SA's purpose is NOT to reduce the accuracy of the cheap-and-cheerful
GPS  receivers of mere mortals.  It is intended to prevent just
anybody adapting accurate GPS to weaponry.  L1/CA with SA and with
DGPS does  *NOT*  make a system suitable for the dynamics of weaponry.
This is commonly misunderstood.

See: http://www.navcen.uscg.mil/gps/policynotes/default.htm
     http://www.navcen.uscg.mil/cgsic/meetings/summaryrpts/30thmeeting/aii/tsld013.htm
     http://earth.agu.org/revgeophys/yunck00/node9.html
     http://www3.hmc.edu/~kjurka/physics/sa.html
     http://www.cnde.iastate.edu/staff/swormley/gps/check_sa.html
 

______________________________________________________________________
Sam Wormley - http://www.cnde.iastate.edu/staff/swormley/gps/dgps.html

 See the OFFICIAL USA POLICY on SA and GPS HERE.