Beating the wireless blues
- — 09 April, 2004 15:00
Banish wi-fi black holes
In its tests, the Wi-Fi Alliance determined that your PC's wireless card can talk to a gateway that's situated 40 to 60 feet away within a home, and 60 to 80 feet away in an office. That range is smaller than the theoretical 150-foot radius promised by some Wi-Fi manufacturers.
You can't do much about the main problem -- interference that is caused by interior walls, floors, or even those walking bags of signal-absorbing water we call human beings. But the antennas on your gateway can cause trouble, too. Even the best antenna can't radiate a perfect sphere of signal strength.
In these situations, you can move your gateway, or you can buy one or more new antennas. Before deciding on a course of action, however, you need to measure the strength of the Wi-Fi signal around the dead spot -- a place where you want to use a computer, but can't. For example, a survey might show that you can get a signal at one end of your dining room table, but not at the other, and that you could solve the problem just by moving your chair.
The utilities that accompany many Wi-Fi-enabled notebooks or cards include a rudimentary signal strength meter, but they rarely give enough data to perform real troubleshooting. With the help of NetStumbler, a free application, you can temporarily turn your laptop (or Wi-Fi-enabled Pocket PC) into a slick Wi-Fi signal analysis device that scans the frequencies used by Wi-Fi devices. The program lists all the nearby Wi-Fi devices it detects, and the precise strength of the signal you can receive.
NetStumbler is a little fidgety, however: It doesn't work with all models of Wi-Fi cards, and there's a steep learning curve to using it. An alternative is Smart ID's WFS-1 WiFi Detector (US$25); like NetStumbler, it displays signal strength in the 2.4-GHz band. The WFS-1 is a handheld sensor about the size of a deck of playing cards, and it contains four LEDs that display signal strength while you hold down a button. Because it's directional, it can even help you figure out if a non-Wi-Fi device (like your microwave oven or a cordless phone) is the source of your problems -- something that NetStumbler can't do.
Once you've ruled out obvious potential sources of interference, your next step is to move your gateway around, if at all possible -- and ideally, closer to the dead spot. Pay special attention to the gateway's spatial orientation; even so-called omnidirectional antennas can be highly directional, so that a gateway hung on a wall might send its signal into the ceiling and floor. Each time you reposition the gateway or antenna, recheck the signal strength where you want to receive a signal.
If moving or reorienting the gateway or its antennas doesn't solve your problem, you may be able to use a different antenna. Apple Computer Inc., for instance, sells two antennas for its AirPort Extreme Base Station. Some companies make high-quality antennas -- such as the SuperCantenna ($50) -- that can work with any gateway, but there's a catch: Though you can legally purchase third-party antennas that will work with your gateway, FCC rules don't allow you to use antennas not specifically designed for your manufacturer's equipment. To our knowledge, nobody's ever gotten in trouble over this, but breaking the rules might pose problems someday.