HARMFUL INTERFERENCE

Introduction | Supplement | Questions | Quiz
INTRODUCTION

Interference that seriously degrades, obstructs or repeatedly interrupts a radio communication service is referred to as harmful interference.

It is unlawful to deliberately interfere with another station's communication.

When interference to the reception of radiocommunications is caused by the operation of an amateur station, the Minister may require that the radio amateur takes the necessary steps to prevent the interference. When possible, operators should take immediate steps to resolve such interference situations before it becomes necessary to involve Industry Canada.

If two amateur stations want to use the same frequency, both station operators have an equal right to operate on the frequency. Be considerate.

In many bands, the amateur radio service has primary user status. However, in some bands, such as the 430-450 MHz. and 902-928 MHz, the amateur radio service has secondary user status. Amateurs also share the heavily used Industrial Scientific Medical (ISM) band between 2300 to 2450 MHz. by licence exempt low power devices.

The transmissions of secondary users may not cause interference to, or be protected from interference from primary user stations. Avoid all transmissions, including test transmissions, if there is a possibility of causing interference to primary users.

Identification and resolution of interference may require the assistance of an experienced individual. Seek assistance for difficult situations.

SUPPLEMENT

Interference can also be broadly defined as any modification to the reception of sound or picture signals that makes them unacceptable.

Interference can originate from a variety of sources. Electrical and electronic appliances in homes, offices and industry, neon signs, motor vehicle ignition systems, medical equipment, power lines and radio transmitters all contribute to background noise that can interfere with radio and television reception.

This problem is compounded by the fact that many radios and televisions were not designed to operate in today's radio frequency environment, in which the number of electrical devices and radio transmissions has greatly increased.

When an electronic device picks up interference, the problem is often assumed to be the fault of the radio transmitting source. But in fact, the affected equipment often lacks the circuitry required to operate properly in the presence of radio signals, or it has a defect that makes it susceptible to interference.

Audio rectification interference occurs when an electronic circuit (usually an amplifier), which ideally should respond only to audio frequency signals, responds to external radio frequency (RF) signals. Typically, the circuit picks up signals from a nearby radio transmitter in addition to the sound the listener wants to hear. The unwanted signal may be constant or intermittent, faint or uncontrollably loud.

Televisions, radios, stereos, telephones, electronic organs and public address systems are all prone to audio rectification interference. When audio rectification occurs, it indicates that the device lacks sufficient shielding or filtering to function properly when in a strong radio signal environment. The solution is to modify the affected audio device.

Electrical devices and appliances used around the home frequently interfere with radio and television reception, producing crackling, clicking, humming or buzzing in the sound, and dots and lines in the picture. Since these appliances are only operated when needed, this type of interference tends to be intermittent, rather than continuous. The solution has to be applied to the problematic electrical device or appliance.

Radio transmitters that are defective or of inadequate design, may radiate excessive spurious emissions or harmonic signals which can result in interference to the reception of broadcast stations. In this case, a solution needs to be designed for the for the transmitting device.

QUESTIONS

B-001-010-001.... What is a transmission called that disturbs other communications?
  1. harmful interference
  2. interrupted CW
  3. transponder signals
  4. unidentified transmissions
B-001-010-002.... When may you deliberately interfere with another station's communications?
  1. never
  2. only if the station is operating illegally
  3. only if the station begins transmitting on a frequency you are using
  4. you may expect, and cause, deliberate interference because it can't be helped during crowded band conditions
B-001-010-003.... If the regulations say that the amateur service is a secondary user of a frequency band, and another service is a primary user, what does this mean?
  1. amateurs are allowed to use the frequency band only if they do not cause interference to primary users
  2. nothing special - all users of a frequency band have equal rights to operate
  3. amateurs are only allowed to use the frequency band during emergencies
  4. amateurs must increase transmitter power to overcome any interference caused by primary users
B-001-010-004.... What rule applies if two amateur stations want to use the same frequency?
  1. both station operators have an equal right to operate on the frequency
  2. the station operator with a lesser qualification must yield the frequency to an operator of higher qualification
  3. the station operator with a lower power output must yield the frequency to the station with a higher power output
  4. station operators in ITU regions 1 and 3 must yield the frequency to stations in ITU region 2
B-001-010-005.... What name is given to a form of interference that seriously degrades, obstructs or repeatedly interrupts a radiocommunication service?
  1. intentional interference
  2. adjacent interference
  3. disruptive interference
  4. harmful interference
B-001-010-006.... Where interference to the reception of radiocommunications is caused by the operation of an amateur station:
  1. the amateur station operator is not obligated to take any action
  2. the amateur station operator may continue to operate without restrictions
  3. the Minister may require that the necessary steps for the prevention of the interference be taken by the radio amateur
  4. the amateur station operator may continue to operate and the necessary steps can be taken when the amateur operator can afford it
B-001-010-007.... Radio amateur operation must not cause interference to other radio services operating in which of the following bands?
  1. 7.0 to 7.1 MHz
  2. 144.0 to 148.0 MHz
  3. 430.0 to 450.0 MHz
  4. 14.0 to 14.2 MHz
B-001-010-008.... Radio amateur operations are NOT protected from interference caused by another service operating in which of the following frequency bands?
  1. 144 to 148 MHz
  2. 222 to 225 MHz
  3. 50 to 54 MHz
  4. 902 to 928 MHz
B-001-010-009.... Which of the following is NOT correct? The operator of an amateur station:
  1. shall not cause harmful interference to a station in another service which has primary use of that band
  2. may conduct technical experiments using the station apparatus
  3. may make trials or tests, even though there is a possibility of interfering with other stations
  4. may make trials or tests, except if there is a possibility of interference other stations
B-001-010-010.... Which of these amateur bands may be heavily occupied by licence exempt devices?
  1. 3.5 to 4.0 MHz
  2. 430 to 450 MHz
  3. 902 to 928 MHz
  4. 135.7 to 137.8 kHz
B-001-010-011.... The amateur radio service is authorized to share a portion of what Industrial Scientific Medical (ISM) band that is heavily used by licence exempt devices?
  1. 430 to 450 MHz
  2. 144 to 148 MHz
  3. 2300 to 2450 MHz
  4. 1240 to 1300 MHz
QUIZ
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