Interference occurs when unwanted radio frequency signals disrupt the use of your television, radio or cordless telephone. Interference may prevent reception altogether, may cause only a temporary loss of a signal, or may affect the quality of the sound or picture produced by your equipment. The two most common causes of interference are transmitters and electrical equipment.

Transmitter interference

Communication systems that transmit signals capable of generating interference include amateur radios, CBs and radio and television stations.

Design flaws such as insufficient filtering and inadequate shielding or frayed or corroded wires may make equipment susceptible to transmitter interference.

To determine whether the interference is caused by a transmitter or electrical equipment, unplug one household electronic component at a time to see if you can isolate any electrical interference source.

If your equipment is reacting to nearby transmitters such as an amateur radio or CB, you will have interference only when the radio operator is talking and you will be able to hear only half of the conversation. If this is the case, you may be able to verify the interference source if you see an antenna mounted on a nearby house or car.

Cordless telephones use radio frequencies and have no protection from interference. If you are experiencing interference on your cordless phone, you should contact the equipment manufacturer for assistance.

Electrical interference and your TV

Electrical interference appears on the audio and video portion of television programming. Short bursts of interference may be caused by hair dryers, sewing machines, electric drills, doorbell transformers and garage door openers. If the pattern is on continuously, it may be caused by equipment that is in use full time, such as aquarium heaters and fluorescent lighting.

Electrical interference may be caused by power lines or electrical equipment in your home. Interference caused by your power company’s electrical equipment is normally continuous and your power company should be notified.

A simple method of determining the location of electrical interference is by using a portable AM radio tuned to a quiet frequency at the lower end of the dial. You should hear static or a buzzing sound as you get close to the source of the interference. The closer you get, the more intense the static will be.

If you cannot locate the interference source in your own house, check with your neighbors to see if they also experience interference. The source may be in their home.

If you cannot determine the source of the electrical interference, contact the customer service department of your local power company. Most power companies will investigate the problem and take steps to correct it.

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Interference with Radio, TV and Telephone Signals (pdf)


Date Last Updated/Reviewed: 
Friday, September 8, 2017