Back in 2006 I reported on a $100 USB spectrum analyzer from Metageek LLC. The Wi-Spy 2.4x, a new enhanced version of the 2.4 GHz spectrum analyzer, is now available, but the cost has increased to $399. The Wi-Spy 2.4x is the same size as the newer DTV USB stick tuner and comes with an SMA connector and a small rod antenna similar to what you'd find on a wireless router. The spectrum is displayed on a computer.
While designed for use in installing and maintaining 2.4 GHz wireless network systems or access points and tracking down interference in the 2.4 GHz band, the unit's coverage from 2400 to 2495 MHz gives it enough range to detect 2.5 GHz broadcast auxiliary service signals on channels A8 and A9 (2450-2483.5 MHz) and much of the grandfathered channel A10 (2483.5-2500 MHz).
The Wi-Spy 2.4x input range is specified as –110 dBm to –6.5 dBm. The analyzer has a resolution of 328 kHz with a sweep time of 195 milliseconds.
The spectrum display is created using Metageek's Chanalyzer 3.1 software. The Chanalyzer 3.1 Web page has a picture of the display showing the conventional amplitude versus frequency analyzer plot as well as a "Topographic" view. A "waterfall" display makes it easy to analyze the 2.4 GHz environment over time. Information about the networks it's receiving, such as the SSID, is displayed in a panel to the right of the spectrum displays. A "signatures" sidebar makes it easier to identify the source of interference—an RFID reader, a microwave oven, X-Box 360, etc. The Wi-Spy 2.4x and Chanalyzer 3.1 software can be operated remotely over an IP network.
A lower cost version, the Wi-Spy V1, is available for $199. Major differences with the Wi-Spy 2.4x are an internal antenna instead of the Wi-Spy 2.4x's SMA jack and external antenna, less frequency coverage (upper limit is 2482 MHz), less sensitivity (–97 dBm instead of –110 dBm), worse amplitude resolution (1.5 dBm versus 0.5 dBm) and a wider resolution bandwidth of 1,000 kHz instead of 328 kHz.
The Metageek software requires Windows 2000 or newer, but Linux users can use Kismet Spectrum-Tools utilities to provide the spectrum and network information displays.
