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

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Maximum Unambiguous Velocity (Vmax) and PRF

Not only is Rmax dependent on the PRF, but so is the maximum unambiguous velocity (Vmax) that the WSR-88D can determine for a volume of targets. By "unambiguous", we are referring to the WSR-88D's ability to accurately determine the largest Doppler radial velocity with its "first guess" or first pass through the data. The relationship between Vmax and PRF can be expressed mathematically as:

Equation 9.  Maximum unambiguous velocity (Vmax).  Click for long description.
    where PRF = pulse repetition frequency (s-1)
    PRT = pulse repetition time (s) = 1/PRF
    and greek symbol lambda = wavelength of energy transmitted.

For a PRF = 1000 pulses/sec (or PRT = .001 s) and greek symbol lambda = 0.105 m (or 10.5 cm), Vmax is 26.25 ms-1 (or ~ 51 kt).

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