A Monopulse Based Correlation Technique for De-Garble Processing of SSR Replies

Secondary surveillance radar (SSR) aids in the identification of aircrafts and often works in conjunction with the primary radar for better target awareness. An important module of the SSR system is the reply signal processor unit. One of the major issues in reply processing is the occurrence of garbled replies, which occurs due to the overlapping of replies. Overlapping occurs when range difference between the two targets is less than de-garble resolution (3045 m). In practical scenarios SSR replies are often garbled (e.g.: formation flights). So efficient de-garbling algorithms are required for providing the target identification. In this paper a new algorithm towards de-garbling of SSR replies is discussed. The information derived from the delta to sigma ratio channel (Delta/Sigma) and the Sigma (sum) channel of the monopulse receiver are effectively combined for separating the garbled replies