National Physical Laboratory

Tracking down radio interference

UK company reduces potential interference from a GPS device for use on police vehicles operating the police secure communications network.

Anechoic chamber

The Challenge

GSD Navigation is a small UK company marketing commercial GPS navigation systems. It specialises in providing bespoke technical solutions to niche customers, which have included the Environment Agency, Police and Network Rail.

In order to supply the police service with GPS navigation-systems the company was advised to seek approval from the National Policing Improvement Agency (NPIA, formerly the Police Information Technology Organisation) who test to ensure that radiated emissions from such devices do not exceed a certain limit so that they can be used with the police secure communications system.

The company carried out some preliminary tests to investigate potential interference signals but found that they needed some additional support and use of specialist facilities to take the investigation further.

The Solution

GSD Navigation was able to benefit from a four-day consultancy with NPL to look into the problem.

To begin with, ElectroMagnetic Compatibility (EMC) tests were carried out in NPL's fully anechoic room to try to determine the source of interference and to identify which component of the circuit needed shielding. Then various solutions were tried to reduce the emission signal to an acceptable level, using metallised polymer adhesive sheets and RF gaskets to shield the units and cables, ultimately leading to an improved performance.

GSD Navigation were very pleased with the results and believe that this will enable them to supply the Police with effectively shielded sat-nav devices.

As a spin-off benefit of this consultancy, NPIA gained an appreciation of the role which the UK NMIs can play in resolving measurement related problems and invited NPL to test and revamp the NPIA facility, resulting in a substantial improvement in performance of the facility.

"I was extremely impressed with your facilities and the work/testing you carried out. This was a difficult task and I was very pleased with the progress made in identifying the RFR 'peak' and assessing the units."
Nigel Rees, GSD Navigation

Find out more about NPL's research in RF & Microwave

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Last Updated: 4 Aug 2015
Created: 7 Oct 2010


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