I like the adafruit gps hat Chip Blach
On Fri, Jun 17, 2022, 1:16 PM Terje Mathisen <terje.mathi...@tmsw.no> wrote: > David Woolley wrote: > > On 17/06/2022 16:34, chris wrote: > >> As for compatibility, while a mismatched connection may work, it's bad > >> practice to do that, where you are dealing with microsecond timing > >> and want to avoid jitter. Use the correct interfaces and do the job > >> right, then you can fit and forget:-)... > > > > RS232 isn't optimal for PPS as it is slew rate limited to 30V/µs, which > > means it will take at least 0.5µs from a resting level until it has > > fully cleared the transition region, if implemented to standard. > > > > TTL is the more natural logic family for high accuracy PPS. > > > > GPS should be able of achieving time transfer accuracies of better than > > .03µs. > > GPS, even at the $80 Shure evaluation board level, have been directly > measured at the ~25 ns level, which is pretty much what you claim here. :-) > > The key idea is of course that in order to know where a GPS is located > with better than 3 m precision, the unit by implication also knows what > time it is, to within 10 ns of UTC(USNO). The only problem is to be able > to convey that info to a connected NTP server. > > Terje > > -- > - <Terje.Mathisen at tmsw.no> > "almost all programming can be viewed as an exercise in caching" > -- > This is questions@lists.ntp.org > Subscribe: questions+subscr...@lists.ntp.org > Unsubscribe: questions+unsubscr...@lists.ntp.org > > > > >
