Medium PRF set selection: an approach through combinatorics

Modern fighter aircraft use a host of different techniques to search for and detect airborne targets. One such technique involves the use of pulse Doppler and a collection of `medium´ pulse repetition frequencies (PRFs). Such a collection of medium PRFs is ambiguous in both range and velocity (Doppler frequency), but can be resolved by correlating data from different members of the set. The PRF set selection is complex, restricted by the particular radar system and its intended use. After briefly discussing constraints, some results concerning ghost minimisation, and the linearity of clear region probabilities, an efficient method is presented for calculating PRF set quality. A discussion of the mathematical (in particular combinatorial) niceties which attend the solution of this problem is included