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

Faced with vocoder intelligibility issues, departments choose to stick with analog a little longer

Amid concerns surrounding digital-radio performance, several public-safety agencies are considering alternatives, including analog radios.

Focus on digital-radio performance in fireground scenarios heightened last month after the release of an International Association of Fire Chiefs (IAFC) report on the issue. Tests conducted by the National Telecommunications and Information Administration (NTIA) indicated that analog systems provided greater audio intelligibility than digital systems in four of nine environments, including when self-contained breathing apparatus (SCBA) masks and personal alert safety systems (PASS) were in use.

These results and anecdotal experiences have caused firefighters in Phoenix, Orlando and Marion County, Ind., to question the wisdom of moving from analog radio to multimillion-dollar digital systems.

“Some fire departments are saying they are not experiencing the issue to the degree that others are,” said John Powell, senior consulting engineer for the National Public Safety Telecommunications Council (NPSTC). “Other fire departments, like Phoenix, are saying they're going to stay on analog until this is resolved. It's a problem any digital radio is going to have — anything that has a vocoder in it is going to have this problem; it's just the nature of the beast.”

In Marion County, some media reports indicating shortcomings in the Metropolitan Emergency Communications Agency's new $37 million P25 system have been inaccurate, but the county plans to take steps to address the problem for firefighters, said David Schwartz, deputy director of technology for MECA.

“We're aware that there's a potential issue with the vocoder — it's a national issue, not something unique to the Motorola system,” Schwartz said. “Right now, they're using the system and using the best practices that the IAFC has released, and they're constantly training to find those times when digital noise can be an issue. We'll be working with them to see if there are any alternative solutions that need to be looked at, and we'll be looking at the pros and cons of those.”

Dale Henson, chief of the Decatur Township (Ind.) Fire Department and president of the Marion County Fire Chiefs Association, said it was apparent from the MECA system's launch in June that a problem existed.

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