[time-nuts] The Demise of LORAN (was Re: Reference oscillator accuracy)
jfor at quik.com
Mon Nov 16 03:42:28 UTC 2009
In fact, GPS has performed so well, it has become "part of the furniture"
and it is really hard now to assess the full impact its loss would have.
Another overlooked aspect would be the perceived impact of a number of
failures. Just look at the hoohaws over lead in toys, defective cribs,
tainted beef, tainted pet food, flamable kids sleepware, trace chemicals
in bottles and many other things.
LORAN is cheap insurance, IMO.
A modern dual receiver could compare LORAN and GPS positions to provide
very high confidence levels at low incremental cost.
> On Sun, Nov 15, 2009 at 08:56:36PM -0600, Didier Juges wrote:
>> I don't disagree that it would be fairly easy to disrupt the consumer
>> devices, but other than a few missed appointments and frustrated gadget
>> freaks, and the occasional emergency vehicle not finding its way to the
>> scene of an accident, that would be more of a problem) I am not too
>> about the consequences of that.
> GPS has been widely used for time and frequency sync in radio
> systems of various sorts - some depend on it for successful simulcast
> from multiple transmitters (including many public safety radio systems)
> and while there is SUPPOSED to be significant holdover, there is are
> always those situations where nobody has EVER checked that it works...
> And what will holdover do about LONG TERM outages of GPS ? Perhaps
> folks are willing to bet the whole infrastructure on the supposition that
> we could NEVER see a complete long term loss of signal (using civilian
> receivers with modest anti jam abilities) in a particular location or
> region - I am not exactly sure what alternative might exist though I
> guess there are some for time and frequency - terrestrial GPS beacons
> from high points that could lock up a cell system in a region come to
> And more and more and more stuff depends on more or less
> ignorant and sometimes not very bright operators expecting that the GPS
> positions are always there or they don't know what to do. And if GPS
> is almost always reliably there there may well be little or no practical
> training about what to do if it fails. Failure modes and paths in code
> and procedures (and sometimes even actual hardware) which aren't often
> tested or exercised usually fail when actually needed and often in
> entirely unanticipated ways - maybe the backup ALSO depends on GPS in
> some way the system designers never thought about (or knew could
> LORAN C represents a viable (albeit not often deployed) backup
> to time and frequency control and could be implemented in modern
> hardware as a backup location service at reasonably low cost for those
> applications where that is important enough.
>> The thread started with the loss of the LORAN system, and nobody (maybe
>> I am
>> going out on a limb here) ever used a LORAN receiver in his car to find
>> nearest restaurant :)
> Actually readers of this list have, though not in recent times I guess.
>> I think the people who should complain the most about the loss of LORAN
>> the boaters, but they are the one who embrassed GPS the first and are
>> biggest advocates!!! I know, I live on the coast of Florida.
> An enhanced LORAN that has some of the accuracy and automation
> of a GPS receiver exists... I suspect boaters care most about
> convenience (and accuracy) and found GPS easier. Certainly so compared
> to earlier LORAN C gear.
> And of course there is another issue with GPS, it is controlled
> by the DOD and is supposed to have the ability to deny service in a
> region if conditions are sufficiently apocalyptic to require it. For
> folks worried about this (more outside than inside the US obviously)
> LORAN is a local resource they may control and certainly can if they
> make a more or less modest investment in the ability to do so. Some
> (large) players are of course planning their own space based systems for
> just this reason but LORAN can be implemented by most nation states...
> Dave Emery N1PRE/AE, die at dieconsulting.com DIE Consulting, Weston, Mass
> "An empty zombie mind with a forlorn barely readable weatherbeaten
> 'For Rent' sign still vainly flapping outside on the weed encrusted pole -
> celebration of what could have been, but wasn't and is not to be now
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