RF ENVIRONMENT

SUMMARY

This sub-theme considers research into the electromagnetic environment, both natural and man-made, that RF sensors must operate in. Efficient target detection and false alarm rejection demands a good understanding of the EM environment, and whilst many existing systems exploit such knowledge successfully, a number of important environmental issues remain poorly understood. This research area aims to extend the understanding of the environment as a basis for future exploitation.

MILITARY BENEFITS

The ultimate aim of this research is to ensure that RF sensors reliably detect objects of interest in the real world environment, with minimal false alarms or unwanted detections. This research can be used for design and performance prediction for future and current radar systems as well as future upgrades to in-service radars.

RESEARCH OBJECTIVE

To improve knowledge of radar sea clutter in two areas- clutter as observed by coherent radars, and sea clutter spikes which are a major source of false alarms
To understand the potential impact on military radar of the advent of commercial ultra-wideband communications devices

RESEARCH OUTLINE

Sea clutter spikes- this research aims to develop a better understanding of the relationship between the environmental conditions and the frequency of occurrence and magnitudes of persistent spikes. The next step is to attempt to derive features of the spikes, which may be exploited in detection and tracking algorithms. Such algorithms will then be developed and evaluated using both real and modelled data. The work is applicable to a range of radars, from X-band airborne systems to S-band shipborne systems.

Coherent clutter modelling- The properties of coherent clutter are poorly understood, and with more and more systems operating in coherent modes this represents a significant knowledge gap. This research aims to fill this gap and will consider a number of different approaches, including EM modelling of scattering from realistic hydrodynamic surfaces, Doppler spectral modelling using Gaussian profiles to model the different scattering components, clutter models that model both the spatial and temporal correlations with a high degree of fidelity and polarimetric clutter modelling. The work aims to validate the resulting models using real data available from a number of sources within the Consortium. As before, the work is applicable across the normal radar bands used by a variety of maritime radars.

It should be noted that the Transducer Embedded Processing Research Theme also considers other techniques for clutter suppression, see Section 4.2.4.3.

Co-existence with ultra-wideband (UWB) communications- In February 2002 approval was given to permit limited use of UWB communications devices, both in the band below 900 MHz and in the band from 3.1 to 10.6 GHz. This upper band covers most existing radar systems, and the potential impact of widespread use of UWB devices is unclear. This research aims to quantify the problem and, if it appears significant, to consider possible measures to ameliorate the impact of such devices on military systems.

CO-ORDINATION WITH EXISTING / PREVIOUS RESEARCH

The sea clutter work is novel but builds on many years of research in closely related fields. The UWB work is novel.

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