The pulse-repetition frequency (PRF) of a radar system determines the
maximum operating range of the radar before ambiguities start to
occur. This is called the maximum unambiguous range
of
the radar. It is important to note that the maximum
unambiguous range is different from the maximum range
of the radar. The latter is the maximum range of
the radar due to power and other constraints. Maximum unambiguous
range is a timing issue. The radar needs
to allow sufficient time for its pulses of energy to
get to the most distant targets and back again before
it transmits the next pulse.