Mitigation of Range/Velocity Ambiguities
Staggered PRT Technique
The performance of
the Staggered PRT technique was evaluated on real weather data. Time series data were
recorded with the KOUN research radar and processed offline using a MATLAB-based
WSR-88D Signal Processing Subsystem simulator.
After a simple ground
clutter filter is applied to the data, covariances are estimated for each
PRT. These are suitably combined in a velocity dealiasing algorithm to
effectively extend the maximum unambiguous velocity (see tables below).
Parameters used for data acquisition depend on the VCP used and are given in the following tables:
VCP 45a
| Waveform type | PRT1 No. | PRT2 No. | Staggered PRT ratio | Surveillance unambiguous range ra (km) Reflectivity field |
Doppler unambiguous range ra (km) Velocity & width fields |
Effective unambiguous velocity* va (m s-1) |
|---|---|---|---|---|---|---|
| Long Staggered | 2 | 1 | 168/233 | 466 | 336 | 26.7 |
| Short Staggered | 8 | 4 | 117/175 | 175 | 117 | 71.2 |
VCP 45b / VCP 46b
| Waveform type | PRT1 No. | PRT2 No. | Staggered PRT ratio | Surveillance unambiguous range ra (km) Reflectivity field |
Doppler unambiguous range ra (km) Velocity & width fields |
Effective unambiguous velocity* va (m s-1) |
|---|---|---|---|---|---|---|
| Long Staggered | 2 | 1 | 168/233 | 466 | 336 | 26.7 |
| Medium Staggered | 23 | 24 | 2/3 | 360 | 240 | 34.6 |
| Short Staggered | 9 | 10 | 2/3 | 276 | 184 | 45.1 |
| Long Uniform | 1 | - | - | 466 | - | - |
| Short Uniform | 5 | - | - | - | 148 | 28.08 |
VCP 46a / VCP 47a / VCP 48 / VCP 49
| Waveform type | PRT1 No. | PRT2 No. | Staggered PRT ratio | Surveillance unambiguous range ra (km) Reflectivity field |
Doppler unambiguous range ra (km) Velocity & width fields |
Effective unambiguous velocity* va (m s-1) |
|---|---|---|---|---|---|---|
| Medium Staggered | 23 | 24 | 2/3 | 360 | 240 | 34.6 |
|
Short Staggered |
9 | 10 | 2/3 | 276 | 184 | 45.1 |
| Long Uniform | 1 | - | - | 466 | - | - |
| Short Uniform | 8 | - | - | - | 234 | 35.52 |
* For the staggered PRT cases the effective unambiguous velocity is the one obtained after the velocity de-aliasing algorithm.
The PRTs are defined as follows:
| PRT No. | Period (μs) | Unambiguous range ra (km) | Unambiguous velocity va (m s-1) |
|---|---|---|---|
| 1 | 3106.7 | 466 | 8.92 |
| 2 | 2240.0 | 336 | 12.37 |
| 4 | 1166.7 | 175 | 23.74 |
| 5 | 986.7 | 148 | 28.08 |
| 8 | 780.0 | 117 | 35.52 |
| 9 | 1226.7 | 184 | 22.58 |
| 10 | 1840.0 | 276 | 15.06 |
| 23 | 1600.0 | 240 | 17.31 |
| 24 | 2400.0 | 360 | 11.54 |
The fields of reflectivity, velocity, and spectrum width are displayed for several events. Labels on the figures indicate the variable (Reflectivity, Velocity, or Spectrum Width), the waveform type (Long Staggered, Medium Staggered, Short Staggered, Long Uniform, or Short Uniform), the elevation angle (EL), the date, and the approximate time. The following selected case studies are available: