On Wed, 25 Oct 2006 11:12:07 GMT, Larry Dighera
wrote:

http://www.newscientisttech.com/chan...e-for-gps.html
Solar storms spell trouble for GPS

I wonder where Cerutti has been for the last few years. The military
has talked about it, hell, it's even been discussed on here.


SOLAR flares can drown out GPS signals with potentially serious
consequences for airlines, emergency services, and anyone relying on
satellite navigation.

It turns out these bursts of charged particles, which produce auroras
and geomagnetic storms, also generate radio waves in the 1.2 and
1.6-gigahertz bands used by GPS.

How was such a clash missed? Because GPS receivers only became common

It wasn't, at least not by those paying attention.
Just a bit over two years ago we had some of the strongest solar
flares on record. Not *the* strongest, but that was because they
pretty much missed us. The aurora was visible all the way to Mexico
and there have been at least two instances of interruptions to GPS in
the last five years.

during a period of low solar activity. By 2011 solar flares will reach
the peak of their cycle and receivers will likely fail. Or so
Alessandro Cerruti of Cornell University, New York, told a meeting of

It's happened twice already. How come he didn't know.

the Institute of Navigation in Fort Worth, Texas, last week. The only
solution would be to redesign GPS receivers or satellites, which may

If you blanket a frequency used by a system with signals stronger than
the system generates, or strong enough to block the receivers,
redesigning them is not going to help unless you move the operational
frequency to something that is not interfered with by anything.
Maybe they could 2.4 Gigs:-))


not be practical, says Cerruti.

As with past interruptions they only lasted a few hours. Of course if
we ended up with a coronal mass ejection in the record class pointed
straight at us we might lose more than a few satellites, hardened or
not. This has also been discussed concerning the safety of
astronauts, but they *think* they'd be safe in the most heavily
shielded parts of the space station.

From issue 2572 of New Scientist magazine, 07 October 2006, page 27

I have talked to stations on nearly every continent using signals
reflected off the Ionosphere during an aurora. OTOH I have seen aurora
so strong instead of reflecting signals it absorbed them. That was
just about two years ago. When it gets that strong few signals make
it through. I think that one created about a two hour outage.

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com