On 2011-08-30, Chris Albertson <[email protected]> wrote: >> If you care about microseconds or nanoseconds, shortwave radio is a poor >> choice. The length of the radio propagation path changes constantly! Not by >> much but if you care about the nanoseconds. . . . >> >> If you REALLY NEED the nanoseconds, buy an atomic clock and have it >> calibrated by your national standards people. If you don't REALLY NEED >> the nanoseconds you can almost certainly save $50K - $100K. > > > GPS, eBay and the cell phone industry have changed that. Prices have > fallen to well below $1K or even below $100 if you can do some soldering. > For example Synergy's "12MT+" receiver has a 2 nanosecond (1 sigma) error > and sells for $60 new. It is easy to find a good working Rubidium > oscillator (a kind of "atomic clock") on eBay for $100 to $150. >
I am not sure that I believe that stated accuracy of 2ns. It would seem others do not as well-- I found a paper by Mumgford in 2003 who compared the performance of the Oncore M12+ , with a Leica CRS1000 survey grade gps unit, and found that the Motorola was about 600ms late compared to the Lassen, and had about a 60ns jitter. Of course since this is a comparison, it is possible that the Leica was 600ns too soon, and the jitter was all its jitter. Mind you even 600ns is pretty good and almost impossible to get into your computer. > > > > Chris Albertson > Redondo Beach, California _______________________________________________ questions mailing list [email protected] http://lists.ntp.org/listinfo/questions
