Sometimes you have to play "hot or cold" when you're looking for a source of interference. In this lesson, you’ll find out the best practices for tracking down constant or intermittent transmitters. When trying to track down the source of interference, it's important to start where the end user says the problem occurs most. Once you're there, try to recreate the circumstance that caused them to experience a problem.
Be sure to look for wireless audio systems, headsets, motion sensors, or other seemingly benign devices, as these can often prove to be the cause of interference. In the Density View you'll see interference represented as either a constant bright red (non-WiFi) pattern, or as an unpredictable, intermittent red when looking at the Waterfall Navigation Pane. A shorter time span will display new transmitting devices quicker.
Some devices transmit all the time, and will appear as a solid line in the Waterfall View. As you survey your area, you may notice the color of this line change.
To track down a constant interferer, start by highlighting the frequency range of the transmitter's peak signal in the Overview Pane. A menu featuring a "Device Finder" option will appear.
After clicking "Device Finder," the Details Pane will automatically switch to the Device Finder tab. You will see a single bold line, which acts as an amplitude history for the frequency range you selected. By visualizing the amplitude levels in this way, you don't have to interpret color ranges. As you get closer to the transmitting device, the line will begin to move upward.
Using a Directional Antenna with Device Finder
A directional antenna like MetaGeek's Device Finder 2.4 GHz Directional Antenna increases the sensitivity in a single dimension. Think of it like this: if an omni-directional antenna is a lantern radiating soft light all around, a directional antenna is a flashlight that shines a focused beam in one direction. So if you're looking for a specific source of interference, you can find it eventually using an omnidirectional antenna, but using a directional antenna will greatly reduce the amount of time you spend tracking down the device.
Some transmitters do not constantly transmit in the 2.4 GHz. Sometimes you can see the device in the Waterfall View, but it appears for only a few seconds. This makes tracking the interfering device more difficult, but it is still possible. Using an omnidirectional antenna (rather than a directional one) will yield better results when trying to find an intermittent transmitter, since you can't be completely certain where it's coming from. Start by turning on "Max Trace" and "Inspector" in the Overview Pane's toolbar. Try moving to different locations, and see if the maximum amplitude point of the transmitter has moved higher.
In this example, you can tell the transmitter is nearby because the line in the Device Finder Tab has moved up.
Always remember: you haven't found the interference source until you can turn it off!