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The Issue of Background Noise in Radio Communications

Issue 7 and Volume 5.

You can’t walk into a fire station today without getting an earful about the issues and concerns that firefighters and fire officers alike are experiencing with their digital radios. Many departments complain that they can’t hear their firefighters because of digitized background noise, which overwhelms their voices and makes radio transmissions unintelligible.

Why does this happen? To some extent, background noise is a problem with any radio system. But many departments that upgraded their systems in recent years weren’t involved with their communication system design and/or the request-for-proposal (RFP) phase. This was a major issue we found in our own department. We had little to no involvement, and then one day, we were told, “Here’s your new radio.”

As with all types of radio systems, it’s critical that digital systems be specced, designed and tested for how they will perform in real-life fireground situations, such as in below-grade operations or building penetration during interior operations. But tests should also include background noise, which is common on the fireground today.
Background noise comes from a variety of sources, including SCBA voice boxes and amplifiers, PASS devices and our overall PPE ensemble. But did our RFPs mention that these items can be sources of background noise? If not, they should have, because all of them come to the fireground with us.

Because these new radio systems cost millions of dollars, it’s unlikely that they’ll be replaced anytime soon, so it’s critical to understand how your system is designed, where it works and how it works so you can minimize the effects of background noise.

What’s being done to address this issue, and what technology or studies are on the horizon to improve our current systems and to ensure that we’re at the table from here on out? Before we decide to throw away our current systems, let’s look at how we can effectively use them to communicate, and how we can improve fireground communications.
 
Training & Best Practices
First and foremost, training our people on the effective use of their radio equipment will go a long way to ensure proper fireground communications. The District of Columbia Fire and EMS Department (DCFD) printed an article in the November issue of “DC’s Bravest” illustrating the importance of training on fireground communications. The article, written by Captain Dan Troxell, states, “Clear and concise radio transmissions are essential to ensure safety of all members operating on the fireground.” The International Association of Fire Chiefs (IAFC) also created a best-practices document that not only includes best practices for the use of radio communications systems, but also outlines the importance of properly training our firefighters on the use of their portable radios.

The best way for us to succeed at anything we do is to train on it, but training needs to go far beyond explaining how to turn on a radio and charge it. Think about it: We train our firefighters on all their PPE. We even show them how to manage a problem while wearing all their gear in an IDLH atmosphere. So should we treat the radio any differently? No. Firefighter training should always include an introduction to the radio, the overall communications system, determining what the radio can and can’t do, radio discipline and policies, and drilled-in, hands-on conditions to minimize confusion and problems when operating on the fireground.

Simply put, we need to train firefighters on how to use their radios in the fire/rescue environment. They need to experience the giving and receiving of transmissions so that they can clearly understand the importance of established best practices, such as how to carry and maintain their radio, and how to use the accessories—such as microphones and microphone holders—that can have a negative or positive impact on their transmissions, depending on how they choose to use them. If firefighters practice these transmissions at the task level in a simulated IDLH atmosphere, they’ll gain an appreciation for why we train as much as we do, and why we adhere to best practices.

On the fireground, I often hear firefighters getting ready to go offensive with a chirping radio in their pocket, signaling that the battery is low. (Are you kidding me?) To me, that firefighter is saying, “My radio is important to me, but not important enough to make sure it’s working properly before I go offensive.” This is just one example of how we need to be absolutely diligent about training our personnel on best practices and taking responsibility for their life-saving PPE—from helmets to hoods to SCBA, bunker gear to boots to portable radios.

Issue at Hand: The Vocoder
Recently I attended a meeting related to digital radio issues. The room was full of fire officials, but there were a staggering number of people who had never heard of the IAFC’s best-practices document and were bewildered by the fact that they were experiencing radio issues on the fireground.

I then realized that many people may be hearing of the problem with digital radios for the first time. Some readers may not have digital systems and may be wondering what the problem is all about. The main issue with digital radio systems stems from a device called the digital vocoder, which basically takes your voice, digitizes it and sends it back out across the radio system (similar to how your cell phone works).

The vocoder is designed to decode human sounds only and convert them to a digital output, filtering out any non-human background noise—as long as the voice isn’t overwhelmed by the background noise, which can come from PASS alarms, chainsaws, K-12 saws, PPV fans, etc. (See the digital radio noise report at http://tinyurl.com/2vslmfd for a more scientific explanation). With this type of background noise, the transmissions of firefighters on the fireground can be unintelligible at times.

Corrective Measures
Efforts to combat background noise have been under way for a while. The Public Safety Communications Research (PSCR) laboratories, housed with the U.S. Department of Commerce in Boulder, Colo., has formed a joint effort between the National Institute of Standards and Technology’s (NIST) Office of Law Enforcement Standards and the National Telecommunications and Information Administration’s Institute for Telecommunication Sciences. Within this effort, or program, practitioners test how digital radios operate in the presence of loud background noise and how technological improvements can overcome background noise issues. The practitioners also test mitigation techniques and have identified immediate behavioral, procedural and technical steps that agencies can take to avoid or minimize emergency response background noise.

Manufacturers have also spent considerable time analyzing the problem and researching how technology and best practices can improve fireground communications to keep our firefighters safe. Harris, Motorola and several other vendors have spent hours working on software improvements. For Motorola, these improvements include an enhanced software upgrade to their XTS radios called “noise shield.” This software uses a series of algorithms in the digital signal processor to more accurately filter out a caller’s voice from the background noise.

Regarding the radios currently on the market, Motorola has provided documentation via its Web site that recommends adjusting the settings on their XTS radios for high background noise conditions. For example, they recommend setting the automatic gain control (AGC) to the “off” position, setting the analog/digital balance to the “on” position and selecting the advanced noise suppression setting.

Motorola also recommends that radios receive periodic preventative maintenance to ensure peak performance. Note: This is a service that should be performed by a radio technician and is not something that would be accomplished by the end user. What plan do you have in place at your fire department to regularly maintain your radios? Remember: Just as annual SCBA testing contributes to firefighter survival, so too does regular radio maintenance.  

The IAFC (along with the IAFC’s Safety, Health and Survival Section and the Communications Committee) has been engaged in the fireground communications issue since 2006, when it established the Digital Project Working Group made up of representatives from the public safety disciplines, government, other national fire service organizations and the private sector radio vendors. Since 2006, much has been learned about best practices and how digital radios work.

What Can We Do Now?
It’s mission-critical that we continue to work cooperatively with the radio vendors to improve technology for our radio systems. In addition, it’s critical for fire chiefs, fire officers and firefighters to follow the guidelines listed below so that we can ensure optimal fireground communications.

  • Firefighters: Follow the policies and procedures of your department. Complete the required training and remember to ask questions. Check your radio regularly, charge the battery and make sure it works.
  • Fire officers: In addition to the above, conduct training specifically on and including the use of portable radios. Make sure all your firefighters are fully aware of every aspect of their radio, including mayday procedures, and what role the radio plays in that. In some systems, hitting the emergency button gives that user high-priority access to the system. What capabilities does your system have?
  • Chief officers: In addition to the above, insist on being involved in the planning and design of any system purchases, changes or upgrades. Make sure that there are written radio SOPs, and that all members are fully trained on how to use the radios, the system and its capabilities. Ensure regular testing of each portable radio, as well as system tests performed by your members (roll call, radio checks, etc.). Make sure contracted portable radio “tune-up” programs are performed regularly by a qualified factory representative.

Conclusion
Each fire and emergency situation we respond to is different, so it’s impossible to plan ahead 100 percent for every situation. However, by providing the best possible tools, equipment and training, we make sure that we’re doing everything we can to achieve our goal of making sure everyone goes home after every incident.