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 <ch...@chriscaudle.org> 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 -- time-nuts@febo.com > 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 -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
