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

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Previous Page: Section 4: Range Issues

Pulse Duration

Pulse duration, t, is the length of time in microseconds (greek symbol musec or 10-6 s) that a pulse is transmitted. The pulse duration of the WSR-88D in short pulse mode (VCP 11, 12, 21, 121, 211, 212, 221, or 32) is 1.57 greek symbol musec. Multiplying pulse duration by the speed of light (c = 3 x 108 m/s) produces a pulse volume whose pulse length, H, is ~ 500 m. In long pulse mode (VCP 31), the pulse duration is 4.7 greek symbol musec producing a pulse length, H, of ~ 1500 m (4,625 ft). In long pulse mode, the total power received from a given target would correspondingly be three times greater than in short pulse mode. As a result, the WSR-88D is more sensitive when operating in long pulse mode than in short pulse mode.

The terms long pulse and short pulse should not be confused with the Pulse Repetition Frequency (PRF) or Pulse Repetition Time (PRT). Pulse duration is independent of the PRF (or PRT) and only describes how long the radar stays on while transmitting a pulse, whereas the PRF (or PRT) determines how often the radar transmits pulses.

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