Wi-Spy 2.4x Spectrum Analyzer Review

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I took the opportunity to test MetaGeek's new Wi-Spy 2.4x product and Chanalyzer software.   The Wi-Spy 2.4x is a USB based 2.4Ghz spectrum analyzer with SMA connector.  The connector can be used to attach a directional antenna for long range outdoor surveys, to pinpoint a indoor source of interference or even locate a rogue access point or client device.   The Chanalyzer software has a Wi-Fi channel report that can help you pick the best channel for your access points based on the noise level.  It can also display the WiFi channels and highlights the frequency occupation.  This give you a good idea why you must not use overlapping channels for WiFi deployment.  Although there are free tools available such as netstumbler to find WiFi access points broadcasting a SSID  there are many non Wi-Fi devices that occupy the 2.4Ghz spectrum that can only be detected by a analyzer.  The Wi-Spy 2.4x would be a great tool for the wireless ISP or Hospitality industries during installs or to troubleshoot problems.  Having a tool like this with you will save time and money in return site visits

We used the  Wi-Spy 2.4x to show the power advantage of the 400mW EnGenius ECB-3220 over a 31mW Linksys WRT54g.  Power is one of the important factors that determines WiFi range and signal quality.  The other being receiver sensitivity where the ECB-3220 also has the advantage at up to -88dBm over the WRT54g's -80dBm.

For the test we used  IxChariot to saturate the link and set the access points to channel 11 mixed mode.  Only one access point was powered up during each test.  Each access point has the stock 3dBi antenna.  The laptop was using a 100mW 802.11 abg EnGenius 5354CB.  I located the laptop 3 feet from the access points on the same plane.

400mW 26dBm ECB-3220 on extreme power setting.


Linksys wrt54g 31mW 15dBm

Although we had no known RF  power source to calibrate the reading against and accurately equate dBm to mW we can clearly see a large difference.  Peak reading were both in the -40dB range but that amounts to only a small fraction of the packets sent during the transmission.  If we look at the average power reading for both plots we can see the ECB-3220 has a dramatic difference of ~23dBm over the wrt54g throughout the channel 11 frequency occupation.