Since you put this as the [PIC] topic, I'm going to invent a PIC solution=
 for=20
this, which I haven't tried, but thinking should be doable...

Measure the low-time and high-time of the first pulse, then generate puls=
es at=20
130% the frequency of that ..... repeatedly in a loop.  While that's=20
happening, in a sort of feedback mechanism, count both input and output=20
pulses and adjust accordingly by offsetting the next pulse(s).

This method should provide low jitter, but would add a small (approx 1/2 =
to=20
1-pulse) delay from input to output, and depending on the actual coding, =
may=20
introduce a limitation on how fast the output will follow the input on fr=
eq=20
change.

Of course this is not totally trivial, but it should be doable with any s=
imple=20
PIC.

Cheers,
-Neil. =20
 =20





On Wednesday 23 April 2003 20:08, Gary Neal wrote:
> Hi,
>
> I've got a variable frequency signal (200hz to 4khz) whose frequency I =
want
> to increase by 30% (5v signal).  IE if the input frequency is 1000hz, I
> want to output 1300hz.  Is there an easy method of doing this?  I've he=
ard
> of PLL, but don't have a clue how to build them, so if there's an easie=
r
> option that would be great.
>
> Thanks,
>
> Gary

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