Design of multi-mode SSR signal simulation device based on dynamically reconfigurable FPGA with on-chip digital modulation

Regarding to automatic test for airborne Secondary Surveillance Radar (SSR) equipment,interrogation and reply from ground beacon must be simulated as the stimulation to airborne equipment for detecting the work status. This paper proposes a system design and its implementation basing on Field Programmable Gate Array (FPGA), adopting Direct Digital Synthesis (DDS) and digital modulation technology for generating beacon signals. The hardware and software structure of system are described in detail. The block diagram of control logic and final output signal waveform are presented. This device can achieve the signal simulation of SSR system such as Mode S, Tactical Air Navigation System (TACAN), Distance Measuring Equipment (DME) etc. It has the advantage of convenient use, simple structure. Therefore it is easy to build automatic test system.