Hi Building a GPSDO *after* you have a lab full of gear is a very different proposition than building one because cash is tight and nobody mentioned the $43 surplus units.
There’s no right and wrong here, just a need to look at “why?” before you get going. Bob > On Apr 5, 2016, at 5:40 PM, Chris Albertson <[email protected]> wrote: > > Thank you, My goal was to build the simplest and lowest cost GPSDO that > could still work. The major cost item was the $20 crystal oscillator I > bought on eBay and a $19 Motorola "Oncore" 8 channel GPS Receiver. The > rest of the stuff cost about $5. I don't count the cost of the GPS > because it was already driving NTP. SO I'd calling it a $25 GPS. It's > performance is acceptable to driving the 10MHz input of a basic frequency > counter. > > I already owned a T-Bolt and an Rb oscillator and a few counters and dual > trace scope. So I compare the $25 unit to the t-bolt and see it drifts off > a tiny bit then the software seethes and pushes it back. If I know more > about running PID controllers it would work better. > > Lars W. actually did the design and posted it here. I build most of his > design, leaving some stuff out and rewrote all the software to be about > 1/20th as many lines of code. My goal was to be as simple and cheap as > possible. > > I think if the goal is to build something and the learn how it works, build > a VERY simple device then in a series of tiny "baby steps" improve it. > > If I ever get around to it. I will add my $35 surplus Rb unit to the same > cheap Arduino. It should work will. I can do hours/days integration > times. The Rb has a digital only freq. adjustment that has steps of about > 10E-11 or so. All I need is to keep it on the correct step. > > Another reason to build rather than buy is because you want something that > you can't buy. That will be my next GPSDO. I want a "good" crystal and an > internal Rb standard that can be used when GPS is not available (for > portable use) and I want it to run on common LiPo batteries used for power > tools. The idea is that when it is at home I plug in the 1PPS cable and > the units "syncs" to GPS and the Rb is put in frequency. I may never get > around tooth's as the Rb is very good all by itself to the limit of my > ability to measure it. > > > > > On Mon, Apr 4, 2016 at 12:00 PM, Chris Caudle <[email protected]> wrote: > >> >> >> want to build next, then go ahead and have fun. Chris Albertson's arduino >> based design is probably as good a place to start as any, it should be >> cheap and I think the pieces are easier to find than that CPLD based >> design that relies on having a GPS that can output 10kHz instead of just >> PPS. >> >> -- >> Chris Caudle >> >> >> >> _______________________________________________ >> time-nuts mailing list -- [email protected] >> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. >> > > > > -- > > Chris Albertson > Redondo Beach, California > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
