> Attila Kinali <[EMAIL PROTECTED]>, on Sun 20 Apr 2008 > 05:50:21 AM PDT: > > > On Thu, 17 Apr 2008 08:47:48 -0700 (GMT-07:00) "Richard W. Solomon" > > <[EMAIL PROTECTED]> wrote: > > > >> You can build a very good GPSDO for about $100 in parts. > > > > Stupid question, but if one builds his on frequency > reference, how can > > you be sure it's acurate and precise? >
If you track the correction voltage of a GPSDO over time and compare it to that of a comparable GPSDO (there is plenty of data to compare to on Tom Van Baak's web site leapsecond.com), you gain some confidence that your unit is performing comparably. Since GPS is referenced to UTC (maybe not from a metrology standpoint, but good enough for most other applications), it is a standard by and of itself. For very basic frequency standard, other reference frequency signals are available over the air (WWV, DCF, Loran and other), but of those, only Loran would qualify as a time standard, the others are at best frequency standards because of the variation in propagation that are difficult or impossible to compensate for HF/LF signals. Now, this is time-nuts, so monitoring this mailing list for a while will show you that there is much more than meet the eyes. Didier Internal Virus Database is out-of-date. Checked by AVG. Version: 7.5.519 / Virus Database: 269.22.5/1358 - Release Date: 4/3/2008 6:36 PM _______________________________________________ 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.