Cutting Through Interference – Information for Radio Licensees

You can take important measures to reduce the risk of radio interference and its effects.

Use certified equipment

Unless you have an exemption, your radio licence requires that all radio equipment used in Canada can be certified by Innovation, Science and Economic Development (ISED). Certified equipment will display a certification number (IC number) on the device label. ISED maintains a Radio Equipment List that includes devices meeting established specifications. Using certified equipment is not only a legal requirement but also helps minimize the chances of radio interference.

Please contact ISED if you are uncertain whether your radio equipment is certified for use in Canada.

Use qualified technicians

It is advisable to hire a qualified radio equipment technician to install and maintain your radio station.

Respect your licence terms and conditions

Installing your radio station in accordance with the terms and conditions of your radio licence is not only a legal requirement, but it also helps minimize the risk of radio interference.

If you need to make any technical changes to your radio station, such as altering the station's location, radio model, antenna type, antenna height, output power, frequency, bandwidth, or emission type, you must first modify your radio licence.

For radio stations using a fixed antenna installation, you must adhere to the requirements outlined in CPC 2-0-03 – Radiocommunications and Broadcasting Antenna Systems. Also, periodically verify that your radio station is operating within the authorized technical parameters such as frequency, bandwidth, and output power.

Check your components

Every radio station component must be installed and maintained according to the manufacturer's instructions

If you change the installation, you must recheck that the station's technical performance is in compliance with terms and conditions of your licence.

Ground your equipment

All radio station equipment, including antennas, must be properly grounded and should have a separate grounding system from the building's AC electrical distribution system. If these grounding systems are not kept separate, reflected radio frequency energy in the form of standing waves can be transmitted into the building's electrical wiring and the neighbourhood's power distribution lines.

Generally, a proper grounding system consists of a copper rod buried at least 2.4 meters deep to account for frost penetration, which can reach up to 1.2 meters deep. Additionally, the ground wire should be made of copper tie wire that is at least No. 12 gauge. It's also advisable to keep both your radio and antenna as far away as possible from neighbouring TV or FM antennas and areas where gaming systems, computers and similar equipment are used. Your situation may differ, so you should always refer to your manufacturer's recommendations and instructions.

Check your antenna

An incorrect antenna type or improper installation can significantly contribute to interference. If the antenna's length is not correctly matched to the transmitter, it may generate unwanted signals that can be transmitted more effectively than the desired signals.

Antenna type

If you are using a vertically polarized antenna, opt for a ground plane type that has three or four radials (refer to the image). This setup will help reduce the signal interference experienced in nearby homes/businesses. Additionally, a mobile antenna that uses a vehicle's body as the ground plane should not be used as a base station antenna unless it is paired with a suitable ground plane.

Antenna location

To minimize potential interference issues, follow the requirements set out in CPC-2-0-03—Radiocommunication and Broadcasting Antenna Systems. This includes positioning your radio station's antenna as follows:

• place it as far away from neighbouring houses/businesses as possible, and ideally higher than them.
• position it away from power lines that could disrupt its operation.
• keep it distanced from any telephone, cable television, or television antenna cables.
• ensure it is as far away from electronic equipment as possible.

It is not advisable to install a transmitting antenna in an apartment or on an apartment balcony.

You may need to obtain approval from land-use authorities and conduct a public consultation before siting an antenna. For more information, refer to CPC-2-0-03—Radiocommunication and Broadcasting Antenna Systems.

There is also an important obligation to comply with Health Canada's Safety Code 6 guideline, which is designed to protect the general public from potential adverse health effects related to exposure to radiofrequency fields.

Antenna transmission line

A high-quality coaxial cable efficiently transmits the radio signal from the transmitter to the antenna while minimizing signal loss. A commonly used type is RG-8/U cable, which measures approximately one centimetre in diameter.

When installing the transmission line, follow the manufacturer's instructions carefully. Ensure the transmission line is securely fastened and avoid placing it close to or parallel with telephone wires, cable TV lines, or television antenna cables. Do not puncture, flatten, or bend the cable sharply. Additionally, ensure that all outdoor connections are well-sealed to prevent water from entering.

Use radio filters

Filters are highly recommended for fixed radio station installations to reduce interference caused by out-of-band emissions. This is particularly important for co-located sites with multiple transmitters. Filters can also eliminate spurious emissions from your transmitter, which may interfere with other users.

The two most common types of filters are:

Band-pass filters: These filters allow signals within a specific frequency range to pass through while blocking signals outside that range.

Notch filters: These filters significantly weaken signals within a narrow frequency range while allowing all other frequencies to pass through relatively unchanged.

It is advisable to consult your radio equipment supplier or manufacturer for suitable filters.

Adjust your transmission signal

If your equipment is functioning properly and you have installed a filter but are still experiencing interference, try lowering the power level of your transmission. Additionally, you can use a directional antenna to focus the transmitted energy either towards or away from a specific direction.

Use channel access controls

When multiple devices attempt to transmit simultaneously, their signals can interfere with one another, resulting in data corruption. This is why most two-way radios have access controls that regulate how devices share a communication channel.

Using these channel access controls is highly recommended, especially in environments where multiple devices need to transmit data over a shared resource, such as a wireless network.

Consult your manufacturer's documentation for more information on your device's channel access control features, and employ an appropriate method to minimize interference.

Keep in mind that different manufacturers may refer to channel access control methods by various names, such as Continuous Tone-Coded Squelch System (CTCSS) or Digital-Coded Squelch (DCS).

Your radio station may still experience interference in certain situations, even after taking preventative measures. The most common causes of radio interference include:

• unauthorized operation
• using uncertified and non-compliant equipment
• malfunctioning radio devices
• improper installation of radio equipment
• insufficient shielding or filtering of unwanted signals

Here are some steps you can take to help identify the cause of the interference.

Verify your equipment is functioning properly

If your radio station is experiencing interference, it is essential to ensure all your equipment is in good working order. Problems such as a damaged antenna, faulty cables or connectors, or issues with the transmitter or receiver can mimic external sources of interference and degrade performance.

To assess the condition of your radio system components, you may need to consult a radio equipment technician. A technician can also assist you in identifying the source of the interference.

Additionally, ensure that your radio station operates within its authorized licensing parameters and that you have checked all the items mentioned in this document's Preventing Radio Interference section.

Test for internal interference

A circuit breaker test can help you identify if the source of interference is coming from within your premises.

To perform the test, disconnect power to a specific room or floor and check if the interference ceases. If the interference stops after turning off one of the breakers, you have likely pinpointed the electrical circuit that powers the device causing the interference.

Note: when performing a breaker test it is important to be aware of devices that have battery backup power as they devices may continue to operate even when the electrical power has been switched off. This could affect the results of your testing.

You may need to repair or replace the problematic equipment to resolve the issue.

Locate external interference

If, after conducting a circuit breaker test, you find that the source of interference is external, it's important to gather detailed information about the nature of the interference to assist in identifying its source. Before contacting ISED for assistance, please document your answers to the following questions:

1. what day and time do you experience the interference?
2. on what date did the interference begin?
3. how often does the interference occur, and for how long? If it is intermittent, what is the time interval between occurrences?
4. does the interference happen at specific times of day or days of the week?
5. does the interference seem to depend on weather conditions?
6. describe the characteristics of the interference and its effects on your radio equipment. Does it take the form of identifiable words, music, or other electrical noise? If possible, record the interference.
7. does the interference complete prevent you from using your radio system or can you talk over it? Does the interference level vary?
8. request help from service provider to verify equipment and help you identify the source of the interference.

Your responses may provide crucial clues to help find the source of the interference. Additionally, check for any changes in or near your location around the time the interference first began. For example, if the interference started when your office fluorescent lights were replaced with LED lights, those lights might be the source of the issue.

If your radio station is mobile, you can pinpoint the location of the interference by testing different spots within your site or area of operation, looking for noticeable changes in the intensity of the interference.

You may also consider hiring a qualified radio technician to help locate the source of the interference. Technicians can use tools such as a tunable receiver, spectrum analyzer, or radio direction finder to help diagnose the issue.

Your responsibilities

When addressing radio interference, it is crucial to collaborate with all affected parties. If a neighbour reports interference, help them determine whether your equipment is the source of the problem. Together, you can identify and implement effective solutions.

Requesting ISED assistance

Certain situations may require assistance from ISED's Spectrum Operations district offices to investigate or resolve interference.

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

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 interference

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.