[time-nuts] Loran - any good for timekeeping?

[M. Warner Losh]

In message: <44491C06.7000704 at febo.com>
            John Ackermann N8UR <jra at febo.com> writes:
: Hal Murray wrote:
: >>The US is keeping Loran-C going as a backup for GPS as well.
: > 
: > ....
: > 
: > How good is Loran for timekeeping?  How does it compare to WWVB?
: > 
: > What sort of receiver do I need?  Any good how-to type web pages?
: > 
: > I'm in Silicon Valley.  The NIST map says that WWVB should work here, but my 
: > quick try didn't get very far.  I was just using a small ferrite antenna and 
: > I didn't check the tuning.
: > 
: > 
: 
: Loran can do great frequency measurement -- almost as good as GPS.  But 
: for timing, it's not so hot.  The problem with current Loran is that it 
: doesn't carry a timecode, or mark the second epoch.  It's possible to 
: recover 1pps from Loran with a bit of work (the Austron 2100T receiver 
: can do this) but it's not a trivial task, and in any event you need 
: something else to disambiguate the seconds.

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?

Warner