Spectrum Analyzers for Wi-Fi: Everybody Needs One

You ever wonder where the previous week went? The previous quarter? The previous year? I do all the time. I like to write off this phenomenon as a side effect of being always busy, that itself a key element in being a workaholic. I am trying this year to be a bit less of that, with limited success so far, but I still wonder where the time has gone.

So, it's time, then, to note that last week Network World published the latest in my series of tests of various Wi-Fi management tools, this time on spectrum analyzers. I remember back in the early days of Farpoint Group (around 1995 or 1996, in this case) meeting with the big test-equipment companies like Tektronix and HP (now Agilent), and asking if (pleading, really) it might be possible to build a portable (ideally handheld) spectrum analyzer just covering the 2.4 and 5 GHz. bands. Sure, they said, maybe in a few years. But the price would still be well above US$20,000, and thus well beyond what most enterprises (and, I assume, essentially all analysts and consultants like myself) could afford. Still, I had hope: why couldn't the faster/better/cheaper inherent in VLSI be applied to test equipment? Even in small volumes (thousands), a cheap(er) spectrum analyzer seemed like a real possibility.

Flash forward to (if I recall correctly) 2004, when Cognio (now part of Cisco) announced a PC card and associated software that could turn a notebook PC into a credible, dual-band mobile Wi-Fi spectrum analyzer. I used this product to do a large series of studies on the effects of interference on a variety of Wi-Fi applications, including voice and video, and it worked great. And at about US$4,000, it was very affordable; I bought one, and it paid for itself in very short order. I recommend that any enterprise Wi-Fi installation of any size (and certainly those with at least tens of APs running mission-critical apps) own a spectrum analyzer to monitor for both intentional and unintentional interference.

The Cognio descendents, from AirMagnet, Cisco, and Fluke Networks, as we saw in the testing, remain excellent choices. But there are less expensive options, as well as products already packaged in highly-mobile Pocket PC and UMPC platforms. Someone commented that an extremely inexpensive (US$39) spectrum analyzer (which I didn't test, or even know about) is available from Wi-Fi products vendor Ubiquiti. This looks a lot (suspiciously) like the early Wi-Spy product (see the test), which was and remains pretty good for basic spectral analysis. Ubiquiti's Web site notes other models as well.

Anyway, spectrum analyzers are going to be a big business going forward. The most important development here will be the incorporation of spectral analysis into Wi-Fi infrastructure, either within APs (some Wi-Fi chipsets provide suitable output in addition to serving their required communications functions) or in dedicated sensors. Both of these approaches are valid, and both have pros and cons. But the point-product spectrum analyzer will also prosper, especially in small businesses and within the installer/consultant community. If you don't have one now, you will. I'm glad I was so persistent in begging all those years ago - this is one technology that I, anyway, can't live without.


Copyright © 2009 IDG Communications, Inc.

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