Pulse Duration

Pulse duration, t, is the length of time in microseconds (sec 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 sec. 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 sec 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.

Next Page: Listening Period