Emergency radio may disrupt pacemakers

A mobile communications system - a digital form of the familiar "walkie-talkie" - which is used by police, firemen and paramedics in 50 countries, has been found to interfere with critical life-saving medical equipment, according to a report.

The Tetra system, short for Terrestrial Trunked Radio, is currently "live" only on a pilot network in the State, under the auspices of the Office of the Director of Telecommunications (ODTR).

The report, in next Saturday's edition of the British weekly New Scientist, claims the Tetra system can disrupt heart pacemakers, interfere with defibrillators and stop ventilators from a distance of several metres.

The ODTR initially planned to issue one licence for Tetra to an operator, in August 2000, but no successful bids were received. The ODTR subsequently decided to withhold the allocation of a licence "for the moment".

Last night, an ODTR spokeswoman reiterated that no licence had been issued and added the only Tetra system in the State was a pilot network set up for testing purposes. "As yet the ODTR has not seen the report but will review the issues when the report is available", said the spokeswoman.

The benefits of Tetra are that it works with the latest online electronic applications, such as those used in commerce, while retaining the traditional benefits of instant, cost-effective communication between individuals and groups.

It operates at a frequency of 400 megahertz, which is below the microwave frequency used by mobile phones. It sends voice data in pulses, at a rate of 17.6 pulses per second, compared with the mobile phone rate of 217 pulses per second.

The lower rate means that Tetra is less prone to interference, which makes it attractive to the emergency services. But the Tetra system is also said to be correspondingly harder to filter out and thus more likely to cause interference in other machines.

The discovery of the interference was reportedly made by the Medical Devices Agency, a British government safety regulator, which found that some Tetra handsets interfered with medical equipment from as far away as three metres. In half of these cases, the effect would have had a "direct impact" on the patient's care.