[email protected] wrote:
John,
If a LORAN transmitter were destroyed by a terrorist team, a backup could
be in operation in hours. A damaged GPS system could easily take many
months or even years to fix.
-John
A LORAN site, with a several hundred meter high mast, a small house full
of transmitter, signal generation and Cs clock(s?)... on a remote
Norwegian island... would not be back online within a few hours after an
attack.
Regardless of location, it will take some time to restore functionality.
About a year maybe.
The LORAN-C station would reduce navigation in a certain area. However,
since most "interesting" targets use GPS, it is a more interesting target.
GPS is supposed to work without _any_ terrestrial support for days or
weeks. I doubt that anyone can get something lethal for the SVs up in
orbit without making it very obvious who they are. GPS now has lots of hot
spare birds in orbit, that a instantly online with one or a few satellites
going bust.
The AutoNAV feature should keep it up for 180 days. It has never been
used. Essentially, what if you wipe out the ground segment and needs to
rebuild it. The ground segment points of GPS is fewer than the LORAN-C
stations.
Firing rockets to down the birds is above the average terrorist budget
and infrastructure. While not all 30 GPS birds needs to go down, a
significant number of them needs to for a significant system impact.
Downing a single of them is sufficient for the political effect, so that
is more likely.
Using jammers is far more likely. It has been analyzed quite deeply.
It is not impossible to locate a GPS jammer. In Iraq, they had relative
high power jammers and they where able to locate them and finally take
them out.
That said, I think LORAN should be kept running as a backup, also with a
firm commitment that it WILL KEEP running for 10+ years, giving vendors a
reason to develop modern receivers.
The electronics needed to support LORAN-C and eLORAN is not very complex
by todays measure. Could be integrated with a GPS receiver.
Cheers,
Magnus
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