On a very hilly road called San Juan road, way up at the end of Steven's Creek
in Cupertino, was this huge house where I live. I'm Pedaling up that steep hill to
get home to try some new programs I found, which was really getting me in shape.
:-)
I lived in a small room in the basement, and despite the heat from the summer, my
room remains 20 degrees cooler. I was deep in the design of the really simple voice
scrambler in "Analog land". This means I was using all analog circuits
to make the voice completely unintelligible.
I was also working on my Fast Fourier transform program I needed to analyze the spectrum.
My heavy computation on Cleo would sometimes have Alex call me to suspend my program
because it was working the CPU so hard. With this program, I was able to find certain
"edge points" in the curves which had to be removed somehow. Using the
computer, I could tell if certain theoretical ideas would actually work in the real
world. My problem was that Cleo's limited number range of 10 X 10e-34 to 10e34 was
really not adequate for more than 7 or 8 "nodes". I was always getting
"Singular Matrix" errors, especially where the circuitry was getting into
the "Unstable" range. This was quite good, because it also warned me that
circuit "Stability" was un-predictable, so I would ditch that design and
try another.
I was constantly scouring a lot of Tom's engineering magazines, looking for basic
programs already written that might be useful for EE applications. Tom was most helpful
and often would come down and hand me a Xeroxed copy of a BASIC program.
Because I was up on a hill, I studied the radio spectrum between 400 and 420 MHz,
which was used by the government and I often spent hours monitoring the FBI and FCC
which used those frequencies and commercial scanners couldn't go into that territory
without modification.
I recall 411.683 being the most active channel. Tom was experimenting with "Spread
Spectrum" technology which was just becoming in use.
Back then, it was not illegal to listen into any frequency. If anyone didn't want
you to listen in, it would be scrambled. There was NO cellular phones back then.
There was GTE's IMTS, which had limited "channels" covering a wide area.
It used 156 MHz, and was a constant source of phone credit card numbers that were
freely given on the air. This was the MAIN method used when the credit card "Check
digit" changed every year. Enough valid credit card numbers were given out that
within hours, they would have the code.
If the 5th digit was a 1, the letter would be "E", if 2, letter would be
"P", and so on. The Phone Co. didn't have a computer to verify credit card
numbers in those days of the early 70's. Anyone could manufacture a credit card number
to a corporation (usually one that isn't environmental friendly like Boise Cascade),
and rack up lots of free calls before someone in accounting notices it. There was
no TSPS (Now currently outdated) so operators were required to take down the credit
card number and authorize the call to go through.
I also designed some really sensitive receiving equipment and hooked it up to the
HP Spectrum Analyzer and fed that to the computer to analyze the spectrum use. If
any radio station went on the air, it would immediately detect it, and was invaluable
in identifying special transmissions normally not noticed. We also had some pretty
neat DF gear (Direction finding), and I was able to identify which direction the
signal came from. I could see clearly out over the entire silicon valley with a 120
degree view. If it was transmitted and over 100 milliwatts, and within a 50 mile
range, the equipment would detect it. I heard numerous pirates, tracked a few of
them down just to see and meet them.