I was trying a couple of
tricks: The modulation was made of two random tones with a 50 ms
duration, then a new set of random tones for 50 ms, etc. (The Basic
Stamp controller can produce two different tones at the same time.)
Furthermore, the power output was changed every 1/2 second, selected
randomly from 7 different levels between 20 mW and 8 W. The power level
was kept at full during the first 15 minutes of the hunt.
The idea was that the tones would confuse Doppler's and the power
fluctuation would make people think the T was farther away than it was
and would make the close-in hunting problematic.
After talking to people, it seems the tones made life a little more
"interesting" but not seriously so. And the power fluctuation caused a
few raised eyebrows, but not a big problem. The close-in hunting went a
little slower, but if the hunter was careful and paid attention, they
didn't seem to have much trouble.
The ID was transmitted at 7.5 minute intervals as simply as possible:
at full power and with no other tones. I figured if someone were really
having trouble, there was at least the hope of getting better readings
during the ID.
The location (south end of Fremont, near the bay) was picked to make
people think the T could possibly be in Alviso (as seen from the start
point). Apparently that worked to some extent too, most people reported
going down at least as far as Dixon Landing. The antenna was placed next
to a major PG&E metal pole so as to shield it from the freeway, but not
the start point. My field strength meter indicated the signal on the far
side of the pole was an order of magnitude lower than on the T's side.
So, my tricks worked to some extent, but there's room for
improvement. It was a "first version" anyway.
73, Gary
