[time-nuts] suggestions on getting 24 Mhz ?

[Pete Lancashire]

14 bit

On Mon, Apr 16, 2018, 8:00 AM jimlux <jimlux at earthlink.net> wrote:

> On 4/16/18 3:45 AM, Pete Lancashire wrote:
> > Access to " the xtal" is not an option the SDR is enclosed in a metal
> box.
> >
> > Do a web search for RSP2Pro
> >
> >
>
> It does have an external reference input..
> There's not a lot of info on the Mirics data sheets (or on the sdrplay
> website)
>
> It sort of looks like this is a somewhat enhanced version of the parts
> used in the RTL-SDR dongles.
> (10 bit ADC, instead of 8 bits in the RTL2832)
>
> And of course it needs 24MHz because it has to run the USB interface.
>
> 10 bit ADC means that you probably don't need *outstanding* clock
> performance - the sample and hold and all the other timing logic is
> probably designed to that sort of performance level - getting
> femtosecond jitter probably isn't worth it.
>
>
> If you're just looking for a 24 MHz driver that doesn't need to be
> locked to anything, one of the SiTime modules would work, or you could
> probably order a TCXO for 24 MHz - it's a standard frequency (viz. USB),
> so it's almost certainly available from stock
>
>
>
> > On Sun, Apr 15, 2018, 6:00 AM Attila Kinali <attila at kinali.ch> wrote:
> >
> >> On Wed, 11 Apr 2018 03:00:23 -0700
> >> Pete Lancashire <pete at petelancashire.com> wrote:
> >>
> >>> Needed for SDR project as external clock source.
> >>
> >> If your goal is, as Jim guessed, to get 24MHz from 10MHz and
> >> you are using something like an RTL-SDR, then how about just
> >> passing the 10MHz through a CMOS gate to square it up and
> >> get nice harmonics, then pass a wire close to the crystal.
> >> This should injection lock the crystal to right frequency.
> >> It wont be a strong lock due to the 5:12 ratio, but for something
> >> like a crystal that is already quite close, that should do the trick.
> >>
> >> Alternatively, using an ADF4002 with a small uC to configure it
> >> and a VCXO/VCO should also work.
> >>
> >>                          Attila Kinali
> >> --
> >> <JaberWorky>    The bad part of Zurich is where the degenerates
> >>                  throw DARK chocolate at you.
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