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The ASA install onto my WinXP SP2 notebook was uneventful, and while there's not a "wizard" to guide you through initial setup, it doesn't take long to get oriented and start playing around. When you first start the program after installation, it goes through an initialization process, then displays a Channel Summary (Figure 3) that shows RF actitivity detected in any of the ASA's currently-monitored bands.

Channel Summary

Figure 3: Channel Summary
(click image to enlarge)

You can customize the monitored bands by using the Monitored Bands settings (Figure 4), selecting from pre-defined bands or even setting up two "User Defined" bands of your own. Note that the "User Defined" band controls don't restrict you to valid setting ranges, and if you enter "illegal" values there's no warning thrown and you won't get the frequencies you set.

Monitored Bands

Figure 4: Monitored Bands

Clicking on the Spectrum button in the left-hand margin gives you your first look at a spectrum analysis display, which defaults to the Real Time FFT display, monitoring from 2.4 to 2.5GHz (802.11b/g) with all three Max, Max Hold and Average traces enabled. Figure 5 is a snapshot of my idle access point on Channel 6, which, of course, is sending out beacons. I liked the markers for non-overlapping channels 1, 6 and 11, but they can be turned off in case you prefer your spectrum view unadorned.

Default spectrum analyzer view

Figure 5: Default spectrum analyzer view
(click image to enlarge)

You can choose from twelve different plots in the Spectrum Analyzer, which are generated from various slicing and dicing of the thousands of FFTs performed each second. (An FFT is a mathematical calculation that takes analog-to-digital data of a waveform sampled at regular time intervals and converts it to a view of the amplitudes of the discrete frequencies that make up the waveform.) I'll be delving further in the Spectrum feature in the next section.

The third and fourth ASA functions are the Interferers display shown at the bottom of each screen and the Device Finder. ASA considers non-802.11 RF devices broadcasting in the same frequency bands as 802.11 devices to be Interferers. It automatically identifies Interferers without user intervention by analyzing various aspects of the captured spectra and logging them to the Interferers display. ASA can identify Bluetooth devices, microwave ovens, cordless phones and base stations, cordless headphones, wireless video extenders as well as continuous signal sources.

The Device Finder is basically an interactive signal strength / history display that you'd use to track down the physical location of an Interferer.

Device Finder

Figure 6: Device Finder
(click image to enlarge)

Figure 6 is taken from the ASA User Guide because my RF environment is pretty clean and the Device Finder can be used to find only active Interferers. I asked both AirMagnet and Cognio why the Device Finder couldn't be used to track down 802.11-based sources - which as we all know can also be sources of interference.

The answer both companies gave boiled down to not wanting ASA to overlap functions available in AirMagnet's other products, which handle device management and troubleshooting for devices emitting real 802.11 signals. I also got the sense, however, that since ASA is a 1.0 product, AirMagnet will be listening to customer feedback and possibly change their stance on this feature lockout.

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