Ada County Idaho was one of the first jurisdictions in the United States to embark on a cutting edge 700 MHz digital trunked radio project. The City of Boise is in Ada County and agreed to participate in the countywide radio system. The Boise Fire Department purchased more than one million dollars of 700 MHz digital mobile and portable radio equipment with the expectation that the new equipment would provide the best possible communication for its first responders. Unfortunately, the Fire Department staff has determined that the digital radios would present a risk to firefighter safety if placed into service. The radios have not been deployed because of this issue.

Boise firefighters discovered that voice transmissions over the digital radio system are usually unintelligible when the VibraAlert feature on a Scott SCBA is alarming, or when multiple PASS alarms are sounding in the same area. The software used in the digital radios that converts voice to digital data cannot isolate the spoken voice from the noise. Voice transmissions are unintelligible when the radios are used in a high-noise environment.

Boise Fire staff conducted extensive tests and determined that the problem is endemic to the digital modulation used in the new radios. The problem is not directly related to the 700 MHz frequency band or to trunking, however the FCC requires that digital modulation be used in 700 MHz radio systems. The only reasonable conclusion is that 700 MHz digital radio equipment is not suitable for use on the fireground.

In 2006, some fire departments discovered that the voice audio from digital radios in the presence of background noise (common to firefighting operations) will cause distortion to the degree of unintelligibility. The International Association of Fire Chiefs (IAFC) have established a working group to study this issue. The IAFC issued an alert to its membership on March 20, 2007. There is no known workaround or solution to this problem as of this writing.

Boise Fire Department and the other fire departments in Ada County will remain on analog VHF radio systems.

The City of Boise Idaho has a population of about 201,000 residents, however the metropolitan area has about 635,000 persons. The City covers approximately 64 square miles.

Please contact me if you would like contact information for the Boise Fire Department to hear this information first hand.

IAFC_Digital_Problem_Working_Group_Report_09/29/2007