Cutting through interference – AM and FM radios

When listening to an AM or FM station, you may sometimes hear other sounds that are not part of the broadcast. These sounds can include white noise, crackling, humming, buzzing, or even voices and music from a different station

If you suspect radio interference, you can perform some basic checks to find if the source of the interference is internal to your radio or external.

• check tuning – Some noises might sound like interference, but they can also be caused by improper tuning or a weak signal, especially if you are outside the station's coverage area. Make sure you are tuned to the exact frequency on which the station broadcasts, such as "101.1 FM" or "680 AM."
• check connections – If the radio has an external antenna, make sure its connection to the radio is not loose or damaged. Also, verify that the power cable to the radio is not damaged. If you use a portable radio powered by batteries, make sure the batteries are not low.
• disconnect all accessories – If your radio is connected to external speakers or earphones, disconnect them one by one and see if the interference persists. Disconnecting and reconnecting each accessory one at a time to identify the accessory causing interference. Good connections and shielded cables between the accessories and the radio may help eliminate the interference.
• perform the equipment substitution test – Test the affected radio alongside another radio at the same location. If both radios experience interference, it's likely that the source of the interference is external. You might also want to talk to your neighbours to see if they are experiencing similar interference with their radios.
• test at different locations – Test the impacted radio at other locations. If the radio is working fine at other locations, the source of interference is most likely external. Pay attention to whether the intensity of the interference changes depending on the location. This approach can also help you pinpoint where the source of the interference might be.
• call the Broadcaster – The broadcaster may be interested to know that some location does not receive their station well. It may be possible to confirm with the station if it is operating at reduced power during maintenance..

Some electrical equipment or installations in the home may interfere with AM radios. To identify types of interference not described below, you can conduct a circuit breaker test, which involves disconnecting power to each outlet one at a time to see if the interference stops. Make sure the equipment you are checking does not contain backup batteries.

Fluorescent, neon, and LED lights

Fluorescent lights often produce a steady buzzing sound when turned on, while neon lights can trigger short clicking noises caused by electrical charges. To mitigate interference, try moving the radio further away. Replacing the tubes, fixtures or ballasts may also solve the problem. A technician can also perform certain repairs to eliminate the issue.

The interference caused by LED lights is often consistent and originates from the power supplies. Since the power supplies are typically internal, it is advisable to consult an electrician for suitable options. Often, simply replacing the LED lights is the most sensible choice. Choose LED lights from reputable manufacturers that are labeled as ICES-005 compliant.

Electric vehicles

Electric vehicles (EVs) can disrupt AM radio reception. Due to this interference, many automakers have opted to remove AM radio from their EV models. AM radio signals are especially vulnerable to the electromagnetic interference generated by EVs, making it impractical to eliminate this disruption.

Household appliances

Household appliances that use electric motors—such as electric shavers, sewing machines, vacuum cleaners, blow dryers, and mixers—can interfere with AM radios. The sound of the interference is similar to that of the device causing it. Since these devices may only be operated briefly, trying to eliminate the interference is often impractical.

Electrical contacts

Certain electrical contacts can cause interference that sounds like small staccato sounds or continuous crackling. After a while, electrical contacts on some thermostatic devices become dirty or pitted, causing sparking when the electrical current passes through. Heating pads, electric blankets, aquarium heaters and doorbell transformers can cause this interference. The circuit breaker test will help locate the source so it can be replaced or repaired.

Dimmer switches

Faulty dimmer switches can sometimes cause radios to emit a high-pitched crackling noise that can be heard throughout the entire AM band. To identify the faulty switch, perform a circuit breaker test and replace the switch with a higher-quality dimmer switch that includes a filter. Additionally, the metal boxes that cover certain dimmer switches provide effective shielding.

Oil or gas furnaces

Furnace interference is characterized by intermittent buzzing that lasts anywhere from a few seconds to a few minutes. This interference occurs due to the spark generated to ignite the pilot flame in the furnace. It is advisable to call a qualified technician to repair or replace the ignition system.

Electric fences

Interference from an electric fence primarily impacts AM radio signals, producing a distinctive "tick" sound that repeats at regular intervals of one to two seconds. Typically, this type of interference is found only in rural areas.

If the interference continues even after the electric fence is disconnected, the issue may lie in the control box. However, if the interference only occurs while the electric fence is in operation, the installation of the electric wire should be inspected. Potential causes of the interference include a damaged section of wire or branches and shrubs making contact with the wire.

Industrial, scientific, or medical (diathermic or heating) equipment

If you hear a repetitive vibrating buzz or hum in your radio, it may be caused by certain radio frequencies used in industrial facilities that process food, plastics, metal, or wood, which can produce heat and create this type of interference.

Medical diathermy equipment is another potential source of this type of interference. It's a good idea to check if such equipment is present in your neighbourhood. In most cases, corrective measures need to be taken with the equipment causing the interference. If you identify the source, you should contact the appropriate officials where the equipment is located.

Intermodulation

In the presence of strong radio waves, corroded metal contacts or connections can act as unintentional mixers, generating unwanted signals that interfere with nearby receivers. This interference can cause a radio to play a mix of voices and music from multiple stations, a phenomenon known as external rectification.

When this interference impacts a wide range of frequencies, the source is typically close to the most powerful transmitter—often on the antenna itself, on the guy wires, or in the vicinity of the broadcast station. It is essential to find any corroded contacts so they can be cleaned or insulated.

It's important to note that there may be multiple sources of interference at a specific location, and the level of interference will decrease as these sources are addressed. Generally, this type of interference diminishes during rainy weather. Radio station operators can often assist you in identifying and resolving this issue.

Weak signal

Broadcasting stations have specific coverage areas, and stronger signals can overwhelm weaker ones especially at the edges of their coverage areas. It can be challenging to tune into a far-away station, as stations that are more near may overpower its signal. This sometimes results in poor sound quality, with whistling or buzzing in the background.

To improve the reception of the desired signal, try changing the orientation of the radio or antenna.

If you are located between two broadcast stations, using an outdoor directional antenna, and pointing it towards the desired station can help amplify its weak signal.

Keep in mind, that trying to tune into a station while you are well outside its coverage area is difficult to do without experiencing interference problems.

Nighttime interference

In the evening, does the sound of your desired radio station fade in and out, or do other stations sometimes drown it out? This could be due to the way AM radio signals propagate at night. Ionospheric changes that happen as the sun sets can create ideal conditions that extend an AM station's coverage area.

At night, transmitters located hundreds or even thousands of kilometers away can disrupt the reception of local stations. Changing the orientation of your AM radio or antenna may help improve reception. However, this solution might only be temporary, as ongoing variations in signal propagation during the night can lead to unpredictable changes in reception conditions.

Electrical power lines

Interference from power lines can sound like intermittent or continuous crackling, sizzling, or sparking. This interference may vary in intensity depending on the weather conditions.

If your circuit breaker test indicates that the source of the interference is outside your home, it is possible that faulty components in the nearby electrical power lines are causing the issue. In such cases, contact your electrical utility company to investigate the problem.

FM radio stations are less susceptible to interference compared to AM radio stations. Below are some common reasons why you may receive interference while listening to a FM radio station.

Weak signal

Have you had trouble tuning into a favorite FM station since a newer station started broadcasting on a nearby frequency? If the new station is located closer to you, its stronger signal could interfere with that of your favourite station if it is much further away.

Pointing a directional antenna towards the desired station can enhance the weaker signal, if the two stations are not in the same direction.

Multiple signals

When you are in a moving car, the receiver may produce a "fut-fut-fut" sound. This type of interference commonly occurs when signals are coming from multiple directions or when they reflect off buildings or other structures. Depending on how you travel, signals may come and go, sometimes disappearing amidst noise.

Reflection is a specific characteristic of FM signals. If the receiver allows it, switching from stereo to mono mode can sometimes improve reception.

LED lights

Certain types of LED lights can interfere with FM radios, resulting in a steady static noise. This interference typically affects both AM and FM stations. The source of the problem is usually the power supply for the LED lights. Since the power supply for LED lights is typically internal, it is advisable to consult an electrician for suitable options. Often, simply replacing the LED lights is the most sensible choice. Choose LED lights from reputable manufacturers that are labeled as ICES-005 compliant.

Certain situations may require assistance from Innovation, Science and Economic Development's (ISED) Spectrum Operations district offices to investigate or resolve interference.

While certainly a nuisance, not all interference is considered harmful.

In fact, many consumer devices must accept interference, as may be written on their label or in their manual.

ISED focuses its efforts on investigating harmful interference, that which:

• endangers the use or functioning of a safety-related radiocommunication system (such as police, fire, ambulance, and aeronautical services).
• or significantly degrades, obstructs, or repeatedly interrupts the functioning of radio apparatus, or radio-sensitive equipment (non-radio electronics).

ISED generally does not investigate interference unless it believes the interference may be harmful or results from regulatory non-compliance.

ISED does not investigate general household or business interference. Instead, it focuses on investigating interference that impacts public safety communications.

If you believe radio interference is severely impacting these critical communications, you should contact your nearest ISED Spectrum Management district office. They will review the information you provide, determine whether the interference is harmful, and take appropriate action to identify and resolve the issue.

If you are a public safety agency (such as police, fire, emergency medical services, the Canadian Coast Guard, or the Department of National Defence – Search and Rescue), please refer to CPC-3-13-03 — Interference Resolution Services on a 24/7 Basis for Public Safety Agencies for important additional information.