PULSE REPETITION RATE
Pulse Repetition Frequency (PRF) is the number of pulses emitted by radar per unit time (seconds).
The radar system emits a probe pulse in space (modulated on the emission frequency), then receives any reflections of this pulse from the targets until the emission of the next probe pulse. The time interval between the beginning of a probe pulse and the beginning of the next pulse is called the pulse repetition period, denoted TR. (PRT - Pulse Repetition Time). During a repetition period, the radar will emit a time equal to the duration of the pulse and will receive the rest. The repetition period is equal to the inverse of the pulse repetition frequency:
TR = 1 / FR
The repetition frequency of a radar determines its ability to measure the distance of the targets without the existence of ambiguities, as well as the duration of a coherent processing interval (and implicitly the possibility of rejection of the clutter by the radar). To measure the distance of a target unambiguously, the interval between pulses (repetition period) must be longer than the time required for the pulse to reach the target and return (delay time). The maximum unambiguous distance is given by the formula:
