This sub-theme comprises a number of complementary research topics covering both ESM and passive radar techniques. The ESM work aims to improve techniques for emitter detection and location in complex electromagnetic environments, whilst the passive radar work will investigate novel techniques for Synthetic Aperture Radar (SAR) surveillance using non co-operative emitters of opportunity.


RF sensing using enemy or third party transmitters can greatly enhance the covertness and survivability of own forces, whilst ideally maintaining the all-weather, long range performance offered by radar.


To review the state-of-the-art in both ESM and passive coherent radar with a view to identifying technology gaps
To investigate the exploitation of Time to Digital Converter (TDC) technology for low cost direction finding and ESM
To develop techniques for bistatic SAR imaging, particularly using non-co-operative transmitters such as navigation satellites
To research the utility of multilateration techniques time-of-arrival methods for both ESM and passive coherent radar systems


ESM and Passive Coherent Radar (PCR)- the research here will centre on the development of an environment model which will be used to baseline existing ESM and PCR techniques, with an emphasis on operation in complex electromagnetic environments. This will be backed up by the use of a simple demonstrator system to carry out de-risking and model validation. This work will provide a basis for assessing limitations of current techniques and directing future research.

TDC Technology- This research will investigate architectures for TDC-based ESM and DF systems including a comparison with conventional architectures. Performance will be compared by analysis and simulation in a representative signal environment. An investigation will be conducted into the cost of manufacture and complexity of integration on a typical platform. In addition, the application of TDC-based ESM will be considered using multiple platforms. Plans will be drawn up for a proof-of-principle demonstrator using the most promising architecture.

Bistatic SAR- The aim of this research is to develop techniques for bistatic SAR as applied to wide area sensing. The work will be based on the use of emitters of opportunity, the most likely being navigation satellites, with an airborne receiver. Such a configuration will allow the development of a sensor system with high reliability, flexibility and interference protection. This is due to the redundancy provided by the large number of emitters and their spatial separation. The research will define, via modelling and experiments, an optimal system configuration and assess its potential performance. Issues to be addressed will include heterodyne synchronisation and specific bistatic internal interference suppression.


This research work consists partly of incremental development of existing work and partly of novel techniques. The bistatic SAR research will be carefully co-ordinated with complementary work on the FOAS programme.

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