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

From: Alexander Carver
Subject: Re: [gpsd-users] Garmin 18X-5Hz
Date: Mon, 15 Aug 2016 08:10:09 -0700
User-agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.2.0

On 2016-08-14 14:14, Gary E. Miller wrote:
> Yo Robin!
> On Sun, 14 Aug 2016 21:18:04 +0200
> Robin Schwab <address@hidden> wrote:
>> Am 14.08.2016 um 19:42 schrieb Gary E. Miller:
>>> You are using the 22 driver, and I, and the howto's, use the 28
>>> driver.  Once again the 22 driver usually works, but it lacks the
>>> fail safes in the 28 driver chain.  
>> Not being a software engineer I am confused by the many drivers that
>> are around. 90% are probably obsolete but not marked as such.
> Yup.  The ntpd driver thing is confusing.  NTPsec has been ripping away
> at old drivers with a vengence.
>> Or am I wrong and there are still thousands of Trak 8820 users around?
> Not relevant.  Driver 22 is for generic PPS.  One of the reasons gpsd
> added a PPS driver years ago was due to the deficiencies of the ntpd PPS
> driver.  Current plans are to eventually rip it out and only support PPS
> by way of SHM, driver 28.
>> Which driver shall one use? 20,22, 28, and 46 are candidates for a 
>> modern setup with NEMA and PPS.
> I use 28.  gpsd does all the work and hands the time corrections to
> ntpd to deal with.  That is how the gpsd time server howto does it, as
> well as the in progress NTPsec RasPi howto.

I find this interesting because on four different hardware platforms
using different OSes and different GPS receivers I can not get gpsd's
PPS SHM output to behave.  It consistently feeds awful time to ntpd and,
in the end, I use the ntpd PPS driver (22) to keep things under control.
 I feed the coarse clock into ntpd via gpsd (so the GPS receiver data
can be monitored or shared with other applications) but PPS via SHM is
terrible (offset in milliseconds and jitter also in milliseconds, using
Driver 22, offset and jitter are single digit microseconds.)

Given that, I would really like to know how you have your whole system
configured because following any available recipe fails.  I see the
config in your link below and I've used that without success.

In any event, is NTPsec a replacement or is this a fork of ntpd?


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