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

Francesco Ledda frledda at verizon.net
Sun Nov 15 03:21:47 UTC 2009


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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