Matthew J Ghio <mg5n+@andrew.cmu.edu> writes: [ several good points ] 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. Also, let's say you had a good design that cost the FCC a fair amount of bucks to design a specific detector using a targeted active filter, for instance. Then you'd be safe right up to the point where it's not worth their while, and the network grows, and then suddenly they invest the time and money to build something that can catch dozens of transmitters per day. In other words, you'd want something that still worked even given growth and success. Doug