[ntp:questions] NMEA ref.clock better than my ISP's timeserver?

David Lord snews at lordynet.org
Thu Jun 11 11:02:20 UTC 2009

David J Taylor wrote:
> David J Taylor wrote:
> []
>> I might be inclined to go for a screened
>> cable if you need a 30m run, but thin 3-core mains cable /might/
>> suffice.

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'm not sure whether the NMEA driver attempts to send anything /to/ the 
> GPS device.  If not, three lines might to (ground, TX from GPS, PPS), 
> otherwise four lines are required.  If you want to take USB power from 
> the server (as I now do), it's five lines minimum.

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.



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