Muting/suppressing/eliminating squelch tail audio on an XTS3000?

[KD6RRR]

Listening to different public safety agency's, as well as amateur radio, repeaters in my area, some of them when ending a transmission will simply go quiet, while others will end with a loud squelch crash. Is this behavior on each system a feature (fault? ) of the individual repeater's configuration, or is it possible to specify a setting of some sort in the CPS that will suppress the noise at the end of the received signal?

Thank you for your help!

 

[NCFire11]

Well on mine if you set a PL Receive tone it usually wont have that noise at the end of it.

But I think it can also be on the repeater-side too. We have one repeater that has a long tail then goes silent without the crash then we have one that has a short tail and has the crash.

Could be several things.

 

[W2NJS]

You should look at the CPS and find the box to check that's marked "Reverse Burst." If the station you're listening to sends a reverse burst when signing off it will eliminate the squelch tail on your radio Ham HTs can't do this because the manufacturers leave the feature off, but it's available on most "later" commercial radios. You can also read up on the feature at Repeater Builder as well as the CPS help file.

 

[cmdrwill]

For receiving stations that do not include reverse burst or the PL or DPL turn off code you can enable AND - OR squelch in the XTS. That way when the signal goes away the receiver squelches upon loss of either PL/DPL OR carrier squelch.

The AND setting only un-squelches the receiver if both PL/DPL and carrier are present.

 

[KD6RRR]

Sorry for the long delay in replying.

Thank you all for your suggestions! I found the combination of switching to the AND/OR setting, and increasing to a default squelch level of 6, the majority of the noisy tail has been eliminated.

There is one particular frequency that I still get the loud crash on, but it was shortened dramatically.

I also came to realize that the particular frequencies I was having the worst problem with are all public safety transmissions that are actually coming from a system that is in the business band and is administered by a for-profit ambulance company that landed the contract to handle dispatch services for most of the county's fire departments. There is an obvious difference in the audio quality and the reliability of the system overall when compared to that of the systems fielded and maintained by the government agencies that I listen to.

One MAJOR feature I sincerely appreciate with the government systems is that they transmit their tones WITHOUT PL enabled, unlike the business band system, which will make you deaf when they tone out a call.

Thank you all again for your help!

 

[jim202]

Sorry for the long delay in replying.

Thank you all for your suggestions! I found the combination of switching to the AND/OR setting, and increasing to a default squelch level of 6, the majority of the noisy tail has been eliminated.

There is one particular frequency that I still get the loud crash on, but it was shortened dramatically.

I also came to realize that the particular frequencies I was having the worst problem with are all public safety transmissions that are actually coming from a system that is in the business band and is administered by a for-profit ambulance company that landed the contract to handle dispatch services for most of the county's fire departments. There is an obvious difference in the audio quality and the reliability of the system overall when compared to that of the systems fielded and maintained by the government agencies that I listen to.

One MAJOR feature I sincerely appreciate with the government systems is that they transmit their tones WITHOUT PL enabled, unlike the business band system, which will make you deaf when they tone out a call.

Thank you all again for your help!

It is all in how good of a radio tech set up the repeater, if the users are using the "reverse burst" feature on the originating radio and if the controller of the repeater has the ability to squelch the audio path to prevent the noise burst that you dislike.

 

[RKG]

You will get the squelch hash whenever your receiver is unmuted at the instant that the incoming RF signal goes to zero.

There are a couple of ways around this. One is the "turn-off code." This is a code that the sending transmitter sends to mute listeners' receivers before the sending RF goes down. Back in the day when PL decoding was done mechanically with resonant reed modules, the "shut down code" was merely a voltage shift induced by momentarily shifting the PL audio phase 120 or 180 degrees, which in essence stopped the vibrating reeds in their tracks. Today the PL shut off code is the same, but it is detected logically by the receiver, which then re-mutes. The DPL shut off code is just a series of 1s and 0s sent at 131 Hz, and it is also decoded logically.

In the alternative, a transmitter that is configured to hold RF transmission (unmodulated) for a period of time (greater than about 155 msec) after it shuts down beating the PL or DPL code should cause all receivers, whether they can recognize the turn off code or not, to re-mute before the squelch hash noise occurs.