[time-nuts] Linear voltage regulator hints...
csteinmetz at yandex.com
Tue Dec 16 10:46:47 EST 2014
>My gut feeling is you are right about the GPS time base being
>sensitive. It would be fun to hack into this and try clocking it off
>the OCXO, but I'm not there yet! :)
One interesting way would be to use the disciplined OCXO output to
drive a DDS synthesizer set to the GPS unit's clock frequency (which,
I'm assuming, is not the same as the OCXO frequency). This approach
has a number of potentially large problems (delay, spurs, DDS
resolution, to name just 3), so I'm doubtful that it would work well
-- but I do think it's worth trying, just because it's so simple and
cheap ($3.85 ebay DDS board) and potentially instructive.
>I might try some good old 'overkill' and put the GPS in it's own
>heavy aluminum box. It's been a thought for a while, and should
>address the thermal integration and time constants you referred to.
Insulate the GPS card from the box (use nylon or teflon standoffs
with no "through" metal screws), and insulate the box from anything
solid (same way); i.e., only air can change the box temperature, and
only air can change the GPS card temperature. Signals and power
should go through bulkhead connectors and feedthrough caps on the box
walls, with "pigtails" to get from there to the GPS card. You
probably don't need anything too massive, just whatever cast Hammond
box it will fit in (allow for the connectors and feedthrough
caps!!). You can always add mass later (bolt slabs of aluminum to
the outside of the box) -- but in this application, you shouldn't need to.
More information about the time-nuts