Radio interference is defined by No. 1.166 of the ITU Radio Regulations (RR) as "the effect of unwanted energy due to one or a combination of emissions, radiations, or inductions upon reception in a radiocommunication system, manifested by any performance degradation, misinterpretation or loss of information which could be extracted in the absence of such unwanted energy". Interference has several levels, as defined in Article 1 of the RR:
- permissible interference (see No. 1.167);
- acceptable interference (see No. 1.168);
- harmful interference (see No. 1.169).
When interference is harmful
Harmful interference is defined in No. 1.169 of the RR and in No. 1003 of the ITU Constitution, as “interference which endangers the functioning of a radionavigation service or of other safety services or seriously degrades, obstructs, or repeatedly interrupts a radiocommunication service operating in accordance with Radio Regulations". Harmful interference (including the blocking, jamming or degradation of service) can take place for a wide range of reasons, which can be either accidental or intentional. Both commercial services as well as critical safety-of-life applications may be degraded and affected.
According to the RR (which reproduces No. 197 of Article 45 of the ITU Constitution), “all stations, whatever their purpose, must be established and operated in such a manner as not to cause harmful interference to the radio services or communications of other Members, recognized operating agencies, or other authorized operating agencies which carry on a radio service, and which operate in accordance with the Radio Regulations".
Jamming is prohibited by No. 15.1 of the RR, which states that “all stations are forbidden to carry out unnecessary transmissions, or the transmission of superfluous signals, or the transmission of false or misleading signals (…)". Special attention needs to be paid to safety services (aeronautical, maritime and radionavigation), that require absolute international protection. The elimination of harmful interference for these services is imperative (No. 15.28 of the RR). Harmful interference can have both short-term consequences (e.g. in degradation of service) or long-term effects (e.g. in jeopardizing dependent services or incentives for future investments).
What can be done
One of ITU-R's main objectives is to ensure interference-free operations of radiocommunication systems by implementing the RR and regional agreements, and updating treaties and agreements in an efficient and timely manner through World and Regional Radiocommunication Conferences.
“It is essential that ITU Member States exercise the utmost goodwill and mutual assistance in the application of the provisions of Article 45 of the Constitution to the settlement of problems of harmful interference". Section VI of Article 15 of the RR sets out the procedure in case of harmful interference, as well as the conditions for the resolution of a problem of harmful interference. The initial procedure is based mainly on a direct approach between the administrations concerned. However, cases of harmful interference may also be communicated to the ITU either for information or with a specific request for assistance, where action on a bilateral basis may have been unsuccessful.
When the source of harmful interference is non-domestic, reporting a case of harmful interference through the national regulatory agency to the ITU Radiocommunication Bureau can help assess the actual situation, resolve the case and prevent its recurrence. ITU has modernized and improved the reporting of harmful interference and offers capacity-building to educate and raise awareness about the impact of and possible solutions to harmful interference.
Any station must be duly licensed by the governments having jurisdiction over the territory where it is intended to operate (Article 18 of the RR). Prohibiting jamming equipment is the responsibility of ITU Member States and their regulatory & enforcement agencies. A growing number of countries have made it illegal to purchase, sell and/or use GNSS jamming equipment. The Bureau reported this matter to WRC-19 and encouraged Member States to strengthen their control mechanisms.
There is a long-standing practice within ITU-R Study Groups preparing ITU-R Recommendations or standards to ensure compatibility between radiocommunication systems. Reserving a portion of the link budget as a margin (additional energy in the wanted signal being transmitted) to compensate for any interference has worked well for decades to protect against unintentional interference.
