Matthew J Ghio <mg5n+@andrew.cmu.edu> said:

Switching frequencies rapidly to prevent triangulation is still the best defense.

Doug Merritt <doug@netcom.com> wrote in reply:

Think from the point of view of the spotters. They can look at a broad-spectrum scan, gradually eliminate known sources, and end up homing in on the remaining high power signals.

This is similar to the discussion of breaking advanced cryptographic techniques, comparing possibility to practicality. Sure anything is possible, given enuff resources. But the question is weather or not its feasible for them to try to track it down. If it takes them a month and costs them $10000 in equipment and salaries to track down one transmitter, then they haven't really accomplished much. I would say frequency switching would be better than a continuous signal spread across many frequencies. Here's why: Once you've locked onto a signal and try to triangulate, it's gone. After one transmitter has swithced off a certain frequency, another transmitter can use it. Multiple broadcast sources on a frequency give confusing readings which makes locating them difficult. Finally, why would the FCC or equivilent be trying to shut down such a network? Someone would have to complain first. And why would someone complain? They would only complain if the broadcast was interfering with their transmissions. This can be solved easily. While data was not being received, have the receivers monitor noise levels on various frequencies, and select only those not being used for transmission. This could be implemented without additional hardware, as we will already have an onboard computer for routing data, this would simly make use of idle time. (BTW many cordless phones already do this.)