On Wed, 8 Aug 2012 08:08:49 -0700 (PDT), bob smith
>Is there such a thing as low-power Wifi?
Sure. Some of the devices that have wi-fi built in have a very
limited range. For example, the SD card for cameras:
>I want to create a WAP that has maybe a 10 or 20 foot range. Is that reasonable?
I've been doing that at coffee shops for years. Just use a terminator
for an antenna and you'll get some limited range. It really depends
on the unit. Most AP's have two antennas. However, the one's with a
single antenna usually also have a 2nd antenna inside the box. Usually
that's a PIFA PCB antenna or chip antenna. Don't try to just unplug
the outside antenna, as there's a huge difference between the MAIN and
AUX antennas. The AP sits on the MAIN antenna all the time, unless
the error rate gets high enough to justify trying to use the AUX
antenna. If you just use the AUX antenna, you'll have really lousy
association time and erratic disconnects as the AP keeps trying to use
the MAIN. Fortunately, you can disable diversity in firmware such as
A few years ago, I worked on a project that was designed to restrict
the USABLE range of a coffee shop wireless to only the floor area. I'm
required to keep my big mouth shut on how it works, but I can assure
that I can measure range and block users outside the usable range.
However, it was expensive and somewhat messy.
A half-posterior approach that almost works is to use two access
points. One is just a monitor, while the other actually does the
connecting. By comparing the relative signal strengths for a given
MAC address, you can calculate a tolerable guess as to the location.
If the numbers are outside the acceptable limits, they get blocked
until it either recovers to acceptable limits, or disconnected if it
stays outside the limits.
Jeff Liebermann email@example.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558