SYSTEM DYNAMIC RANGE ENHANCEMENT

SUMMARY

Both military and commercial electronic systems are limited by the dynamic range of the hardware used to implement them. The proposed work for the DTC will try and take a holistic view of this problem in order to provide techniques that could help across a number of domains. The work will be generic in nature. Typical problems include:

The ability to operate sensitive ESM and COMS receivers close to transmitters operating in the same bands.
The ability to operate radars in urban and littoral clutter environments without loss of sensitivity.

MILITARY BENEFITS

If current limitations to system sensitivity in the presence of all too common large signal sources could be overcome then the additional capability would radically change the ability of the military to operate in currently “difficult” environments e.g. urban or littoral.

RESEARCH OBJECTIVE

To have a full understanding of the current limitations to dynamic range in existing hardware systems.
To know how much extra performance was available i.e., how many of these limitations are already governed by the laws of physics rather than implementation methods.
To have completed a number of the proposed first year “quick win” projects that achieve positive, demonstrational results via experimental validation.

RESEARCH OUTLINE

This programme will be based around a reasonably high fidelity model of a radar and receiver system. Modelling of the individual sub-systems will be used to determine the minimum and maximum signal levels supportable within each sub-system. From this analysis will flow a definition of the difference between the instantaneous dynamic range and the post-processed dynamic range of a system. In each of these cases the key limiting factors will be identified. Having determined the limiting factors further study will be carried out to try and ascertain how close to the physics limits the current hardware is. From this work will flow a prioritised list of areas that need to be addressed by the later stages of the research programme.

During year one a number of projects will be commissioned to create a portfolio of projects with the intention that these projects could produce “quick wins” if they are successful. Just as importantly they will provide a better insight from a number of viewpoints from within the DTC, academic and SME community. This will help inform the system analysis.

Initial projects would include:

Transmitter linearisation techniques for exploiting different classes of amplifier in both radio and radar systems, particularly identifying the benefits that this produces in terms of either cost, spectral spreading or power added efficiency.
Analogue to digital conversion spurious free dynamic range improvements via signal processing.
Phase noise mitigation – this project will investigate the physics limits to phase noise and whether there are improvements to be achieved from device technology. It could also investigate the various phase noise mitigation algorithms that have been developed both from within QinetiQ and elsewhere in order to determine their utility in real systems.
Processing non-linear data – this project will look at the effects of non-linear data within standard processing algorithms. In some areas improvements can be made by simply ignoring the harmonics of interfering signals (where target signatures are distinguishable from stable harmonic structures). This could be exploited to allow operations further into the non-linear region than currently employed. Clearly this has implications on CFAR threshold setting etc. that will be reviewed.

All of the above work will be tested via experimental data gathering using breadboard receiver and transmitter circuits, available from within the Consortium. In this way, gains will be demonstrated and research ideas tested as soon as possible in the development process. This will be done in order to maintain a very strong practical bias to what could become a very algorithm-intensive activity.

CO-ORDINATION WITH EXISTING / PREVIOUS RESEARCH

This research will make maximum use of internal funded programmes in this area. It will also endeavour to align itself with CRP programmes but currently we are not aware of any on-going projects in this area.

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