Why does the squelch keep opening and closing?

mayidunk · #1 (**permalink**) 11-30-2011, 2:07 PM

Why is it that, on some conventional channels, I sometimes encounter a situation where the squelch will keep opening and closing, like someone keying the mic button on and off repeatedly? It's very frustrating!

I searched the forums, but couldn't find this question.

GrayJeep · #2 (**permalink**) 11-30-2011, 2:52 PM

Quote:

Originally Posted by mayidunk

Why is it that, on some conventional channels, I sometimes encounter a situation where the squelch will keep opening and closing, like someone keying the mic button on and off repeatedly? It's very frustrating!

I searched the forums, but couldn't find this question.

I've found that on some frequencies where an LTR system lives that the system is periodically transmitting a very, very short data burst. It's not enough to hear but it's enough to trigger the squelch.

Try sitting on the channel in manual and opening the squelch. Your ears will tell you if there is a signal that's tripping the squelch.

If you don't hear anything it could be some other frequency causing interference to your scanner.

kermitdafrog · #3 (**permalink**) 11-30-2011, 2:52 PM

Your squelch might just be set right on the edge of the noise threshold, tighten it up just a bit.

Check and see if it favors any particular frequency. If so it might be a "birdie". If your radio is a PSR-800, look on page 78 of your manual and it explains what a birdie is. You can find the PSR-800 users manual here (http://www.greamerica.com/support/) and the explanation applies regardless of what radio you have

If it seems to occur in a particular geographical area if you are driving around, it could be the result of two or more strong signals from nearby transmitters mixing and causing a "spurious" output on a third frequency.

Kermit

scannerboy01 · #4 (**permalink**) 11-30-2011, 4:09 PM

What setting to you have the squelch knob at? Sometimes if you have the setting so close to the point that it will allow static to get through. Imagine the squelch knob as a clock, try put it close to the 11:00 or 12:00 position. If you have really strong signals of static, you might have to go further. If it sounds like someone keying their mic repeatedly, it could just be someone sitting on their mic and not knowing it.

mayidunk · #5 (**permalink**) 11-30-2011, 5:58 PM

It happens even if the squelch is all the way up, so it may be that I'm actually on an LTR channel. Oh well, it's only happening on the one channel so I'll lock it out, and not worry about it.

Thanks all!

Ed_Seedhouse · #6 (**permalink**) 11-30-2011, 10:59 PM

Quote:

Originally Posted by mayidunk

It happens even if the squelch is all the way up, so it may be that I'm actually on an LTR channel. Oh well, it's only happening on the one channel so I'll lock it out, and not worry about it.

Intermod from nearby powerful transmitters can cause systems to fire up and transmit noise at level high enough to break even full squelch. This is why a lot of systems use CTCSS tones, so as to be more resistant to this, but enough rf can overload any front end and even some systems with CTCSS have problems, which is a good reason to program the scanner to only break squelch when they detect the "subaudible" tone from those systems. Even that can't cure every problem, and sometimes you just have to lock out a problem channel.

Essexscan · #7 (**permalink**) 11-30-2011, 11:05 PM

don't forget wireless keyboards/mice and tv remotes will interfere too. i have a TIVO remote that gives off RF when changing channels&volume

GrayJeep · #8 (**permalink**) 12-01-2011, 10:47 AM

Quote:

Originally Posted by mayidunk

It happens even if the squelch is all the way up, so it may be that I'm actually on an LTR channel. Oh well, it's only happening on the one channel so I'll lock it out, and not worry about it.

Thanks all!

If that channel has users that are equipped with tone squelch (CTCSS or DCS- the database would show that) if you program the radio to require tones to match the users then the problem will go away. When using tones the squelch only opens if both the signal strength is high enough AND the tone is present.

I have to use tones for some county EMS channels on my commute - otherwise they get triggered by other much stronger transmitters that are close in frequency.

mayidunk · #9 (**permalink**) 12-01-2011, 11:32 AM

Excellent info, guys! Thanks. I'll probably explore these options if it becomes more of a problem. However, it was a CAP freq, and it kind of looks like they may not even be worth the trouble. Besides, it's a new scanner (Pro-107) and I'm still getting acquainted with it, so nothing's set in stone yet.

GrayJeep · #10 (**permalink**) 12-01-2011, 11:55 AM

Quote:

Originally Posted by mayidunk

Excellent info, guys! Thanks. I'll probably explore these options if it becomes more of a problem. However, it was a CAP freq, and it kind of looks like they may not even be worth the trouble. Besides, it's a new scanner (Pro-107) and I'm still getting acquainted with it, so nothing's set in stone yet.

CAP around here uses tones (though I don't know what it is offhand) so that solution will probably work unless you're using a freq in the air band where they don't use tones.

mayidunk · #11 (**permalink**) 12-01-2011, 12:06 PM

Quote:

Originally Posted by GrayJeep

CAP around here uses tones (though I don't know what it is offhand) so that solution will probably work unless you're using a freq in the air band where they don't use tones.

Good to know. As for not being worth it, I meant that in regards to other interference I seemed to be picking up on that freq. Seems there is another system using that freq that keeps busting in at random times, making the freq kind of unusable from where I'm located. If I were closer to the airport, it probably wouldn't be an issue, as the interfering system is most likely the source of the squelch popping in and out.

Thanks!