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Re: [gpsd-dev] RaspbPi HOWTO
From: |
Gary E. Miller |
Subject: |
Re: [gpsd-dev] RaspbPi HOWTO |
Date: |
Thu, 5 May 2016 10:39:40 -0700 |
Yo Gary!
On Thu, 5 May 2016 10:19:49 -0700
"Gary E. Miller" <address@hidden> wrote:
> I have never seen a USB GPS w/ PPS be the limiting factor, always the
> NTP over the ethernet. I'll do a test today on a Pi2 to see if that
> continues to be true.
After shoving a bit more espresso in my face, and looking at a Pi2 that
has been runnning ntpd, no gpsd, for a few days, I get the answer that
should have been painfully obvious at first.
The NTP over the 100Base-T that goes in the USB High-Speed to the Pi,
gets 0.3 milliSec of jitter.
address@hidden:~# ntpq -p
remote refid st t when poll reach delay offset jitter
==============================================================================
+spidey.rellim.c .GPS1. 1 u 685 1024 377 0.282 0.417 0.302
*catbert.rellim. .SHM. 1 u 405 1024 377 0.329 1.168 0.707
+darth.inow.com 204.17.205.1 2 u 889 1024 377 0.582 0.723 0.448
That would be about 2x worse than I would expect from a High-Speed USB GPS
w/ PPS. Better than a Full-Speed, like the GR-601W, at 0.500 milliSec.
RGDS
GARY
---------------------------------------------------------------------------
Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
address@hidden Tel:+1 541 382 8588
pgpeNDTk0a4sl.pgp
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- Re: [gpsd-dev] RaspbPi HOWTO, (continued)
Re: [gpsd-dev] RaspbPi HOWTO, Eric S. Raymond, 2016/05/03
- Re: [gpsd-dev] RaspbPi HOWTO, Hal Murray, 2016/05/03
- Re: [gpsd-dev] RaspbPi HOWTO, Eric S. Raymond, 2016/05/03
- Re: [gpsd-dev] RaspbPi HOWTO, Hal Murray, 2016/05/04
- Re: [gpsd-dev] RaspbPi HOWTO, Fred Wright, 2016/05/04
- Re: [gpsd-dev] RaspbPi HOWTO, Gary E. Miller, 2016/05/04
- Re: [gpsd-dev] RaspbPi HOWTO, Frank, 2016/05/05
- Re: [gpsd-dev] RaspbPi HOWTO, Gary E. Miller, 2016/05/05
- Re: [gpsd-dev] RaspbPi HOWTO,
Gary E. Miller <=
- Re: [gpsd-dev] RaspbPi HOWTO, Gary E. Miller, 2016/05/05
Re: [gpsd-dev] RaspbPi HOWTO, Frank Nicholas, 2016/05/03
Re: [gpsd-dev] RaspbPi HOWTO, Dan Poirot, 2016/05/04
Re: [gpsd-dev] RaspbPi HOWTO, Clark B. Wierda, 2016/05/03