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Recently, we had a very close call here at home and we think the voice amps and digital radio combination may have played a part in the break down in communications.

Several tests have been ran by various companies and we have determined that the SCOTT voice amps and MayComm digital radios don't like each other. We're pretty sure the filter in the digital radio is causing the glitch but I would really be interested if any of you have observed the same problem or maybe a different problem that we haven't ran into yet.

Let us hear all about it.

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We have trouble with the digital radios. Not so much with the Scott voice amps if you have the mic on the side of the face piece away from the voice amp. Our biggest problem with the transmission of digital noise is back ground noise. Fire alarms, machinery or merely a strong wind blowing over the mic. In our testing (we went to the 800 mHz digital system in December of '07) the vibra-alert for low air is a real problem. Now before someone says we should watch our air, we do. But the inherent problem is should someone be low on air, we really need clear comminication.

As far as other problems, dependability with the software seems to be the big concern. Our 800 mHz system is down now and has been for one week tomorrow. The repeaters are acting up. We went back to the old VHF system. I have been told the 800mHz repairs will be complete today, but that hasn't happened either. Probably next week. I am not sure if most of the problems are operator error but I believe they are a factor.
Another reason to make sure we have all people out before the alarm sounds. Anything after the alarm is an emergency and should require a Mayday, per NFPA 1404.
Same problem here using SCOTT voice amps and Motorola. Also keying up a Motorola 800 mgh radio next to an LG cell phone will keep the phone from finding a signal for around 15 minutes. Remind me why we went to this technology.
We switched over to a motorola trunked 800 system last year with the county, We had been using high band VHF before. Two things with these systems,. First, it took a long time to work the bugs out of the system. We also had a problem with the new system not playing well with the older equipment in the system. We have a large bluff that transects the county in half and it is 200 ft high. with the old sytem, we had the transmitter on the bluff so it would cover the areas along the base of the bluff. with the new system, when you transmitted to the west tower on the bluff, it would confuse that transmitter and throw an open carrier. The biggest problem though just recently came to light. In a forum on firehouse, Prince George county in Virginia had a LOD that they feel is in part by failure of the 800 system. After reading this, we undertook some real life festing of our radios. We found that if you are in an enclosed space, ie a interior fire attack. with our masks in place if you set off your pass device, that the digital vocoder(the thing that converts your voice to a digital signal) could not pick up or distinguish between the voice and the PASS, basically wiping the voice out. So when you need the damn thing the most, it wouldn't work. I have also found that the IAFC ant NIST are working on these very problems. We plan to keep abreast of this and I will relay any developments. For right now, though we are going to keep both systems in place until someone figures his out.


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