Minimum variance power spectrum based calibration for improved clutter suppression in PCL on moving platforms

Passive radar has reached a stage of maturity such that it can be mounted on mobile platforms for the purpose of moving-target-detection. However some constraints limit the capability of target detection within the Doppler spread clutter region which arises due to the receiver's movement. Typically employed terrestrial illuminators of opportunity transmit in the Very High Frequency/Ultra High Frequency band, which puts some constraints on the size and number of employed antenna elements. If two antenna elements are employed, the Displaced Phase Center Antenna (DPCA) approach provides a meaningful possibility to suppress the clutter. However, the performance of this clutter suppression technique is severely degraded in case of non-ideal DPCA condition or if the employed channels are not properly calibrated. Here we suggest a technique to re-establish inter-channel calibration based on the Minimum Variance clutter power spectrum estimation. Specifically, we regard the technique as a dedicated adaptive digital calibration stage in order to improve clutter cancellation. The validity of the proposed approach is tested against real data, showing improved clutter cancellation capability.