Suppression performance of reciprocal filtering in DVB-T based passive radar

Passive radars exploit illuminators of opportunity, such as radio or television transmitters, to detect moving objects. The broadcast signals, however, are not optimized for radar applications. With conventional radar signal processing, the digital video broadcast - terrestrial (DVB-T) signal has several ambiguities and a noise floor with a high level due to random sidelobes. However, if crafted by specialized signal processing methods, it is possible to remove the ambiguities and reduce the random sidelobes that cause the elevated noise floor. We analyze the reciprocal filtering method that has been shown to improve the ambiguity surface of the DVB-T signal. However, simulations showed that when targets were present at long range, the range-Doppler floor increased, which subsequently masked weak targets. We conduct a real measurement where several synthetic targets are introduced at ranges that should cause an increase in the range-Doppler floor. The experimental results show that the increase in the range-Doppler floor under worst case conditions is considerably lower than the case that was simulated. This implies that reciprocal filtering is more relevant for DVB-T based passive radar, than reported previously.