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DLOC Principles of Meteorological Doppler Radar:
WSR-88D Fundamentals

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Previous Page: Sampling Techniques

VCP Characteristics

The WSR-88D currently employs 9 different Volume Coverage Patterns (VCPs) that involve different sampling techniques. Tables 6-14 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 rotations is 16 since the 0.5° and 1.5° angles are sampled twice in Split Cut mode. The VCP tables provide the following:

  • Angle: Antenna angle above horizontal
  • AZ Rate: Antenna rotation rate in degrees per second (o/s)
  • Period: Total time required to complete a 360° rotation
  • WF type: Waveform employed; Will be one of the following:
    • CS (Contiguous Surveillance)
    • CD (Contiguous Doppler)
    • B (Batch)
    • CDX (Contiguous Doppler without range unfolding)
    • SZCS (SZ-2 Contiguous Surveillance)
    • SZCD (SZ-2 Continguous Doppler)
  • PRF #: The Pulse Repetition Frequency (PRF) number (1-8)
  • # Pulses: The number of pulses per radial

VCP Animations

In general, a larger number of pulses per radial are used at the lower elevations, transitioning to fewer pulses per radial as the antenna angle increases. Animations of how each VCP employs these characteristics are available. These animations present the PRF #, waveform, Rmax, and Vmax for each elevation angle and give you a relative perspective of antenna rotations per elevation.

Default VCPs

It's important to note that the tables and animations above show the default version of each VCP. Adjustments to these VCPs are made by the Automated Volume Scan Evaluation and Termination (AVSET) and Supplemental Adaptive Intra-Volume Low-Level Scan (SAILS), depending on the VCP implemented. Details on which VCPs are affected by AVSET and/or SAILS are included in the Figures 16-24 and Tables 6-14 for each VCP.

Next Page: Pulse Repetition Intervals