Radionavigation Systems

Transcription

1 Radionavigation Systems Börje Forssell 1 ARTECH HOUSE BOSTON LONDON artechhouse.com

2 Contents Preface xiii Part I: Terrestrial Systems 1 1 The f undamentais of terrestrial navigation The shape of the earth Maps and coordinate systems/datum Distances and directions on the surface of the earth Great circle course on a spherical earth Loxodrome course Distances and directions on an ellipsoidal earth 16 2 Error calculations Lines of position Errors in lines of position The geometrical influence on two-dimensional position errors Errors in measurements of distance and distance differences Distance measurements Measurements of distance differences Error ellipses Distance measurement error ellipses Error ellipses for a hyperbolic navigation system Accuracies Two-dimensional position determination by means of more than two LOPs 45 v

3 vi Contents 3 Wave propagation 3.1 Free space propagation 3.2 Reflection from surroundings 3.3 The ground wave 3.4 Tropospheric influence 3.5 Ionospheric influence System descriptions 4 Hyperbolic Systems 4.1 Introduction 4.2 General 4.3 Phase measurements 4.4 OMEGA General Signal format Wave propagation at VLF General Conditions in the lower part of the ionosphere The directional dependence of the reflection coefficient of the ionosphere Influence of the earth and the Solution of the wave equations Receivers Transmitters Accuracy Differential OMEGA Prospects 4.5 DECCA Introduction Frequencies Receivers Transmitter stations Maps and corrections of the measurement result Accuracy and coverage Perspectives 4.6 LORAN-C General Signal format Interference and use of pulse groups

4 Contents vii Coded pulse groups Receivers Grouping of pulses for automatic search Transmitters Accuracy and ränge Differential LORAN-C Prospects Direction finding Introduction Frequencies and transmitters Directivity Receiver antennae Antennae for improved accuracy The Adcock antenna Doppler direction finders Accuracies Aircraft Systems Introduction VOR Operation The receiver Doppler VOR DME Principles of Operation Search procedure The transponder Accuracies/Use DME/P ILS System principles Markers Angular Information Accuracy/Sources of error MLS Introduction TRSB angular information The data message Use Accuracies and coverage Costs and perspectives 191

5 viii Contents Part II: Satellite Systems Satellite orbits and geometry Introduction Kepler'slaws Distortionof theorbit Coordinate Systems Satellite navigation principles Frequency measurements Time measurements Measurement principles Error calculations Error sources The geometrical influence on the accuracy Frequency measurements Time measurements Calculation of geometrical dilution of position 217 System descriptions TRANSIT Introduction The satellites Navigation principles Satellite Signals Position measurements The receiver The use of two carrier frequencies The iteration procedure Accuracy Translocation Fields of utilization/future Spread spectrum: coding of satellite Signals Introduction 250

6 Contents ix 11.2 Spread spectrum Principles Spreading functions The correlation function Generation of the codes (spreading functions) Thereceiver Spread spectrum in NAVSTAR/GPS NAVSTAR/GPS Introduction 12.2 Satellite orbits 12.3 The satellites 12.4 The control segment 12.5 The navigation message Introduction TLMandHOW Data block Clock corrections Age of data/group delay Corrections of ionospheric delays Data block Introduction Parameter representation selection Data block Receivers Introduction Receiver types Receiver description Clock and frequency stability Antennae 12.7 Differential GPS Presumptions and possibilities Work up to now 12.8 Interferometric use 12.9 Accuracy Integration with other navigation Systems GPS and inertial navigation Systems GPS and LORAN-C Other combinations Perspectives

7 X Contents 13 GLONASS Introduction Satellite orbits The navigation Signals The codes The navigation message Receivers Accuracy Other satellite navigation Systems Introduction TSIKADA STARFIX GEOSTAR/LOCSTAR NAVSAT Appendix 1: Datum transformation 335 Appendix 2: Formulas from spherical trigonometry 338 A2.1 Theorems concerning right-angled spherical triangles 338 A2.2 Theorems concerning arbitrary spherical triangles 339 Appendix 3: The radii of curvature of an ellipsoidal surface 341 Appendix 4: The Standard deviation of the error in a two-dimensional position 344 Appendix 5: Position determination by the method of least Squares 346 Appendix 6: Errors in DECCA user lines of position due to phase errors caused by the master-to-slave, master-to-user and slave-to-user Signal paths 352 Appendix 7: Satellites in orbit 356 A7.1 Derivation of Kepler'slaws 356 A7.2 The orbital velocity 361 A7.3 Orbital coordinates as time functions 363 A7.4 Launching of satellites into a desired orbit 368

8 Appendix 8: A method of satellite selection in time Contents xi measurement Systems 371 Appendix 9: Basic Kaiman fiiter equations 375 References 377 Index 387