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

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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 – PowerPoint PPT presentation

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


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 Maxwells 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
Experimental Results
  • FMCW Radar signal

Finding the signal component along each sweep
20
Experimental Results
  • 630PM local time Spectrograms

21
Experimental Results
  • 630PM local time Time fading

22
Experimental Results
  • 630PM local time Frequency fading

23
Experimental Results
  • 730PM local time Spectrograms

24
Experimental Results
  • 730PM local time Time fading

25
Experimental Results
  • 730PM local time Frequency fading

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

27
Fading Separation
  • 730PM local time Time fading revisited

28
Fading Separation
  • 730PM local time Time fading separation

29
Fading Separation
  • 630PM local time Time fading revisited

30
Fading Separation
  • 630PM local time Time 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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