[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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