Analysis of amplitude modulation effect on pulsed passive coherent location system

The purpose of this paper is to analysis the amplitude modulation effect caused by the rotating transmit antenna pattern, which results in pulses loss within the direct-path pulse train. The loss mechanisms of signal to noise ratio (SNR) were discussed for these modulation phenomena. The analytical expression of the peak output of cross-ambiguity function was derived, which correspond to the cases of pulses loss occurrence. Simulation results show that the maximum SNR loss is less than 4 dB in the worst case, and the SNR loss curves for various Doppler frequencies and different number of pulse loss are conformed to the theoretical analysis. The worst Doppler frequency estimation bias is about 0.75 times the frequency resolution cell when there is no ambiguity in Doppler estimation.