Back in the early 1970s, a local repeater used a
slow-turning wheel and a roller microswitch to key a
PL encoder for their CW ID. It was barely audible in
most radios, but it got the job done. Of course, this
was back in the days when repeaters didn't have or
need coded squelch encode or decode, so it didn't
conflict with normal repeater operation. It probably
ran at 10wpm and the power to the encoder was switched
on and off, so the reed took some time to start and
stop, giving it a nice rise and fall time that
smoothed the transitions.
You could do something similar as long as it didn't
interfere with any existing CTCSS/DCS encode signal.
This might be easier to deal with than true FSK.
If the CW ID tone generation is done with an external
oscillator, then the logic signal driving it would be
exactly what you want: FSK. If it's all done with a
microprocessor, then you'd probably be better off
using something external to do all the work.
Bob M.
======
--- Paul Plack <[EMAIL PROTECTED]> wrote:
> Has anyone on the list adapted a modern controller
> for frequency-shift keying?
>
> I'm brainstorming options for an IRLP node. I have
> an Scom 7K. I'd like to experiment with using FSK
> IDs to keep them inaudible for FM users, but legal,
> during in-band downlinking. This will require keying
> a DC voltage for insertion at the appropriate point
> in the transmitter.
>
> Macros to "key" a logic output might work, but would
> tie up execution of other commands. A separate
> hardware keyer, enabled by a logic output, would
> also work, but that's more parts.
>
> I'd like to be able to turn FSK IDs off when not
> needed, and avoid hacking up the controller. Any
> thoughts?
>
> 73,
> Paul, AE4KR
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