postal97321 wrote:

Sunday, October 17, 2004
Last modified Saturday, October 16, 2004 10:40 PM PDT


Ryan Gardner/Gazette-Times
Chris van Rossman's television sent out a distress signal that was
picked up by an orbiting satellite.


"All electronic equipment creates a frequency called a tempest," he
said. "Sometimes these frequencies emit low-level signals that are
close to the 121.5 MHz signal."

Mandrell has heard of this sort of thing happening with customized
computer gear. Sometimes CAP equipment will pick up these signals, he
said, but they are usually weak enough to ignore.



What exactly are these search and rescue people listening for? Wouldn't
an emergency beacon be sending some kind of intelligent signal, like SOS
in morse code, or some kind of RTTY? At the very least, a certain kind
of modulated tone. It seems to me that if they're going to chase after
every spurious signal that pops up on 121.5, no matter what it sounds
like, that's a recipe for failure. No wonder 90% of their hits are
false positives.