Hi Stewart,.......answer below...sent direct
----- Original Message -----
From: "Stewart Nelson" <[email protected]>
To: <[email protected]>
Sent: 25 February 2004 07:42
Subject: LF: Re: WOLF development
Your keyed oscillator idea is interesting, but it appears to
introduce another unknown. For example, if the 136 kHz oscillator
drifted up 0.01 Hz, it would affect the audio in the same way
as the receiver LO drifting down 0.01 Hz. One way to resolve
this ambiguity would be to digitally divide the 136 kHz into
the audio range, and feed that into the sound card, too.
Do you have a simpler solution?
I suspect you have "forgotten" the properties of a keyed oscillator in this
application. If the 136khz oscillator is stopped and re-started by the 1pps
signal it will lock and not drift. I agree that if just the oscillator
output is keyed (so the whole comb drifts as well) then the osc drift will
be a variable, but the keyed oscillator becomes a locked comb-generator.
(Tube technology revisited !!) Thus it should be possible to construct this
as an LC oscillator. I have not done the maths but I suspect that the
smallscale sawtooth FSK created by the drift during the interval between
locking pulses will "spread" the line a little, but averaging should be able
to remove this satisfactorily.
My LF RXs (AOR 7030 s ) whilst stable (TCXO), have no facility to feed in an
external standard. The TCXO is a "funny frequency" too.
Fascinating stuff.
Cheers de Alan G3NYK
[email protected]
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