> Hi, > > My 18x is linked with an Odroid C1+ and I use only driver 20 with 0x10000 > mode enabled to have a better look on NMEA sentences. It's by looking 'ntpq > -c clockvar' results that I discovered the quality of my 18x comparing with > some others 'Adafruit' or basic GPS chips. > > from my ntp.conf: > server 127.127.20.0 mode 65553 minpoll 5 maxpoll 5 > fudge 127.127.20.0 time2 0.550 flag1 1 flag3 1 flag4 1 > > Knowing that by default flags are set to 0 I don't explicitly feel the need > to reset them again to 0. > Having only one physical device (GPS) connected I also don't feel the need to > rename the driver with 'refid' option. > > Jean-Michel
Hi Jean-Michel, You came up with so many good information. Thank you so much. Regarding this specific point you did not say how accuracy you got through the driver 20 (both with/without internet)? In my understanding, Driver 20 gives NMEA sentences and its accuracy suppose to fluctuates in millisecond range! I am very keen to get a stable clock with 1 micro accuracy. Aiming this I have tested many settings. According to my achievement, I have got: 1. 1 micro accuracy in driver 22! 2. then I compiled the kernel and get nano second level accuracy in driver 22! Though it fluctuates in microsecond range as well, not stable but average I was able to develop around 800ns there. But in driver 22, it is just merely a precise tick without time, my system always follows driver 20 (showed asterisk on it *). But still I can't develop microsecond accuracy on it. My question, if I can't develop microsecond accuracy on the usable reference ID, then what's the point of saying GPS is as accurate as microsecond? However, I have got a link here, https://www.lammertbies.nl/comm/info/GPS-time.html According to this site, it uses shared driver 28 (127.127.28.1) to develop achievable accuracy in microsecond range (follow the asterisk). remote refid st t when poll reach delay offset jitter ============================================================================== +SHM(0) .GPS. 0 l 6 16 377 0.000 28.775 10.971 *SHM(1) .PPS. 0 l 5 16 377 0.000 -0.001 0.002 However, I haven't able to develop it yet, for some reasons it is not working with my Rpi system! Will appreciate your further comment at this stage. Kind Regards, Fida _______________________________________________ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
