A Study Of Digital Receiver Techniques

In modern radar system, digitized directly IF receiver plays a more important role. IF digital receiver eliminates the residual at the image frequency resulting from the amplitude and phase unbalance between I/Q channels in conventional approach to coherent detection. This dissertation researches the theories of directly IF sample and digital quadrature coherent detection. Firstly, the dissertation introduces the problem of the conventional receivers, and analyses the relation between the error of amplitude and phase and mirror frequency. Second, the dissertation gives the principle of sampling theory and multi-velocity signal processing. Then,it researches the principles and structures of three quadrature coherent detection methods. The simulating results obtain their different suppressing performance of mirror frequency. The dissertation presents the realization of quadrature coherent detector and gives the circuit block and the simulation. Lastly, this dissertation analyses the effect to the mirror frequency of the number of bits of A/D convertor and the filter. It is a good reference for practical using.