Tetra, the multi-billion pound public safety radio system, received another blow when the Dutch fire service said that the system's problems, which nearly killed a New York firefighter recently, could also happen in Europe.

Frans Schippers, a commander in the Dutch Fire Brigade, which has been testing the technology for three years, confirmed that the weakness was in the Direct Mode Operation (DMO) used in Tetra. He said that while it was vital to firefighting, DMO caused major problems with the system.

In DMO mode, radio throughput decreases with the increase in frequency. "If the frequency is higher, power output must also be higher to give the same coverage," he said.

Tetra requires a higher frequency than other professional radios and needs more power to provide the same coverage.

"We are trialling the technology at 170Mhz, but when we move to the Tetra standard later this year, we will use 450Mhz. We must see if we can increase the power to ensure the signal gets through," said Schippers.

Failing signal throughput was the cause of the New York Fire Department's (NYFD) objections to its digital radio system. It is now considering reverting back to analog radios after recalling new $4.5m digital radios when a fireman's mayday call got lost in a coverage glitch.

Chief Dickson, of the NYFD, added that digital radios were "unsafe" when two people transmitted at the same time. "With digital radios, the message gets lost, while an analog radio can hear at least one with interference from the other," he said. "We may have to revert back to analog radios."

But increased power output could involve a health risk for firefighters. Warwick University biophysicist Dr Gerrard Hyland has said that Tetra causes more danger from brain damage than mobile phones or other radio systems, but manufacturers have dismissed his concerns.

BT Airwave, responsible for the Tetra project in the UK, was unable to comment on the Dutch and US fire services' statements.

Also published in Network News