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

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Pulse Repetition Intervals

Each VCP has unique characteristics concerning how often the atmospheric targets are sampled. To avoid interference with other neighboring radars, different rates of E-M transmission are invoked via different Pulse Repetition Intervals (greek symbol deltaPRI). Each WSR-88D radar is installed with one of five possible greek symbol deltaPRI's (Table 15, Table 16,Table 17, Table 18, and Table 19) that determines which PRF is to be used for each PRF No.

Assume that your radar is operating in VCP 21 and was installed with greek symbol deltaPRI #3 (this is the default table installed on most radars) and you want to know what type of scan is being invoked for the 1.45° elevation slice. By using Table 8 and Table 17, you will see that in CS mode, 28 pulses will be transmitted along each radial at the rate of 321.89 pulses per second (PRF #1). In CD mode, 75, 88, 95, 103, or 111 pulses will be transmitted along each radial at the rate of 857.14, 1013.51, 1094.89, 1181.10, or 1282.05 pulses per second (PRF #4, 5, 6, 7, or 8), respectively.

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