Dane County Fire/EMS Paging

[balmplant]

Over the last few months they've been having troubles with paging when they are speaking it gets all garboled with squeeling, this has happened few and far between but when the problem occured they would switch headsets(I believe) and that would solve the problem. As of Tuesday the problem has really gotten bad on what was almost every page. Now if they use the dial page, there is no problem(hence probably a headset issue), however the normal method has been having problems. Last night they individually tested every single fire and ems pager on it's own, I think to see if they could rule something out...not sure what. I hope they can get it worked out!

As of right now we are on emergency traffic only on CNTY Fire/EMS with a marker tone on A ADAM.

Stay Safe!

 

[biglaz]

I did hear that last night. I have a feeling it could be a transmitter issue. Not only is the audio garbled, but sometimes the tones themselves are garbled too. I'll have to listen a little closer. The only other time I've heard the same effects is when they send out two pages too close to one another and the audio overlaps on the repeat.

Why'd they have restricted traffic this morning?

 

[balmplant]

I've been rethinking the headset issue since they sound fine on the fire and ems channels. Perhaps it could be a power amplifier issue. It seems that the dial page sounds better than the normal dispatch page, however it still is having problems.

Whatever the problem is I am very surprised that it is not fixed yet.

I think they interchanged the words "heavy traffic" and "emergency traffic" this morning. It was probably just a heavy traffic situation.

 

[cpd38]

I've heard that fried sounding paging tones and audio for a couple months now.

Sometimes it's really horrible and other times it sounds good. Or the first page will sound good and the repeated page sounds horrible or vice versa.

I did hear the radio shop doing some test pages this afternoon so I don't know if the problem has got worse or not.

 

[biglaz]

Here are a few recordings from just an hour ago or so:

squeal.mp3 (406KB)
distortion.mp3 (307KB)

That distortion one is terrible. The noise just washes out everything.

 

[biglaz]

Now this one is just unreadable both times.
bad.mp3 (233KB)

This is the second page for Middleton 36. The first page, 5 minutes earlier, was clear as day.

 

[RevGary]

Having been in the comm maintenance business for more years than I care to think about, this SOUNDS as if the speaker on the console AND the operator headset and mic are both active at the same time. Many consoles have a "speaker mute' switch that turns off the console speaker if a headset is being used. Some consoles also have a headset jack on the console that automatically mutes the console speaker when the headset is plugged in.

If the tones are going out, the console speaker is on as well as the mic on the headset being live during the page out, feedback can occur and that is part of what may be heard in the transmitted signal. There are other possibilities of course, but I have run into this situation several times in the past where a speaker mute switch was left in the wrong position, had dirty contacts and was not fully "off" or a headset/ speaker muting jack had failed to mute the speaker.

One other slight possibility if this only happens during a snow and ice event... Most repeater systems use a duplexer so only one antenna is needed for T and R. IF enough ice and snow collects on the antenna, a higher than normal SWR can be introduced. This MAY POSSIBLY cause harmonic distortion of the primary transmitted signal and a harmonic getting back into the repeater receiver from the transmitter itself. These can have many different sounding audio distortions in the transmitted signal.

 

[CPFD25]

I find it hard to believe it’s a feedback issue through the console since it is not happening when the dispatcher goes to a different channel. The dispatcher that puts out the page is 90% of the time also the dispatcher that you acknowledge the page and do any of your fire/EMS operations through; they are just using a different channel. Also another reasoning I believe it is not a console issue is that sometimes it’s happening on the live page and not the recorded page, or vice versa, or sometimes its happening on both pages. It’s been an issue for a few months now but it was just off and on maybe once or twice a day. And then yes they would say lets change headsets and that seemed to work. But most likely that was working because it was quite intermittently. But I guarantee it has gotten worse from Wednesday on. And I’m more than sure that they would have ruled out a simple feedback issue through the console or a faulty headset.


J. Radtke
CPFD/CP-EMS
KC9IWG

 

[kc9fnm]

So as it turns out the problem is with the simulcast system and one of the six sites not working right. I found it hard to believe it was a console cross mute issue, especially with the way it is done on the centracom series.

I did notice more fading and a weaker signal than usual the past few days while I was mobile outside the county. This made me think PA/antenna issues but it still didn't explain why most of the tones would sound good but voice bad.

Simulcast is a whole different beast to work on. Timing is everything. I am a little surprised it hasn't been fixed yet, but there are many components to such a system and getting replacement parts over a weekend could be hard. Hope they get it working soon but at least you don't hear the hum of the cooling fans riding on the audio anymore

 

[biglaz]

I missed that hum, too. How was that getting in there anyway?