Digital processing of today’s radar signals


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by Patrick Beasley of QuinetiQ made at the BMEA Conference 2010

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Digital processing of today’s radar signals

  1. 1. High Resolution Surveillance Radar Patrick Beasley, Tom Leonard, Tim Lamont-Smith A presentation to: BMEA 20 th October 2010 QinetiQ Proprietary
  2. 2. Content <ul><li>1 Introduction </li></ul><ul><li>2 PILOT radar </li></ul><ul><li>3 Tarsier® radar </li></ul><ul><li>4 Cheddar reservoir </li></ul><ul><li>5 Recent advances </li></ul><ul><li>6 Future radar </li></ul><ul><li>7 Conclusions </li></ul>
  3. 3. 1 Introduction <ul><li>The use of high range resolution radar for harbour and coastal surveillance </li></ul><ul><li>Background to the World’s first production marine navigation radar – PILOT </li></ul><ul><li>Tarsier®, an example of a state-of–the-art high resolution radar </li></ul><ul><li>Trials results from Cheddar reservoir </li></ul><ul><li>Current technology </li></ul><ul><li>Future harbour and coastal radar </li></ul><ul><li>Conclusions </li></ul>
  4. 4. <ul><li>The World’s first FMCW production marine navigation radar (1987) </li></ul><ul><li>Developed by Philips Research Laboratories and Hollandse Signaal Apparaten </li></ul><ul><li>Designed to have equivalent performance to ZW06 pulsed radar </li></ul><ul><li>Detection performance </li></ul><ul><li>1m 2 Swerling 1 target at 7.2km (P d = 50%, P fa = 10 -6 ) </li></ul><ul><li>Instrumented to 36km, minimum range 9m </li></ul><ul><li>Range resolution 4.5m to 36m </li></ul><ul><li>Dual antenna to minimise transmit – receive leakage </li></ul><ul><li>Later versions used reflected power canceller for single antenna operation </li></ul><ul><li>Frequency linearity derived from YIG oscillator limited effective range resolution </li></ul>2 PILOT
  5. 5. 2 PILOT – technology demonstrator
  6. 6. 2 PILOT <ul><li>Advantages </li></ul><ul><ul><li>Solid state transmitter </li></ul></ul><ul><ul><ul><li>Reliability </li></ul></ul></ul><ul><ul><ul><li>Low voltage supplies </li></ul></ul></ul><ul><ul><li>Very good range resolution </li></ul></ul><ul><ul><li>Low probability of intercept </li></ul></ul><ul><ul><ul><li>Waveform mismatched to ESM </li></ul></ul></ul><ul><li>Disadvantages </li></ul><ul><ul><li>Frequency linearity challenging to achieve </li></ul></ul><ul><ul><li>Phase noise requirement </li></ul></ul><ul><ul><ul><li>Inconvenience of separate Tx and Rx antennas </li></ul></ul></ul><ul><ul><ul><li>Can’t cancel reflected noise from very large targets </li></ul></ul></ul><ul><ul><li>Range-Doppler coupling </li></ul></ul>
  7. 7. 2 PILOT PPI recorded in the strait between Sweden’s mainland and the island of Oland with a bridge approx 50m high at 15nm. Range rings every 4nm Note phase noise flash from large target
  8. 8. 2 PILOT <ul><li>Scout Mark 2 Squire Page </li></ul>courtesy Thales Marine navigation Battlefield surveillance Air surveillance
  9. 9. 3 Tarsier®
  10. 10. 3 Tarsier® - parameters <ul><li>Centre frequency 94.5GHz </li></ul><ul><li>Transmit power 100mW </li></ul><ul><li>Frequency sweep 600MHz </li></ul><ul><li>Antenna gain 47dB </li></ul><ul><li>Azimuth beamwidth 0.2 ° </li></ul><ul><li>Elevation beamwidth 2° </li></ul><ul><li>Polarisation Circular </li></ul><ul><li>Noise figure 8dB </li></ul><ul><li>Detects a 2” bolt at 1 mile. </li></ul>
  11. 11. 3 Tarsier® - The effect of phase noise from large targets
  12. 12. 3 Tarsier® - Providence RI
  13. 13. 3 Tarsier® - Providence zoomed in
  14. 14. 3 Tarsier® - rain at Malvern, 90s intervals
  15. 15. 3 Tarsier® Floodlights Houses Trees Phase noise flash Ground clutter
  16. 16. 4 Cheddar Reservoir <ul><li>High resolution clutter map of intensity, collected staring into wind </li></ul><ul><ul><li>Dark pixels show high intensity (dB scale) </li></ul></ul><ul><li>Lines remain visible over ~100 s </li></ul>
  17. 17. 4 Cheddar Reservoir
  18. 18. 4 Cheddar Reservoir <ul><li>Zoomed in image </li></ul><ul><ul><li>Waves are modulated (faint lines) </li></ul></ul><ul><ul><li>Individual waves travel at phase velocity, modulation envelope propagates at half that velocity </li></ul></ul><ul><ul><li>Higher RCS of waves at peak of modulation envelope </li></ul></ul>
  19. 19. 4 Cheddar Reservoir – Raytheon display
  20. 20. 4 Cheddar Reservoir - Geese
  21. 21. 4 Cheddar Reservoir - Geese
  22. 22. 5 Recent Advances – Harbour / Coastal surveillance requirement <ul><ul><li>Traditionally, a safety aid </li></ul></ul><ul><ul><li>Recent requirement for anti-terrorism </li></ul></ul><ul><ul><ul><li>Jet skis, swimmers, divers, RHIBs </li></ul></ul></ul><ul><ul><li>Small targets vs. sea clutter </li></ul></ul><ul><ul><li>Choice of RF frequency </li></ul></ul><ul><ul><ul><li>Cost </li></ul></ul></ul><ul><ul><ul><li>Size </li></ul></ul></ul><ul><ul><ul><li>Weather </li></ul></ul></ul><ul><ul><ul><li>Transmit power and noise figure </li></ul></ul></ul><ul><ul><ul><li>Licensing and available bandwidth </li></ul></ul></ul><ul><ul><li>Coastal surveillance very challenging for a CW based radar </li></ul></ul><ul><ul><ul><li>High CW transmit power </li></ul></ul></ul><ul><ul><ul><li>Ultra low phase noise </li></ul></ul></ul><ul><ul><ul><li>High Tx/Rx antenna isolation </li></ul></ul></ul>
  23. 23. 5 Recent Advances <ul><li>Non-coherent </li></ul><ul><ul><li>Fast scan rate (60rpm) </li></ul></ul><ul><ul><ul><li>Good update for tracking algorithms </li></ul></ul></ul><ul><ul><li>Minimises clutter cell (sea, land, rain) </li></ul></ul><ul><ul><li>Excellent range resolution, 10cm </li></ul></ul><ul><ul><li>Two target discrimination based on range resolution </li></ul></ul><ul><ul><li>Excellent geolocation, especially if used in multistatic mode </li></ul></ul><ul><li>Coherent </li></ul><ul><ul><li>Low scan rate (12rpm) </li></ul></ul><ul><ul><ul><li>Slow update but additional Doppler information for tracker </li></ul></ul></ul><ul><ul><li>Rejects clutter based on Doppler </li></ul></ul><ul><ul><ul><li>Sub-clutter visibility </li></ul></ul></ul><ul><ul><li>Very good range resolution, 1m </li></ul></ul><ul><ul><li>Target discrimination based on range resolution and Doppler </li></ul></ul><ul><ul><li>Very good geolocation, especially if used in multistatic mode </li></ul></ul>Optimal solution is to adapt the mode to the environment
  24. 24. 5 Recent Advances – coherent operation <ul><li>Provides phase and Doppler information </li></ul><ul><li>Traditionally exploited for military applications </li></ul><ul><ul><li>Now low cost, high stability oscillators and DDS make coherent operation viable </li></ul></ul><ul><ul><li>Advantages of coherent integration </li></ul></ul><ul><ul><li>Integration of thermal noise improves sensitivity </li></ul></ul><ul><ul><ul><li>Target discrimination based on range resolution and Doppler </li></ul></ul></ul><ul><ul><li>Provision of target Doppler </li></ul></ul><ul><ul><ul><li>Improves tracking </li></ul></ul></ul><ul><ul><ul><li>Aid to target classification </li></ul></ul></ul><ul><ul><li>Rejection of sea and land clutter </li></ul></ul><ul><ul><ul><li>Sub-clutter visibility </li></ul></ul></ul><ul><ul><li>Rejection of rain backscatter – important at higher RF frequencies </li></ul></ul>
  25. 25. 6 Future radar Parameter PILOT (military only) 24GHz harbour radar (military or civil) Range resolution 4.5m to 36m (range scale dependent) 1.5m (all range settings) Clutter rejection Poor (non-coherent) Very good (coherent and non-coherent) Phase noise -110dBc/Hz at 166kHz -135dBc/Hz at 166kHz (COTS) -160dBc/Hz (custom) Instrumented range 36km 24km Antenna size 1.8m 0.7m Interference Susceptible in highly populated band – uses frequency diversity Sparsely populated band
  26. 26. 6 Conclusions <ul><ul><li>High range resolution radar is achievable and affordable. </li></ul></ul><ul><ul><li>Excellent detection of small targets. </li></ul></ul><ul><ul><li>Coherent processing has many benefits. </li></ul></ul><ul><ul><li>Advantages in moving to a higher RF frequency. </li></ul></ul>