[ntp:questions] Tutorial for setting up Garmin 18 LVC on FreeBSD 8.0

unruh unruh at wormhole.physics.ubc.ca
Mon Feb 22 18:02:56 UTC 2010

On 2010-02-22, ryandoyle <rd at ryandoyle.net> wrote:
> On Feb 23, 1:03?am, Thomas Laus <lau... at acm.org> wrote:
>> On 2010-02-22, ryandoyle <r... at ryandoyle.net> wrote:> For anyone interested in setting up a Garmin 18 LVC GPS receiver on
>> > FreeBSD 8, I wrote up a fairly detailed tutorial of my experiences
>> > here:http://blog.doylenet.net/?p=145
>> > If there are any comments or errors, please let me know
>> present. ?Configuring the min and max poll for a reference clock sort of
>> goes against the grain of how ntp is supposed to work. ?Let the daemon
>> adjust things according to how the clock is performing in relation to
>> the it's other sources of information. ?It needs to have the maximum
>> degree of freedom in order to converge on the best solution!
> All the sample ntp.conf files had max and mix poll configured, I was
> just following these. Should these not be entered? Thanks for the info
> on the ntp-devel port.

His comments are a bit of nonsense. It is always advantageous to poll
rapidly, unless what you want is that the clock frequency be the most
accurate possible ( rather than the offset from true time). If you ae
going to be out of contact with your time source, then there is a
balancing act between keeping the system accurate over the long term
while the  source is decoupled, or keeping your system most accurate
while the source is connected. The suggestion for refclocks is to set
max and min to 4. Less than 3 may introduce instabilities.

> I could have left this out, but I chose to include it as bash makes
> the average Linux user feel more at home. A bit of bash and vim with

Uh, why would the linux user then not just use Linux to run his clock?
AFAICS there is no difference in accuracy between Linux and Freebsd.
(Running chrony instead of ntp would give another 2-3 times improvement
in accuracy, and 10 times faster convergence, but that was not the point
of your post, so I will not mention it.)

More information about the questions mailing list