[135341] in North American Network Operators' Group
Re: anyone running GPS clocks in Southeastern Georgia?
daemon@ATHENA.MIT.EDU (Owen DeLong)
Fri Jan 21 18:06:36 2011
From: Owen DeLong <owen@delong.com>
In-Reply-To: <AANLkTim=Rks3MH+ySoYHYKaauZkhgV1-xJ05wXLxi=wE@mail.gmail.com>
Date: Fri, 21 Jan 2011 15:01:10 -0800
To: Gary Buhrmaster <gary.buhrmaster@gmail.com>
Cc: nanog@nanog.org, "Robert E. Seastrom" <rs@seastrom.com>
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
On Jan 21, 2011, at 1:45 PM, Gary Buhrmaster wrote:
>> NTP isn't going to be the only "ripple".
>
> Most of the "brand name" GPS NTP solutions have a clock
> with is more than stable enough to survive without GPS
> lock for 45 minutes(*). Some of the more expensive units with
> temperature controlled oscillators have hold times in the
> many weeks. My guess is that the NTP ripples will be
> limited to those NTP servers just (or recently) booted
> which have not yet achieved a stable clock state.
>
> Gary
>
> (*) This presumes that this test results in loss of signal
> lock, and not intentionally injected false information.
Loss of lock is a non-issue.
However, the tests they are doing do not necessarily cause loss
of lock. Sometimes, instead, they give you a wrong enough time
to insure that your navigational fix is off by, well, enough to
guarantee that you don't hit what you're aiming at.
Owen
