In Use

MetaGeek completely revamped the Wi-Spy software around the beginning of 2007, dubbing it Chanalyzer. Chanalyzer requires Microsoft .Net 2.0 to run on Win 2000, XP or Vista. The installation disk also comes with Linux and Mac OS Beta software. But you should visit MetaGeek's Third-party Applications and Chanalyzer pages to make sure you get the latest versions.

The file format for Chanalyzer's record and playback features has changed from CSV to a proprietary "WSR" format. But MetaGeek has documented the WSR file format so that third party apps can be developed to process it. In case you think your captured session is worthy of sharing, Chanalyzer has buttons for sending a captured file to MetaGeek or to a friend. If your capture makes the cut, it might get included in the MetaGeek Recordings library.

The Cognio product still beats Wi-Spy in frequency coverage, data views, signal range and plotted frequency resolution. But the 2.4x is significantly better than the original and still significantly less money than the Cognio, even at $400 (vs. almost $4000).

Figures 2 - 4 show how the Cognio, original Wi-Spy and Wi-Spy 2.4x display the same 802.11g signal on Channel 6. I produced the test signal with a Linksys WRT54G router and WPC54G client and running IxChariot's throughput script continuously sending data between the client and AP. I suggest you open all the larger versions of all three images to really examine the differences.

Figure 2: Cognio Spectrum Expert - 11g Ch 6

As expected the Cognio still displays the sharpest traces due to its high resolution bandwidth and frequency resolution. I think the fact that Cognio doesn't fill the area under the traces as Chanalyzer does also helps to make the traces appear sharp.

Figure 3: Wi-Spy original - 11g Ch 6

Figures 3 and 4 show Chanalyzer's three views, Planar, Spectral and TopoGraphic, using the original and 2.4x Wi-Spy versions respectively. The Planar view corresponds to the original Analyzer view, which shows the classic "spectrum" amplitude vs. frequency view.

The Spectral view is the same as the old Spectrograph view, which shows a "waterfall" graph of amplitude over time for each frequency, with dark blue representing low amplitudes and bright red representing high amplitudes.

Figure 4: Wi-Spy 2.4x - 11g Ch 6

I'll let MetaGeek explain the new TopoGraphic view:
"The Topograhic View contains an amplitude over frequency graph similar to the Planar View, but instead of showing the current amplitude of each frequency it shows the popularity of each frequency/amplitude coordinate during the time displayed. The coloration of the Topographic View is similar to the Spectral View with blue being low and red being high, but the coloration now represents the "popularity" instead of the amplitude."

You can, of course, close each view to provide room for the others to expand.

In examing the plots, you'll once again notice different amplitude results for each product. The Cognio registers about -77 dBm maximum near the middle of Channel 6, while the original Wi-Spy comes in ~ -50 dBm and the 2.4x at -54 dBm.

It's hard to directly compare the three products since they don't allow you to change resolution bandwidth or sweep speed, which directly effects the amount of energy seen in each frequency "bin", which in turn effects the displayed values. But since the Cognio has the highest resolution bandwidth, its displayed amplitudes will be more representitive of the actual signals.

Tags: MetaGeek, Spectrum Analyzer, WiFi, Wireless Reviews,

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