Pa. County Conducts Digital Audio Test
October 14, 2008
By Eric Bistline
York County, Pa., plans to roll out its new Project 25 (P25) digital trunked radio system next month. The county conducted digital radio audio tests to determine how its new system is affected by specific noise conditions.
The county’s $68 million, multifaceted technology system and infrastructure project, which began four years ago, includes a new emergency services center; a fully functional, geographically redundant long-term backup facility (LTBF); CAD system; automatic number identification/automatic location identification (ANI/ALI) controllers; VoIP telephone system for administrative functions; UHF Project 25 (P25) T-band digital trunked radio system with full microwave connectivity; 22 transmission sites, complete with hardened climate-controlled shelters with full generator backup power; and a 16-site full simulcast digital alphanumeric UHF fire and EMS alerting system.
York County, located in central Pennsylvania, has a population base exceeding 411,000 in an area of 911 square miles. The county has an annual growth rate near 4.5 percent. The York County Department of Emergency Services (YCDES) is comprised of the Office of Emergency Management; the 9-1-1 department, the county’s public-safety answering point (PSAP); and the hazardous materials (Hazmat) response teams. The 9-1-1 department, which received more than 264,000 calls for service in 2007, provides public-safety dispatch and communications services for 23 law enforcement agencies, 68 fire departments and 35 EMS agencies.
In late 2006 and early 2007, during York County’s radio implementation, fire services across the country began reporting concerns to the International Association of Fire Chiefs (IAFC) with possible communications problems involving digital two-way radios while in close proximity to common fireground noise. For more information on the IAFC report, visit "IAFC Releases Reports with Digital Audio Recommendations" and "P25 Task Group to Investigate Fireground Noise Issues".
In the wake of the report, YCDES and its consultant L. Robert Kimball and Associates decided to conduct controlled, nonlaboratory tests where radio technicians could simulate or create specific noise conditions and then test the new Tyco Electronics Wireless Systems digital radio equipment to see what impact, if any, these conditions may have. YCDES technical staff wanted to be aware of what public-safety users could experience under real fireground conditions, where the potential exists for higher-than-normal background noise levels.
In June, YCDES conducted seven specific scenario tests assisted by Assistant Chief Steve Kehr, Capt. Andy Rabenstine and Lt. Chris Keech from Fire Station 19 of the York Township Fire Department. Each of the seven tests was conducted using the Tyco noise-reducing speaker microphone with an antenna (SMA) of the type and model issued as part of the standard portable package purchased by every public-safety user on the new trunked radio system. Five of the seven tests were also conducted by transmitting the voice message directly into the portable radio without the use of the SMA.
The tests with the SMA were conducted with the microphone attached to the technician on the left shoulder area. A technician simply tilted his head to the left and spoke in the direction of the SMA, in effect, speaking across the microphone. This condition best simulated real life. The tests without the SMA were conducted by a technician speaking directly into the front area of portable radio, held about 3 – 4 inches in front of the mouth.
Preliminary Recommendations for End Users
After an in-depth review of the IAFC’s report and data from the field tests performed by YCDES technical staff, the YCDES strongly endorsed the recommendations made by the IAFC. The YCDES staff released the following recommendations for fire service leadership.
• Train all personnel to properly use the assigned radio equipment in conjunction with all components of the protective ensemble. Comprehensive and continual training is critical to the successful use of complex communications equipment.
• Establish a regular training program for these recommendations. Currently, most agencies don’t incorporate this type of training into regular programs. This lack of training increases the potential for communications failure at critical times and adversely affects firefighter safety.
• Develop standards and guidelines for scenario-based user training with communications equipment. This training must include integration of communications policies and procedures into everyday agency operations.
• Evaluate background noise in the environment as a safety consideration in the issuance of public-safety personnel task assignments. Incident commanders may determine additional personnel need to be assigned to tasks to ensure communications capability isn’t compromised when there are high levels of background noise in the environment.
• Consider the use of accessories, when practical, such as throat, helmet and in-ear microphones to help reduce the impact of background noise.
• Use the radio, when practical, for the initial distress call before manually activating the personal alert safety system (PASS) device in a mayday situation. PASS devices create a great deal of background noise close to the radio microphone, as demonstrated by YCDES staff during their field tests. Transmitting on the radio before activating a PASS optimizes the probability that a voice message can be transmitted successfully.
• Maximize microphone performance by having the audio coming directly into the microphone and not entering the microphone from the side or back.
• Speak in a clear and controlled voice to maximize intelligibility.
• Turn or move away from noise sources, when practical, before conducting radio transmissions.
• Consider using a free hand, when practical, to muffle a mask-mounted self-contained breathing apparatus (SCBA) low-air alarm when trying to transmit on a radio.
The IAFC’s interim report should be considered a work in progress, and the recommendations published by the IAFC’s best practices work group offer a sound foundation and common-sense, first-step approach. The YCDES supports agency review, using the IAFC and county recommendations, and encouraging leaders and commanders in the York County emergency service agencies to place these practices and procedures into operations manuals.
For a chart with the results of the YCDES tests click here.The table indicates the testing scenarios, equipment, parameters and results. All scenarios were conducted with a Tyco Electronics Model 5100 series portable radio.
Eric Bistline is the executive director of the York County (Pa.) Department of Emergency Services.
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