Re: [gpsd-users] Garmin 18X-5Hz

[David J Taylor]

Hello Gary
Your graphs are by characteristic very similar to what I got with a
raspberrypi 2 and the adafruit GPS. I got much better on an absolute
scale but the sawtooth-like waveform remains. Strange thing: It can
happen that the periodic error disappears but it's unclear to me under
which circumstances. Without the periodic error I could stretch the
graph to -+10 us which is imo pretty good for a 100$ hardware setup.

Big advantage of the adafruit: You can set NEMA update rate and UART
baud rate separately.

Regards

Robin
====================================

Robin, Gary,

I recently did some tests with the tickless/not setting, and found that 
using "nohz=off" on the Raspberry Pi's /boot/cmdline.txt could produce a 
worthwhile improvement in offset and jitter.  More details and some results:

 http://www.satsignal.eu/ntp/Raspberry-Pi-NTP.html#nohz

Cheers,
David
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