Generalized Passive Radar Processing Chain For Use With Different Signals of Opportunity

A Passive Radar (PR) is a multi-static RAdio Detection and Ranging (radar) that makes use of signals transmitted by Illuminators of Opportunity (IoO)'s to detect targets in a scene. An IoO is any preexisting transmitter that is used as the illuminator for the PR such as Frequency Modulation (FM) radio. The exact performance of a PR depends on both the physical geometry of the transmitter and receiver combination as well as the signal properties of the IoO. By using multiple different IoO's concurrently, transmitter diversity can be increased, improving overall system performance and reliability as well as improving resilience against jamming. Typically this would require separate processing pipelines specific to each signal type. This is cumbersome, requiring separate maintenance, deployment and streamlining for each one. In this project a generalised PR processing pipeline capable of efficiently processing any signal to create an appropriate range-Doppler output is proposed and demonstrated. A typical PR processing pipeline consists of primarily four stages; pre-processing, DSI-cancellation, range-Doppler map generation and finally detection and tracking. The pre-processing stage is signal dependant and therefore cannot be generalized. DSI-cancellation is the most resource intensive of the stages and along with range-Doppler map generation, detection and tracking can be generalised. Digital signals such as Orthogonal Frequency Division and Multiplexing (OFDM) signals have high bandwidths and are required to be processed in the Frequency-Domain (FD). Therefore, an appropriate FD Direct Signal Interference (DSI) cancellation algorithm that works for both analogue and digital signals was necessary for the generalised processing pipeline. For this, an investigation into the use of Extensive Cancellation Algorithm by Carrier/Doppler (ECA-CD), a FD approach, applied to FM signals for generalisation was carried out. By generating Amplitude Range-Doppler (ARD) maps and comparing the results to ARD maps generated when using Conjugate Gradient Least Square (CGLS), a Time Domain (TD) approach, for cancellation, it was found that ECA-CD is an effective and efficient cancellation algorithm for FM signals. It was, therefore, selected as the DSI-cancellation algorithm for the processing chain. To demonstrate the feasability of the suggested chain, three signals were used; FM, DVB-T2 and Long Term Evolution (LTE) as these represent some of the most commonly used IoO's. The results demonstrate that an efficient generalised processing chain can be realised using an FD approach with ECA-CD for DSI-cancellation and Batches for ARD processing.

Grantor

Department of Electrical Engineering

Year dc:date.issued

2024

Author dc:creator

• Benz, Heinrich

Advisor dc:contributor.advisor

• Paine, Stephen

• Engineering

Handle dc:identifier.uri

http://hdl.handle.net/11427/40121

OAI identifier oai:identifier

oai:open.uct.ac.za:11427/40121