Why does Denver FD 154.070 have periods of sound that is similar to a keyed microphone no vocal? I've never heard any other agency do this and Denver's FD channel has done this for as long as I can remember. Do dispatched calls get missed when this happens? or does the dispatcher override this when HE/SHE keys up?
Denver FD VHF Dispatch
- Thread starter lazierfan
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rickak
Member
I think the carrier stays up until dispatched calls get acknowleged in the station(s).
Rick
Rick
Sorry I didn't mean to place this in the incidents area, if a mod could move to Colorado area instead thanks.
Okay. I will interpret your answer as normal operations of the repeater, and that this condition gets override status when someone keys up. It does not block traffic, if this is the repeater operating as it was set up to operate.
Sure is unique to 154.070 in Denver for Denver FD.
Sure is unique to 154.070 in Denver for Denver FD.
The VHF is the Vocalarm, not dispatch. That's the system that tones out the individual stations. I don't know exactly how it works, but I do know that even though it simulcasts dispatch traffic, it's independent of the Dispatch TG, which continues to be Channel 1 on the trunked system. 1 doesn't stay keyed if the Vocalarm transmits dead air.
Okay, so the vocalarm 154.070 VHF DFD has had dead air since about 16:30. It is now 16:58 and I am wondering if this is by design ?
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Guess I have to ask what's the value of monitoring this anyways, the box alarm and above assignments get aired on Ch 1 anyways so all you miss by having this VHF channel locked is is a hell of a lot of EMS first response calls.
Jim<
Thats where you and I part at the fork in the road, Jim. I don't listen to the EMS calls, so I don't miss them. VHF is easy to monitor in my shop, in the car, in the mountains, and in town in skyscrapers.Not even the $4 million radios that belong to the agency can say that with a straight face.
Hi Laz,
From Curt's site, denverradio.com:
"The Vocalarm is a system which allows dispatchers to dispatch stations, and make announcements to any or all stations, similar to a P.A. system, separate from the main dispatch channel."
So what you're listening to on 154.07 is P.A. via radio.
From Curt's site, denverradio.com:
"The Vocalarm is a system which allows dispatchers to dispatch stations, and make announcements to any or all stations, similar to a P.A. system, separate from the main dispatch channel."
So what you're listening to on 154.07 is P.A. via radio.
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K4XB
Member
Unnecessary transmission on 154.070
I doubt it. The FCC prohibits unnecessary or unidentified transmissions. With this lenghth of "dead air" that is an unnecessary transmission.
There is most likely an equipment failure or adjustment gone wrong in the system for this channel. It can easily happen. Even a local test microphone plugged into the base station with a bad mic cord (intermittently shorting on the keying line) easily cause this.
It is up to the Denver Fire Line Shop to monitor their channels and take action as necessary to correct.
Scotty, K4XB
I doubt it. The FCC prohibits unnecessary or unidentified transmissions. With this lenghth of "dead air" that is an unnecessary transmission.
There is most likely an equipment failure or adjustment gone wrong in the system for this channel. It can easily happen. Even a local test microphone plugged into the base station with a bad mic cord (intermittently shorting on the keying line) easily cause this.
It is up to the Denver Fire Line Shop to monitor their channels and take action as necessary to correct.
Scotty, K4XB
We always Monitor it. The Station is do to be switched out with narrow banding. It is a Mastr II.
Hope to have the problems solved..
Hope to have the problems solved..
K4XB
Member
Corection, changed in 2003?
On the other hand, after looking at the license history, it appears in 2003 the Denver Technology Services section assumed responsibility for this license in 2003. Perhaps they take care of it now and no more Line Shop involvement.
On the other hand, after looking at the license history, it appears in 2003 the Denver Technology Services section assumed responsibility for this license in 2003. Perhaps they take care of it now and no more Line Shop involvement.
No, the lineshop still takes care of it.
Toneslider12
Member
I could be totally wrong, but in my observations it seems as though it's all the dispatcher's doing. There are times when a call hasn't been dispatched for a considerable about of time, then the "dead air" sound keys up for a while before a new call is aired. It seems to be a longer time before a group assignment goes out so I attribute that to either all of the individual stations getting lit up on the VA, or the dispatcher reviewing the info before airing it. When the "dead air" stops, it generally sounds like a mic keying off. I notice it happening with certain dispatchers and not others.
As for monitoring this frequency... It's been priceless for me covering DFD incidents. A fire will go out on the VA more than a minute before it does on TG 06-021 if all the units are in quarters... Even more time if dispatch gives the first due station a jump.
Just my two cents.
As for monitoring this frequency... It's been priceless for me covering DFD incidents. A fire will go out on the VA more than a minute before it does on TG 06-021 if all the units are in quarters... Even more time if dispatch gives the first due station a jump.
Just my two cents.
K4XB
Member
Receiver squelch
I have monitored 154.070 just a little bit now, I need to listen more. It seems to me that the problem with this channel is the repeater base station receiver, or if this is a voted system, one of the voter receivers. I believe the receiver squelch is set too close to squelch threshold. I have noticed signals coming in from what appears a mobile or portable and when they key down, the repeater TX remains on the air for some time.
Another indication of loose squelch on this channel is the relatively long squelch tails I hear.
I think it is the receiver remaining unsquelched and keeping the base TX up until the receiver finally squelches.
If it is a squelch adjustment, that is easily fixable.
Scotty, K4XB
I have monitored 154.070 just a little bit now, I need to listen more. It seems to me that the problem with this channel is the repeater base station receiver, or if this is a voted system, one of the voter receivers. I believe the receiver squelch is set too close to squelch threshold. I have noticed signals coming in from what appears a mobile or portable and when they key down, the repeater TX remains on the air for some time.
Another indication of loose squelch on this channel is the relatively long squelch tails I hear.
I think it is the receiver remaining unsquelched and keeping the base TX up until the receiver finally squelches.
If it is a squelch adjustment, that is easily fixable.
Scotty, K4XB
From DFD:
"The problem that the VHF hangs up has nothing to do with the dispatch talk group. It is unknown why it hangs up. Since it is not impairing anything, no one has spent much time trying to figure it out."
"The problem that the VHF hangs up has nothing to do with the dispatch talk group. It is unknown why it hangs up. Since it is not impairing anything, no one has spent much time trying to figure it out."
While there is a silence, I have heard more calls go out from the dispatcher on another scanner through 154.070. The Vhf scanner stays stuck in that silence while my Trunking scanner picks up the other calls. So the dispatcher doesn't overide the silence.
Conversely, tonights arson fire went over 154.070 and not the trunked digital system until 26's and chief 7 got onscene. I contend both VHF and UHF are pieces of the puzzle that need to go together in order not to miss anything. I wonder if the feed provider could patch in 154.070? Heck, you could build a scanner with springs and 25 gauge wire to pick it up.
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