Programmable wideband signal generation and matched filtering through a full digital approach

In this paper, the implementation of a full-digital system for real-time generation and matched filtering of wideband signals is described. The system consists of a Direct Digital Synthesizer, suitable for being used in the transmitter section of communication or Radar links, and a digital filter, to be inserted in the receiver. The latter device, based on high-speed FFT processors, operates in real-time in the frequency domain, by multiplying the received signal spectrum by a `matched' spectrum stored in ROM, and by transforming the product back to the time-domain. The system is capable of processing FM signals with high time-bandwidth products, at a throughput rate of several MHz. Experimental results demonstrate that it can produce almost ideal output signals. In particular, when used for application to Radar Pulse Compression, it yields sidelobe levels as low as -70 dB, a result which, as far as we know, has not yet been achieved using other approaches. Furthermore, the design methods used to achieve these goals are discussed, and compared with those used in SAW-based systems.