VCP Characteristics

As mentioned previously, the WSR-88D currently employs 9 different Volume Coverage Patterns (VCPs) that involve different sampling techniques. Table 6, Table 7, Table 8, Table 9, Table 10, Table 11, Table 12, Table 13, and Table 14 contain the various modes of operation for each elevation angle that comprises each VCP. For example, Table 6 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, R_max, and V_max for each elevation angle being sampled. There are two speed options, actual speed and 5 times actual speed.

Animation 1 VCP 11	Animation 2 VCP 12	Animation 3 VCP 21
Animation 4 VCP 121	Animation 5 VCP 211	Animation 6 VCP 212
Animation 7 VCP 221	Animation 8 VCP 31	Animation 9 VCP 32

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