[ntp:questions] ntpd: time reset problem

Hal Murray hal-usenet at ip-64-139-1-69.sjc.megapath.net
Tue Sep 15 05:05:54 UTC 2009


>> IF the latency is known to be symmetric ( which it is
>>  on an interplanetary system) then large latency is no
>>  problem.
>
>I don't see how they are likely to have symmetric latency.
>
> e.g.
>  The earths orbital velocity is something like 67k mph?
>   mars orbital velocity is something like 54k mph?
>
>  If you were to send a message, and wait for a response,
>   the planets would by significantly closer or farther
>   apart when the response was sent?
>
>   {Then again I know almost nothing about astrophysics.}

It's close to symmetric because there aren't any queueing
delays.

Your point is valid.  It can be corrected for.

If you are really serious, you have to correct for relativity.
There is a blue shift from Mars to Earth since Earth is deeper
in the Sun's gravity well.  (Or something like that.)

-- 
These are my opinions, not necessarily my employer's.  I hate spam.




More information about the questions mailing list