Help!!!! Cm 300 at work is driving us crazy!!!

[SFD790]

Hi all. At my Firehouse, we have our Fire Base Radio, and EMS Has there own Base Radio. After they get a call and the radio alerts, it maj es a sound that o can best describe as " BBBGGGRRRUHHHHGGGG" And it is about to drive me and my guys insane!! Can anyone tell me what this is so we can get it fixed??

Thanks, Michael

 

[ramal121]

If it does it again, try turning down the volume and see if it goes away. If it does it's probably a microphonic radio, kind of an audio feedback from the speaker to the board. CMs are pretty bullet proof and I've yet to see one do this, but they do have crazy loud audio for a small dash mount.

 

[Avery93]

It sounds like it could be a digital station on the same frequency EMS uses for paging. Does the noise sound something like this MotoTRBO sample, or this P25 sample? If so, that is probably the case. The reason you would only hear it after the radio alerts is because under certain circumstances, the radio enters monitor mode after receiving a page. If EMS uses PL/DPL, and their radio alerts for pages but still hears other traffic on their channel (signalling squelch is set to "Or"), then the radio will enter monitor mode after receiving a page.

The easiest way to stop it is to decrease the Auto Reset Timer to 1 (the minimum), and set the Auto Reset Type to "Auto w/o Carrier Override". Although if they have a paging only channel (with signalling squelch set to "And"), doing this will of course screw that up and they will no longer hear voice traffic after the radio alerts on that channel. Another option would be to disable page decoding altogether. All of this must be done using the programming software.

In the mean time, if this is indeed what's happening, the only thing you can do is go to the radio and press the monitor button (if programmed), or change to a different channel then back again after the radio alerts. Either of these will reset the muting conditions.