CONTENTS (Continued)

Page

11.2 DGPS Applications........................................................................................................11 1

11.2.1

Potential Uses of DGPS..................................................................................11 1

11.2.1.1 Instrument Approach ......................................................................11 1

11.2.1.2 All Weather Helicopter Operations.................................................11 1

11.2.1.3 Narrow Channel Maritime Operations............................................11 2

11.2.1.4 Reference Station for Testing/Calibration of

Navigation Equipment................................................................11 2

11.2.1.5 Surveying for Mapping and Positioning..........................................11 2

11.2.1.6 Blind Take Off................................................................................11 2

11.2.2

DGPS Data Link.............................................................................................11 2

11.3 GPS Used as an Attitude Reference System..................................................................11 3

11.3.1

Introduction.....................................................................................................11 3

11.3.2

Concept of Operation......................................................................................11 3

11.3.3

3 D Attitude Reference System.......................................................................11 4

11.3.4

Use of Multiple Receivers and a Reference Oscillator.....................................11 5

11.3.5

Error Sources and Degradation of Performance .............................................11 5

11.3.5.1 Absolute Position Uncertainty.........................................................11 5

11.3.5.2 PDOP..............................................................................................11 6

11.3.5.3 Antenna Location............................................................................11 6

11.3.5.4 Antenna Position Difference Uncertainty

in the Body Frame ......................................................................11 6

11.3.5.5 Measurement Accuracy and Error Budget......................................11 6

11.4 Precise Time and GPS ...................................................................................................11 7

11.4.1

Introduction.....................................................................................................11 7

11.4.2

Applications of Precise Time...........................................................................11 7

11.4.3

Interrelationship Between Different Definitions of Time.................................11 7

11.4.3.1 Time Based on the Rotation of the Earth

On Its Axis..................................................................................11 7

11.4.3.2 Atomic Time/UTC Time.................................................................11 8

11.4.3.3 GPS Time .......................................................................................11 9

11.4.4

Precise Time Dissemination from GPS............................................................11 9

11.4.4.1 Precise Time Dissemination Under Dynamic

Conditions.................................................................................11 12

11.4.4.2 Reduced Time Accuracy Due to SA.............................................11 13

11.4.5

Time Transfer Using GPS .............................................................................11 14

11.4.5.1 Coordinated Simultaneous View Time Transfer...........................11 14

11.4.5.2 Coordinated Simultaneous View Time Transfer

with USNO...............................................................................11 14

11.5 Satellite Orbit Determination Using GPS.....................................................................11 15

CHAPTER 12:  GPS INTEGRITY AND CIVIL AVIATION ........................................................12 1

12.1 Introduction ...................................................................................................................12 1

12.2 Military Use of National Airspace..................................................................................12 2

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