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

paul swed paulswedb at gmail.com
Thu Feb 13 11:32:08 EST 2014


See thats the pointer I need there was just tons of information.
Quite nice and the price is right.
Regards
Paul


On Thu, Feb 13, 2014 at 11:11 AM, Chris Albertson <albertson.chris at gmail.com
> wrote:

> You can buy the chip already on the PCB with supporting circuitry for
> less then the price of the chip alone.  No need to go with a bare
> chip.  I think the reason is that the tiny SMT package chips sell in
> the millions and only a hob best would use the larger DIP through hole
> package.   Look at eBay #221326355393 as an example.  The 3>71 price
> includes shipping.  The advantage is __Programming__.  When you are
> working on something like this you tend to want to re-program the
> chips ten times an hour and it s VERY convenient to be able to leave
> it plugged into the USB port on your computer.  Also for debugger a
> continuous stream of data on your computer screen, maybe captured to a
> file, gives yo insight to the internals.
>
> That is the advantage of development with the Arduino vs. a bare chip,
> you don't have to pull the chip to re-program it.  Yousimply change a
> line of code using a text editor and click the "load" icon and a few
> seconds later you are running again.  It is a very fast development
> cycle.
>
> You don't save either cost or space by using a large DIP chip the SMD
> chip soldered to a PCB is about the same cost and size but also comes
> with the pull up resisters, voltage regulater, standard 6-pin FTDI
> interface and so on.
>
> On Thu, Feb 13, 2014 at 6:36 AM, paul swed <paulswedb at gmail.com> wrote:
> > 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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>
> --
>
> Chris Albertson
> Redondo Beach, California
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