Reference Signal Reconstruction Under Oversampling for DTMB-Based Passive Radar

The robust reconstruction of the reference signal is one of the key technologies in passive radars. This paper investigates the reference signal reconstruction problem for digital television terrestrial multimedia broadcasting (DTMB)-based passive radar. The conventional digital signal processing for the DTMB signal is usually based on the assumption of the equal bandwidth sampling (EBS) in which the sampling rate is equal to the nominal bandwidth 7.56 MHz defined in the DTMB standard. But we reveal that the high-frequency subcarriers of the DTMB signal are aliased under the EBS, which will degrade the reconstruction performance. Thus we suggest the oversampling approach for the DTMB-based passive radar. The least squares (LS) channel estimation under oversampling is thoroughly analyzed. Moreover to solve the problem that the LS algorithm cannot estimate the time-domain response of the channel under oversampling, we propose two modified LS channel estimation algorithms, namely the Tikhonov regularization LS and reduced rank approximation LS. The advantages of the reference signal reconstruction under oversampling over that under EBS are validated by both the simulation and field experimental data.