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Distinguished Sage
Distinguished Sage
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Message 21 of 22

Re: R e: Wi-fi dropping and range radically reduced - Hub4

I would expect the carrier detection would be restricted to a fairly narrow bandwidth, around the centre frequency, but you would have to delve into the design of the radio chipsets in use, and I expect there is quite a variation between manufacturers.

 

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Gary_C
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Message 22 of 22

Re: R e: Wi-fi dropping and range radically reduced - Hub4

Looking at the specification for CSMA for wifi it has a function called Clear Channel Assessement which has two components Carrier Sense and Energy Detection. CS seems to be a simple read of the channel and read in frames that another source is producing when it can read the length of the packets and predict a clear channel. ED looks at any noise on the channel and decides if it's low enough to allow a transmission, so in theory, an adjacent channel, if it couldn't actually read the frame, would still be detected as busy by ED, so it looks as if it can do CSMA with overlapping channels, just not as efficiently. Which also makes sense I suppose. Not sure how effective CA would be, need to think about that bit.

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