Vendors moving steadily in the right direction on digital radio noise problem
Personal alarms, chainsaws and spraying water are just a few of the background noises that firefighters typically encounter while using their public-safety radios at an emergency scene. Understandably, such ambient noise interferes with their ability to hear and understand what people are saying on the radio — which can be a matter of life and death.
Last year, the International Association of Fire Chiefs (IAFC) released a report citing lab tests indicating that analog radios outperformed P25 digital radios in certain noise environments, including in the presence of personal alerting safety system (PASS) alarms. Some fire agencies still are using analog systems for that very reason, although some lab tests showed problems with those portable radios, too.
As such, the vendor community has been challenged to come up with solutions to make digital radios better — and there isn’t one answer. Vendors are looking at a series of solutions: better vocoders, enhanced noise suppression techniques, new microphone placement (such as embedding microphones in masks) and improved microphone technology — to name a few.
Harris RF Communications showed the ability of its multiband, P25-compliant Unity portable radio to operate in high-noise environments during demonstrations at the Association of Public-Safety Communications Officials conference last month. Noise simulations included street-level noise, pump-engine noise, PASS-alarm noise and chainsaw noise, which reached 101 dB to demonstrate how the device with an enhanced vocoder and noise-cancellation technology could successfully navigate through these sounds.
Harris is careful and correct to note that the effort to improve radio intelligibility will continue to be an ongoing effort. It will always be a moving target given the unpredictable nature of sound and the fact that digital radios aren’t simply re-transmitting sound. The software in digital radios converts human voice into data bits for transmission and reconverts the digital signal back into voice on reception, providing a rough replication of voice.
I don’t ever anticipate any vendor declaring that the problem is 100% solved. Noise is too unpredictable. Some noise is steady in amplitude and frequency, while other noise lasts just a few seconds but is equally as damaging. But I think vendors can get pretty darn close. Couple technology with adequate training and industry best practices, such as requiring users to speak loudly and clearly, and the situation should be dramatically improved. Unfortunately, it won’t happen overnight.