Towards a MIMO radar based on commensal use of FM broadcast transmitters of opportunity

This paper will discuss some of the ongoing and planned developments at the University of Cape Town concerning FM Broadcast based air traffic control radar. This research area has been pursued widely in the last 10 years, but we believe we report on the development of the most comprehensive system yet attempted. Previously we reported the design and working of a prototype system [1]. Given the pseudo mono-static, "over the shoulder" arrangement of the bi-static geometry used in previous measurements, the system yields an equivalent mono-static range in the order of 100km when making use of a 1.3kW FM channel from the Tygerberg transmitter in Cape Town. Given the credible range performance of the prototype system, it is currently being expanded into a multi-static configuration with the aim of performing target positioning and tracking using multilateration, including multiple transmitters at diverse frequencies. We summarise the sophisticated propagation modelling used to identify optimal receive sites, as well as the filter technology used to effect multilateration. Finally we introduce the new term, commensal, to describe such sensor systems.