[time-nuts] FE5680 GPS Disciplined Controller

Chris Albertson albertson.chris at gmail.com
Thu Jun 19 20:39:30 EDT 2014

On Thu, Jun 19, 2014 at 11:47 AM, Tom Van Baak <tvb at leapsecond.com> wrote:

> Chris,
> I'm glad you're making progress on your Arduino GPSDO. You've mentioned it
> in a dozen postings the past half year. Perhaps you will post the source
> code sketch, full design, and actual phase / frequency / adev results some
> day. Many of us are willing to help as independent testers and see actual
> results.

I've posted the schematic and source code.  I don't have any good way to
measure performance except with the device itself.  A GPSDO measures itself
every second.  Could I use that data?  It would be easy to push it across
the USB interface to a computer.

My goal was to make something as simple and low as possible.  I'd make it
better except for I need some way to see if it really is better.

> Meanwhile... Now would be the time for you to let Bert have the stage; he
> has an actual working design, with PCB, and several tests in progress.
> High-performance results. This represents a year of work on his part, and
> others who have freely collaborated and contributed to all aspects of his
> project. It's really nice.
> Please do not hijack the thread of another time nut's superb effort. Some
> week it will be your turn to post final results of your project. This is
> not the week.
> Thanks,
> /tvb
> ----- Original Message -----
> From: "Chris Albertson" <albertson.chris at gmail.com>
> To: "Discussion of precise time and frequency measurement" <
> time-nuts at febo.com>
> Sent: Thursday, June 19, 2014 8:31 AM
> Subject: Re: [time-nuts] FE5680 GPS Disciplined Controller
> > I've been working in the same thing BUT I don't want anyone who builds it
> > to need a PCB.  And I want the firmware to load over USB so there is no
> > need to ship programmed chips or deal with external programmers.   I
> think
> > I can get the cost below $20.     That said I doubt I'll get 1E-13
> > performance out of my Rb.
> >
> > My little Arduino based controller has been running now for a couple
> months
> > and keeping a crystal in lock.  The board has a pins left over for a
> serial
> > port that I'll hook up to the Rb.
> >
> > The trick to getting the cost down is NOT to do a custom PCB.  Take
> > advantage of one of the uP development boards and then for under $5 you
> get
> > the USB interface, D/A and A/D, serial ports, timers and quite a bit of
> > logic all  1/3rd the size of a credit card.
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Chris Albertson
Redondo Beach, California

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