[time-nuts] US considers shutting down Loran

[John Ackermann N8UR]

Hal Murray said the following on 01/19/2007 11:12 PM:
> From http://www.fcw.com/article97298-01-08-07-Web
> 
>> Norman said the Alliance for Telecommunications Industry Solutions
>> (ATIS), whose membership includes all the telecom carriers in the
>> country and equipment vendors, views eLoran as the "only viable
>> alternative to GPS for providing [Coordinated Universal Time] of day
>> and frequency accuracy that is suitable for a telecom primary
>> reference source."
> 
> How good is Loran for timing?  What's the right parameter for "good"?

When used for frequency measurement, Loran is good to parts in
10e-13/day -- ie, not much worse than GPS.  Of course, that's referenced
to the Cesium clock at the Loran station, so you need to do a little
juggling to trace back to NIST.  I believe that as they enhance the
stations to the new hardware, the discrepancy from NIST will be much less.

I recently got one of the (relatively rare) Austron 2100-T Loran
receivers that do timing; you basically lock the receiver to one of the
periodic Loran pulses that coincides with a UTC second marker and it
generates a PPS signal tracking that.  I haven't had a chance yet to run
any long-term experiments to measure its stability, but that's on my
list of things to do.  (I also plan to hook it up as a refclock for an
NTP server; I'm not sure if there's another Loran-based stratum 1 server
out there today.)

John

John