help understanding CTCSS decoding

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help understanding CTCSS decoding

Joe Erlewein N8CN
Hello,
I have our repeater set to carrier access at the moment.
I did define both carrier access and tone access for 114.8.
We have not yet removed the HPF from the receive audio on the receiver, so tones can’t currently pass to the sound card for decoding, which is why both carrier access and PL access are enabled. We’ll get there, it just takes time..

But, in the meantime, I’ve been noticing this in the log file:

“(date) RepeaterLogic: 114 Hz tone call detected"

Normally, this will happen when a station with PL tone transmit comes on (and the tone is REALLY loud) and the controller actually hears it. (I have an older HT with an add-on tone module that produces this result, the tone is loud enough that it’s almost audible without a decent speaker/headphone plugged into it, but I digress).

Up until seeing this, I figured it was normal to see this in the log when occasionally the tone got through to the controller.

But today I saw:

Mon Dec  7 13:10:00 2015: RepeaterLogic: Sending short identification...
Mon Dec  7 13:10:00 2015: Tx1: Turning the transmitter ON
Mon Dec  7 13:10:01 2015: RepeaterLogic: 114 Hz tone call detected
Mon Dec  7 13:10:08 2015: Tx1: Turning the transmitter OFF


There is no active receiver in the above log snippet. The repeater had been used some minutes ago, and decided to identify.
During identification, it detected said call.

Maybe what the log entry is indicating is not what I’ve been thinking it was indicating? Does anyone have input on how to explain this?

Thanks!

73
Joe
N8CN
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Re: help understanding CTCSS decoding

Tobias Blomberg
On Monday 07 December 2015 13:14:55 Joe Erlewein N8CN wrote:

> Hello,
> I have our repeater set to carrier access at the moment.
> I did define both carrier access and tone access for 114.8.
> We have not yet removed the HPF from the receive audio on the receiver, so
> tones can’t currently pass to the sound card for decoding, which is why
> both carrier access and PL access are enabled. We’ll get there, it just
> takes time..
>
> But, in the meantime, I’ve been noticing this in the log file:
>
> “(date) RepeaterLogic: 114 Hz tone call detected"
>
> Normally, this will happen when a station with PL tone transmit comes on
> (and the tone is REALLY loud) and the controller actually hears it. (I have
> an older HT with an add-on tone module that produces this result, the tone
> is loud enough that it’s almost audible without a decent speaker/headphone
> plugged into it, but I digress).
>
> Up until seeing this, I figured it was normal to see this in the log when
> occasionally the tone got through to the controller.
>
> But today I saw:
>
> Mon Dec  7 13:10:00 2015: RepeaterLogic: Sending short identification...
> Mon Dec  7 13:10:00 2015: Tx1: Turning the transmitter ON
> Mon Dec  7 13:10:01 2015: RepeaterLogic: 114 Hz tone call detected
> Mon Dec  7 13:10:08 2015: Tx1: Turning the transmitter OFF
>
>
> There is no active receiver in the above log snippet. The repeater had been
> used some minutes ago, and decided to identify. During identification, it
> detected said call.
>
> Maybe what the log entry is indicating is not what I’ve been thinking it was
> indicating? Does anyone have input on how to explain this?

I have seen this in one of our repeaters as well but I'm not sure what cause
it. One theory is that it is some kind of crosstalk between the TX audio and
the RX audio. That is, if you transmit the same CTCSS tone frequency it may
leak into the receiver audio. Do you have CTCSS transmission enabled?

73's de SM0SVX / Tobias


>
> Thanks!
>
> 73
> Joe
> N8CN


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Re: help understanding CTCSS decoding

Joe Erlewein N8CN

Actually, I do have CTCSS TX enabled. 
I will disable and see if it continues. THanks!

On Tue, Dec 8, 2015 at 4:55 PM, SM0SVX <[hidden email]> wrote:


I have seen this in one of our repeaters as well but I'm not sure what cause
it. One theory is that it is some kind of crosstalk between the TX audio and
the RX audio. That is, if you transmit the same CTCSS tone frequency it may
leak into the receiver audio. Do you have CTCSS transmission enabled?

73's de SM0SVX / Tobias 


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