[GreenKeys] SELCAL - auto start proposed

[Bob Camp]

Hi

I would also vote for making the mark frequency a nice round number in 
kHz. Depending on what we are doing we can each translate to an 
appropriate set of frequencies on our end. There are simply to many 
different ways to generate a pair of tones these days to define it in 
terms of any one method. I have examples of at least four different 
approaches running around my shack ....

	Enjoy!

		 Bob Camp
		KB8TQ



On Apr 19, 2004, at 10:48 AM, Eric Scace K3NA wrote:

>    Defining frequency based on the suppressed carrier frequency of a 
> transmitter using AFSK to generate a signal encourages a great
> deal of confusion:
>    -- there are both "high" and "low" pairs of audio frequencies used 
> to produce AFSK.
>    -- one has to also understand whether the transmitter is running 
> LSB or USB.
>
>    [To make matters worse, using AFSK introduces two variables into 
> the frequency stability issue: the accuracy and stability of the
> transmitter, and the accuracy and stability of the tone generator.  
> Then there are the pitfalls associated with producing a good
> quality AFSK signal, free of intermodulation products...]
>
>    I would encourage folks to identify frequencies based on the mark 
> RF frequency.
>
>    I also support the suggestions by many to use 45.45 baud (60 wpm 
> ITA-2 code).  Because a SelCal frequency will be used at times
> when propagation is less than ideal, the slower baud rates will help 
> improve the accuracy of copy.
>
>    Have any proposals been made for the sequences to be used to start 
> and stop the selective calling phase and to stop a
> transmission, and for the actual selector codes?
>
> -- Eric K3NA