[ICOM] Tone squelch operation, "uniformed" question - REPLY

[George J. Nixon Jr.]

Thanks to all who responded.  The reason for the question is that my daughter and her husband (both relatively newly licensed amateur radio operators) are getting involved in a local emergency response program in their area, heard discussion of using the tone squelch feature from another local ham and didn't understand it.  I explained setting the transmit/receive tones, but had this question to throw into information for them. 73 - George, N9EJS = = = = = = = = =

--- On Tue, 2/14/12, C.Whitaker <whitaker at pa.net> wrote:

From: C.Whitaker <whitaker at pa.net>
Subject: Re: [ICOM] Tone squelch operation, "uniformed" question
To: icom at mailman.qth.net
Date: Tuesday, February 14, 2012, 8:11 AM

de WB2CPN
Good thoughts, Dick.
A clearer picture is this.  Only A or B is transmitting at any one time,
so it doesn't matter which one it is.  So that means the one that is
not transmitting will hear whatever happens.
Then, same for C and D.  Only one is transmitting at a time, so it
doesn't matter which one is a source of interference.
Let's keep C, and discard D.
Now, if B is listening to A, and C starts a transmission, what B hears
will depend on the relative strength of A and C, as heard by B, and
the carrier frequencies of A and C.  If they are not synchronous,
exactly,  what B hears will depend on all the factors Dick mentioned.
FM is not like AM in receiving a signal.  AM will sum + and -, but
FM won't do that.  Shades of higher math, such as FM sidebands.
Who said "clearer"?
73  Clete


On 2/14/2012 3:35 AM, Dick Flanagan wrote:
> 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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----
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Icom Users Net: Sundays, 1700Z, 14.316 MHz
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