Performance analysis of the reference signal reconstruction for DVB-T passive radars

The present work investigates the reference signal reconstruction method for passive coherent location (PCL) radars exploiting Digital Video Broadcasting-Terrestrial (DVB-T) signals. The reference signal reconstruction improves the signal-to-noise ratio (SNR) of the reference signal, which enhances the detection probability for DVB-T based PCL systems. The existing approach for the reference signal reconstruction is performed by demodulating the received reference signal to retrieve the transmitted quadrature amplitude modulation (QAM) symbols and modulate them to obtain the reconstructed signal. For low SNR values, the QAM symbol detection is accompanied with a significant error, which leads to a mismatch between the reconstrued signal and the exact one. Consequently, the expected improvement due to the signal reconstruction is limited. In this work, we propose an optimum reconstruction method which filters the detected QAM symbol prior to the remodulation step. To validate the proposed method, we retrieved analytic expressions for the detection and false-alarm probabilities and verified them through Monte-Carlo simulations. In addition, real-data sets were used to evaluate the proposed method performances. The results show that the proposed method outperforms the conventional one by extending the feasibility of the reference signal reconstruction for low SNR values.