Digital processing of today’s radar signals

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by Patrick Beasley of QuinetiQ made at the BMEA Conference 2010

by Patrick Beasley of QuinetiQ made at the BMEA Conference 2010

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