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An Efficient Propagation Simulator for High Frequency Signals And Results from HF radar experiment

An Efficient Propagation Simulator for High Frequency Signals And Results from HF radar experiment. Kin Shing Bobby Yau Supervisors: Dr. Chris Coleman & Dr. Bruce Davis School of Electrical and Electronic Engineering The University of Adelaide, Australia. Overview.

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An Efficient Propagation Simulator for High Frequency Signals And Results from HF radar experiment

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  1. An Efficient Propagation Simulator for High Frequency SignalsAnd Results from HF radar experiment Kin Shing Bobby Yau Supervisors: Dr. Chris Coleman & Dr. Bruce Davis School of Electrical and Electronic Engineering The University of Adelaide, Australia

  2. Overview • HF Ionospheric Propagation Simulator • Simulation results • Comparisons with Experimental Results • Discussions • Conclusions

  3. Introduction HF radio system is still prevalent • Military Over-the-Horizon RADAR • HF communications • Commercial broadcasting

  4. Ionospheric Propagation Simulator • A need for wideband HF propagation simulator • Focussing on the fading effects of HF signals • Employ theoretical model of fading • Efficient algorithm based on analytical expressions • Two components of fading model: • Polarization Fading Model • Amplitude Fading Model

  5. Polarization Fading Model • Faraday rotation due to O and X wave interference

  6. Polarization Fading Model • Perturbation techniques to ascertain the change in phase path due to irregularities • Use of frequency offset method to take into account of the magnetic field

  7. Amplitude Fading Model • Focussing and defocussing of radio waves due to movement of large scale ionospheric structure

  8. Amplitude Fading Model • Parabolic approximation to Maxwell’s equation (Wagen and Yeh): • U is the complex amplitude,  is the refractive index with irregularities • g and t are the local longitudinal and transverse coordinates

  9. Amplitude Fading Model

  10. Simulator Implementation • Numerical ray tracing is used for the path quantities • Accurate ray homing for finding all possible paths (Strangeways, 2000) • Fading is calculated by the fading models

  11. Simulation Results • Alice Springs to Darwin

  12. Simulation Results • 10.6MHz -  = 0.05, L = 350km, v = 200m/s

  13. Simulation Results • 10.6MHz -  = 0.05, L = 350km, v = 200m/s

  14. Simulation Results • 10.6MHz -  = 0.05, L = 350km, v = 200m/s

  15. Simulation Results • 10.6MHz -  = 0.20, L = 350km, v = 200m/s

  16. Simulation Results • 10.6MHz -  = 0.20, L = 350km, v = 200m/s

  17. Simulation Results • 10.6MHz -  = 0.20, L = 350km, v = 200m/s

  18. Comparison – Experimental Results • Signals from Jindalee Radar transmitter in Alice Springs • Dual-polarization receiver in Darwin

  19. FMCW Radar signal Experimental Results Finding the signal component along each sweep

  20. 6:30PM local time – Spectrograms Experimental Results

  21. 6:30PM local time – Time fading Experimental Results

  22. 6:30PM local time – Frequency fading Experimental Results

  23. 7:30PM local time – Spectrograms Experimental Results

  24. 7:30PM local time – Time fading Experimental Results

  25. 7:30PM local time – Frequency fading Experimental Results

  26. Fading Separation • Separate amplitude and polarisation fading • Two orthogonal antennas: • A - amplitude component  - phase component • Therefore:

  27. 7:30PM local time – Time fading revisited Fading Separation

  28. 7:30PM local time – Time fading separation Fading Separation

  29. 6:30PM local time – Time fading revisited Fading Separation

  30. 6:30PM local time – Time fading separation Fading Separation

  31. Fading Separation • Fading separation works well for single-mode case • For multi-mode propagation: • Exploit FMCW radar signals • Separating the modes using Range-gating techniques • Applying fade separation to each of the modes

  32. Discussion • Further analyzing with experimental data • Comparisons with ionosonde data • Discover the structure of the ionosphere during the period of rapid fading • Simulating propagation under realistic irregularity strctures • Possible applications: • Real-Time channel evaluation • Test-bed for fading mitigation techniques

  33. Conclusion • Efficient Ionospheric Propagation Simulator has been developed • Experiment to observe fading of HF signals was done successfully • Comparisons between experiment and simulation are promising, especially for single-path polarization fading • More work to be done on the experimental data

  34. Acknowledgements • Defence Science and Technology Organisation (DSTO) • Dr. Manuel Cevira • Dr. Chris Coleman

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