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From: | Robin Schwab |
Subject: | Re: [gpsd-users] Garmin 18X-5Hz |
Date: | Fri, 12 Aug 2016 21:45:48 +0200 |
User-agent: | Mozilla/5.0 (Windows NT 10.0; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.2.0 |
Am 12.08.2016 um 20:37 schrieb Gary E. Miller:
On thing that is coming to light, ntpd tends to chase quantization errors rather than averge them out. No solutions yet. For exammple: https://pi3.rellim.com/day/
Hello GaryYour 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
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