3.20 The operation of radio equipment in close proximity to other types of electronic device may result in interference and police radio systems are no exception. Guidelines have existed for many years about the use of radios where interference might be particularly problematic, for instance in hospitals or aircraft. Existing police radio terminals are also known to affect certain makes of traffic law enforcement devices (e.g. radar guns and digital breathalysers) and police guidelines exist which put restrictions on transmitting radio messages while using such equipment.
3.21 During the pilot phase, concerns were raised that Airwave terminals were affecting more equipment than the radios they were replacing. PITO and the Home Office therefore asked the Defence Evaluation Research Agency (DERA) to conduct tests on the electromagnetic compatibility of Airwave terminals with the various law enforcement devices in use in this country. The interim report from DERA identified additional makes of equipment, particularly older models, affected by TETRA radios and recommended that the existing police guidance be expanded accordingly. Manufacturers of these devices are being advised to increase the shielding on their equipment to protect them from the interference.
3.22 Technological fixes to TETRA terminals have also been proposed, such as an ability to inhibit the transmission function temporarily. The European Telecommunication Standards Institute5 is expected to incorporate this as an additional requirement in the TETRA standard specification. Manufacturers consider this solution complex as it poses problems about how and when to resume transmissions, as well as needing to prove that transmissions have been inhibited at the correct time. However, the manufacturers have indicated to PITO that they expect to include such a facility in new terminals within a year.
___________________________________________________________________________
5 The European Telecommunications Standards Institute is a not for profit organisation representing stakeholders in the telecommunications market developing technical standards for use in Europe and elsewhere.