On Fri, 1 Apr 2011 08:04:16 +0100, "Fred Burnett Preston UK"
>I'm trying to understand the fundamentals of Wi-Fi.
There are numerous web sites that explain how wi-fi works. This is
kinda scraping bottom, but it's a fair start:
>So far I have
>ascertained that the 2.4 GHz band is divided up into 11 channels in Europe,
The number of channels varies by country. Some countries have 14
channels, most have 11 channels. There are also differences in
allowed power levels and EIRP (radiated power).
>and because several routers can work on the same channel in the same area, I
>have come to the conclusion that the rf carrier is switched on and off every
>time a packet is transmitted, as in packet radio.
Correct. It's a simplex system. The radio is either in transmit or
receive at any given time. Never both.
Also, like packet radio, there are long periods of time between
transmissions. This is to allow other users of the channel to find
some "air time" to operate. In other words, a single system cannot
monopolize a channel.
>I can access my router and
>change its channel, hence its frequency, but I have yet to find an option
>using Windows 7 that allows me to change my adapter channel.
You won't find one. In Infrastructure mode (that's the one using an
access point or wireless router), the operating channel is controlled
by the access point. The client radios just follow. If you change
the access point channel, the clients will scan for a suitable access
point, find the new channel, and reconnect.
However, in ad-hoc mode (also known as peer to peer mode), there is no
central controlling access point. The channel must therefore be set
individually by each client radio. If you want to change channels,
you have to change the configuration in every client radio in the
>wireless adapter can see several routers within range and therefore is
>capable of receiving a band of frequencies/channels, what determines the
>channel it transmits on.
The client is scanning *ALL* the channels before making a connection.
When you see a list of available access points, they're on any of the
11 channels. Once the client connects to a given access point, it
stops scanning, and uses just that channel.
>Does it automatically switch to the same channel as
>the router it attempts to connect to?
Jeff Liebermann firstname.lastname@example.org
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558