I went to the trouble of downloading the .pdf from http://www.national.com/cgi.... the documentation source for National Semiconductors.
These guys, Linear, TI, and others routinely make 'evaluation boards' available for techies to play around with. There's a lotta jargon in it I dont understand, but it seems to use an IF around 156mhz, with various options to go all the way down to 13 mhz, or up to 300 something or other. I wont bother with it because it requires Matlab and win 9x to do anything with. But I find it noteworthy that it uses the com port to adjust the settings of the board. Noteworthy too, is that nowhere in the documentation does it mention RF rather than IF; but if you used an antenna/receiver to transfer RF to IF on a cable, I dont see how the board would know the diff. What strikes me about the design is how it appears to have chips that are capable of detecting the presence or absence of clipped waveforms in the megahertz range of signals that dont appear to be any stronger than what the AGC chips in your TV can detect. And that TV technology is 50 years old. But rather than working with an analogue image, it provides a 24 bit data stream. I suggest keeping this in the back of your mind, in case the sabotage software evolves enough to knock down the net, or in case the ISP providers all get so suckered by Microsoft that your SURVPC cant, like mine, logon any more. All you'd need is a wireless link, which could be 50km or more, to a PC that will listen to yours, and operate like a firewall for you.
