Re: Follow-up Antuino question
|
Gareth Evans
We have the same last name...are we related?? ?8-)
H&P stabilization is interesting because by default it sets the tuning? step size as well as holding frequency drift to around 1 Hz, sometimes? less.? However it does introduce its own type of slow jitter.? H&P? stabilization is based on alignment?of edge of an LF clock with an edge? of a VFO cycle.? If the VFO edge is before the LF clock edge it pushes? the VFO slightly higher.? If the VFO edge is after the LF clock edge it? pushes the VFO slightly lower.? Design of H&P stabilization is for it to? be only slightly more aggressive than the VFO drift as referenced to? the VFO drift during one period of the LF clock.??
? ? ?
The LF clock probably needs to be in the 10 Hz to 30 Hz range and can? be derived from dividers on the output of an HF crystal oscillator.? Some? GPS receivers also can be programmed to give stable clock output in the? 10 Hz to 32 Hz range.??
Arv _._
On Sat, Nov 14, 2020 at 2:33 PM Gareth Evans via <headstone255= [email protected]> wrote: Perhaps the Huff-and-Puff stabiliser needs revisiting, where an occasional
frequency correction is applied to correct drift?
To do this, up to what frequency will the counters of an Arduino work!
A much more complex form of that stabilisation was used in the Eddystone
1837 RXs.
73 de Gareth G4SDW
On Sat, Nov 14, 2020 at 07:01 PM, Ashhar Farhan wrote:
> Contrary to a popular opinion, a free running LC oscillator can be the
> quietest there is. Any attempt that holding it to a frequency (phase locked
> loop) starts adding to the phase or amplitude noise. Consider the phase
> correction being applied like a modulation (which it is), hence it will
> spread the signal from being a single solid carrier. That's the phase noise!
|
