Strange sounds coming from Centracom Elite *updated*

nmfire10 · Post by **nmfire10** » Thu Jan 01, 2004 10:55 am

Here's a few little quirks I want to try and nail down. This is all tone remote on a Centracom Elite.

On one of our radios, we get this intermitant buzzing tone over the speakers. I'm having a hard time describing it, it kinda sounds like the old fire alarm horns that used electromechanical buzzers. It will emit this tone every 5-10 seconds for a minute or so, then go away for about 15 minutes. Then start doing it again. It isn't coming from or going over the air, just in the audio circut. It either isn't loud enough to activate the recorders or isn't making it to the recorders. It is really damn annoying. Could this be something in the Centracom or would this be in the phone lines somewhere?

Lets say you have a system with 3 reciever sites and on the centracom, there are the buttons to manually "vote" a site regardless of channel activity. If there is no radio traffic, I would think that manually voting the site would yield nothing, no sound, no nothing on the phone lines. Manually voting sites here, I get all kinds of really loud humming and buzzing. Is this normal?? When actually recieving transmission, the sound is good. I'm just wondering if something is wrong.

mastr · Post by **mastr** » Thu Jan 01, 2004 8:46 pm

Is wire line squelch enabled on your BIM cards?

Post by **wavetar** » Fri Jan 02, 2004 4:37 am

The first issue sounds like a typical phone line problem, although it could be just about anything. I take it the radio is connected to the system remotely through leased lines? Easiest thing to do would be to unplug the line where it comes in the building when the noise starts. If it goes away, then it's the line or equipment on the remote end. How are you doing the recording? Are you using LOMI/LORI configuration, or logging directly off the standard logging output in the back of the CIE console?

I can't help you with the second question, I have no experience with using voting on Centracom.

Todd

Post by **xmo** » Fri Jan 02, 2004 8:48 am

I believe what happens is that the console 'Vote' function forces the SQM into Monitor [same function as pressing the monitor switch on the SQM]. That enables the audio gate onto the phone line. With no activity the console audio gain will rise [AGC/DLM] and you will hear background noise & crosstalk off the phone line.

There probably is no real problem - almost all phone lines will have some noise. The fact that this is not heard during real traffic confirms this.

What MASTR is referring to is a jumper on each BIM card that enables an audio gate. That gate was put in specifically so noise below a certain level won't get ramped up and be heard during quiescent periods. The down side is that with the gate enabled sometimes you can miss a quiet real transmission so a lot of installers disable the gate routinely.

Setting up a Centracom properly isn't quite as plug-n-play as many believe.

mastr · Post by **mastr** » Fri Jan 02, 2004 3:51 pm

If memory serves the wireline squelch is generally disabled on a new BIM card, right out of the box. If your personnel can break themselves from the "L A lean" (looking out into thin air mumbling while leaning your ear against the PS mic, as seen on many popular police TV shows), use of the wireline squelch is OK. It reduces console operator fatigue somewhat when the dispatchers routinely use headsets, as the audio gate eliminates some of the residual low level headset noise from status tones, circuit noise etc.

YMMV, of course.

nmfire10 · Post by **nmfire10** » Fri Jan 02, 2004 6:01 pm

I'll try and make some recording of these specific sounds this weekend. I can see the voter thing being "normal" and frankly if it sounds normal when recieving, who cares.

This other sounds I am guessing is phone line thing. Perhaps if I make a recording, someone will hear it and know exactly WHAT it is.

nmfire10 · Post by **nmfire10** » Sat Jan 03, 2004 10:09 am

OK. I made a recording of the strange sound. If you can, listen to this and see if it sounds familiar. It is more or less constant today.

http://www.lawrenceweb.net/radio_sound.wav

mastr · Post by **mastr** » Sat Jan 03, 2004 12:38 pm

What ever it is, the use of wire line squelch won't help it any, the level is probably high enough to open the audio gate. Time to get a butt set or TIMS and start looking for it.--If the sound is audible on the field side of the telco demark, go to the station's wireline terminals. BTW, what kind of station is on the other end?

nmfire10 · Post by **nmfire10** » Sat Jan 03, 2004 12:53 pm

Not sure of that. It is our tie to the Facilities and Engineering repeater. It shouldn't be to hard to find out. There is a repeater (Some model /\/\) and one other tone remote in their office (also /\/\). Could the other tone remote deskset be doing this?

I wasn't able to find what set of clips was that radio in the back so I will probably have leave it to the SNET guys on Monday. One of them stopped by today for a few minutes and he had never heard anything like it before.

mastr · Post by **mastr** » Wed Jan 07, 2004 4:05 pm

"One of them stopped by today for a few minutes and he had never heard anything like it before."

Well? What in the world was it?

nmfire10 · Post by **nmfire10** » Thu Jan 08, 2004 6:50 am

Windows? In a communications center? Yea, right.

It is on my list of things to address next week with SNET. I had a lot of other higher priority things to deal with this week.

Post by **alex** » Thu Jan 08, 2004 6:51 am

Could that be a trouble indicator of sorts?

I know on one of the VHF MSF's up here you will occassionally get something that sounds almost like a recording tone - not quite like what you have. This is usually an indicator that there is a problem of some sort somewhere.

Might be something to consider. I'm not firmiliar with the setup that causes this, I'm sure someone can enlighten.

-Alex

Post by **wavetar** » Thu Jan 08, 2004 8:41 am

After listening to it, I agree with Alex, in that it's not just random noise. The duration & timing are too specific. It does sound similar to the MSF/MTR/Quantar warning tones, which can be programed to put the tones over the wireline, or over the air, or both. Not exactly like them though, so perhaps it's another make of base station/repeater? It could indicate low power, high VSWR, A/C failure, etc. Then again, I suppose it could be a piece of telco equipment doing it as well, though I've never heard of any doing so.

Todd

nmfire10 · Post by **nmfire10** » Thu Jan 22, 2004 8:47 am

I talked to our onsite SNET tech yesterday afternoon. I described the sound and I could tell he knew what I was describing and had heard it before. It seems this sound is being picked up in one of the buildings in our complex and it is on ALL the pairs going into it. Yes, 2,200 pairs feed this building and is somehow being introduced into all of the lines, probably something with inductance. We suspect it is one of the fancy electroninc machines that is near the cablehead. If you put an inductive amplifier near the massive cable, you hear it. If you clip a butset into any of the lines, you also hear it.

It just so happens the engineering office is in the building and has a desktop tone remote in there. Since it is in parrallel with our console in another building, the noise just comes right back to us. I'm betting we disconnected the pair going to that tone remote in the switch room in the main building, the sounds would disappear.

Unfortunately, none of us have a clue what it is that causes it or how to make it go away. At least now he knows he isn't going nuts and I know I'm not going nuts.

d119 · Post by **d119** » Thu Jan 22, 2004 9:43 pm

I was going to guess it could be some sort of recording marker that was improperly installed. Until I read the last post.

Please keep us updated on this - I for one am very interested to know what the sound is.

KE9XB · Post by **KE9XB** » Fri Jan 23, 2004 5:27 am

I've dealt with problems very similar to this in my 20 years as a technician in the service. I would like to say that you are right it will be very difficult to track down if it is coming over all the lines in one particular building.

First you will need isolate every thing in that building. One by one obtain down time (permission from the user to turn off the equipment) for each piece of equipment. Some equipment items may be obvious so you may not need to get the downtime. Second, if you can get a inductive amplifier pickup. We call these wands in the service. it has a speaker on one end and a very large needle looking thing on the other. When you press the on button and place the needle on or near a cable pair it will pick up the noise.

Once you have determined nothing in the building is causing the problem, then you can continue with another building. This will ensure your equipment is not causing the problem.

If none of your equipment is causing the problem, start pulling jumper pairs at the DEMARC box to determine which pair the noise is coming in on.

I hope this gets you started.

nmfire10 · Post by **nmfire10** » Fri Jan 23, 2004 8:39 am

Unfortunately, that is going to be easier said than done. We're talking 6 floors of labs, diagnostic imaging, MRI, radiation therapy, and all kinds of other funky stuff I know nothing about. A lot of it can't just be "shut off" either. Pulling 2,200 jumpers to see which one it is doesn't sound like fun either.

KE9XB · Post by **KE9XB** » Fri Jan 23, 2004 9:14 am

I feel your frustration, been there, done that, got my tee-shirt. I'm sure you get the concept of what has to get done. Either put up with the sound, or do a thorough investigation to isolate everything possible. I learned this be cause Air Traffic Controllers were picky on getting the radio operating console to work properly. Every little foriegn sound I had to eliminate because they don't want to hear it.

mark102 · Post by **mark102** » Mon Jan 26, 2004 7:01 am

We too were having an odd tone coming from our Gold Elite on one of our tone remote channels. This tone was a long, odd sounding tone every five minutes or so. It was not coming down the line from the control station and it was not being recorded by our audio recorder. Disconnected the phone pair feeding the control station and the tone stopped. Adding a desk set to the pair also stopped the tone. After much headache we found a problem with the tone board in the control station. Apparently the Gold Elite CEB was doing a diagnostic and saw a problem with the tone board and was sending an "error" tone on that channel thru the CEB. The tone board was repaired and the tone went away.

Strange sounds coming from Centracom Elite updated

Strange sounds coming from Centracom Elite updated

Odd Tones on Gold Elite