[ARDF] AM A2A Modulation...

[Matthew Robbins]

What if, instead of a single frequency tone, you used a double tone,
like DTMF?  You'd want the difference to be a normal CW frequency,
right?  About 600-800Hz?

http://www.shout.net/~wildixon/telecom/dtmf/dtmf.html

I'm not sure a PicCon can produce a DTMF-like tone, but a Pic could be
programmed to.

I can see the benefit of doing this for practice when you've got a
multimode rig.  I don't know if it has any utility for building ARDF
transmitters.

Matthew
AA9YH
Cincinnati, Ohio

On 10/10/05, Matthew Robbins <cedarcreek at gmail.com> wrote:
> Earlier, I wrote:
>
>     ...they recommended using SSB.  That way,
> I could key the PTT, and key an audio tone into the mic input.
>
> Just to be clear, the PicCon held the PTT on the whole minute, and
> then it put audio tone into the microphone input during the dits and
> dahs, and no tone in the spaces.  The little jumper for HTs combined
> PTT/mic input was not connected.
>
> I did not account correctly for the SSB offset. Next time I do this,
> I'll key the radio on FM (tuned to the fox frequency), and measure it
> with a frequency counter, then I'll switch to SSB and the PicCon and
> adjust the tuning knob until it's the same as the FM frequency.  I did
> try to account for the offset by tuning around and peaking the
> received signal with my Ackerly radio with it set to 146.565.  Instead
> of 146.565, I was transmitting on 146.562MHz indicated.  Since the
> audio tone is 600-800Hz, a 3kHz offset doesn't make sense to me, but
> it did peak the whoopee tone.  I was on upper sideband (USB).  That's
> what my radio defaulted to---I couldn't remember the "normal" sideband
> for 2m.
>
>
> Matthew
> AA9YH
> Cincinnati, Ohio
>