On 2010-06-18, Richard B. Gilbert <[email protected]> wrote: > David J Taylor wrote: >> "Richard B. Gilbert" <[email protected]> wrote in message >> news:[email protected]... >> [] >>> If you have a GPS timing receiver (different from navigation >>> receiver), with a PPS output, one edge of that pulse should be >>> accurate to within 50 nanoseconds. A serial output will tell you >>> which second is marked by the pulse. >> >> .. although the very popular GPS 18x LVC specifies: >> >> "Accuracy: Measurement Pulse Output Time: +/- 1 microsecond at [the] >> rising edge of the pulse." >> >> so not quite as good as 50 nanoseconds. >> >> Cheers, >> David > > The difference is not significant unless you can somehow take advantage > of the greater accuracy! The difference in price between the Motorola > device whose specifications I was citing and the GPS 18x LVC is quite > significant; ISTR that I paid about $300 for mine. If I had to replace > it, I'd go with the GPS 18X LVC.
Agreed. The interrupt serviced routines are simply not accurate enough to make use of the accuracy better than about 1us. In tests I ran I got roughly 1us random variations in the itnerrupt servicing. > > _______________________________________________ questions mailing list [email protected] http://lists.ntp.org/listinfo/questions
