Array Gain And Phase Calibration And Implementation

Gain and phase errors of array are unavoidable errors in array signal processing. The gain and phase errors would cause the flow vector array mismatch. As the same time, the performance of the spatial spectrum estimation algorithm and the performance of static direction digital beamforming will decrease. Therefore, it is necessary to analyze the influence of gain and phase errors of the signal array in practical. Several aspects will be carried out in this paper around the analysis of the array amplitude and phase errors as followed:(1) The mathematical models of the array signal and channels errors are established, respectively. At the basis, the effects from the channels errors on the spatial spectrum estimation and digital beamforming are analyzed.(2) The spectrum estimation result is analyzed in the condition of low signal-to-noise-ratio (SNR). And two modified correction methods of single auxiliary source are presented. One method takes advantage of the irrelevance of noise and signal and the other uses the second order covariance matrix of the acquired signal to calculate the amplitude and phase errors. Besides, a method to reduce the source error is presented by rotating the signal array.(3) The traditional self-correction method based on subspace orthogonal is analyzed. Then another modified ISM self-correction is proposed where a matching filter is added to increase the performance in the condition of low SNR.(4) The correction circuit based on high speed ADC+FPGA+DSP hardware system is designed. Firstly, the circuit of the hardware system is designed by Cadence. Then the preprocessing of the signal is realized using FPGA, so the IF signal is changed to baseband signal. Lastly, the correction algorithm using QR decomposing and inverse power method in DSP is simulated by MATLAB, which verifies feasibility of algorithm in DSP.