AW: [sdiy] top octave and dividers

[Czech Martin]

Well, this would be modulation then, I think the resulting spectrum
is not what you want.
The basic idea was that it was all synchronous, one time divide by N,
the other by M, perfectly , no glitches etc.

Another idea could be to throw away every Nth pulse of the vco
output, this could be done via analog circuitry. 
This can be done in a synchronous way, too, if some
sampling is involved. Ok, you never can escape meta stability...

Since
this is then feed into dividers , the wiggle will be 
averaged.

m.c.

> -----Ursprüngliche Nachricht-----
> Von: jhaible at t-online.de [mailto:jhaible at t-online.de]
> Gesendet: Montag, 26. November 2001 14:00
> An: Czech Martin
> Cc: diy (E-Mail)
> Betreff: Re: [sdiy] top octave and dividers
> 
> 
> Czech Martin schrieb:
> > Yes, this idea stems from HAM radio also.
> > Because you need a few Hz acuracy, this would mean very 
> > low 
> > frequency after the pll divider (or divider increment).
> > This in turn will make the loop filter requirements slow,
> > this will then make the pll slow und thus introduce phase
> > noise.
> > 
> > Instead it was chosen to divide a couple of times by N,
> > and then by M, thus giving fractional scaling.
> 
> Interesting !
> Does it also work the other way round, running M and N
> dividers in parallel, and doing a Fast PWM switching
> between the M and N diver output ? (Like "chop" vs.
> "alternate" on scopes - you get the idea ...)
> Would be interesting what the PD would make out of such
> a signal !
> 
> JH.
>