[time-nuts] Loran - any good for timekeeping?
John Ackermann N8UR
jra at febo.com
Fri Apr 21 17:09:55 EDT 2006
Hi Brooke --
Thanks for that. I was going from memory as the manual is at home and
I'm not. I set the time with the 2100T several months ago but haven't
played with that functionality since.
John
----
Brooke Clarke wrote:
> Hi John:
>
> Setting the 2100T is really a two step process. After you have done
> all the setup possible and then connect you house 1 PPS and put in a
> phony TOC that's say 10 seconds ahead, then at the TOC the 2100T will
> sync it's 1 PPS output (you will get a red error light). You need to do
> this to get the seconds ticking with UTC. Then you can set the time so
> it ticks over on the UTC second edge. Then do a real TOC sync.
> More at:
> http://www.pacificsites.com/~brooke/A2100F.shtml#2100T
>
> Have Fun,
>
> Brooke
>
> John Ackermann N8UR wrote:
>
>
>>M. Warner Losh wrote:
>>
>>
>>
>>
>>>Can't you recover the time by tracking multiple chains and using the
>>>relationship between them to come up with at least small number of
>>>possible seconds? Hasn't the US started broadcasting data that can be
>>>used to know which second you are at?
>>>
>>>
>>
>>I don't think that the US has started broadcasting a timecode, though I
>>think those plans are in the works.
>>
>>I have to look at the Austron 2100T manual to get the exact sequence of
>>events, but basically you set the clock, feed an external PPS signal
>>that is roughly accurate (within some tens of milliseconds, I think),
>>and then enter the next time of coincidence (TOC) which you obtain from
>>the USNO (http://tycho.usno.navy.mil/lortoc.html). The TOC is when the
>>Loran pulse coincides with the UTC second. When the TOC rolls around
>>(which occurs a couple of times per day, the receiver locks to that and
>>you can remove the external PPS. From that point on, the PPS output
>>should track with the stability of the Loran signal unless/until it
>>loses lock.
>>
>>Not sure about the idea of tracking multiple chains; it seems like that
>>should work, but that's not how the Austron receiver, at least, does it.
>>
>>John
>>
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>>
>
>
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