Ew Wideband Digital Receiver Channel Correction Based On Adaptive Filtering

In modern Electronic Warfare, the precision of the passive direction suffers from the mismatches between the components of the amplifiers , the LOs and the LPFs in the channels. Especially in the way using the phases information, such as interferometer to direct the signal. Because the phase mismatch is more seriously than that of the amplitude, sometimes it is impossible to finish the direction accurately. So how to correct the mismatches between wideband digital receivers'channels is very important. In this dissertation, A feasible adaptive digital signal processing method, using a type of LMS algorithm, which gives a solution for the correcting channel mismatches in EW receivers, has been proposed, and some improved way on algorithm has been researched and analyzed. The channel calibration based on adaptive algorithm researched in this dissertation doesn't need reference-signal source and has been found to correct the channel imbalances efficiently through experiments. After introducing the new correction system structure, we select the simplest adaptive algorithm, namely a type of LMS algorithm. And two improved NLMS algorithms has been researched in this dissertation, which guarantee fast convergence speed and small misadjustment. Moreover, some research on LFM signal calibration has been implemented. Via theoretic analysis and computer experiment, we obtain the optimum step size and minimum misadjustment , which has some engineer value. At last, the conclusions are drawn, and some further research about adaptive channel calibration is pointed out.