The Applications of Polyphase Filtering in Digital Quadrature Detection of SAR

In a general radar and communication system, the digital quadrature detection is necessary for implementing direct IF or RF sampling. The Digital Product Detection (DPD), applied easily in a real engineering, is a method to implement the digital quadrature detection. But the datum acquired by the method should be corrected. The paper presents the polyphase filtering to correct the I/Q datum acquired in combination with the Synthetic Aperture Radar (SAR) signal processing by contrast with Bessel filtering. The simulation results show that the method is simpler, more flexible and applied easily. The correct error by the polyphase filter with the same order is smaller than the error by the same order Bessel filter. The former maximum absolute error is 5.839410-4. The latter maximum absolute error is 9.30710-4. In addition, the polyphase filtering can implement the unequal interval filtering easily.