[ICOM] Tone squelch operation, "uniformed" question

[Dick Flanagan]

GASP!  Disagree???  No problem, Mac.  I was accessing brain cells I 
hadn't used recently and there is always much room for error when I do 
that.  :)

Dick

--
Dick Flanagan K7VC
dick at k7vc.com


On 2/14/2012 5:42 AM, D C *Mac* Macdonald wrote:
> I believe I must disagree with Dick on this one.
>
> You are speaking of FM mode communications
> here, not AM or SSB. The FM mode exhibits a
> characteristic known as "capture effect" where
> the strongest signal will capture the receiver.
> One of the specifications for an FM receiver is
> the quality of that capture effect, expressed in
> dB. The lower the capture effect rating in dB,
> the smaller the difference in signal strength
> must be for the stronger to capture the receiver.
> This might be as low as 1 dB for a GOOD receiver!
>
> Therefore, I would expect the tone of the weaker
> input signal to be greatly suppressed and very
> little of the lower strength signal would be processed.
>
> Even if both signals are using the same tone, the
> stronger signal will "win out" although you may
> hear some scritch AND even a heterodyne if both
> signals are within a few dB in signal strength.
>
> * * * * * * * * * * *
> * 73 - Mac, K2GKK/5 *
> * k2gkk at hotmail.com *
> * (Since 30 Nov 53) *
> * Oklahoma City, OK *
> * USAF, Ret (61-81) *
> * * * * * * * * * * *
>
>
>
>
>
>> Date: Tue, 14 Feb 2012 00:35:33 -0800
>> From: dick at k7vc.com
>> To: icom at mailman.qth.net
>> Subject: Re: [ICOM] Tone squelch operation, "uniformed" question
>>
>> Yes. In my experience the two encoded tones will mix and you will hear
>> the audio products (sum/difference) and the stronger of the four RF
>> carriers will capture the others. Depending on the tone filtering and
>> other characteristics of the radios, the tonal grunge can be either
>> minimal or overwhelming. It is one of those things that just has to be
>> tried as there are too many variables to give a definitive answer.
>>
>> Is this just an academic question or are you actually trying to create a
>> useful application?
>>
>> Dick
>>
>> --
>> Dick Flanagan K7VC
>> dick at k7vc.com
>>
>>
>> On 2/13/2012 11:25 PM, George J. Nixon Jr. wrote:
>>> Suppose that operators A and B have IC-W32a or equivalent ICOM VHF
>>> capable radios, and are having a QSO with normal settings on a VHF
>>> simplex frequency.
>>> Suppose that operators C and D have similar rigs, get on the same VHF
>>> simplex frequency, and set the same subaudible transmit and receive
>>> tones. When operators C and D start a QSO at the same time when A and
>>> B are in their QSO, will they hear (be QRMd) by the QSO of C and D?
>>> 73 - George, N9EJS
>   		 	   		
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