[time-nuts] The Demise of LORAN (was Re: Reference oscillator accuracy)

Glenn Little WB4UIV glennmaillist at bellsouth.net
Sun Nov 15 03:47:36 UTC 2009


And all the GPS goodness can easily be disabled by a missile and a 
near nuclear burst or a portable handheld jammer at the airport.
The portable handheld jammer is a very real threat to GPS due to the 
signal levels from the satellite.

Now they are trying to revive a miswired SVN and add it to the network.

It is very hard to jam the LORAN signal without a high power jammer.
If a LORAN station is taken out by enemy action, it is not 
unreasonable to rebuild or replace it.

GPS is just too fragile to be heavily relied on.

I know that we do it every day, but, you need to have a backup 
navigation system.

LORAN is time proven to be functional and the technology is in place 
on a number of platforms to utilize it.


73
Glenn
WB4UIV
ETCS(SS) USN Retired (Electronic Navigation)

At 10:21 PM 11/14/2009, Francesco Ledda wrote:
>LORAN is a good back up, but it has problems and limitations.  Navigating
>next to a storm can overwhelm the receiver and make it unusable.  The LORAN
>system doesn't have a build in accuracy degradation system like GPS(RAIM -
>receiver autonomous integrity monitoring), and this make LORAN unfit to fly
>Non-Vertical Guidance approaches. GPS with its accurate positioning, fast
>update rate and WAAS make is an awesome aircraft navigation system that can
>replace almost all NAVAIDS including ILS. Today with GPS, we can fly in
>instrument conditions from take off to landing without ever tuning any
>external NAVAID; not even INS can't do that. It is pretty amazing to me!
>
>
>
>
>
>
>-----Original Message-----
>From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com]On
>Behalf Of Hal Murray
>Sent: Saturday, November 14, 2009 7:13 PM
>To: Discussion of precise time and frequency measurement
>Subject: Re: [time-nuts] The Demise of LORAN (was Re: Reference
>oscillator accuracy)
>
>
>
> > I've read and heard from this forum as well as a number of other
> > sources that GPS can be easily jammed.  What makes GPS so vulnerable?
> > How can it be jammed?
>
>The signal is very very very weak.  The question is not how can it be
>jammed,
>but rather how can you find the signal at all.
>
>There was a recent message here reporting on the 5th harmonic of a small 315
>MHz radio link wiping out GPS for a 1/2 mile:
>   http://www.mail-archive.com/time-nuts@febo.com/msg22033.html
>
>Here is a good story:
>   Unjamming a Coast Harbor
>   James R. Clynch, Andrew A. Parker, George Badger,
>   Wilbur R. Vincent, Paul McGill, Richard W. Adler
>   GPS World, Jan 1, 2003
>   http://www.gpsworld.com/gps/system-challenge/the-hunt-rfi-776
>
>
>
>--
>These are my opinions, not necessarily my employer's.  I hate spam.
>
>
>
>
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