Analysis and experimental results of digital quadrature coherent detector

One of the key problems in high performance radar signal processing is the quadrature coherent detector. It is very difficult for the classical analog quadrature detector to satisfy the requirement of a high performance signal processing technique. The solution of this problem is to use the direct sampling of a low IF signal and generate quadrature samples by a digital filter. The performance of a quadrature IF sampling system based on a digital product detector is analyzed. The scheme is designed and the circuit is implemented by using the INMOS A100. The experimental results are tested. Several important problems about the realization are discussed and analyzed. It is shown by the experimental results that the requirement of a high performance signal processing technique can be fully satisfied by the digital quadrature coherent detector.