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VCP Characteristics
As mentioned previously, the WSR-88D currently employs 9 different Volume Coverage Patterns (VCPs) that involve different sampling techniques. , , , , , ,,, and contain the various modes of operation for each elevation angle that comprises each VCP. For example, lists characteristics of VCP 11 which scans 14 elevation angles in 5 minutes. The total number of elevation scans is actually 16 since the 0.5° and 1.5° elevation angles are sampled twice in the Split Cut mode. A breakdown of the information contained in the VCP tables is listed below:
- Angle is the antenna angle above horizontal.
- AZ Rate is the antenna rotation rate in degrees per second.
- Period is the total time required to complete a full 360° revolution at that elevation angle. Notice that the antenna does not rotate at the same rate for all elevation angles.
- WF type is the waveform employed which will be either CS (Contiguous Surveillance), CD (Contiguous Doppler), B (Batch), or CDX (Contiguous Doppler without range unfolding).
SZCS and SZCD are SZ-2 Contiguous Surveillance and Contiguous Doppler waveforms employed on the split cuts of VCPs 121, 211, 212, and 221.
- PRF No. is the Pulse Repetition Frequency number (1 through 8) and not the actual rate of pulses transmitted. With the WSR-88D, the PRFs are fixed and the only options are 1 of 8 PRFs. For example, for VCPs 11, 21, and 32, PRFs #1-3 are used for surveillance mode and #4-8 are used for Doppler mode.
- # Pulses is the number of pulses that are transmitted along each 1° radial. For example, in VCP 11 at 0.5°, the WSR-88D transmits 17 pulses (at ~ 322 pulses/sec) in Surveillance mode and anywhere from 52 to 66 pulses when operating in Doppler mode. In Batch mode operations (2.4° to 6.2°), the number of pulses transmitted in Surveillance mode is 6 or 10 employing PRFs #1, 2, or 3. Switching to Doppler mode, 41 to 50 pulses are transmitted (PRFs #5, 6, 7, or 8). This means that along each 1° wide radial, the radar begins at a low PRF and transmits 6 or 10 pulses and then quickly switches to a higher PRF and transmits 41, 43, 46, or 50 pulses.
VCP Animations
Animations of how each VCP employs these characteristics are available. These animations present the PRF #, waveform, Rmax, and Vmax for each elevation angle being sampled. There are two speed options, actual speed and 5 times actual speed.
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