On 25 Oct 2006 07:00:43 -0700, "Walt" wrote in
.com:


FWIW, the last solar maximum occured around 2001, and GPS was in common
use then; I know I was using mine on a pretty regular basis then.

I don't recall any widespread disruptions. Not even slimspread
disruptions. :)

I'm thinking this may be much ado about nothing.

Perhaps you might bring this up with Professor Paul Kintner
): http://people.ece.cornell.edu/paul/

Here's some more information:

http://www.news.cornell.edu/stories/...es.gps.TO.html
Sept. 26, 2006
Solar flares cause GPS failures, possibly devastating for jets and
distress calls, Cornell researchers warn.
Alessandro Cerruti of Cornell University, New York



http://www.ion.org/meetings/gnss2006...D&session=3#p5
Observed GPS and WAAS Signal-to-Noise Degradation Due to Solar Radio
Bursts
A. Cerruti, Cornell University

GPS signals, systems, and navigation accuracy are vulnerable to a
variety of space weather effects that are caused mostly by the
ionosphere. However, the sun, which is sometimes a strong radio
source, is the cause of GPS signal interference presented here. The
first direct observations of GPS L1 (1.57542 GHz) signal-to-noise
ratio degradation on two different models of GPS receivers due to the
solar radio burst associated with the 7 September 2005 solar flare are
presented.

Signal-to-noise ratio data from three identical, collocated receivers
at Arecibo Observatory and also from four identical receivers of a
different model located in Brazil, were available at the time of the
solar radio burst. These receivers were all in the sun-lit hemisphere
and all were affected similarly. The maximum solar radio burst power
associated with the 7 September 2005 flare had a peak intensity of
about 8,700 solar flux units (1 SFU = 10-22 W/m2-Hz) RHCP at 1,600
MHz, which caused a corresponding decrease in the signal-to-noise
ratio of about 2.3 dB across all visible satellites. Only the
right-hand, circularly polarized (RHCP) emissions affected the GPS
signals.

To confirm the effect, the solar radio burst associated with the 28
October 2003 flare was investigated. Although polarization data were
not available for this event, the maximum degradation at GPS L1 was
about 3.0 dB, and a degradation of 10 dB was observed on the
semi-codeless L2 signal for a solar radio burst of 13,600 SFU.

The event analyzed herein can be used to scale historical solar radio
bursts of 80,000 SFU. Decreases of 12 dB (21 dB) in the L1 (L2,
semi-codeless) signal-to-noise ratio are implied along with loss of
tracking for inadequately designed GPS receivers. Since solar radio
bursts affect all satellites in view of a receiver, all receivers in
the sun-lit hemisphere, the new Galileo navigation system, and all
space-based augmentation systems such as WAAS and EGNOS, they are a
potential threat to life-critical systems.



Institute of Navigation in Fort Worth, Texas: http://www.ion.org/