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The prime factor in determining the maximum unambiguous range of a primary radar is the..
  • A
    pulse repetition frequency.
  • B
    size of the parabolic receiver aerial.
  • C
    power output.
  • D
    height of the transmitter above the ground.

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:

  • 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).

Note: The minimum detection range of a pulse radar is determined primarily by the pulse length/width.

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