Digital Systems and the Fire Ground

Over the past two weeks, several articles about Hamilton County firefighters and the problems they've reported with fire scene communication have circulated throughout the media. We wanted to take this opportunity to address the concerns brought forward in these articles, discuss some best practices, clarify misconceptions in the media reports and let you know what we as your COG Technical Committee are doing to address concerns.


Two articles in the January 15^th edition of the Cincinnati Enquirer that were reposted by several Columbus area media outlets allege the system used by Cincinnati firefighters failed during recent fires. The articles speak in generalities about these failures when, in reality, they are speaking of very distinct and separate issues. These issues include:

• the ability of digital radios to isolate and transmit a voice in high-noise environments
• coverage in densely constructed downtown Cincinnati high-rises
• multiple firefighters trying to transmit at the same time
• “busy signals” experienced when all of the system frequencies are in use
• mayday calls not being heard on the fire ground.

While these issues were presented together in the articles, each must be examined separately. Below is some information that we have compiled with the help of representatives from the Hamilton Co/Cincinnati P25 radio system and representatives from the Butler Regional Interoperable Communications System (BRICS).

Digital Radios in High Noise Environments
The International Association of Fire Chiefs (IAFC) formed a digital working group in 2007 to address potential problems found in digital radios in the presence of loud background noise. In the early years of digital public safety radios, the audio processing hardware and software in the radio did a poor job picking the voice out of background noise like chain saws and PASS alarms.

The IAFC working group comprised of fire-service personnel and manufacturers studied the issue to develop reliable data to address the extent and nature of the problem. As a result, Motorola has made several improvements to the hardware and software that, while not perfect, do greatly improve voice quality during those situations.

In 2008, Motorola issued a bulletin with recommendations for best practices in programming radios with settings for high noise environments. These settings were incorporated in all radios programmed as part of the Dublin/Worthington system cut-over. Since Delaware County radios were programmed prior to 2008 these changes have not been incorporated in those radios.

In Butler County, the Hamilton Fire Department, in conjunction with BRICS system administrators, conducted extensive testing of these recommendations. The tests demonstrated that these settings made a significant improvement in high noise environments. Radios with the recommended settings were tested against those without in situations with SCBA and PASS alarms.

On February 8^th, the Washington Township Fire Department will conduct a similar set of tests to validate the Hamilton FD findings. Those results will be reported back to the Technical Committee and posted on the web site.

The IAFC released an interim report on their findings which recommends many best practices for fire department leadership and radio field users.

The leaders were charged with training “all personnel to properly use the assigned radio equipment in conjunction with all components of the protective ensemble.” They pointed out the need for “scenario-based user training utilizing their communication equipment,” and “integration of communication policies and procedures into agency operations.”

Field users were advised to, when practical:

• use the radio for the initial distress call before manually activating the PASS alarm in a mayday situation.
• ensure the microphone is placed one to two inches from the mouth or SCBA voice port with the microphone positioned directly in front of the audio source
• speak in a loud, clear and controlled voice to maximize audio intelligibility
• shield the microphone from noise sources to improve the intelligibility of the audio in high-noise environments

To read the full list of recommendations, you can download the report and presentation from Motorola on their Best Practices in High Noise Environments page.

Coverage in Dense Buildings

No radio system can cover every part of every building. The Dublin/Worthington side of the system was designed off of the standard set for the Dublin analog system, which was to provide 95% coverage for portable radios in 15db buildings. Preliminary testing indicates 98% plus coverage in all areas. The original Delaware side of the system was also designed with the same coverage standard. However, because of the density and size of buildings in the Polaris area north into Delaware City, the standard was increased to 95% in a 20db building.

We recommend making radio coverage testing a part of your fire preplanning efforts. Knowing gaps in coverage ahead of time will allow the incident commander to plan accordingly which includes using alternate talk-groups on the Columbus system, Ohio MARCS or the car to car simplex frequency.

We also encourage users to share with us those locations where they experience coverage problems. We will investigate those areas for future coverage expansion and the possibility of adding bi-directional amplifiers in specific buildings to enhance coverage.

Busy Signals vs. Multiple Users Trying to Talk

Cited as a failure of the radio system, media reports point out that users of Hamilton County’s system get “busy signals” when others are talking. There are actually two different situations that sound the same: either the system can be busy (every channel across the system is in use) or someone else can be talking on your selected talkgroup when you attempt to transmit. In either case, you can’t transmit and your radio tells you so – with two different tones. This is not a failure; it’s by design.

Radios are typically “half duplex”, meaning you can either receive or transmit, but you can’t do both. This works the same way on our new system as it does on the Hamilton County system. Having to wait your turn to talk is nothing new.

Analog systems would often allow a second user the ability to transmit over top of another user. Because these systems employ multiple receivers, when two users talk, the system essentially renders the audio from both users unintelligible. In addition, the second person who transmits will not have their push-to-talk ID transmitted. The most serious problem was both thought they were heard. The difference with the digital system is the user will actually know whether or not their message will be transmitted, because the user will get immediate confirmation by receiving the permit-to-talk tones or the tone that tells you to wait. It’s an improvement over analog.

Maydays/Declared Emergencies
The Cincinnati Enquirer article titled “Mayday Call Met with Silence on Radio” describes a situation where two firefighters became trapped by a burning stairwell. One of the firefighters declared “Mayday, mayday, mayday,” according to the article, and received no response from the incident commander. The article goes on to indicate “All three blame the county's digital radio system for what they believe was a missed mayday”. However, responding apparatus heard the mayday call and all of the mayday transmissions were heard by the agency logging recorder. Three minutes elapsed before a rescue operation was initiated.

The fact that the mayday was heard by other users and the system’s logging recorder demonstrates that the call went through. Why the calls were missed by the incident commander is unknown.

Unlike the Cincinnati scenario, the dispatch centers that serve our users assign a dispatcher to actively monitor the fire ground talk-group. The dispatcher serves as another set of ears to ensure the incident commander is notified of the mayday. Also, the dispatcher will receive any emergency banners activated during an incident.

Our recommendation is for each agency to review their mayday procedures to ensure firefighters both vocally declare their mayday on the fire ground and activate their emergency banner on their radios to alert incident command and the dispatcher to their situation.

Summary
We thought it was important to respond to this because we knew many of our users would see the articles and have questions concerning the applicability to our system. Hamilton County and Butler County were very open with us and helped a great deal during the planning stages of our system. Both of those systems, as well as ours, are Motorola Astro 25 and for the field users essentially operate the same. The main difference in Dublin/Worthington is, with the benefit of having programmed our radios in 2009, we were able to take advantage of the best practices for noise reduction issued by Motorola in 2008. With the input of Motorola, our partner systems and user community, we believe our radios are programmed with the best available settings and capabilities for fire ground safety.

LINKS
"Dropped Calls Put Firefighters in Danger" - Cincinnati Enquirer - January 15, 2010

"Mayday Call Met with Silence on Radio" - Cincinnati Enquirer - January 15, 2010

"Background Noise & Radio Performance" - Motorola Position Paper - 2008

"IAFC Digital Project Resouce Page"

"LODD Fact Finding Committee - Preliminary Report" - Colrain Twp - July 11, 2008

Acknowledgements
A special thank you to those listed below for the assistance in putting this information together:

• Greg Wenz, Operations Manager - Hamilton County Communications Center 
• Matt Franke, Systems Administrator - BRICS
• William Vedra Jr, Comm Tech - BRICS