Re: Spread-spectrum net (vulnerability of)

[tcmay@netcom.com (Timothy C. May)]

Doug Merritt writes:

> On the other hand, this particular approach to spread spectrum is
> mostly depending on avoiding getting the FCC annoyed in the first place,
> which means that bandwidth consumed per unit metropolitan area must be
> below some particular threshold. If that net became very popular, it
> might be difficult to hold down to the required level.
> 
> If the FCC *did* go after the transmitters, it wouldn't cost them anything
> like $10K per to find. Well, I dunno, I suppose you could assume that
> the transmitters are awfully hard to distinguish from ambient sources,
> but it would take more than handwaving to establish such a high cost to
> the FCC. I'm willing to believe some such design is possible, but I
> wouldn't want to leave it to chance and oversight.

Reports in newspapers I've just been reading about the search for
"Warlord" Aidid in Modadishu indicate that tracking "low-tech"
transmitters (low-power walkie-talkies, small radios) has been a real
problem for the military, the CIA, and the NSA.

This week's "Newsweek" reports:

"Why can't Mohammed Farah Aidid be captured?...Aidid rarely talks on
the radio, preferring messengers. The Pentagon tries to use signal
direction-finding equipment to home in on his propaganda broadcasts.
But Aidid usesa mobile, low-power transmitter, turned on erratically,
making it impossible to fix his position. "Low tech is baffling high
tech," says a Pentagon aide."

("Newsweek," 10-18-93, p. 38)

Now this does not disprove Doug's point...I just submit it as evidence
that the combined forces of the CIA/military/NSA/etc. are probably
spending a whole lot more than "$10K per" and still can't find the
transmitters reliably.

Given many thousands of low-power transmitters, complying with "Part
15" FCC restrictions (i.e., down near the noise level of equipment and
consumer radio devices requiring no licenses), and given dispersion in
hundreds of cities, including some "just across the border" in Mexico
or Canada, and I'd expect few busts.

(And if the transmitters are really Part 15, what would be the grounds
of the bust? After all, computers put out RF at these levels, as do
many other sources.)

Food for thought. 

--Tim May


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