6

Data Demodulation.........................................................................1 14

1.4.2.7

P(Y) Code Signal Acquisition.........................................................1 14

1.4.2.8

PVT Calculations............................................................................1 14

1.4.2.9

Degraded Operation and Aiding .....................................................1 17

1.5

Program Management ...................................................................................................1 17

1.5.1

System Development and Management ..........................................................1 17

1.5.2

System Requirements, Planning, and Operations ............................................1 17

1.6

GPS Program History....................................................................................................1 18

1.6.1

Pre Concept Validation (1960s 1972) ............................................................1 18

1.6.2

Phase I   Concept Validation (1973 1979)......................................................1 18

1.6.3

Phase II   Full Scale Development (1979 1985)..............................................1 19

1.6.4

Phase III   Production and Deployment (1986 to Present)..............................1 20

1.6.4.1

Space Segment (1986 to Present) ...................................................1 20

1.6.4.2

Control Segment (1986 to Present) ................................................1 21

1.6.4.3

User Segment (1986 to Present) .....................................................1 22

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