eWeek - February 1, 2010

and microwave ovens. The main panel, meanwhile, shows separate graphs depicting real-time FFT and spectrum density across all the channels.

From a pull-down box at the top left, I could expand my analysis to other frequency bands. I could isolate detections to the lower, middle and upper ranges of the 5GHz bands individually (as well as the 4. 9 band), or I could conduct a mixed scan that cycled through all the bands.

Choosing the mixed option will change the default view to show the real-time FF T graphs for the 2.4GHz band and for each segment of 5GHz band. Users can adjust the views to showcase ample other analysis perspectives for each band, including channel power, channel duty cycle, interference power, and a new event spectrogram view that displays strength of interference of a particular device plotted over time and affected channel.

With Spectrum XT, I could also cull more information about Wi-Fi sources of interference when using the product with a supported Wi-Fi adapter. Armed with the Wi-Fi adapter, I could, from the base screen, detect the number of APs on a given channel, their MAC addresses and the received signal strength. I could also break down the number of clients and Wi-Fi phones on each channel.

There is also a series of Wi-Fi-spe-cific graphs that can be accessed via the main panel. Among the graphs, I could view channel occupancy ( targeting the primary channel and those affected by the transmitter), channel speed (the number of kilobytes sent at a particular connection speed on each channel) and per-channel traffic mix (unicast versus broadcast or multicast). I could also take a more device-centric view of things, identifying the busiest APs in the airspace or those needing the most retries.

I tested in conjunction with a Card-
Bus-based AirMagnet C1060 802.11
a/b/g/n card; a list of other supported
adapters can be found at http://air-
magnet.com/products/spectrum_
xt/. An unsupported adapter will
show some basic information about
the Wi-Fi environment culled from
Windows’ built-in Wi-Fi tools.

I liked the new Find Device tool, which somewhat eases the tricky process of tracking down non-Wi-Fi interferers. Intended to act a little like a Geiger counter would with radiation, the tool displays the current signal strength of the detected interference, constantly refreshing the value. Walking around slowly (AirMagnet recommends a snail’s pace of 1 meter every 3 to 5 seconds), the dial adjusts according to the detected signal strength, indicating whether I moved away from the interferer (weaker signal) or toward it (stronger signal). There are optional aggravating sound cues to help drive home changes in detected signal strength.

An on-screen dial displays both
the current strength detection as
well as the maximum detected value
during the session, while a time-
line plots the signal strength over
time. Device finding would be easier
with a directional antenna instead
of the included omni-directional
antenna, however, as users could
more easily home in on the direction
from which the signal emanates.

The tool can also be used to track down and locate Wi-Fi devices, although other tools are better suited to that activity.

Spectrum XT does integrate with other AirMagnet tools, including Analyzer Pro and Survey Pro, as long as those applications are installed on the same laptop.

In Analyzer Pro, enabling the connection between the applications adds an RF Spectrum Interferer box to the Interference tab. In tests, this allowed me to view some limited information on non-Wi-Fi sources of interference. While it would be handier to extend the coordination between applications to the visual walkabout tools like those in Survey Pro—to tie non-Wi-Fi interferer detections to both a place and time on a map in case further analysis is needed after the analysis session—that level of integration is not yet possible.