What Is a Simple Way to Detect EMI?

by Stephanie Hancock

EMI, or electromagnetic interference, can cause disruption with electronic items in your household, such as your cell phone, radio, television, satellite and computer. Conducted current, voltage, and radiated electromagnetic fields cause EMI. Detecting EMI can help you determine the safety of an electronic device. EMI detection can save the life of someone with a pacemaker. EMI interferes with the rhythm of the heart produced by the pacemaker.

Step 1

Tune an AM radio to a low frequency that does not bring in an audible radio station.

Step 2

A cell phone can help you understand what to listen for to detect EMI.

Turn on your cell phone or cordless phone and place a phone call. Hold the phone near the AM radio and pull it away. You will hear a difference in the standard interference noise when you move the phone closer to the device. This will help you understand what to listen for.

Step 3

A television antenna can cause EMI.

Find the area in which you think EMI happens. Check areas near communication or other electronic devices that rely on waveforms of information to work, such as a satellite television or wireless Internet. Put your AM radio near the source of the potential EMI.

Listen for interference that sounds like a pulsating change in the regular "snow" or white noise. You may hear bleeps or blips, people speaking or loud buzzing. If there is no EMI, you will hear no difference in the white noise.


  • Items that can cause EMI include fluorescent lights, improperly grounded equipment and dimmer switches. Static, flickering, loud buzzing noises and abnormal voice interruptions in an electronic device may indicate EMI.


  • If you think EMI has affected an electronic device, unplug the device and take it to a reputable repair shop for diagnostics and repair. The device may not have proper grounding and can cause electrocution.
  • Do not tamper with the internal workings of an electronic device while it is plugged in.
  • Do not go near known EMI areas if you have a pacemaker. EMI affects the device and can result in an abnormal heart rhythm that can lead to a heart attack.

Items you will need

  • AM radio
  • Cell phone

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