Peter wrote in message ...

Doug Carter wrote

Keep in mind that GPS is a broad band spread spectrum waveform, not a
narrow band FDM channel like a VOR uses.

GPS is a narrow band signal.

One implication (and the
principal reason military customers like spread spectrum system) is the
difficulty in jamming. Depending on the coding gain and distance it
takes a lot of transmitter power. However, power amplifiers (even at L
band) are commercially available so it can be done.

1 watt at 30,000 feet (e.g. hanging under a very low cost baloon) will
jam GPS over a radius of about 500 miles.

Reference already discussed in this thread.


Peter.
--

http://www.mayflowercom.com/testresults.htm

a recent Lincoln Laboratory study (Gilmore and Delaney [2]) indicated that
a modest 1 W in-band interference source may deny C/A code receiver
operation up to a range of about 85 km.

I get 53 miles.

These guys say you are off by a factor of ten.