Chicago Fire Department is scheduled to begin testing new digital radios starting at 8:00 a.m. Sunday October 14, 2012. Chicago Fire Department may be testing their new digital radios citywide for three days, and then will switch back to their existing VHF frequencies. The Motorola digital radios that will be operating on UHF frequencies were purchased in 2006 — under a $23 million no-bid contract. The digital radio implementation was delayed because of problems with transmission and reception of radio signals.
In a hazardous environment wearing a breathing device inside a building, digital frequencies come in garbled and broken up in some cases. It was not reliable
— Former Fire Commissioner Robert Hoff (September 2011)
The radios went through extensive testing, and are finally about to be implemented. Digital radios are subject to digital distortion which results in quacking noise that is often unintelligible. Analog radios tend to pick up hiss and static, but the integrity of the sound of voice is usually intact, albeit weaker.
Similar problems with digital radios have been noted worldwide. Some fire departments refuse to use digital radios on the fireground frequencies because of failures and distortions. The fireground frequency is the tactics channel that is used after firefighters arrive on the scene of a fire or other incident.
There are many critics of the digital system. Some digital systems are also encrypted, which requires that the encryption key as well as the voice message be transmitted. Interference that distorts a voice could possibly also disrupt the encryption key from being transmitted. If the encryption key is not recognized, the transmission could be prohibited or blocked, and the radio signal might not be heard at all. A distorted voice is better than no voice at all, because even a distorted voice could be recognized as a call for help. Firefighters would probably have a rough idea where a crew is located, even if they couldn’t understand the precise location because of voice distortion. With the encryption on, it is possible that nothing would be heard at all.
Chicago Fire Department recently declared that their radio transmissions will be in the clear, which means unencrypted.
Citizens can listen in on a radio stream of the new radio channel at Radioman911.com, which utilizes radio monitors located in several strategic locations in Chicagoland — including a monitor in Willis Tower. The Radioman911.com Chicago Tower specific feed is also located at http://www.justin.tv/radioman911 is now streaming every possible CFD VHF, UHF and 800 MHz, analog and digital fire frequency including O’Hare, marine, MABAS, and sometimes CTA Power Control.
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