1. 1 Spectral identification & suppression of ground clutter contributions for phased array radar Spectral identification of ground clutter Spectral identification of ground clutter Svetlana Bachmann, Dusan Zrnic, and Chris Curtis CIMMS, University of Oklahoma NSSL/OAR/NOAA, Norman, Oklahoma 9A.4

2. 2 Each pixel on a radar display (one resolution volume) is obtained from many samples. For a large number of samples, a Doppler spectrum can be estimated. Doppler spectrum A Doppler spectrum is a distribution of echoes (from one resolution volume) in Doppler velocity. Doppler velocity –v a –½v a 0 ½v a v a Power, dB Ground clutter Weather Noise Doppler Spectrum

3. 3 Doppler velocity –v a –½v a 0 ½v a v a Power, dB Weather Noise Doppler Spectrum v vvvv Ground clutter

4. 4 Sample Time Back in the Time Domain Doppler velocity –v a –½v a 0 ½v a v a Power, dB –½v a 0 ½v a Power, dB –½v a 0 ½v a Power, dB Phase-based clutter identification –½v a 0 ½v a  eo, radians

5. 5 100 simulations: PRT = 0.8 ms, SNR = 20 dB, CSR = 40 dB,  v = 2 m s –1, v = 10 m s –1 Pulse repetition time Signal to noise ratio Clutter to signal ratio Spectral width of weather Velocity, m s –1 Power, dB  eo  eo, radians –½v a 0 ½v a  eo, radians Simulations Phase  eo is close to 0 at Doppler bins with ground clutter  eo is a spectral density of spectral density of phase coherence phase coherence diff. phase between diff. phase between spectral coefficient of spectral coefficient of even- and odd-indexed even- and odd-indexed time series time series

6. 6 Power, dB Doppler velocity, m s –1  eo  eo, radians Simulations - zoom in 100 simulations: PRT = 0.8 ms, SNR = 40 dB, CSR = 40 dB,  v = 2 m s –1 1.5 1.0 0.5 0 -0.5 -1.5

7. 7 Simulations – with & without clutter PRT = 0.8 ms, SNR = 40 dB,  v = 2 m s –1, v = -5:5 m s –1 Simulation CSR = -40 dB CSR = 0dB velocity, m s –1 OriginalNotched Velocity, m s –1 NotchedOriginal Power, dB

8. 8 Radar data collected by Dave Priegnitz Sept. 25, 2007, 13:49:59 UTC velocity, m s –1 Range, km Power,dB

9. 9 July 26, 2007, 13:32:29 UTC Radar data velocity, m s –1 Range, km Power,dB

10. 10 Spectral identification & suppression of ground clutter contributions for phased array radar 9A.4 Phase-based Phase-based Thank you! Questions?

11. 11 Sept.25, 2007, 15:14:52 UTC July 30, 2007, 15:50:10 UTC Sept.19, 2007, 13:46:46 UTC Power, dB More examples

12. 12 OLD NEW How does this technique compare to NEXRAD spectral GCF?

13. 13 OLD NEW How does this technique compare to NEXRAD spectral GCF?

14. 14 NEW OLD How does this technique compare to NEXRAD spectral GCF?