Raspberry Pi NTP config with fudge factors

[Frank Nicholas]

> On May 9, 2016, at 5:59 PM, Eric S. Raymond <esr at thyrsus.com> wrote:
> 
> Frank Nicholas <frank at nicholasfamilycentral.com>:
>> This is the “/etc/ntp.conf” I used when I ran my NTP server on a Raspberry Pi with the Adafruit breakout board (same as current hat).  I list it because of the “fudge” line.  This was commonly accepted as the proper fudge settings, especially for time2 - 0.350:
> 
> How do we know this will be correct for the HAT? Is that fudge really
> associated with the MTK3339 itself, independent of surrounding hardware? 

I think it was more specific to the MTK339, because it was setting time2 (time from start of second to when the sentence came that provided rough/NMEA time).  That’s been a long time ago, so I may not remember it so well.

My references were:
https://www.eecis.udel.edu/~mills/ntp/html/drivers/driver20.html <https://www.eecis.udel.edu/~mills/ntp/html/drivers/driver20.html>
https://www.raspberrypi.org/forums/viewtopic.php?f=41&t=1970&start=80 <https://www.raspberrypi.org/forums/viewtopic.php?f=41&t=1970&start=80>

>> server tock.usshc.com iburst
>> server clock.isc.org iburst
>> server tick.apple.com iburst
> 
> What is special about these servers?

There were reliable, GPS based servers that I trusted, that served from a GPS pool.

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