digital radio frequency memory.pdfVIP

Digital radio frequenc: r memory Digital radio frequency memory (DRFM) is a technique in which high-speed sampling and digital memory is used to store radio frequency and microwave signals. It is becoming a popular technique for the implementation of false-target ECM systems. The paper discusses the principles of DRFM and the advantages of alternative system architectures. by S. J. Roome 1 Introduction Digital radio frequency memory (DRFM) is a technique in which high-speed sampling and digital memory is used for the storage of radio frequency and microwave signals. The ability to store and recall radio and microwave signals has many possible applications. Currently the main application of DRFM technology is the storage and recreation of intercepted radar signals in order to deceive hostile radar systems.’ 2 Digital radio frequency memory A simple block diagram of a DRFM system is shown in Fig. 1. The incoming RF signal is down- shifted in frequency, sampled, and the resulting numbers stored in a high-speed digital memory. To recreate the stored signal the stored values are coherently reconstructed and then up- converted to the original RF frequency. The instantaneous bandwidth of the DRFM system is primarily determined by the sampling rate of the A/D convertor. However, in order to extend thc operational bandwidth of the system the local oscillator may be switched. The high-speed digital memory will need to be dual-ported so that radio signals may be recorded and replayed simultaneously. A multiported memory in which recording and multiple replays can occur simultaneously is desirable in many applications. In addition to the record and diagram, DRFM systems may also have signal-processing abilities.2 These may be implemented in analogue form within the replay circuitry or digitally. A particularly versatile option is to include facilities to transfer data between the high-speed memory and a general-purpos