Details: First I installed NTP4.2.4p8 Then I updated the binaries with your updates labeled 4.2.7p8 Then I installed the serial PPS driver 20091228
Although for NTP purposes, you would like only one output string, I have to output two NMEA strings because there is another device looking at the serial stream also. I am outputting GGA and RMC messages. According to the GPS manufacturer (I am using a Garmin GPS15H) the PPS signal is applied just before outputting the NMEA sentences that would be for that time period. I have the PPS signal set to 80ms width. One oddity about my configuration is that the NTP server will not be up 24x7. The machine will be booted, and I would like the ntpd to discipline the local clock to a reasonable (+-10ms) accuracy within 10 minutes. I have another machine that I will then synchronize to the computer with the GPS. Looking at the documentation it appears you can specify which NMEA string to use so perhaps this is better server 127.127.1.0 #the below line is just to remind me how cruddy the base clock might get fudge 127.127.1.0 stratum 5 #tell NMEA reflclock to use RMC messages server 127.127.20.1 minpoll 4 mode 1 # tell NMEA refclock to use PPS fudge 127.127.20.1 refid gps stratum 1 flag1 1 It really doesn't matter to me if I install the serialPPS driver or not. From your discussion it appears using the serialPPS driver is more accurate than the NMEA driver? Does that make it a better choice or is that just making it more confusing? And I really appreciate your help, I have been trying to research this as much as possible on the internet, but I am having a little difficulty because it appears that there are a fair number of differences between the Linux usage of PPS and the windows PPS, etc. _______________________________________________ questions mailing list [email protected] http://lists.ntp.org/listinfo/questions
