Strange beep

EC-7 · Post by **EC-7** » Mon Oct 22, 2001 11:24 pm

Our central fire dispach uses Motorola mobiles, I think there Maxtracs, wired to a Motorola computer dispach system. Recently the radio has been transmiting a short double beep at random when the dispacher is transmitting. Could this be something wrong with the radio or the computer software/system?

jim · Post by **jim** » Tue Oct 23, 2001 5:12 am

Recently, I noticed one of our local centers have a short "beep" every time they transmit. It sounds like some numb-nut with a keyup-ping on the CB. Does this serve a purpose, or is it just there to be annoying?
I've never heard anyone else do this and it's not a built-in feature to any radio I've ever worked on.

Post by **alex** » Tue Oct 23, 2001 5:26 am

On 2001-10-23 09:12, jim wrote:
Recently, I noticed one of our local centers have a short "beep" every time they transmit. It sounds like some numb-nut with a keyup-ping on the CB. Does this serve a purpose, or is it just there to be annoying?
I've never heard anyone else do this and it's not a built-in feature to any radio I've ever worked on.

My guess - Probably is a wait to talk beep that comes over as the mic is being turned on by the circuit. The campus safety dispatch console (I think it's a command star... looks like the Radius of consoles) will beep to notify the dispatcher that it's sent the MDC data, and you can talk now. I know that in Monroe County they have several EMS and Fire transmitters scattered throught the county, linked by microwave. If you listen to the microwave signal, you'll actually hear a databurst, talking, and then another databurst (so i'm told.) The first databurst keys the transmitter, and the second will de-key the sites. The de-key signal your able to hear over the air bec. the sites are still keyed. These dispatchers have an audio indication (like a beep) when they can start talking (much like the tone if you have a Pre MDC 1200 databurst on an HT*), however, I believe they wear headsets, and the mic wouldn't pick up the sound from the earphons.

As I was writing that, I thought you might also be talking about another sound... It might be that the system is switching remote recievers. I'm not positive, but I believe that's what it means.

These are both guesses, I have no idea if i'm on the right track, but I may be...

-Alex

jim · Post by **jim** » Tue Oct 23, 2001 5:12 pm

The beep I'm referring to is a pure sinewave beep. It's not a databurst and it's not being picked up by the mic. I assume it's just a tone to let all units know that a transmission from the base is coming.

Dale Earnhardt · Post by **Dale Earnhardt** » Tue Oct 23, 2001 10:01 pm

HI all,

When I was in my friends car,and he had a maxtrac with MDC on it, everytime it keys you hear that beeping sound, its hard to decribe, but I wouldnt doubt that its the MDC that is being transmitted and letting you know when its over.

JAYMZ · Post by **JAYMZ** » Wed Oct 24, 2001 10:46 am

We get the same thing at our county dispatch center on certain towers. You'll hear a "pleek" or beep coming from then every time you key up. We use tone remotes so it's the transmit tone that is sent that isn't completely filtered out. Could that be it?

Blitzbug2u · Post by **Blitzbug2u** » Thu Oct 25, 2001 3:55 pm

May well be a secure radio operating in non-secure mode. Thaose w/ Sabers, for example, can get this by programming radio as a "secure" model, even if it is not. The radio injects a beep, primarily to remind user he is not in "secure" mode.Hope this helps-Blitz

Will · Post by **Will** » Sat Oct 27, 2001 2:54 pm

Guys, this "tone" you are hearing may be part of the Tone Remote tone sequence generated by the console that is used to key up the transmitter. It consists of a short burst of 2175hz tone followed by a 1950hz function tone burst that tells the transmitter which frequency to use followed by a continious 2175hz tone at a very low level to keep the transmitter keyed. The 2175 hz tone is usally filtered out prety well in the transmitter but the "function tone' sneeks through fairly easyly on some radio transmitters. We used to have to make a gate in the transmitters to mute the function tone out of the transmit audio path.

Scruffy · Post by **Scruffy** » Sun Oct 28, 2001 8:32 pm

Something else to look at is if the base/repeater has alarm/alert tones programmed over the air. Our system (MSF-5000's and MSR-2000's) send this when the AC power is off and the site is running on the batteries. It will also send when other faults in the radio ie:low PA power on the MSF's. You may want to have your techs check your system if it has not been programmed or changed recently.

<font size=-1>[ This Message was edited by: Scruffy on 2001-10-28 23:33 ]</font>

EC-7 · Post by **EC-7** » Sun Oct 28, 2001 10:41 pm

Scruffy you are RIGHT! I told our dispach supervisor to check to see if the system was on backup power and they said the radios at central dispach were all on AC power. Well two days ago our East fire repeater went down in the AM, COMPLETLY. Later in the PM we had TORNADO WARNINGS! What our luck! The 911 dispachers had to re-program our dispach counsels to use our two other towers (while a tornado TOUCHED DOWN). The radio company that we use, has yet to fix the repeater, leaving us with a lot of upset firefighters who can't use thier handhelds due to loss of repeater. Thanks for the info, it's a little late, but NOT your fault. EC-7