PCL Detection Based on DAB Symbol Processing

The classical passive coherent location (PCL) processing makes use of at least two antennas and is based on a calculation of cross-ambiguity function (CAF) between reference (REF) and surveillance (SURV) signals. In the modern approach, which is dedicated to communication signals with orthogonal frequency division multiplexing (OFDM) and known as an OFDM radar, the REF signal can be reconstructed from the SURV one. Then, the channel frequency response (CFR) is estimated, and information about moving targets is extracted from it. Such an approach enables building a simple, single physical channel passive radar, which requires relatively low computational power compared to the classical, two-channel CAF approach. This paper shows what signal processing operations should be added to a standard digital audio broadcasting (DAB) receiver to obtain the PCL functionality. Several field tests confirm the correctness of the described enhancement. Two low-cost software-defined radio (SDR) devices were used in the hardware setup, i.e., RSPduo and RTL-SDR, to detect airplanes of different sizes flying at various altitudes, in outdoor and indoor receive scenarios. The investigated DAB-based PCL radar's operating range has been also estimated based on a reference from ADS-B data. The opportunity of a single-channel PCL radar design, operating with minimum hardware and just one omnidirectional antenna, opens up the possibility of deploying a network of small and inexpensive PCL sensors.