Augustine wrote: > On May 9, 2:17 am, "David J Taylor" <david-tay...@blueyonder.not-this- > part.nor-this.co.uk.invalid> wrote: >> >> Background: I have a GPS 18 and USB >> serial converter, and I wanted to see how well that actually >> performs. > > Very interesting experiment. May I suggest using USB directly? > > TIA
Augustine, You may indeed suggest that, but the key point here is (I think) that the USB/serial preserves the PPS (pulse per second) signal from the RS-232 connection, and it is the PPS signal transition which is used provide the precision part of the timing. I understand that USB alone will typically not have any PPS information, so the timekeeping accuracy would be just that of the serial port messages, degraded by whatever USB latency adds, but improved by the fact that the messages are much shorter on USB than on serial. It would indeed be interesting to see how well it performed, either with FreeBSD or with Windows. I don't know if a USB/GPS driver is available with the present version of NTP. Cheers, David _______________________________________________ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
