Target Detection in Analog Terrestrial TV-Based Passive Radar Sensor: Joint Delay-Doppler Estimation

Abstract

Due to 64- $\mu \text{s}$ line fly-back time of the analog television (ATV) signal producing a range ambiguity at ranges corresponding to the multiples of 19.2 km, it seems that we cannot determine the targets’ ranges in ATV-based passive bistatic radars (PBRs). Based on this standpoint, all discovered works on a target-detection problem in an ATV-based PBR have focused on the Doppler information in echoes of the television video carrier signal not range information. To cope with the severe range ambiguity of the ATV signal and make it possible to jointly estimate targets’ delays and Doppler shifts, we propose a new detector performing target detection in a layered manner. In each layer, one target is detected. Detection in each layer is done using a generalized likelihood ratio detector. Interference due to the detected target in the first layer is estimated and subtracted from the received signal. From the first layer’s interference canceled signal, another target (if exist) is detected in the second layer. The interference due to the second layer’s detected target is estimated and subtracted. These detection and interference cancellation steps are carried out in each layer, until all the targets are detected. The proposed detector is also implemented based on the chirp z-transform to efficiently obtain targets’ Doppler shifts over a limited range of Doppler frequencies. To obtain an effective cancellation of the strong interfering targets as well as off-grid targets, a robust version of resulting algorithm is also presented. Extensive simulation results are provided to demonstrate the high performance of the resulting target-detection algorithms.