Diagnose WiFi Problems With a Spectrum Analyzer
Instead of doing a localized version of warwalking around your business and manually running though all the wireless channels in different locations, the easiest and quickest way to get an overview of what is happening with your wireless network is by using a spectrum analyzer. A spectrum analyzer can give you a visual representation of the complete wireless network spectrum, showing you which channels are being used by nearby wireless access points and which frequencies are subject to interference from nearby electronic devices, such as cordless phones and microwaves. Typically, spectrum analyzer-based solutions, such as from companies like AirMagnet, can easily cost several thousand dollars. But Boise, Idaho-based MetaGeeks has been offering a number of relatively inexpensive solutions--as low as $199--for the last few years now, and it has just released its first dual-band solution that analyze 802.11n wireless networks, the Wi-Spy DBx spectrum analyzer, which costs $799.
The Wi-Spy DBx uses a dual-band (2.4GHz and 5GHz) antenna that can analyze 802.11a, 802.11b, 802.11g, and 802.11n wireless networks. It can sample the 2.400 to 2.495 and 5.150 to 5.850 frequency ranges, has a frequency resolution of 24KHz to 3MHz, a resolution bandwidth of 53KHz to 600KHz, an amplitude range of -100dBm to -6.5dBm, and an amplitude resolution of 0.5dBm. The antenna is a small USB device and it comes with MetaGeeks's Chanalyzer software (which works with Windows 2000, XP, or Vista, and requires that .NET 2.0 or above be installed).
Chanalyzer provides three different views: a spectral view, which "highlights bandwidth use over time;" a topographic view, which "shows the density of the spectrum by plotting the percentage of activity for each frequency and amplitude over a selected time period;" and a planar view, which "shows the density of the spectrum by plotting the percentage of activity for each frequency and amplitude over a selected time period." With these three different views, you can identify which channels suffer from the least amount of interference, if there are nearby access points that are interfering with your network, and can even help identify what kind of electronic devices are interfering with your network by providing sample "signatures" for devices such as cordless phone and wireless mice. Chanalyzer even includes a lightweight remote host module that will let you remotely connect to a Wi-Spy device as long as the system with the attached Wi-Spy device has an IP address that is accessible from the remote system.
While you don't necessarily need to know how to read the visual charts created by a spectrum analyzer, having that kind of knowledge ahead of time will get up to speed much faster. Users who are new to using a spectrum analyzer would be well-served by thoroughly reading the product's documentation as well as spending some time perusing the many helpful FAQs and forum posts on the MetaGeek Website.