On Tue, Jan 30, 2007 at 03:48:18PM -0500, Robert E. Seastrom wrote:

Lucy Lynch <llynch@civil-tongue.net> writes:

...

and hard to read... http://www.ntia.doc.gov/osmhome/allochrt.pdf

I had the same reaction at first. Incidentally, you can get this for cheap from the GPO. I have it on my wall as "reference art". It came in handy the other day when looking for the possibility of interference between cell phone and wifi.

different frequencies of RF have different performance characteristics. unlike ip addresses, a 1 mhz allocation at 180 mhz and a 1 mhz allocation at 6.5 ghz are not fungible.

Plus, large installed bases; xceivers for different frequencies are not always interchangable, even with PLL/xtal changes. But yeah, any HAM can tell you that different bands do different things... some bounce off the ionosphere (shortwave/HF) and some penetrate walls better than others (low frequencies). Some are refracted and diffused by rain, and some aren't, etc. Heck, some can be bounced off the moon (it's called moonbounce, but don't expect anything but morse to be understandable). I think I read somewhere that the USS Liberty SIGINT ship had a large dish for this kind of communication (makes direction-finding fairly difficult). As a consequence, you find bands for "radiolocation" (RADAR) and "mobile radio" and such spread all over the place. If you're 300 miles from civilization, and it's raining, and all the "mobile radio" bands were in the range ruined by rain, and someone suffered a life-threatening injury, that would be "bad". There are a lot of lobbyists and vested interests in allocation fights, but I think that's a smaller factor than the others mentioned above. -- "That is not dead which can eternal lie, and with strange aeons even death may die." - H.P. Lovecraft, The Call of the Cthulhu <URL:http://www.subspacefield.org/~travis/> -><- dharma <>< advaita For a good time on my UBE blacklist, email john@subspacefield.org.