Analysis and compensation of dual-channel IF response mismatch for passive coherent locator receivers
DOI:
https://doi.org/10.54939/1859-1043.j.mst.114.2026.55-62Keywords:
Passive coherent locator system; Clutter; Range - Doppler image; Direct-signal interference.Abstract
This paper investigates the effect of inter-channel IF imbalance on interference cancellation performance in a frequency modulation-based passive radar receiver. Differences in the magnitude and phase responses of the reference and surveillance channels can significantly reduce the effectiveness of direct-signal interference cancellation. A least-squares-based extensive cancellation algorithm combined with frequency-domain channel equalization is investigated to compensate for these mismatches. Simulations are performed in MATLAB using a frequency modulation signal centered at 96 MHz with a bandwidth of approximately 180 kHz. The results show that a 3 dB channel mismatch reduces the direct signal interference cancellation depth from 62.18 dB to 15.33 dB and degrades the output signal to noise ratio from 6.71 dB to −40.24 dB. After channel-response equalization, the cancellation depth and output SINR are restored to 61.97 dB and 6.47 dB, respectively. These results demonstrate that intermediate-frequency channel equalization can effectively mitigate inter-channel mismatch and significantly improve interference cancellation performance in passive radar receivers.
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