Jul 1, 2008 12:00 PM, By Donny Jackson

Difficulties associated with digital-radio communications in a fireground environment could require several changes, including FCC reconsideration of its narrowbanding plans below 512 MHz, according to an International Association of Fire Chiefs (IAFC) interim report released yesterday.

In addition to including previously released best-practices guidelines and results from lab tests, the IAFC interim report made several recommendations to address shortcomings in the audio intelligibility of digital radios operated in fireground scenarios compared to analog radios. Firefighters are seeking “analog voice intelligibility quality or better in digital radios, particularly in those areas tested where firefighter communication is paramount to their survival,” the report states.

Those areas include the use self-contained breathing apparatus (SCBA) masks and personal alerting safety systems (PASS). When using such technology, tests conducted by the National Telecommunications and Information Agency (NTIA) indicated that digital systems often were not as intelligible and analog systems.

These test results have made an impact throughout the country, as several fire departments have taken steps to stop using new digital communications systems in fireground situations and others are considering delaying the deployment of digital systems.

This is a disturbing trend within the industry, because many federal grant programs require the use of digital P25 radios to secure funding, and the FCC is counting on digital efficiencies to reduce channel widths for public-safety communications below 512 MHz from 25 KHz to 12.5 KHz by 2013. The FCC also has indicated it plans to narrowband to 6.25 KHz channels eventually, which could prove more challenging to developers of vocoder solutions.

With this in mind, the IAFC recommends that it approach the FCC about the “timing” of an eventual migration to 6.25 KHz channels.

“We want to make sure that, before we move forward, we don’t make things worse than they already are,” Charles Werner, chairman of IAFC’s digital project working group, said during an interview with MRT.
Meanwhile, Werner said it is important for the industry to develop audio-intelligibility standards, so products can be tested objectively. In addition, more testing is needed to better determine the environments in which digital radio systems are reliable, he said.

“I see this as just the first step,” Werner said.

Copies of the IAFC report are available online at http://www.iafc.org.

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