Maybe digital radios aren’t the problem

Aug 22, 2008 2:21 PM, By Glenn Bischoff

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Lately we’ve been writing about the problems that firefighters are having on the fireground with digital radios, which in some cases have had difficulty distinguishing between a human voice and background noise. Indeed, recent tests conducted by the National Telecommunications and Information Administration (NTIA) indicated that analog systems provided greater audio intelligibility than digital systems in four out of nine environments, including when self-contained breathing apparatus (SCBA) masks and personal alert safety systems (PASS) were in use.

But tests conducted by a radio technician in Florida suggest that the problem isn’t the digital radios at all, but rather firefighters who haven’t been trained adequately on how to use them in high-noise environments.

Terry Forehand, systems manager for Nassau County, said he put Motorola’s XTS series and EFJohnson’s 5100 ES series to the test in a variety of scenarios designed to replicate conditions on the fireground. Chainsaws were fired up, PASS alarms were triggered and a tunnel collapse was simulated. According to Forehand, the radios performed well. He said a few minor adjustments needed to be made to the Motorola handsets, which included turning off the automatic gain control.

But no adjustments needed to be made to the EFJ radios, which feature the enhanced half rate IMBE vocoder that has been specified for the second phase of the Project 25 standard (see story). Currently, EFJ is the only digital radio vendor using this vocoder.

Forehand was impressed. Right now, the county exclusively uses Motorola radios, but “I would choose to buy the EFJohnson radios based on this testing—they work,” he said.

The real problem according to Forehand is the firefighters. “They need to do more training. We have to get them comfortable with being in noisy environments,” he said.

John Oblak, EFJohnson’s vice president of standards and regulatory affairs, agreed and said an International Association of Fire Chiefs working group came to a similar conclusion, recommending “common sense” best practices that included talking directly into the microphone, knowing how to hold the microphone in relation to the voice port on the SCBA mask and—when possible—talking on the radio before triggering the PASS alarm.

“This will go a long way to mitigating the problem,” Oblak said.

This writing is not intended to suggest that the NTIA study is off base. Rather, it is intended to offer some additional food for thought. Apparently, some fire departments are considering abandoning their digital systems and going back to analog. Certainly others that have been considering an upgrade might now be putting those plans on hold, perhaps permanently. Given the clear performance advantages of digital technology, such knee-jerk reactions would be unfortunate.

E-mail me at glenn.bischoff@penton.com.