Message-ID: <40A1EEF5.21854.37C481@localhost>
From: cta at hcsin.net (Bernie, CTA)
Subject: CHANNEL FREQ'S

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@...in.net
Chief Technology Architect / Chief Security Officer
Euclidean Systems, Inc.
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// "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>      
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