[ntp:questions] Stick to PPS, even if the prefer server fails
John Ackermann N8UR
jra at febo.com
Sat Mar 28 01:34:19 UTC 2009
Poul-Henning is doing some really neat stuff with a software defined
LORAN receiver, but he's not actually using that one for timekeeping
(that I know of). I didn't know he also had your design running as well.
John
----
David Mills said the following on 03/27/2009 08:24 PM:
> Johm,
>
> Don't get me going on the Austron 21--. I had one and a 2200, too, and
> they cost me more in repeated repari bills than new Spectracom GP
> receivers, so I junked them. As for the Coasties, they have threatened
> to turn LORSTAs off every few years since 1990. As for your suspicion
> that you are the only NTP server synchronized to LORAN-C, be advised
> Poul-Henning Kamp has a clone of my receiver running in Denmark with a
> Rubidium timebase. Apparently, LORAN-C has new life in Europe.
>
> Dave
>
> DaveJohn Ackermann N8UR wrote:
>
>> David Mills said the following on 03/27/2009 05:44 PM:
>>
>>> To John: I suspect you know that all LORSTA stations run by the Coast
>>> Guard include in the weekly announcement series a time-of-coincidence
>>> (TOC) second at which the epoch of the second is equal to the epoch
>>> of the GRI. My Astron LORAN-C receiver, which was modified by the
>>> Coast Guard, flashes a light at the TOC. The TOCs and the intervals
>>> between them vary up to several minutes depending on the GRI of the
>>> chain. I made provisions for the TOC in the LORAN-C receiver I built
>>> some years ago, but never completed the code to exploit them.
>>
>> Hi Dave --
>>
>> Yes, the TOC can be used to generate an on-time PPS. The Austron 2100
>> (sometimes referred to as the "T" model) receiver has that capability
>> (the more common 2100F version does not; it is useful only for
>> frequency comparisons).
>>
>> I drive one of my NTP servers (a modified Soekris SBC running nanoBSD)
>> tied to the Austron 2100, and its crystal oscillator is locked to an
>> Austron 2010B disciplined oscillator that is driven from the LORAN
>> receiver. I suspect that this may be the only LORAN-based NTP system
>> running anywhere today. It keeps very good time; in fact, its noise
>> is comparable to a similar Soekris box that gets its PPS and
>> oscillator from a Z3801A GPSDO.
>>
>> Of course, the Coast Guard just announced that they plan to turn the
>> US LORSTAs off in 2010 as part of budget cuts. I don't know if that
>> is political maneuvering to get a bigger piece of the pie, or a done
>> deal.
>>
>> John
>
>
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