Hi The accuracy required by NTP can be met with a <$20 GPS board. It’s much easier to simply do a stand alone device than to try to tie everything together. Fewer ground loops / fewer things to go wrong / easier to keep running.
The frequency offset in the device appears to be a design choice made by the people running the project. There is no way to find out if they have changed their design other than buying more devices. That *assumes* that the later devices have later firmware versions …. Bob > On Apr 28, 2015, at 2:57 PM, John Laur <[email protected]> wrote: > > Hello all. Long time listener; first time caller. > > I picked up one of the BG7TBL GPSDO units from Ebay, and I am still waiting > for it to arrive. I understand it has its flaws, but my needs are fairly > simple, and I think it will serve. > > My intent is to use it as a reference which is better than the 0.1ppm TCXO > in my HF radio, an ANAN-100D (HPSDR architecture); I would like a PPS > reference so that I can experiment with timestamped IQ samples; and I would > like to build an NTP server using a BeagleBone Black. I think this will > serve to do these things even if it is not the ideal equipment. > > I have read I believe all of the previous discussion on this list over the > past few months including the excellent study by John KE5FX, and I had a > few questions to see if there had been any new developments. I understand > some may have communicated with the designer as well. > > Does anyone else have further information on the serial interface? Is the > NMEA data directly to/from the U-Blox module or does the internal firmware > filter/augment it to allow monitoring or tuning of other internal > parameters - for instance can one set cable delay? What is its suitability > for running as a GPS/PPS reference for an NTP server? Any other software > suggestions for keeping an eye on it? > > Second, has the small frequency error identified by John been corrected, or > is it a problem endemic to the design (I think maybe this was identified as > a resolution limit of the DAC providing OCXO control voltage; could it be > dithered?) > > As this is my first moderately accurate device in the shack, is my best > approach just to put it on the shelf, leave it on for a long time, and > trust it? I can see how its easy to begin the slide when there is only one > clock to stare at skeptically. > > Thanks, > John Laur > K5IT > _______________________________________________ > 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.
