Cutting through interference – Audio recording and stereo equipment

Certain audio recording and playback devices, such as microphones, amplifiers and stereo systems, can experience interference from nearby radio transmitters, even if they are not wireless themselves. These devices are considered radio-sensitive if they are not adequately shielded from external radio frequency energy, making them prone to picking up unwanted radio signals. The interference may present itself as various sounds, including voices, crackling, buzzing, humming, and clicking.

One way to verify if the interference is external to your device is to test it in various locations inside and outside your home or workplace. If the device performs normally without being interfered with at other locations, then the interference is external to your device. This exercise may help you isolate the general area of the source of the interference.

If a radio station antenna is located nearby, it may be contributing to interference. This phenomenon occurs when the intense electromagnetic field around the antenna makes your equipment pick up unwanted signals.

To identify a potential source of the interference, check your neighbourhood for transmitter antennas. Then work together with the operator of the transmitter to verify whether they are the source of the interference. If a source is proven, work with the operator to find a suitable solution. Filters, shielding, or grounding may be required to fix the issue.

Recording equipment and stereo systems

1. disconnect all accessories: Begin by disconnecting all accessories attached to the equipment, including auxiliary speakers, and interconnecting stereo system cables.
2. reconnect each cable: Reconnect each cable one at a time to identify which accessory is causing the interference. Ensuring proper grounding and connections between the accessories and the equipment can sometimes eliminate the interference.
3. For stereo systems, check the volume control circuit: If the interference continues even after all accessories have been disconnected, the issue may reside between the volume control circuit and the speakers. If adjusting the volume control does not affect the unwanted radio signal, the interference is likely entering through the speaker wiring. To verify this, disconnect the speaker wires from the amplifier and use headphones to listen for interference. If the problem disappears, consider replacing unshielded speaker wires with shielded audio cables.

When a component or wire in your equipment unintentionally acts as an antenna, it can pick up unwanted signals. Power cords and speaker wires are often the source of this issue, especially if they are poorly shielded or improperly routed.

By implementing these solutions, you should be able to minimize or eliminate unwanted interference signals.

Speaker wires

To eliminate interference originating from the speakers, consider the following steps:

• ensure you are using shielded audio wires, which are available online or in specialty stores.
• remove any excessive wire length.
• if interference persists, install an audio filter between the terminals and the speakers. These filters can also be found online or in specialty stores.
• unshielded speaker leads may be wound around a ferrite core.

Power cords

To determine if the power cord is causing the interference, briefly unplug it and observe whether the interference continues. The equipment should still operate for a few moments during this time. If the interference remains, the issue likely lies within the equipment itself. However, if the interference stops immediately upon unplugging the power cord, the cord may be the problem. Be sure to remove all extension cords before conducting this test.

Other electrical devices

Certain electrical devices can cause interference. Common examples include thermostats, dimmer switches, and LED lights. The nature of the interference can vary significantly between different devices.

To identify the source of interference in a home or workplace, you can conduct a circuit breaker test. This involves disconnecting power to a specific room or floor and checking whether the interference stops. If the interference disappears after turning off one of the breakers, you have likely identified the electrical circuit supplying the device that is causing the interference.

To resolve the issue, repairing or replacing the problematic equipment may be necessary.

In certain situations, assistance from Innovation, Science and Economic Development's (ISED) Spectrum Operations district offices may be required to investigate or resolve interference issues.

While interference can be frustrating, 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 does not usually investigate non-harmful interference unless there is suspicion of regulatory non-compliance.

Reporting harmful interference

Please report harmful interference to 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.