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.