An experimental study on secondary radar transponder UMOP characteristics

Under the ever more complex and dense electromagnetic environment, specific emitter identification (SEI) technique opens up prospects for discriminating and identifying different emitters of the same class. SEI is implemented by employing the unintentional modulation on pulse (UMOP), which is unavoidable and unique to individual emitters. However, the characteristics of UMOP have not been sufficiently investigated via real-world data experiments. To this end, this paper focuses on an experimental study of UMOP characteristics based on measured data of secondary radar transponders. Pulses from 411 transponders of the same class are first collected during a data collection experiment. Time domain features are then extracted and used to validate the consistency and uniqueness of UMOP. Lastly, several UMOP features are defined and applied to SEI tests, showing that 104 emitters can be identified with a recognition accuracy exceeding 92%. This work sufficiently substantiates the feasibility of the SEI technique and offers practical guidance on how to put it into practice. The conclusions derived in this paper are applicable to the identification friend or foe (IFF) systems, and can also be easily expanded to general radar emitters.