Localization of interrogators with a 1030/1090 MHz spectrum monitoring system

We present a new method for localizing Mode S Secondary Surveillance Radar (SSR) interrogators, which compared to previous work only requires the reception of aircraft transponder replies using one receiver on the ground. Because too high interrogation loads can lead to the suppression of targets, there is an interest in localizing unknown interrogators. To test the proposed localization method a proof-of-concept spectrum monitoring system based on Software Defined Radio (SDR) receivers was implemented. Results obtained from data recorded with the spectrum monitoring system show that Mode S SSRs at distances of up to ca. 320 km could be localized with a distance error