This may be an alternate way of looking at what you are proposing.
I suspect you are describing a phase-locked-loop.
And that yes, you have tried it.
There's a phase-frequency-detector inside the Si5351.
The VCO in the Si5351 can be pulled anywhere between 600 and 900 mhz
(and quite a bit beyond, actually).
But if instead of that VCO we have a VFO that is first manually tuned very near the
target frequency, the error detection will have far less work to do.?
And the output will have far less jitter.
Jerry, KE7ER
On Sat, Nov 14, 2020 at 05:39 PM, Ashhar Farhan wrote:
I was expecting Arv to write in about H&P schemes. Between him and Hans, there is all we know about how this scheme works.
The challenge of Huff and Puff is that it needs a very stable oscillator to begin with. It should have very minimal wobble (short term drift). The drift between two correction pulses should be less than its step size. That is not difficult to obtain.
The inherent drawback of H&P is that the oscillator is always being pushed up or down from the central frequency between two cycles. This can have a disastrous effect on digital modes.
There is probably another way to fix this. It is to use two flip flops as parallel mixers, each is fed the clock pulse that is 90 degrees out of phase from the other (imagine it to be a phasing receiver). Noe, the combined DC output of the two will indicate if we have drifted above, below or stayed on the frequency. I haven't tried this, but I am guessing that this will work. In the professional literature it is called a phase frequency detector.
- f
