[time-nuts] Arduino GPSDO with 1ns res TIC

paul swed paulswedb at gmail.com
Thu Feb 13 09:36:55 EST 2014


Lars has done a very good job here and good to see the comments and
excitement.
Have to agree with HAL that holdover is far more than a second and I am in
a good location with the GPS antenna at 90'. I see my 3801 go into holdover
occasionally and its not seconds.

Cheapest tinker 10 Mhz is a Xtal with a varicap diode in circuit to adjust
frequency.
Sub $ 5 I would guess.

I was intrigued by the Arduino also and then went looking for information.
Just about drowned in whats out there and pricing for the chip is from 99
cents to $5.
What bootloader X Y or Z. I like the pure chip 28 pin approach and do
appreciate that this won't be H maser accurate.

Looked at the schematic and would appreciate a more complete picture.
Lars thats a bit more painful to do because everything has to be explicit
in the schematic when other may build what you have shared.
Though I have shared some ugly schematics on time-nuts. Guilty as charged.
Regards
Paul.
WB8TSL


On Thu, Feb 13, 2014 at 3:59 AM, Hal Murray <hmurray at megapathdsl.net> wrote:

>
> [Context is cheap VCXO]
>
> > When used inside a GPSDO it only has to "hold over" for one second until
> the
> > next correction.
>
> Only if you have a good antenna and/or antenna location.
>
> I have several low cost GPS units located in far-from-ideal locations.
>  They
> work most of the time but often fade out for minutes at a time.
>
> [This is a poor setup for using the output of a GPSDO to feed other
> measuring
> setups, but it's great for finding corner cases in things like ntpd.]
>
>
> --
> These are my opinions.  I hate spam.
>
>
>
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