1 / 53

Staggered PRT and Phase Coding Algorithms on the KOUN Research Radar

NEXRAD Range-Velocity Ambiguity Mitigation. Staggered PRT and Phase Coding Algorithms on the KOUN Research Radar. Sebastian Torres. Part One. Research RDA (RRDA) Capabilities. VCP Definitions. Legacy VCP definition RPG Message 7 ICD RDA/RPG (Doc. # 2620002A) Provision for

helia
Download Presentation

Staggered PRT and Phase Coding Algorithms on the KOUN Research Radar

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. NEXRAD Range-Velocity Ambiguity Mitigation Staggered PRT andPhase Coding Algorithms on the KOUN Research Radar Sebastian Torres

  2. Part One Research RDA (RRDA) Capabilities

  3. VCP Definitions • Legacy VCP definition • RPG Message 7 • ICD RDA/RPG (Doc. # 2620002A) • Provision for • Waveform Type • Constant or Random Phase • Waveform Configuration • Staggered Pulse Pair • Not supported on the WSR-88D! • No provision for systematic phase codes • No provision for staggered pattern definition

  4. VCP Definitions • RRDA VCP definition • Concurrent with NPI and Homeland Security Experiment • High-resolution data • Horizontal raster, vertical raster, searchlight scans • Backward compatible with Legacy definition for supported modes • R/V mitigation techniques are specified on a scan-by-scan basis • Proposed VCP for R/V

  5. VCP Definitions • Phase Coding Features • Can specify phase coding sequence number for each scan • Standard (or predefined) • Downloadable • Proposed new RPG Message to define phase coding sequence • Sequence length • Phases specified as multiples of 2p/128

  6. VCP Definitions • Staggered PRT Features • Can specify patterns using • Up to 3 PRI’s • A pulse count (M) for each PRI • An overall pattern count (Mp) • Examples • Standard staggered pattern: T1, T2, T1, T2, … • PRI1 = 1, M1 = 1, PRI2 = 2, M2 = 1, Mp = 32 • Block staggered pattern: T4, T4, T2, T2, T2, T4, T4, T2, T2, T2, … • PRI1 = 4, M1 = 2, PRI2 = 2, M2 = 3, Mp = 10

  7. Hardware Enhancements • Synchronizer • Phase coding of transmitted pulses • Uses legacy phase shifter (7 bits) • Generation of staggered pulse patterns • Generation of expanded set of PRTs • Legacy has limited set • Requirements for precise T1/T2 ratios • Requirements for different ra • Resolution given by 9.6 MHz clock

  8. Software Enhancements • Archive I Recorder • Handling of variable range-sweep sizes • Associated tools to handle phase-coded and staggered PRT data • Signal Processing • SimSPS model • Rapid prototyping • Real-time implementation • Phase coding: 1st trip decoding • Staggered PRT: full processing with simple GCF

  9. Part Two RRDA Implementation of the Staggered PRT Algorithm

  10. Assumptions • Transmission sequence alternates two PRT’s for a total of M pulses • N1 and N2 are range gates for T1 and T2 • No echoes beyond max(ra1, ra2) • Overlay of “short” into “long” • Echoes extending beyond max(ra1,ra2) can be censored • Does not assume: • M is even • T1/T2 is rational • T1 < T2 • In what follows T1 < T2 for clarity

  11. Inputs • Time-series data V(n,m) = I(n,m) + jQ(n,m)0 <m < M0 <n < N1 for even m0 <n < N2 for odd m • Associated metadata • GCF Maps • Adaptation Data As in legacy PSP

  12. Outputs • Base data • ReflectivityZ(n), for 0 <n < N2 • Doppler velocityv(n), for 0 <n < N1 • Doppler spectrum withw(n), for 0 <n < N1 • Z is computed through ra2 • v and w are computed through ra1 • Could include censored data up to ra2

  13. T1 T1 T2 Algorithm • Suppress interference • Legacy PSP algorithm • Compute powers and correlations • P1, R1 for short range sweeps • P2, R2 for long range sweeps

  14. Algorithm • Apply GCF: DC removal • Compute time-series mean: Vm • Remove |Vm |2 from P1, P2, R1, and R2 • Use bypass map • Could use Sachidananda’s GCF (Rep. 3 & 4) • Suppress point clutter • Legacy PSP algorithm • Compute Doppler velocities • v1 based on R1 • v2 based on R2

  15. Algorithm • De-alias v1 using v2 • Use v1 and v2 to determine Nyquist interval • De-alias v1 • Close to MMSE for SD(v1) >> SD(v2) • Compute Doppler spectrum widths • w based on P2 and R2(Zrnić and Mahapatra, 1985)

  16. T1 T2 Algorithm • Compute combined Echo power (N2) • Compute Reflectivity • Legacy PSP algorithm • Determine Significant Returns for Z • Use reflectivity threshold

  17. T1 T2 Algorithm • Compute individual Echo powers (N1, N2) • Determine overlaid echoes • Overlaid echoes do not bias v, but act as noise • Use overlaid threshold • Could use Sachidananda’s overlaid resolution scheme • Determine Significant Returns for v and w • Use velocity and width thresholds

  18. Algorithm Performance Staggered PRT Velocity De-aliasing va1 = 22.58m s-1, va2 = 15.06m s-1, va = 45.17 m s-1

  19. Algorithm Performance

  20. Future Work • Sophisticated GCF • Spectral (Reports 3 and 4) • Others (Regression?) • One-overlaid resolution • Sachidananda and Zrnic, 2003 • Extension beyond ra2 • For T1/T2 = 2/3 up to 2ra1

  21. Part Three Preliminary Case Studies

  22. Case Data • Data acquired with RRDA archive I recorder • Staggered PRT • Custom VCP’s alternating uniform and staggered PRT scans at 3 elevations • Phase Coding • ROC/NSSL VCP’s alternating non-phase-coded and phase-coded scans at 2 elevations • Proposed VCP for R/V Ambiguity Mitigation • Phase coding at lower elevations, staggered PRT at higher elevations (Report 6)

  23. EL = 0.5 deg KTLXVCP 11 KOUNStaggered 336/466 02/13/2003 20:58 GMT

  24. EL = 0.5 deg KTLXVCP 11 KOUNStaggered 336/466Recalibrated 02/13/2003

  25. EL = 0.5 deg KTLXVCP 11Needs Split Cut KOUNStaggered 336/466No need for Split Cut va = 28.08 m s-1 va = 31.96 m s-1 02/13/2003

  26. EL = 0.5 deg KTLXVCP 11 KOUNStaggered 336/466 02/13/2003

  27. EL = 1.5 deg KTLXVCP 11 KOUNStaggered 336/466 02/13/2003 20:58 GMT

  28. EL = 1.5 deg KTLXVCP 11 KOUNStaggered 336/466 va = 28.08 m s-1 va = 31.96 m s-1 02/13/2003

  29. EL = 0.5 deg KTLXVCP 11 KOUNStaggered 336/466 02/13/2003 22:42 GMT

  30. KOUNStaggered 336/466GCF OFF KOUNStaggered 336/466GCF ON KOUNStaggered 336/466GCF ON w/censoring 02/13/2003

  31. EL = 0.5 deg KTLXVCP 11 KOUNStaggered 336/466 va = 28.08 m s-1 va = 31.96 m s-1 02/13/2003

  32. KOUNStaggered 336/466GCF OFF KOUNStaggered 336/466GCF ON KOUNStaggered 336/466GCF ON w/censoring 02/13/2003

  33. EL = 0.5 deg KTLXVCP 11 KOUNStaggered 336/466 02/13/2003

  34. KOUNStaggered 336/466GCF OFF KOUNStaggered 336/466GCF ON KOUNStaggered 336/466GCF ON w/censoring 02/13/2003

  35. EL = 1.5 deg KTLXVCP 11 KOUNStaggered 336/466 02/13/2003 22:42 GMT

  36. EL = 1.5 deg KTLXVCP 11 KOUNStaggered 336/466 va = 28.08 m s-1 va = 31.96 m s-1 02/13/2003

  37. EL = 0.5 deg KTLXVCP 11 KOUNStaggered 184/276 03/17/2003 21:39 GMT

  38. EL = 0.5 deg KTLXVCP 11 KOUNStaggered 184/276 va = 28.08 m s-1 va = 45.17 m s-1 03/17/2003

  39. EL = 0.5 deg KTLXVCP 11 KOUNStaggered 184/276 03/17/2003

  40. EL = 0.5 deg KTLXVCP 11 KOUNStaggered 184/276 va = 28.08 m s-1 va = 45.17 m s-1 03/17/2003

  41. EL = 0.5 deg KTLXVCP 11 KOUNStaggered 184/276 03/17/2003

  42. EL = 0.5 deg KTLXVCP 11 KOUNStaggered 336/466 03/17/2003 21:44 GMT

  43. EL = 0.5 deg KTLXVCP 11 KOUNStaggered 336/466 va = 28.08 m s-1 va = 31.96 m s-1 03/17/2003

  44. EL = 2.5 deg KTLXVCP 11 KOUNStaggered 240/360 03/17/2003 22:44 GMT

  45. EL = 2.5 deg KTLXVCP 11 KOUNStaggered 240/360 va = 28.08 m s-1 va = 34.63 m s-1 03/17/2003

  46. EL = 2.5 deg KTLXVCP 11 KOUNStaggered 240/360 03/17/2003

  47. EL = 1.5 deg KTLXVCP 11 KOUNStaggered 184/276 04/06/2003 04:37 GMT

  48. EL = 1.5 deg KTLXVCP 11 KOUNStaggered 184/276 va = 28.08 m s-1 va = 45.17 m s-1 04/06/2003

  49. 04/06/2003 KOUNLegacy sv computation KOUNR(T2)/R(T1) sv computation

  50. EL = 1.5 deg KTLXVCP 11 KOUNStaggered 240/360 04/06/2003 04:42 GMT

More Related