http://www.iol.co.za/news/newsview.php3?click_id=79&art_id=qw956180101425B252&set_id=1
John Pike, director of space policy at the Federation of American Scientists, told the magazine that it was "simple" to jam the GPS, because the satellite signal is weak.
Yes, GPS relies on an enormous 63dB of process gain to overcome signal path losses and small receiver antenna gain. Because it uses direct sequence coding, jamming via simple CW signals is often the most effective. Having the jamming signal hop about in the passband can make active noise/interference methods less effective.
But he believed that the latest generation of global communications satellites would be immune to similar home-built equipment, as they are "heroically resistant to jamming". - Sapa-AFP
Yep, best to use the older analog transponders. Relatively simple to ride along with a high process gain signal (60dB or better) undetected, especially if care is taken to identify, in real-time, to identify those frequencies in the dowlink passband have lower power and adjust your uplink to fill them in. See http://www.patents.ibm.com/details?pn=US05029184
--Steve
