Audio Testing Complete

On Monday February 8th, the crew from Engine 95 assisted in testing the audio performance of walkies used in high noise environments. In particular, the 2008 Motorola recommended settings for high noise environments were tested against the factory default audio settings in two sets of XTS5000 walkies. The details of the test and recommended outcomes are contained in the report document posted below.

If you have any questions about the testing, or need more details on the methods used in the testing, please contact Jay Somerville.

DDW800MHz – Fire Service Radio Audio Testing

Monday 02/08/2010 @ 10am

Washington Township Fire Admin

Purpose:           To compare the audio settings on the XTS5000 between the factory default AGC settings and the advanced settings for high noise environments recommended by Motorola in their 2008 bulletin.

Problem:           All radios programmed on the DDW800MHz system used by the fire service are not programmed with the same audio settings. Since radios used by agencies in Delaware County were programmed and distributed prior to the 2008 Motorola bulletin, they utilize the factory default settings. Radios used by Washington Township Fire and Worthington Fire were placed in service in December 2009 and were programmed using the recommended settings. Users at Worthington Fire, especially those who operate radios at Delaware County agencies through secondary employment, report a distinct audio difference. Those users have indicated to the Technical Committee that they prefer the Delaware settings but would like to participate in the testing to be sure there is not some other issue causing the audio difference they are hearing.

Method:            Four radios will be programmed specifically for this testing. Two radios will be programmed with the factory default audio settings and two will be programmed with the 2008 Motorola recommended settings. The settings will only be known to the programmer, CT Paul Richmond of Dublin, with each group of two radios having the same color faceplate. Also, one radio from each group will be outfit with a new, never before used coil cord lapel microphone. Utilizing the crew of Engine 95, we will perform a series of tests using each radio at least one time in each scenario. All scenarios will be recorded using the logging recorder at the Dublin Communications Center.

Results:            Results will be logged as they occur by those present for the testing. Since the sound of the audio as it is presented to the person receiving has been the concern, users will help evaluate how the audio sounds in each test while on site (much like while at a scene). We will also have the ability to compare audio by playing back the logger recordings in a controlled environment at a later time.

Notes:               The training was conducted between 10:00 and 12:20 at the WTFD Admin building in the storage garage using members of Engine 95.

                        The minimal background noise was generated using conversation of those in the testing area. The significant background noise was generated using a saw idling within 5 feet of the participants. The extreme background noise was generated by revving up the saw within 5 feet of the participants. All tests were done inside the garage area.

                        Chief Highley of Worthington Fire and Jay Somerville of Dublin Communications were present for all testing and listened to the audio using an XTS5000 while sitting in a conference room removed from the testing area. BC Chuck Aston of WTFD was present for the final 20 minutes of testing. CT Richmond coordinated the testing with the participants from Engine 95. 

Conclusions:     After testing was complete and discussion about the results, Chief Highley of WFD and Battalion Chief Aston of WTFD ultimately selected the ORANGE radio settings as the preferred settings. It was revealed by CT Richmond that the ORANGE radios were programmed with the 2008 Motorola recommended settings for high noise environments. The group came to a consensus that although there was not a significant difference, it was noticeable that background noise was more suppressed using the new settings; neither solution could minimize the extreme level. The group agreed that training users on the general radio use practices should be developed to ensure optimal communication capabilities on the fire ground. Specific training recommendations are made below.

Training:            1.The most critical recommendation relates to the rescue of a down firefighter. When the firefighter performing the rescue transmits while the victim firefighter’s radio is turned on, the feedback creates a “reverberation” noise and the voice is unintelligible. Unlike the squeal created on an analog system, the rescuer cannot “talk-though” or “out talk” the squeal to get the message out. The recommendation is that training for firefighters performing mayday rescues be revised to include a step directing the rescuer to either turn off the victim’s radio or turn it off channel once the victim is found.

2. When operating SCBA, users should be instructed to use their voice amplifiers whenever possible and to hold the lapel microphone approximately 6 inches from and directly pointed at the speaker. If operating SCBA without voice amplification, hold the lapel microphone against and directly pointed at the voice pass through area.

3. Turn away from noise sources when transmitting whenever possible.

4. Mount the pass device on the side of the coat opposite to the lapel microphone and the SCBA voice port.

5. Revise mayday training and procedures so that activation of the radio’s emergency button is completed before any radio transmissions are made by the victim. This will give the user declaring the mayday top priority on the system and will ensure the dispatch center receives the emergency banner allowing them to confirm receipt with the incident commander.

 

6. Check portable radio accessories regularly for optimal functionality and replace any damaged or questionable accessories immediately.

7. Incorporate training for all users on the feature differences between each of the radio systems utilized, in particular those features lost when going to a simplex conventional channel (car to car)

8. Include awareness training for all incident commanders and encourage them

to avoid noise sources while commanding the scene.

Test Scenarios

No background noise / No gear

Minimal background noise / No gear

Significant background noise / No gear

Extreme background noise / No gear

No background noise / SCBA

Minimal background noise / SCBA

Significant background noise / SCBA

Extreme background noise / SCBA

From the pump panel / Not running

From the pump panel / Running

Mayday / SCBA / Two Radios

Mayday / No SCBA / Two Radios

Pass Alarm Activated

SCBA Timer Alarm