TABLE OF CONTENTS 
Few parameters of a pulsed radar are more important than the PRF. This is particularly true of doppler radars. Other conditions remaining the same, the PRF determines to what extent the observed ranges and doppler frequencies will be ambiguous. That, in turn, determines the ability of the radar not only to measure range and closing rate directly, but to reject ground clutter. In situations where substantial amounts of clutter are encountered, the ability to reject clutter crucially affects the radar's detection capability.
In this chapter we will survey the wide range of pulse repetition frequencies employed by airborne radars and see in what regions significant range and doppler ambiguities may occur. We will then take up the three basic categories of pulsed operation low, medium, and high PRF and learn what their relative merits are.
The pulse repetition frequencies used by airborne radars vary from a few hundred hertz to several hundred kilohertz (Fig. 1). Exactly where, within this broad spectrum, a radar will perform best under a given set of conditions depends upon a number of considerations. The most important of these are range and doppler ambiguities.
As we have seen, for range to be unambiguous, the...
