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The main factor which determines the minimum range that can be measured by a pulsed radar is..
  • A
    pulse amplitude.
  • B
    pulse frequency.
  • C
    pulse length.
  • D
    pulse repetition rate.


Pulse Repetition Frequency (PRF) is the number of occurrences (pulses) each second. The PRF has a large significance on maximum range. Depending on how far the radar wishes to search for objects and what the visible range is, the Pulse Repetition interval has to be set in a way to always allow the pulse to reach the range limits and return.

The maximum theoretical unambiguous range is calculate by the formula:

  • Maximum Range [km] = 300 000 ÷ (PRF × 2)

In the above formula, the range is given in kilometres and the PRF is in pps. The formula includes "300 000" which represents the number of km the light travels every second (speed of light).


Pulse length or width is the measurement taken from the leading to trailing edge of a pulse and is a good indicator of the amount of power contained within the pulse. Generally, longer pulses emitted from a radar return more power. The minimum range capability of a radar is determined primarily by the pulse length or width.

  • Minimum Range [km] = (300 000 x Pulse length) / 2

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