[time-nuts] Microstepper

[Azelio Boriani]

Something like this? (see image)

On Wed, Dec 25, 2019 at 1:02 AM Magnus Danielson <magnus at rubidium.se> wrote:
>
> Hi,
>
> I realize that I lack a microstepper. Consider that I have a stable and
> low-noise 5 or 10 MHz but I want to resynthesize to correct frequency
> and do phase-steps, and doing so without too much loss of noise.
>
> This has traditionally been done using a variation of techniques, but if
> we would use some of the things that happened lately, pretty OK
> performance should be possible to achieve without too much hardware.
>
> OK, so after a discussion with Bob, here is one sketch for a
> possibility, just to toss one proposal to crush into pieces and propose
> improvements or better versions.
>
> So, consider using a modern Silabs chip clocked from an oscillator,
> producing a offset generator with I/Q and then do an I/Q mixdown to a
> beat frequency, which is digitized by a pair of ADCs. A pair of DACs
> produces I/Q which is used to mixed to produce the output signal using
> the signals from the Silab. The ADCs/DACs can be either be fed to some
> CPU platform or FPGA. With this platform one can choose to servo the
> reference oscillator, or just modify the beat received. Maybe use a
> Raspberry Pi as platform. Rotating the vector and steering the rate of
> rotation should not be extremely hard to do. The input vector can be
> added internally or used to steer the oscillator. Either way, the in
> loop noise from the Silabs will be fairly well suppressed since it only
> acts as a transfer oscillator.
>
> So, suggestions, thoughts and improvements?
>
> God Jul and Merry Christmas!
>
> Cheers,
> Magnus
>
>
>
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