5.6

Spectrum Monitoring and Compliance

Spectrum monitoring is one of four key spectrum management functions which include spectrum planning, spectrum engineering and spectrum authorization. Spectrum monitoring helps spectrum managers to plan and use frequencies, avoid incompatible usage, and identify sources of harmful interference. Key spectrum monitoring activities explained in this section include data collection and compliance enforcement.

Properly designed and functioning spectrum management processes including planning, authorization and engineering activities require data derived from monitoring technical procedures and from components which are characterized by varying degrees of complexity and cost. Spectrum monitoring and compliance activities help users to avoid incompatible frequency usage through identification of sources of harmful interference.

Furthermore, spectrum use planning and resolution of spectrum scarcity issues can be accomplished through study and analysis of spectrum occupancy data. Maintaining interference free assignments includes the use of data and electro magnetic compatibility (EMC) verification activities, as well as monitoring and enforcement activities needed to ensure user compliance with licence conditions and technical standards.

In the next three parts of this section, we expand on the topic of Spectrum Monitoring and demonstrate its importance in supporting spectrum management activities. In the first section, we provide more detailed explanations of spectrum monitoring objectives, activities and strategies. Spectrum monitoring technology is outlined in the second section. The last section deals with compliance enforcement activities.

Reference Documents

5.6.1 Spectrum Monitoring

Even though electromagnetic spectrum is theoretically boundless, the portion currently useful for key applications such as communications, while substantial, is finite. In practice, the properties of radio wave propagation and electronic equipment limit radio communications to frequencies allocated between 9 KHz and 30 GHz. These properties also constrain particular types of communications systems to certain portions of the allocated spectrum, limiting the spectrum available for specific uses.

The demand for interference-free frequency assignments is steadily increasing. This is a result of the worldwide liberalization of telecommunications, the subsequent appearance of new market entrants along existing operators of competitive wireless services, and users of frequencies for non-telecommunications applications. Making interference-free assignments requires the use of data and involves Electromagnetic Compatibility (EMC) verification activities. These monitoring and enforcement activities are also needed to ensure user compliance with licence conditions.

Accomplishing this involves several management and process models. Monitoring and enforcement of licence and technical standards has traditionally been a responsibility of spectrum regulators, whether within independent agencies, or attached to the Ministry of Telecommunications. Departments such as Defence and Transport also often have responsibility over frequencies allocated to governmental use. In addition to public sector agencies, private sector participants are sometimes involved in the monitoring and problem resolution processes. These include industry associations, advisory councils, etc. In some countries, band management organizations govern specified frequency ranges under government authorization.

Regulators in developing countries may not have access to a sufficient amount of monitoring capacity or expertise to engage in the full range of monitoring activities. Careful decisions are needed to determine what investments to make in equipment and development of processes or formalized activity. Administrators will also have to decide what use of which segments of spectrum are most important to monitor. Priorities will need to be set to make efficient use of existing equipment and capabilities, including outsourcing and utilizing existing industry sector resources.

In the next sections we discuss spectrum monitoring objectives and provide an overview of related technical topics including: emissions and interference; a description of spectrum monitoring activities, as well as a perspective on how countries cooperate and coordinate monitoring activities.

5.6.1.1 Spectrum Monitoring Objectives

Spectrum Planning and Authorization are central functions supported by spectrum monitoring. Monitoring supplies information used in determining compliance with rules and regulation, such as license conditions, and in achieving compliance with technical and operational standards. It provides general measurements which are used by the spectrum manager to understand and plan channel and band usage as well as confirm the effectiveness of current planning and authorization activities. Understanding the level of spectrum use or occupancy in comparison to assignments is important for efficient use of the spectrum resource. Spectrum monitoring provides statistical information on the technical and operational nature of spectrum occupancy. Conversely, spectrum authorization and spectrum engineering functions support spectrum monitoring by providing accurate, complete and timely information on current assignments and licences.

The overall goal of spectrum monitoring activities is to support the proper functioning of the general process of spectrum management. Central objectives for spectrum managers include the following:

    • Spectrum efficiency in determining planned and actual frequency usage and occupancy, assessing availability of spectrum for future uses;
    • Compliance with national spectrum management regulations to shape and sustain radio environments and user behaviour, maximizing the benefit of the spectrum resource to society;
    • Resolution of interference problems for existing and potential users.

One radiocommunication system is more "spectrum efficient" than another if it conveys the desired information using less of the spectrum resource. Spectrum efficiency also involves the arrangement of communication systems within the spectrum resource. In this broader sense, spectrum is used inefficiently when systems are not packed together as tightly as possible in frequency bands (as when excessive guard bands are used), or when portions of frequency bands are unused while other bands with similar physical characteristics are congested. The allocation of frequency bands, the development of channeling plans, and the assignment of frequencies to specific systems all affect spectrum efficiency.

In order to promote spectrum efficiency, spectrum managers must possess some means of quantifying spectrum use and evaluating various radio technologies and frequency selection techniques. Management decisions can then be based on the relative spectrum efficiency of the various technologies and techniques. Data is collected through spectrum monitoring measures of spectrum occupancy and utilization for purposes of making assignments including the effects of spectrum reuse and band clearing efforts. As well, as spectrum becomes scarcer in highly congested areas, monitoring data is used to support spectrum engineering activities including validation of tolerance levels, determining the probability of interference and development of band-sharing strategies.

In addition to supporting assignment and authorization activities, spectrum monitoring supports the second goal: compliance with licence conditions and regulations through determination of deviations from authorized parameters, identification of sources of interference and location of legal and illegal transmitters.

A radio system can deny the use of part of the spectrum resource to another system that would either cause interference to, or experience interference from, the first system. A radio system is said to "use" spectrum resources when it denies other systems the use of those resources. Spectrum use can be quantified, subject to certain assumptions, both for a single radiocommunication system and for a related group of systems.

The facilities, equipment and approach employed in achieving these objectives will depend heavily on current use and congestion, technical capacity of the spectrum management organization and funding of spectrum management operations.

Reference Documents

5.6.1.2 Emissions, Interference and Spectrum Use

This section explains the differences in meaning between emissions and interference and conveys the importance of each to spectrum monitoring. It also provides an explanation for spectrum use and occupancy.

The International Telecommunication Union has created a system which classifies radio emissions according to the bandwidth, method of modulation, nature of the modulating signal, and type of information transmitted on the carrier signal. These form the technical basis for establishing equipment specifications for radio systems designed to operate within certain frequencies.

Emissions of a radio transmitter are authorized to an assigned frequency band within the necessary bandwidth and tolerance for the frequency band. Emissions which do not meet technical parameters are unwanted emissions consisting of spurious emissions and out-of band emissions. These types of emissions can be generated accidentally or through distortions caused by various components of the radio system.

Transmission of radio signals emitted by a radio transmitter can therefore be in-band in accordance with technical parameters or unwanted and due to several causes including out-of-band emissions and spurious emissions.

Electromagnetic Interference (EMI) is a term applied to unwanted emissions from both intentional and unintentional radiators. EMI or interference is the negative effect on reception of radio signals by a radio receiver caused by emissions by radio transmitters or other sources of electromagnetic waves. The negative effect on reception can vary by degree from permissible, to acceptable to harmful interference resulting in partial degradation to complete loss of information. Other sources of electromagnetic waves causing interference include devices such as radio receivers, electrical motors, and electronic devices. The need to turn off computers, video players, and CD players during take-off in an aircraft is due in part to the possibility of interference to navigational and communication aids.

Spectrum managers are therefore interested in both emissions and interference. Emissions by transmitters can become a source of interference. Planning to use frequencies requires that the spectrum manager understand how frequencies are being used and the technical characteristics and performance of the transmission devices operating within and adjacent to the frequency band(s). Interference causes problems and can ultimately impair radiocommunication services. Determining the nature and source of interference are important objectives for the spectrum manager.

Practice Notes

Reference Documents

5.6.1.3 Spectrum Monitoring Activities

This section outlines the monitoring activities associated with specific spectrum monitoring objectives reviewed in Section 6.1.1: Spectrum Management Objectives.

Compliance with Rules and Regulations

Monitoring is done to obtain detailed information on the technical or operational characteristics of radio systems. Radio Equipment Standards are discussed in Section 2.4.4. The spectrum manager will monitor radio equipment to determine conformity with applicable standards. This can be done as part of an equipment certification process where measurements can be taken and recorded and then used in analyzing the compatibility of radio systems - Electromagnetic Compatibility (EMC).

One of the most important technical parameters to measure is the emission of radio transmitters. This is done to determine whether the transmitter is operating within specified limits.

The modulation techniques and types of systems employed and frequencies vary. The spectrum manager needs to choose the measuring system carefully and to ensure capabilities exist with the spectrum management agency to effectively monitor and analyze frequency bands. Circumstances will vary by country and monitoring solutions should be tailored to meet needs, budget and institutional capacity.

Interference Issues

Spectrum monitoring activities determine measurements of radio waves and radiation causing interference to authorized transmitters and receivers. Interference may be the result of authorized emissions causing unintended results such as spurious emissions. Interference may also be caused by unauthorized transmitters or devices operating beyond technical specifications. In either case, the spectrum manager will use a combination of engineering analysis and data obtained from spectrum measurements to resolve problems associated with interference problems.

The identification of unauthorized transmitters can be very difficult to achieve, especially in congested areas and where various services share the same frequencies. In some bands, where spectrum sharing is encouraged through the use of Class Licences or Radio Frequency Authorizations, no protection is provided from acceptable levels of interference. For more information on this topic, see Section 3 Authorizations and Section 4 Spectrum Sharing.

For a brief description of common types of interference see Section 6.3.2: Solving Interference Problems.

Frequency Use and Occupancy

Access to radio spectrum is at a crossroads. More and more technological alternatives are becoming available and demand from both public and private sectors is increasing very rapidly, if not exponentially. There is increasing recognition that the root of the problem is that most of the spectrum is actually unused, and that the present system of spectral regulation is grossly inefficient. Current spectral regulation is based upon the premise that slices of the spectrum, representing uses within specified upper and lower frequency bounds, must be treated as exclusive domains of single entities: the recipients of exclusive licences to use specific frequency bands.

Spectrum measurements are critical to policy makers and researchers in the development of new spectrum access technologies. Specifically, spectrum occupancy studies identify what spectrum bands have low or no active utilization (and thus may be appropriate for spectrum sharing). They provide information on the signal characteristics within these bands, which is needed to design spectrum sharing algorithms.

Figure: Figure: Sample Spectrum Occupancy Report

Sample Spectrum Occupancy Report: Each band averaged over six locations. National Science Foundation: M.A.McHenry Shared Spectrum Co - Click for full sized image

Note: Each band averaged over six locations. Source: National Science Foundation: M.A. McHenry Shared Spectrum Co.

Practice Notes

Reference Documents

5.6.1.4 International Spectrum Monitoring Cooperation

Member countries of the International Telecommunication Union typically operate monitoring facilities which aid spectrum managers in the prevention, detection, and control of (harmful) interference to radio transmitters. This is done to ensure that frequencies are used in accordance with the internationally planned spectrum framework. Since it is recognized that development and duplication of monitoring facilities is both uneconomical and operationally inefficient, cooperation exists among member countries in the operation of an international monitoring system. Article 16 of the Radio Regulations lays down the provisions governing the establishment and operation of the international monitoring system.

Stations comprising the international system check for transmissions that have effects beyond national boundaries, particularly for frequencies below 30 MHz, are in accordance with the internationally agreed conditions of operation. This includes checking frequency, bandwidth, emission type and usage. Where non-compliance with any prescribed condition is determined, the ITU provides for an infringement report to be sent via the Radiocommunication Bureau to the country responsible.

A good example of the far-reaching implications of interference is the international cooperation is demonstrated in the case of maritime coast stations and interference with maritime mobile services in New Zealand, Belgium and the United States.

Cooperation also occurs between countries on a bilateral basis and involves non-governmental organizations and industry associations who advise regulators on policy and technical matters. For example, broadcast and microwave propagation issues and solutions are identified and analyzed by associations and confirmed through spectrum monitoring tasks performed by the regulator.

Practice Notes

Reference Documents

5.6.2 Spectrum Monitoring Technology

Fixed, remote, unmanned and mobile monitoring stations can be combined to provide a network of integrated tools for verification of licensing compliance, channel occupancy, spectrum planning, and regulatory enforcement. Those can also provide greater flexibility in the design of national and regional monitoring systems. Monitoring equipment and integrated software tools are very complex and expensive and integrated monitoring systems can be very expensive as well. Fortunately, advances in computerization, monitoring technology, and security techniques have permitted greater use of remote unmanned monitoring techniques involving integrated spectrum observations.

Alongside advances in technology, tactics and work practices are also changing. There is a reduced emphasis on continuous monitoring of all utilized spectrum to focus on areas of known problems and congestion. Memoranda of agreement can be used whereby an agency of government or non-governmental organizations (NGOs) assumes responsibility for essential monitoring activities and shares information on problems affecting civilian applications. Another example involves industry associations taking responsibility for monitoring and taking steps to resolve interference problems in fixed-link microwave services. Finally, the spectrum regulator concentrates its monitoring resources on public priority frequency bands affecting essential services, including air navigational aids, fire, safety, ambulance, police and areas of concentrated commercial activity such as is typically found in VHF/UHF.

Spectrum management policy decisions involve trade-offs: the desire and needs of the regulator and industry for complete and accurate information; cost of implementation and maintenance; and accountability and technical capabilities.

Practice Notes

Reference Documents

5.6.2.1 Monitoring Equipment

The basic types of monitoring equipment include radio receivers, spectrum analyzers, direction-finding equipment and antenna. These basic types can be further categorized by frequency range (HF, VHF, UHF, etc.) and signal type – analogue or digital. With the advent of spread spectrum and computer-based radio technologies like Cognitive Radio, the sophistication, complexity and prices for monitoring equipment have risen. As well, the approaches to monitoring and the architecture of the spectrum manager's monitoring system have a bearing on the types of systems needed and the configuration of operations and resources. The approaches to system architecture are outlined in Monitoring System Architecture. Options and strategies for configuring and resourcing Spectrum Monitoring Operations are discussed in Monitoring Operations – Options and Strategies.

The regulator's monitoring capabilities depend on three types of equipment: antennas, spectrum analyzers, and radio direction-finding equipment.

Antennas

An antenna is simply an electronic component designed to radiate energy and transmit or receive radio waves. Antennas have practical use for the transmission and reception of radio frequency signals (broadcast radio, TV, etc.), which have different propagation characteristics and can transmit, in the case of low frequencies, over great distances. Different antenna types are used for different radio frequencies and for different coverages. All antennas radiate some energy in all directions but careful construction results in large directivity in certain directions and negligible power radiated in other directions. There are two fundamental types of antennas, which, with reference to a specific three-dimensional (usually horizontal or vertical) plane, are either omni-directional (radiate equally in the plane) or directional (radiate more in one direction than in the other).

Antennas are linked to either radio receivers or signal generators of direction-finding equipment. As mentioned in the previous paragraph, different antenna types are needed for each application. Antenna products encompass a wide range of highly sensitive active and passive antennas which can be applied in Mobile and Stationary Systems, providing complete coverage of the frequency range from 100 Hz to 30 GHz and beyond in the case of some manufacturers. Examples of different antenna types (HF or VHF) and application (stationary and mobile) are depicted below. Antennas are used often under extreme weather conditions and need to be designed to operate in those conditions.

Fixed VHF/UHF Station (Argus-Thales)

Mobile HF/VHF/UHF Antenna (Argus-Thales)

Fixed HF Antenna (Rohde & Schwarz)

Rotatable Microwave Antenna System - 1GHz to 40GHz (Rohde & Schwarz)

Spectrum Analyzers

Since regulatory agencies allocate different frequencies for various radio services, it is critical that each service operate at the assigned frequency and within the allocated channel bandwidth. Due to scarcity, transmitters and other intentional radiators will be planned to operate at closely spaced adjacent frequencies. Power amplifiers and other components used in these systems are measured to determine the amount of signal energy that spills over into adjacent channels and causes interference. The concern is that these unwanted emissions, either radiated or conducted (through the power lines or other interconnecting wires), might impair the operation of other systems. The design or manufacture of electrical or electronic products also involves the testing for emission levels versus frequency according to Technical Standards set by various government agencies or industry standards bodies. The common measurements taken by a spectrum analyzer include frequency, power, modulation, distortion, and noise. Understanding the spectral content of a signal is important, especially in systems with limited bandwidth. Transmitted power is another key measurement. Too little power may mean the signal cannot reach its intended destination. Too much power may drain batteries rapidly, create distortion, and cause excessively high operating temperatures. Measuring the quality of the modulation is important for making sure a system is working properly and that the information is being correctly transmitted by the system. Tests such as modulation degree, sideband amplitude, modulation quality and occupied bandwidth are examples of common analogue modulation measurements. It is important to note that for digital modulation techniques there are additional measurements which need to be taken, including: error vector magnitude (EVM) and phase error versus time, among other measurements. There are several basic types of spectrum analyzers. These are: Fourier, Vector Signal and Superheterodyne Analyzers. Each type is briefly described in the next few paragraphs. Fourier signal analyzers measure the time-domain signal and then use digital signal processing (DSP) techniques to perform a fast Fourier transform (FFT) and display the signal in the frequency domain showing both phase as well as magnitude of the signal. Like Fourier analyzers, Vector signal analyzers (VSA’s) measure the time domain signal, but have the advantage of extending to the 5-6 GHz. RF frequency range. VSA’s offer faster, higher-resolution spectrum measurements, demodulation, and advanced time-domain analysis. They are especially useful for characterizing complex signals such as burst, transient or modulated signals used in communications, video, broadcast, sonar, and ultrasound imaging applications.

Because the signals that people must analyze are becoming more complex, the latest generation of spectrum analyzers include many of the vector signal analysis capabilities previously found only in Fourier and Vector signal analyzers. Superheterodyne analyzers are able to mix; that is, to translate frequency at frequency ranges above the audio range.

Typical Spectrum Analyzer Display (Rohde & Schwarz)

Automated Field Strength Measurement Equipment (Rohde & Schwarz)

Radio Direction-Finding Equipment

Radio Direction-Finding, or RDF, is the technique for determining the direction of a radio transmission. Radio direction-finding using triangulation techniques can also be used to determine the location of a radio transmission. Radio direction-finding is used by spectrum managers to locate the source of radio frequency interference. There are two common technical approaches to radio direction-finding. The first approach involves the use of directional antennas which are designed to be more sensitive to signals received in some directions rather than in others. As the antenna is turned in various directions, a signal being received will either increase or decrease in strength. All other things being equal, the direction in which the signal is strongest is the likely direction in which the radio transmitter is located. The movement of the antenna and the determination of the peak signal strength can be made by a human operator or can be done automatically by electronics. The second approach exploits the effects of phase shift. Fixed antennas are deployed in a precise geometric pattern and an electronics system switches between the antennas very rapidly. By computing the amount of phase shift present on the signal from antenna to antenna, a direction to the signal source can be computed. There are anomalies of radio propagation which at ground level can affect both of these techniques. Common potential problems include reflections or multi-path loss. In a multi-path situation, the radio signal may be arriving at the antenna or antennas from multiple directions, perhaps because the signal is reflecting off nearby buildings, hills, or metal structures such as fences. The strongest signal may, in fact, be coming from a reflection rather than the direct path, especially if the direct path includes terrain features that might attenuate the signal. This can result in false directional readings. The preceding paragraphs provide a brief summary of the main types of equipment used in monitoring. The complexity and cost of equipment varies with the level of computer integration, number of functions and types of analysis performed and the speed at which a number of frequencies can be scanned and analyzed. Simple systems for VHF/UHF monitoring can be comprised of several fixed antennas, receivers and limited function spectrum analyzers. More complex systems can consist of multiple sites and mobile and fixed stations. Monitoring System Architecture is further explored in Section 6.3.2.

RELATED INFORMATION

Recommended HF Receivers, Spectrum Monitoring Handbook, ITU, 2002: Chapter 2, Table 15, p. 135

Recommended VHF/UHF Receivers, Spectrum Monitoring Handbook, ITU, 2002: Chapter 2, Table 16, p. 136

Practice Notes

Reference Documents

5.6.2.2 Monitoring System Architecture

Design Considerations for Spectrum Monitoring Systems

Due to spectrum congestion and sophistication of wireless communication technologies, it is an ever-increasing challenge to monitor spectrum, particularly considering the rapid growth of wireless, satellite, and point-to-point communication devices. Regulators are asked to hunt for and resolve RF interference in this crowded and complex spectrum.

There are two likely scenarios. There is a-priori information on the emitters to be tracked or tested, e.g., approximate frequency and amplitude. Here, traditional spectrum analysis techniques and equipment will work extremely well. Alternately, there is no prior knowledge.

Without control of the RF/microwave airspace and with little information about the target signals, the RF spectrum-monitoring task is a discovery process. Signals of interest reveal themselves to spectrum monitoring because many wireless signals vary in power, duration, and bandwidth. Some of the complex interactions between systems may actually be harmonics of known emitters, translated into frequencies where they become unwanted interferers. There can be thousands, even tens of thousands of irrelevant signals that need to be ignored when capturing data on emissions of interest.

Key considerations in the design of spectrum monitoring systems include types of equipment, speed and sophistication of data capture and processing, degree of integration with software tools for analysis and comparison with other license and type approval data. Other considerations include proximity to active airspace, staff skills, and mobile versus fixed locations.

State-of-the-art spectrum monitoring equipment is highly integrated. Integration typically involves the use of graphical user interface (GUI) based spectrum management tools and systems which are specifically designed to operate multiple electronic components simultaneously and remotely over data protocols such as TCP/IP. This allows for an integrated network system for management of the radio spectrum using remote devices. These devices can be located at existing government sites and facilities on the outskirts of population centres. Remote devices permit access to monitoring equipment from anywhere through compatible computer, a modem and a telephone line or network connection (LAN or WAN). Remote devices can be controlled in several ways:

    • Locally from the server;
    • Remotely across a LAN;
    • Modem over a WAN.

Architecture Components

There are equipment and organizational and functional aspects to architecting spectrum monitoring systems.

The key technical equipment components are described in Section 6.3.1 Monitoring Equipment. Additional equipment components in a monitoring system include: buildings, power supplies, mobile vehicles and man portable components.

Organizational components include centralized, regional and remote locations for siting of monitoring equipment in stations and operational staffing or use of unmanned remote capabilities, where applicable.

In addition to technical equipment, functional components of spectrum monitoring systems include: central monitoring control; operational consoles for operation of equipment and analysis of data; and data networking and management systems for data communications and repository.

Practice Notes

Reference Documents

5.6.3 Enforcing Compliance

Spectrum management also requires that users comply with licence requirements and technical rules and regulations. Without effective regulations and enforcement procedures, the integrity of the spectrum management process can be compromised. The spectrum regulator needs an appropriate framework and process for responding to and managing complaints and for settling disputes. Consideration needs to be given to penalties, remedies, enforcement and alternative dispute resolution (ADR) mechanisms for industry disputes with the aim of ensuring rapid resolution.

5.6.3.1 Monitoring Compliance with Technical Standards

Monitoring is used to obtain detailed information on the technical and operational characteristics of radio systems which are in use or are being tested for future use. Measurements will typically include frequency, power and emission spectrum of a transmitter. Licence conditions can be verified against actual use of equipment aiding in the determination of electromagnetic compatibility (EMC).

Because technical standards are associated with certain allocations and assignments, the spectrum manager can detect the existence of unauthorized transmitters which affect other users by causing interference and by reducing the value of licensed spectrum.

Practice Notes

5.6.3.2 Solving Interference Problems

Electromagnetic interference (EMI) is a term applied to unwanted emissions from both intentional and unintentional radiators. Here, the concern is that these unwanted emissions, either radiated or conducted (through the power lines or other interconnecting wires), might impair the operation of other systems. Almost anyone designing or manufacturing electrical or electronic products must test for emission levels versus frequency according to regulations set by various government agencies or industry-standard bodies. Resolution of interference problems is often a difficult task for spectrum managers since the source of interference is not necessarily known nor easily identified.

Through the ITU, an international framework has been established taking form as the International Frequency Allocation Table (Article 5 of the Radio Regulations). This table is used to protect against harmful interference, and coordinate for services of an international nature. Examples include satellites, maritime and aeronautical services (devices). International harmonization of allocations and other operational matters is necessary to allow users to operate safely and effectively (e.g. international air travel, ships at sea, etc.). Spectrum managers are particularly concerned about interference problems affecting public safety and security services including; ambulance, fire fighting, police, and navigational services at airports. The Radio Regulations set forth the principles under which spectrum will be managed and requires Member States to prevent harmful interference.

The Regulations therefore set out with regards to interference:

  • Member States undertake that, in assigning frequencies to stations, which are capable of causing harmful interference to the services rendered by the stations of another country, such assignments are to be made in accordance with the Table of Frequency Allocations and other provisions of these regulations;
  • Any new assignment or any change of frequency or other basic characteristic of an existing assignment shall be made in such a way to avoid causing harmful interference to services rendered by stations using frequencies assigned in accordance with the Table of Frequency Allocations in this Chapter and the other provisions of these Regulations, the characteristics of which assignments are recorded in the Master International Frequency Register.

Coordination with the complainant is often needed, even if only to know the frequency of the receiver operation. Direction finding equipment is often used to determine the source of interference. Deciding on what to use will depend on the range of the affected frequencies. Sources of interference can be from atmospheric effects such as precipitation, long-range HF and UHF frequencies from across national borders, or from intentional efforts to interfere with transmissions, a practice sometimes referred to as “jamming”.

Box  ITU Radio Regulations: Article 4

The sources of interference are broad and varied. (See Section 4.3.2 Interference Management)Other sources of offending interference can come from industrial applications of radio energy, such as microwave dryers used in manufacturing. Understanding sources of emission, developing and adopting relevant technical standards while also having access to technical tool’s methods and processes are developed by spectrum managers to resolve these types of interference problems.

The main steps for resolving interference problems are:

  • Communication and Acknowledgement of an interference problem by a user;
  • Diagnosis of an interference problem by the regulator, spectrum manager or some other relevant authority;
  • Identification through monitoring and measurement of the potential source of interference;
  • Confirmation of the source of interference and communication with responsible persons;
  • Determining steps to correct and mitigate interference such as the use of filters, reducing transmit power, re-locating transmit antennae, and changing transmit frequencies.

Joint Task Group 5-6

GE06, WRC-07 and the work of Joint Task Group 5-6 are excellent examples of the coordinated planning work done in the advance to study and rectify potential interference problems. Resolution 749 (WRC-07) and Agenda item 1.17 of WRC-12 tasks the ITU-R Sector “to conduct sharing studies for Regions 1 and 3 in the band 790-862 MHz between the mobile service and other services in order to ensure adequate protection of services allocated to the band and to take appropriate action." Joint Task Group 5-6 (JTG 5-6) was established to study how mobile services can share the band 790-862 MHz band with:

the Broadcasting service (Issue A);

the Aeronautical radionavigation service (Issue B); and

the Fixed service (Issue C).

These issues were further sub-divided by cases according to either an ITU-R Region (for Issue B and Issue C) or to whether the countries were or were not Contracting Members of the GE06 Agreement (Issue A). Appropriate methods have been proposed for each issue and case.

The work of the Joint Task Group in providing the text for the draft CPM Report addressing the results of sharing studies for fixed, mobile and broadcasting services in the band 790-862 MHz in Regions 1 and 3 was completed in May 2010 and indicated that there is a need to protect certain other primary terrestrial services from the newly allocated mobile service in Region 1. Of particular significance is ensuring coordination and interference avoidance between mobile services and aeronautical radionavigation services (ARNS) in those countries where ARNS has a primary allocation.

Practice Notes

Reference Documents

5.6.3.3 Inspections

In the course of conducting exercises to resolve interference problems, the spectrum manager may be required to enter user premises and inspect radio equipment to determine compliance with licence conditions and technical standards.

An important aspect of fulfilling these tasks is the requirement under law and regulation to establish the powers, authorities, duties and obligations of the spectrum manager/inspector and protection of rights for the public under circumstances where inspection of property is necessary.

Equipment Seizure and other Enforcement Actions

There are (hopefully rare) occasions when the user of a transmitter causing harmful interference is endangering the public in a persistent and wilful manner and the reasonable course of action requires the spectrum manager to seize equipment to prevent such endangerment.

Again, it is necessary to provide the spectrum manager with the appropriate authority to seize equipment under carefully defined conditions to prevent abuses of power and ensure the user’s right to due process.

When it is determined that harmful interference may be caused by any particular equipment, the spectrum manager may, by first informing the person in writing, direct the owner or user of that electrical, electronic or radiocommunication equipment to do, at their own expense, any one or more of the following:

    • Take suitable measures to eliminate or reduce the interference or disturbance;
    • Remedy a fault in or the improper operation of the equipment;
    • Modify or alter the equipment; or
    • Disconnect the equipment.

Otherwise, the owner or user risks having the equipment seized by the spectrum manager.

Reference Documents

5.6.3.4 Equipment Seizure and other Enforcement Actions

There are (hopefully rare) occasions when the user of a transmitter causing harmful interference is endangering the public in a persistent and wilful manner and the reasonable course of action requires the spectrum manager to seize equipment preventing future endangerment.

Again, it is necessary to provide the spectrum manager with the appropriate authority to seize equipment under carefully defined conditions ensuring the user’s right to due process and preventing abuses of power.

Typically, when the spectrum manager determines that harmful interference may be caused by any particular electrical, electronic or radiocommunication equipment, whether subject to licensing or not, the spectrum manager may, by first informing the person in writing, direct the owner or user of that electrical, electronic or radiocommunication equipment to do, at their own expense, any one or more of the following:

    • Take suitable measures to eliminate or reduce the interference or disturbance;
    • Remedy a fault in or the improper operation of the equipment;
    • Modify or alter the equipment; or
    • Disconnect the equipment.

Otherwise the owner or user risks having the equipment seized by the spectrum manager.

The Radio Regulations of Singapore, Trinidad and Tobago and Canada provide examples of the types of regulation used to define the actions of spectrum managers when it comes to enforcement action.

Practice Notes

Reference Documents

Next: 5.6.3.4 Equipment Seizure and other Enforcement Actions