[App_rpt-users] Local squelch tail problem clarification. (copy of message to Ken) for comment.

Peter Elke pete.elke at esquared.com
Sat Jan 22 13:48:25 EST 2011


Wow Steve,

That is interesting, I guess I could find internal gated audio and skip
the DSP for all the MSF5000s.

I would have thought the COS/PTT controls would be time synced or in
stream "ie:inband" with the audio packets so PTT-On would lead and
PTT-Off would follow.  I assumed that last audio packet had an
"end-transmission" bit inside. 

I guess adapting existing phone controls with real-time PTT/COS is a bit
tricky...

Thanks for the clarification.

Actually this may bring to light another issue.  Does my problem show
that the local RX DSP is not identifying the mobile's reverse burst
phase shift?  Should it?  (Mobile = Spectra)

73's



-----Original Message-----
From: app_rpt-users-bounces at ohnosec.org
[mailto:app_rpt-users-bounces at ohnosec.org] On Behalf Of Stephen Rodgers
Sent: Saturday, January 22, 2011 10:23 AM
To: app_rpt-users at ohnosec.org
Subject: Re: [App_rpt-users] Local squelch tail problem clarification.
(copy of message to Ken) for comment.

On 01/22/2011 09:42 AM, Peter Elke wrote:
> From: Peter Elke [mailto:pete.elke at esquared.com] 
> Sent: Saturday, January 22, 2011 3:26 AM
> To: Ken
> Subject: RE: [App_rpt-users] Location dependant squelch tail?
> 
>  
> 
> Hi Ken,
> 
>  
> 
> What I meant to get across was...  There is a squelch tail when the
> local mobile unkeys (before the hang time) but you only hear it if you
> are monitoring the local node's transmit frequency.  Remotely
connected
> stations don't hear the tail, only a soft click or nothing from the
same
> transmission. 
> 
>  
> 
> The local repeater transmitter dropping does not cause a tail if the
> mobile is in PL decode.
> 
>  
> 
> I thought this was just strange, so much so that I sound ignorant
> reporting it...
> 
>  
> 
> 73's Pete (WI6H)
> 
>  
> 
> 
> 
> 
> 
> _______________________________________________
> App_rpt-users mailing list
> App_rpt-users at ohnosec.org
> http://ohnosec.org/cgi-bin/mailman/listinfo/app_rpt-users

Packet propagation across an the Internet and the use of jitter buffers
in Asterisk causes this. On a network-based
connection, the unkey control message is reaching the far end before the
audio packets containing the squelch tail
noise.  On a local connection, the audio packet delay is much less.

I suppose a delay could be added to the local audio packet stream, but
this impairs full duplex operation even more
as the delay there is already annoying enough.

Steve.
WA6ZFT

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