We hear you

Oct 1, 2010 12:00 AM, By Mary Rose Roberts (maryrose.roberts@penton.com)

As federally funded researchers continue to test digital radio technologies, manufacturers bring to market new and improved models, based in large part on user input, that perform better on the fireground — but there's work still to do

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Not everyone is a fan of digital radios. In fact, many argue that such radios are inadequate for emergency communications because they fail to deliver clear voice transmissions in certain environments. This is especially true on the fireground, where roaring pumpers, chain saws and street noise often overwhelm voice communications between incident commanders and firefighters.

To study the issue further, the U.S. Commerce Department’s Public Safety Communications Research (PSCR) arm is conducting a second round of digital radio performance tests to determine whether improvements have been made regarding fireground communications. The tests are being held as part of a joint effort between the National Institute of Standards and Technology and the Institute of Telecommunications Services, and will evaluate the noise pollution that interrupts communications on the fireground, said D.J. Atkinson, a lead electronics engineer at PSCR.

A couple of years ago, the International Association of Fire Chiefs’ Digital Project Working Group performed initial investigations into digital radio use on the fireground and offered best practices to manufacturers, Atkinson said. The current tests, being held in a controlled environment at PSCR laboratories in Boulder, Colo., will quantify what improvements have been made and target where work still is needed to further enhance audio quality for public-safety communications, he said.

The tests compare digital and analog communications technology in laboratory simulations of public-safety communications environments (see graphic). Atkinson said that speech and noise from such environments will be tested in a manufacturer-independent manner using reference communication systems.

“This is accomplished through the examination of the system performance in a subjective listening test, in which the relative performance among the systems is measured in a quantitative and repeatable way,” he said.

Communication degradation also is being tested, specifically the effect of fireground background noise. Researchers will include law-enforcement and EMS background noise, as well. For example, Atkinson’s team recorded noise at a local nightclub then scientifically determined the level of noise that would be encountered if police or EMS responded to an incident at a bar, and how such background noise would affect their communications.

For the first time, intelligibility —how understandable the speech is coming across the radio — and radio channel degradation will be tested, Atkinson said.

“We are adding both background noise and channel impairments — bit error rate, things like that — to see how those problems may compound to see if that has any additional detrimental effect or intelligibility issues,” he said.

Atkinson expects to find measurable improvements in comparison to the first test. But he admits that digital radios “still have a little way to go before [they] are the best that they can be.”

Fundamental design

Manufacturers are working with end-users to develop digital radios that solve voice clarity issues with a form factor tailored to users working in hazardous environments. For example, Motorola developed its multiband portable firefighter radio with end-users in mind, by studying human stress reactions, participating in live-fire training and listening to fire personnel’s feedback on prototypes. The result was an ergonomic radio with a two-microphone design and acoustic- and noise-cancelling software that filters out fireground noises.

At Motorola, a hazard radio’s development starts with internal experts and outside academics who research how people process information under stress, a condition known as high-velocity human factors, said Mark Palmer, a psychologist and director of the company’s human factors and research division.

“Staff scientists research how people operate under high levels of stress and what it means for the design of products, with a focus on firefighters and police,” he said.

Field tests are next. For the company’s firefighter radio, engineers worked with the Sunrise (Fla.) Fire and Rescue Department. As part of the partnership, a dozen Motorola engineers were outfitted with bunker gear and spent a day participating in live-fire training exercises, said Div. Chief Tom O’Connell.

“Engineers began to learn the shortcomings of communications under [fireground] environments,” he said.

Palmer said that scientists learned the difficulty of communicating while also trying to put out a fire. In addition, they found that the heavy equipment used by firefighters –including bunker gear, heavy gloves and self-contained breathing apparatus (SCBA) — causes a situational disability that can hinder communications during an incident.

“You start to appreciate the problems firefighters go through … simple things like changing a channel so they can talk to each other,” Palmer said. “This does not make us experts on being a firefighter, but it does show us the barriers and problems.”

O’Connell said that company engineers then presented rough designs to firefighter user groups and asked about ergonomic needs, such as the size and height of knobs, with consideration given to gloved hands. They also documented the frequency range of background noises encountered on the fireground, such as a rotary saw cutting through metal or diesel engines revving.

Documenting what firefighters experience and listening to their feedback is part of participatory design, or co-creation, said Bruce Claxton, Motorola’s senior director of innovation and design. Claxton said that such knowledge was used in the design phase to develop a physical prototype that could perform in extreme environments. In this phase, the company realized the unique nature of firefighting and the need to custom-fit a radio to that work environment — for instance, that the radio is accessible while wearing bunker gear. It further drove the desire to develop a tailored form factor that offered unique ergonomics specific to the fire service, he said.

“Ergonomics was a key driver for good design,” Claxton said. “It was a fundamental principle.”

Claxton said that because knobs and buttons needed to be more easily located and operated with gloved hands, company designers tested out exaggerated controls and radio form factors.

“Today in our labs, we have bunker gear hanging on hooks and gloves and gear sitting in our design studio desks so designers can use the equipment while designing,” he said. “It’s not unusual to see someone in our office evaluating a prototype with full turnout gear on."