David Lord wrote: > I'm intending buffering the pps to give 75r output to coax with > another converter back to ttl at the server. The NMEA should manage > the distance over twisted pair at 4800 baud. [] > I'd rather have the option for two way in case the Garmin needs to be > set to a different mode. I have a reel of utp I think should do. > > I'll have some sort of fan-out box to get a pps signal to each of > servers that are powered up continuously. > > I've now seen an error in ntp log and suspect pps isn't enabled in > kernel by default (NetBSD-5). I'll check tomorrow. > > Cheers > > David
David, if you have UTP cable, I think that's four twisted pairs, so I would just use one pair per signal (TX, RX, PPS) and the remaining pair as an earth/+5V. Unless you have a noisy electrical environment, I think that will be fine over 30m. Screened would be better, if you have it. Fan-out would be nice - I've used two RS-232 input in parallel fed from one GPS 18 without problems. I thought the offset figures you were quoting were for Windows - "between -74us and +62us". For a PPS signal on a FreeBSD system I would expect much better. I recall needing both the NMEA and the ATOM driver configured. Oh, yes, I vaguely recall having to compile the kernel as well. It was a few years ago.... http://www.satsignal.eu/ntp/FreeBSD-GPS-PPS.htm Cheers, David _______________________________________________ questions mailing list [email protected] https://lists.ntp.org/mailman/listinfo/questions
