Comparative Use of Unlicensed Radio Spectrum

Rob Flickenger

Metrix Communication LLC

Sharing the air

These considerations are important to keep in mind when using devices that operate using unlicensed spectrum.

Common 2.4GHz devices

Which common communication devices operate at 2.4GHz?

Other 2.4GHz noise sources

There can often be other unintentional noise sources that are not even related to communications.

Seeing the noise

Detecting interference

Tools you can use to detect interference on your network

Error packet counter

Watch for excessive errors on a network interface


Use Kismet to find local networks


Wi-Spy network analyzer

Tools are available from the Kismet project at

Spectrum analyzer

A good spectrum analyzer is usually the best (and most expensive) tool for detecting noise sources.

802.11b DSSS

Here is a DSSS signal from an 802.11b radio

802.11g OFDM

Here is an OFDM signal from an 802.11g radio

Two different OFDM cards

This is the output from two different 100mW 802.11g cards

Live demo

Watch the effect of these sources in real time.