Metageek makes the WiSpy series of WiFi analyzer devices. We are going to use one to look at potential interference with our WiFi network from other radio sources.
These are the Wi-Spy DBx3 and 24i USB devices. When you purchase a WiSpy you will receive a license code for the Chanalyzer Windows application. Spectrum Tool has fewer features and works on Linux.
Install spectools from your package manager. We can launch from GUI or type $ spectool_gtk in your CLI. Open Device and you will see WiFi channel bands. The Wi-Spy 24i only works in the 2.4 GHz range. If there is no suitable device the menu will say so. Remember that 1GHz is 1000MHz we will switch back and forth.
Now we see a display of what the Wi-Spy sees in this spectrum. Spectral View is a waterfall display and it shows signals as they come and go. Topo is a topological view. Planar View combines the peak and average power.
Spectrum Tool shows the channel numbers for the 2.4GHz WiFi channels. Click the triangles to collapse a view.
Right click and uncheck peak and average so the display is only the current signal. Turn on a bluetooth device or find a wireless mouse. Put something in the microwave oven. You will see a burst of activity in the 2.4 GHz microwave band.
Detect InterferenceThese Audio/Video sender devices transmit analog video. The 2.4GHz sender interfered with bluetooth and wifi during testing and my devices disconnected.
Turn on the 2.4GHz AV sender and we see the signal immediately with the Wi-Spy. Find the channel selector switch on the sender and change settings. Our bluetooth, logitech and cable had interference because they share this band of radio frequencies.
The manual for the 5GHz sender says its lowest channel is 5790MHz. Let's see if it shows on our Wi-Spy. You will see a different spectrum shape if you connect audio and video.
According to the FCC this sender has 4 channels at 5790MHz, 5828MHz, 5847MHz and 5866MHz. Find the slide switch and we will try them all.
To see any of these frequencies we need a Wi-Spy that works in the full 5GHz range. I switch to the Wi-Spy DBx3 that works in both 2.4GHz and 5GHz WiFi.
Open the Spectral view and the Planar view. Turn on the AV sender and slide the channel switch. Try all four channels. Two of our channels do generate a signal that we see at the top of the WiFi spectrum.
Yes. Leaving our sender on its two lowest channels does risk interfering with our wifi. Wikipedia lists WLAN channels and shows which channels will be affected.
Chanalyzer Lite
The Wi-Spy 24i also works with Chanalyzer Lite on Windows. I had to give my name and e-mail address for download.
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