FAQs – Interference and Electromagnetic Compatibility

Do TETRA terminals interfere with TVs or other electrical equipment?

There are regulations that require all electrical equipment to work within a defined frequency band. Some equipment that pre-dates or does not comply with these regulations (electro-magnetic compatibility standards) might be affected – for example older televisions and some car alarms. But this is because that equipment does not comply with the standards and is therefore susceptible to interference. TETRA does comply and operates squarely within its allocated frequency band.

Since 1 July 2010 the BBC has been responsible for investigating interference issues associated with domestic TV and radio reception (through the Radio & Television Investigation Service, which is for all broadcasters – click here to visit its web site). If further investigation and enforcement action is required, the BBC will refer cases to the Office of Communications (Ofcom). Ofcom no longer accepts consumer complaints of interference from any source other than the BBC, however Ofcom remains responsible for investigating interference issues relating to broadcast and radio licence holders. For more information about these changes of responsibilities, click here to visit the Ofcom web site.

Could TETRA equipment inadvertently trigger bombs when used in anti-terrorism operations?

TETRA equipment offers a number of features such as encryption, setting up of talk groups and direct mode operation. These features have substantial operational benefits in emergency situations, from anti-terrorist operations to major road traffic accidents. They can facilitate rapid and effective working within and between emergency services. This is invaluable in an emergency situation, such as was experienced in London on 7/7 (7 July 2005) or earlier in Madrid.

The emergency services all have robust operational procedures and these cover the use of TETRA equipment if an explosive device is suspected or known of. Emergency services workers are all trained in the correct and safe use of the equipment and TETRA systems all offer a transmit-inhibit facility that can be activated by the user, to prevent the radio transmitting a signal at all. TETRA equipment is no more likely to trigger detonation of a suspected bomb or explosive device than any other radio handset or any other piece of electrical equipment.

Does the signal affect things like pacemakers?

Laboratory and clinical tests have found that digital wireless phones, which operate in a similar manner to TETRA, might interfere under certain conditions with some pacemakers and hearing aids. Users can take steps to minimise or prevent interference, such as keeping an operating handset the recommended minimum distance from an implanted pacemaker or adopting other measures to accommodate the use of hearing aids. Following US research in the mid-1990s, a minimum distance of six inches (15 cm) was recommended; however, more recent research in Austria, carried out during the period 2009-2011 with the aim of ensuring that citizens with pacemakers were not put at risk during any encounters with the emergency services whose personnel were using TETRA handsets, recommends a minimum distance of 30cm between an implanted pacemaker and a TETRA handset. The Austrian study’s findings are summarised in a short brochure which may be viewed here. In general. users should always follow the advice provided by the manufacturers of medical equipment.

Are TETRA terminals safe to use in hospitals?

It is a requirement of most hospitals that equipment that transmits radio waves is switched off on hospital premises in case there is interference with sensitive medical equipment. TETRA handsets are no different in this respect from any other radio equipment except that they benefit from a transmit-inhibit feature that enables users to prevent transmission without turning off the equipment altogether.

Regulatory agencies like the UK’s Medicines and Healthcare Products Regulatory Agency (MHRA) accept that communications equipment can be essential in hospitals but acknowledge the risk of interference. The MHRA does not recommend a blanket ban on the use of mobile phones in hospitals; however, under certain circumstances, the electromagnetic interference from a mobile can affect the performance of some medical devices. See the relevant page of the MHRA web site for further information – click here (opens in a new window). Users should respect any local guidelines and should switch off or use transmit-inhibit mode in any areas where critical care or life support equipment may be in use.

Are TETRA terminals safe to use in ambulances?

TETRA-based systems designed for use by doctors and paramedics in ambulances are designed specifically to suit the operating circumstances, and high standards of installation practice are followed. Professional users follow detailed operating procedures to make sure that interference is not an issue.

Are TETRA terminals safe to use in explosive situations where sparking may be an issue?

Firefighters may have a requirement for special ‘intrinsically safe’ handsets, for example for use at incident scenes where there is danger of explosion or where the presence of inflammable gas or chemicals is suspected. Any TETRA equipment used in these circumstances would meet appropriate standards.

What are the risks when using TETRA terminals at petrol stations?

  • The risk is very low, but unless operationally vital it is good practice to switch off equipment, as is suggested for mobile phone users, or to put it into transmit inhibit mode before entering the petrol station (or other potentially explosive environment).
  • It is the responsibility of site owners (petrol companies) and employers (of those using TETRA terminals) to make a risk assessment and establish a policy.
  • For a vehicle-mounted terminal it should be possible to perform a risk assessment based on the position of the antenna mounting; for hand-held terminals the position is more variable.
  • If an organisation undertakes regular operations within a petrol station environment or similar, consideration could be given to the use of intrinsically safe terminal equipment.


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