Full Disclosure mailing list archives
Re: CHANNEL FREQ'S
From: "Bernie, CTA" <cta () hcsin net>
Date: Wed, 12 May 2004 09:31:33 -0400
On 12 May 2004 at 7:27, Tyler, Grayling wrote:
Geqqam69200, I've seen a few people refer to the lower 6 channels of wireless as operating in the Ham freq. spectrum. I am a bit confused where this is coming from as 802.11b operates in the ISM (Industrial Scientific and Medical) band. This band (~2.4 GHz) is used by 802.11b to transmit using spread spectrum signals so technically speaking all channels are sent in the same frequency band. I have always been under the impression that the channels simply referred to the code necessary to retrieve the spread spectrum signal sent.
<<< This is not true. 802.11b uses the unlicensed 2.4 GHz band which in the US ranges from 2.410 to 2.4510 GHZ. This band, in the US, is divided into 11 channels, each rooted on its own center frequency with overlapping sidebands. i.e Channel 1 = 2.4010 (Bottom) 2.4120 (Center) 2.4230 Top Channel 2 = 2.4060 (Bottom) 2.4170 (Center) 2.4280 Top Channel 3 = 2.4110 (Bottom) 2.4220 (Center) 2.4330 Top Channel 4 = 2.4160 (Bottom) 2.4270 (Center) 2.4380 Top Channel 5 = 2.4210 (Bottom) 2.4320 (Center) 2.4430 Top Channel 6 = 2.4260 (Bottom) 2.4370 (Center) 2.4480 Top Channel 7 = 2.4310 (Bottom) 2.4420 (Center) 2.4530 Top Channel 8 = 2.4360 (Bottom) 2.4470 (Center) 2.4580 Top Channel 9 = 2.4410 (Bottom) 2.4520 (Center) 2.4630 Top Channel 10 = 2.4460 (Bottom) 2.4570 (Center) 2.4680 Top Channel 11 = 2.4510 (Bottom) 2.4620 (Center) 2.4730 Top
If I'm wrong in my assumptions I'd like to become more educated. To that end I'd appreciate you (or anyone) posing the reference stipulating that the lower channels are in the Ham frequency spectrum while the others are not. Thanks
<<< Well, under FCC part 74 "Broadcast Auxiliary", ENG or Electronic News Gathering video links overlap 802.11b channels in the range of 2.450 - 2.467 GHz, and; There are aviation services operating pursuant to FCC part 87 in the range of 470 MHz - 2.450 GHz which overlap 802.11b channels, and; Under FCC rule part 90, licensed Land Mobile Radio services frequencies overlap 802.11b channels in the range 2.450 - 2.483 GHz, and; Amateur Radio frequencies under FCC Part 97 overlap 802.11b over the range 2.390 - 2.450 GHz which involve channels 7,8,9 and 10, and; There is also an overlap under FCC part 101 for licensed LTTS and POFS services which range over 2.450 - 2.5 GHz, and channels 9 and 10 of 802.11b, and Finally, the US Government under NTIA/IRAC clause, the US Gov can use the entire range allocated to 802.11 for what it dubs radiolocation or radionavigation uses, blasting high levels of EIRP. Bottom line is that spectrum is full of noise and one must learn to talk to loud yet find a way to punch through. - -- **************************************************** Bernie / cta () hcsin net Chief Technology Architect / Chief Security Officer Euclidean Systems, Inc. ******************************************************* // "There is no expedient to which a man will not go // to avoid the pure labor of honest thinking." // Honest thought, the real business capital. // Observe> Think> Plan> Think> Do> Think> ******************************************************* _______________________________________________ Full-Disclosure - We believe in it. Charter: http://lists.netsys.com/full-disclosure-charter.html
Current thread:
- CHANNEL FREQ'S Tyler, Grayling (May 12)
- Re: CHANNEL FREQ'S Konstantin Gavrilenko (May 12)
- Re: CHANNEL FREQ'S Bernie, CTA (May 12)