[time-nuts] Navsync CW-12 GPS Board - I don't believe it!!

[Azelio Boriani]

It depends on the option ordered: the FTS125s we have are FTS125-COO
(double OCXO) the -CTV option is the TCXO/VCXO option, there is the -COV
option too.

On Wed, Jan 4, 2012 at 10:08 PM, <SAIDJACK at aol.com> wrote:

> Hi Ed,
>
> sorry to hear that, contact me off-list and I will try to solve your
> problem. I tried sending you an email, but my mails must be getting
> filtered by
> your spam filter..
>
> bye,
> Said
>
>
> In a message dated 1/4/2012 11:33:14 Pacific Standard Time,
> ed_palmer at sasktel.net writes:
>
> On  1/4/2012 11:13 AM, Said Jackson wrote:
> > Hi Ed,
> >
> > Since  the oscillator is typically free-running in an NCO, and
> periodically corrected  by phase drops to stay "on frequency" the error
> you are seeing
> may be caused  be the offset in your crystal, combined with the limited
> digital resolution of  the NCO trying to correct for this offset.
> >
> > If this is the  case, your measured error would change with temperature.
> >
> > Does  it do that?
>
> Yes, it does.  Cooling the unit by using a heatsink  causes a significant
> increase in the output frequency.  The change is  large enough to be
> obvious on an oscilloscope where one channel is the 10  MHz from the
> Z3801A and the other channel is the 10 MHz from the  CW12.
>
> > If yes, the NCO resolution is not fractionally corrected all  the way.
> Replacing the on board Tcxo with an ocxo hand-tuned to the correct
>  frequency
> would help, but that sort of defeats the purpose of the  product..
>
> Yes, it appears that the CW12 is just not appropriate for  what I was
> thinking of doing.  However, to be fair, the 1 PPS output  is much better
> than the older receivers.  I'll have to think about  where I go from  here.
>
> Ed
>
>
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