WiFi Detector

Model: WFS-1
Price: $28.00 (plus $10 shipping)

Pros: Geiger counter-like function
Cons: Doesn’t tell you if nodes are open

A very specific category of the Wi-Fi product market has eluded review here for a while, that of the inexpensive “Wi-Fi detector.” Kensington, famed for locking down laptop PCs, has one but never sent it to us. We’ve reported on people building them into clothes and handbags, but I had not seen one up close until this week.

Direct from SmartID in Singapore comes the aptly named WiFi Detector, a small rectangular unit about the size of a pack of cigarettes that weighs less about 1.5 ounces. The blister pack it came in calls it the “Ultra Sensative Instant WiFi Detector” and claims it can find a Wi-Fi network in the 2.40-2.48GHz frequency bands (either 802.11b or 11g) within 200 meters outdoors, and 50 meters indoors. It even came with two AAA batteries (the other copper tops: PowerSonic Ultras).

Here’s how it works: The back of the unit is really the directional antenna — point it where you think the RF signal would be. There’s a single button on the front of the unit that you push and hold down. A green light indicates if your batteries are up to snuff. A series of four flickering red lights indicate signal strength. No lights mean there are no Wi-Fi radio signals present. Four lights mean you’re in the presence of a very strong signal.

Because of the directional nature of the antenna, it can act as a sort of Wi-Fi Geiger counter, leading you in the direction of the nearest access point. The lights usually blink when detecting 802.11 signals, but stay steady for other signals like microwave ovens (they might appear steady in the presence of an extremely strong Wi-Fi signal, as well).

And it works like a charm, exactly as advertised, no more, no less.

In my home, where the access point is in the basement, the signal was strong on the first floor, a little weaker on the second. At the local mall, it definitely knew the local Borders Books and Music had a T-Mobile hotspot inside, and it found a couple of other access points, as well.

That’s all well and good, but the Detector doesn’t tell you if these networks are open or closed. You don’t know if security is turned on, you don’t know if you’ll be directed to a “walled garden” page at a hotspot, you don’t know if the density of users at the access point might prevent you from logging on. All you know is there’s an RF signal nearby. In essence, the detector can’t give you any indication at all if it’s worth whipping out your laptop to try the connection — you won’t know until you actually whip out your laptop and try the connection.

However, if you know there’s a hotspot available and you want to position yourself to get the best signal — all the better to download high-bandwidth movie trailers on your lunch hour — the Geiger counter aspect of the WiFi Detector lets you sweep an area to see where the best signal is, taking you as close as possible to the access point.

The WFS-1 unit also makes for a quick and dirty security device. I found out that my Wi-Fi signal does indeed travel outside of my house (but someone would have to park in my driveway to get a signal). For locations that don’t want any Wi-Fi network at all, the Detector could be the first and cheapest line of defense against rogue access points.

This unit is definitely not as thorough as a true site survey tool or RF detector you can get from companies such as AirMagnet or Berkeley Varitronics Systems, which can not only detect signals, but analyze them. Even an 802.11-equiped PDA with Netstumbler will tell you more. But, none of the above cost only $40.

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