Quasi-Coherent Detector Performance with Application to CW Radar.

The evolution of a quasi-coherent detector having application to CW Radar is presented. The detector is configured as paralled correlator channels which use digital techniques to process video signals. Doppler frequency channels and channels representing the initial phase of the received signal, or return, are employed to approximate a coherent detector. A distinguishing feature of the quasi-coherent detector lies in the use of a rectangular pulse train as the local signal which is correlated with the return. The rectangular pulse structure provides computational efficiency, while being optimized with respect to signal-to-noise ratio. Analytical results of particular interest pertain to the comparative performance of the quasi-coherent detector and the optimum coherent detector, the latter providing a detection performance benchmark. In the absence of errors in estimation of doppler frequency and initial phase, it is shown that the detector performs about 0.35 dB inferior to optimum. With limitations of a finite number of processor channels, trade-offs between implementation complexity and performance in the presence of estimation errors are discussed. Criteria for design of the quasi-coherent detector are presented. Author