Squelch Tail Question

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fwfdengine2

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How can I get rid of squelch tails when monitoring? I have DPL tones in and this helped on two channels.. But all other channels still have it..

I can put my scanner (BC346XT) right next to a Fire Dept. radio.. The radio will not have a tail, but the scanner will..

How can I change the scanner to get rid of the squelch tail?

Thank you!
fwfdengine2
 

N5AMS

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there isn't a way to get rid of the tail on the scanner other than tightening the squelch up but if you do it too tight you won't hear anything
 

fwfdengine2

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I have the squelch setting at 2.. Thats as far as it will go without sqeulching all the time.. or should i put it at 9-15?

fwfdengine2
 

jackj

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The squelch tail is caused by your radio. The squelch circuit has to see the noise after the carrier drops before it will mute the audio. Motorola and RCA radios (and maybe some other brands) have something called a squelch tail eliminator (I don't remember the different trade names they used). Back in the days of PL reeds, they would reverse the phase of the PL tone for a few microseconds before they dropped the transmitter and that would stop the reed from vibrating and mute the audio before the carrier dropped. Today's solid-state PL circuits do the same thing when they sense the phase reversal. DPL uses and end code do to the same thing.

There is no way you can completely eliminate the squelch tail on carrier squelch radios. There will always be a small amount of time required for the squelch circuit to sense the noise and mute the audio. You'll just have to live with it.
 

SAR923

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The Pro-96/2096 are the best consumer grade radios I've used in terms of eliminating the squelch tail. If the frequency is CTCSS or DCS, there is no squelch tail, and even the CSQ frequencies have a very short squelch tail. Don't know if the the Pro-106/197 have continued that feature.
 

fwfdengine2

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I like my unidens.. Have never owned a different brand.. Going for a BC996T & BC396T for my next additions..

This problem will soon be gone as the state of Minnesota goes P25 and there will be no squelch tail to deal with..

Thank you all for your help!
fwfdengine2
 

n1das

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Well there's your problem. Most Unidens have terrible squelch circuits. Try a GRE unit next time.

Uniden's horrible squelch circuits are easily fixed by modification. GREs aren't perfect either and often require modification to improve them. Between the two, I like GRE's designs far better than any Uniden design.

BC785D squelch hysteresis fix, should be similar on a BC796D:
http://forums.radioreference.com/1391226-post12.html
 
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wb0wao

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It may not be a "squelch tail", but a MDC1200 data burst sent at the end of each transmission. If so, there is almost nothing you can do to keep from hearing it.

Dennis
 

JPSan

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The squelch circuitry in the commercial transceivers ( Moto, Icom etc) is a LOT different design than most scanners. The Uniden BC-15X, I get NO squelch tails on analog freq's unless it is a WEAK signal ( considered NOT FULL QUIETING).
And if I use tone squelch ( PL, CTCSS) I get the nice reverse burst effect. Cheaper and OLDER scanners squelch are VERY basic and you pretty much can expect the tail effect. IN SIMPLE TERMS. Your Motorola transceivers ( as an example), on analog use a REVERSE BURST ( when you unkey the mike the radio shuts down the transmitting PL before the transmitter shuts down, microseconds!) mode,especially when transmitting station is sending PL AND the receiving station has PL DECODE set. No squelch tail, just a "quieting of the receiver" usually one second voice, unkey and quiet. Most of the newer generation scanners seem to work like this, from my experience. A good quality signal strength and usually you get no burst and again if you are able to use the DECODE function, better yet.
Your mileage my vary....
 
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The Pro-96/2096 are the best consumer grade radios I've used in terms of eliminating the squelch tail. If the frequency is CTCSS or DCS, there is no squelch tail, and even the CSQ frequencies have a very short squelch tail. Don't know if the the Pro-106/197 have continued that feature.

Wish I could agree with this statement, my 2096 still has a sq. tail sometimes, even with CT code and sq. closed all the way. Same OSP freq on a different night, none. Maybe it has something to do with the transmitting radio?
 

jackj

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Because of the way squelch circuits work on FM radios, there is always going to be SOME squelch tail when ALL non-PL / non DPL transmitters drop off the air. In short, the noise has to be there for the squelch circuit to detect before it can mute the audio....bingo - squelch tail. This fact is true regardless of the some people's opinion of the quality of Uniden's, GRE or Radio Shacks squelch circuits.

PL and DPL squelch circuits are different animals. The DO NOT use the noise to trigger muting the audio. They use a sub-audible tone or a digital data stream to tell when to open the audio, they're muted at all other times.

I suppose that it would be possible to build a ~250 ms delay line into the audio and have the carrier squelch mute signal jump around that delay. This would mute the audio before the noise makes it to the speaker and the delay wouldn't be detectable by the user. But it would add to the cost of the radio and be of little benefit to the user.
 

n1das

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I suppose that it would be possible to build a ~250 ms delay line into the audio and have the carrier squelch mute signal jump around that delay. This would mute the audio before the noise makes it to the speaker and the delay wouldn't be detectable by the user. But it would add to the cost of the radio and be of little benefit to the user.

You could add it yourself to any scanner provided there is room to fit the board inside the scanner... NHRC-DAD Digital Audio Delay
 

N9NRA

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Personally i kinda like the ability to hear the squelch taill, reason is when one is in a noisy area (like when i`m outside and it`s noisy from city and traffic noises) i know when a transmission ends. Same for when i`m using my ham HT, i like to hear the taills so i know if i`m reaching the repeater, or when on a simplex channel, i can hear when the person i`m in contact with has ended his/her transmission. So, somethines it`s a good thingy to be able to hear the squelch taills :). Another good thing about that is i don`t need to look at the display too much when i`m using ether the scanner or the ham HT, as the squelch taill gives m an indication of what channel/repeater i`m listening to or (in the case of my ham radio) talking on, i just memorize the way the repeaters sound (including the squelch taill and any marker or "courtesy tone" that is included), that way i know which repeater or channel i`m hearing. N9NRA
 
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