GPS World

Tag: RNSS

  • UN agencies denounce GNSS interference

    UN agencies denounce GNSS interference

    The International Telecommunications Union (ITU), International Maritime Organization (IMO) and International Civil Aviation Organization (ICAO) recently issued a joint statement urging “Protection of the Radio Navigation Satellite Service from Harmful Interference.”

    All three organizations are United Nations agencies and have previously issued similar statements independently. This is the first time they have spoken on this in one voice.

    In 2020, ICAO issued a letter to all member states urging them to “strengthen CNS systems resilience and mitigate interference to GNSS.” It contained 13 recommendations resulting from three different work streams within the organization. The last of the recommendations was “… to support the multi-disciplinary development of alternative positioning, navigation and timing (APNT) strategy and solutions to complement the use of GNSS in aviation in coordination with ICAO and airspace users.”

    In 201, IMO issued a circular on deliberate GNSS interference.. It called on nations to prevent interfering transmissions coming from their territories, issue warnings about known interference, and consider taking actions to prevent unauthorized interfering transmissions.

    ITU issued a circular on “Prevention of harmful interference to Radio Navigation Satellite Service Receivers in the 1559 – 1610 MHz frequency band” in 2022. It emphasized that, according to ITU Radio Regulations, “All stations are forbidden to carry out unnecessary transmissions, or the transmission of superfluous signals, or the transmission of false or misleading signals…”

    This ITU circular urged nations to “address the critical issue” by: 

    • Reinforcing navigation systems’ resilience to interference.
    • Increasing collaboration between radio regulatory and enforcement authorities.
    • Reinforcing civil-military coordination to address interference risks associated with RNSS testing and conflict zones.
    •  Increase coordination between aviation, military and radio-regulatory authorities.
    • Retain essential conventional navigation infrastructure for contingency support in case of RNSS outages and develop mitigation techniques for service loss.

    A resolution by ITU’s 2023 World Radiocommunications Conference echoed similar themes. Still, it was criticized because its cautions and prohibitions came with the caveat, stating “…without prejudice to the right of administrations to deny access to the RNSS, for security or defense purposes.”

    Many observers opined that there are few reasons for nations to interfere with GNSS other than security or defense concerns, which allows malicious actors to have carte blanche. Furthermore, it was suggested that the resolution might have included language to ensure that security and defense-related disruptions do not extend beyond a nation’s borders or similar provisions.

    While no specific events are cited in the statement as motivating its publication, the death on Christmas Day of thirty-nine people aboard an Azerbaijan Airlines flight could have been the reason. The aircraft was approaching a Russian airport during an intentional interference event and was apparently misidentified by Russian forces. It was subsequently damaged by ground fire and crash-landed in Kazakhstan.

    The recent joint statement cites, among other international agreements and actions, the ITU Constitution, which says, “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 Member States.”

    The joint statement concludes with:

    Therefore, ITU, ICAO and IMO jointly and urgently call on their respective Member States to:

    • Protect the RNSS from transmissions that can adversely cause harmful interference, degrading, interrupting, or misleading signals used for civilian and humanitarian purposes.
    • Reinforce the resilience of the systems that rely on RNSS for navigation, positioning, and timing in relation to this type of interference.
    • Retain sufficient conventional navigation infrastructure for contingency support in case of RNSS outages and misleading signals, and develop mitigation techniques for loss of services.
    • Increase collaboration between radio regulatory, civil aviation, maritime, defense and enforcement authorities.
    • Report cases of harmful interference affecting RNSS to the appropriate telecommunication, aeronautical, and maritime authorities and the ITU Radiocommunications Bureau to enable the monitoring of the situation.

    The United Nations and its agencies are collaborative bodies that operate by consensus and through the cooperation of members. As such, they have no ability to enforce standards or compel compliance with recommendations.

    Read the joint statement here.

  • With 10,000+ aviation events in 2021, ITU issues GNSS interference warning

    With 10,000+ aviation events in 2021, ITU issues GNSS interference warning

    By Dana A. Goward

    Earlier this month, the International Telecommunication Union (ITU) issued a circular urging its member states to prevent interference with GNSS signals and receivers.

    ITU is the latest United Nations body to express such concerns and issue an advisory. The International Maritime Organization issued a similar document in 2021, as did the International Civil Aviation Organization in 2020.

    ITU is the United Nations agency that deals with information and communications technology. Its remit includes coordinating spectrum use and satellite orbits.

    ITU’s Radio Communications Bureau sponsors the World Radiocommunication Conference every three to four years. The issue of interference with GNSS signals was reported at the 2019 conference.

    Since that time, according to this month’s circular, the group “has been informed of a significant number of cases of harmful interference to the radionavigation-satellite service…”

    Despite concerns expressed by maritime and other interests, the circular focuses entirely on aviation interference. It says the reports it has received have been about “receivers onboard aircrafts and causing degradation or total loss of the service for passenger, cargo and humanitarian flights…” These have included “misleading information provided by RNSS [radionavigation satellite service] receivers to pilots.” An often cited example of this is a well-publicized 2019 incident in Sun Valley, Idaho. In that case a passenger aircraft nearly hit a mountain.

    Describing interference with GNSS as a global and recurrent problem, the circular cites data collected by a major aircraft manufacturer. The company found “10,843 radio-frequency interference events … globally in 2021. The majority of these events occurred in the Middle East region, but several events were also detected in the European, North American and Asian regions.”

    This year’s uptick in GNSS interference in Scandinavia, the Baltics, and around Ukraine since Russia’s February invasion of Ukraine is not mentioned. This is likely due, in part, to timing. ITU’s Radio Regulations Board met in March 2022 and directed the circular be issued.

    Many within the positioning, navigation, and timing community have long asserted that interference with GNSS signals, whether deliberate or accidental, constitutes a violation of ITU rules and regulations. This month’s circular affirms this and cites several applicable provisions.

    These include prohibitions on harmful interference with any authorized radio frequency transmission, requirements for users to transmit only in bands for which they have authorization, and for all to generally safeguard aviation operations.

    The circular highlights provision 15.1 of ITU’s Radio Regulations as particularly applicable. It states:

    “All stations are forbidden to carry out unnecessary transmissions, or the transmission of superfluous signals, or the transmission of false or misleading signals, or the transmission of signals without identification…”

    As is the case with almost all international agreements, enforcement of ITU rules is the responsibility of its member states.

    While most expect the advisory to have little immediate impact on reducing global interference with GNSS signals, it does help reinforce the issue as one of international concern.

    According to a retired government official, “Member states that fail to comply with international rules to which they have agreed lose credibility and standing in the community of nations. Even when they have little credibility or standing to begin with, the behavior adds to their marginalization and life is just a little more difficult for them. This can, in the long run, nudge them toward being more responsible players.”

    Photo: jpgfactory/iStock/Getty Images Plus/Getty Images
    Photo: jpgfactory/iStock/Getty Images Plus/Getty Images

  • More interference potential from another tower set

    Satellite operator Iridium asked the Federal Communications Commission (FCC) in April 2017 to modify its license to add a new class of ground stations called Certus for expanded terrestrial, maritime and aeronautical operations.

    Iridium’s 66-satellite constellation provides, in addition to mobile communications signals, the Satelles time and location service: microsecond timing accuracy and 20- to 50-meter unaided position accuracy worldwide (see the “Innovation” column, July 2017 GPS World).

    GPSIA. The GPS Innovation Alliance (GPSIA) commented in September, “GPSIA seeks to ensure that radio navigation satellite service (RNSS) receivers operating in the 1559–1610 MHz band are adequately protected from out-of-band emissions (OOBE) generated from the new Certus mobile Earth station (MES) terminals that will operate on the second-generation Iridium satellite system.

    “GPSIA and Iridium are actively engaged in constructive discussions regarding the adequacy of that protection, but no final resolution has yet been reached. [….]

    “In the unlikely event that GPSIA is unable to reach an agreement with Iridium, it asks the commission to impose limitations on the operation of Certus terminal devices to protect GPS/RNSS operations in the 1559–1610 MHz band at a level equivalent to what terrestrial terminals in the same and other frequency ranges provide at –95 dBW/MHz.”

    Iridium Certus infographic.


    Hexagon.     Hexagon, the parent company of GPS manufacturer NovAtel, commented on Jan. 8, “Certain statements in the modification application regarding output power and amount of terminals to be deployed cause great concern regarding the unimpeded operation of radio navigation satellite service (RNSS) receivers. The application does not include enough information to simulate the impact properly.

    “Hexagon politely requests that the FCC will exercise the same due diligence [as] during previous modification applications close to the RNSS bands (for example docket 11-109) and establish a technical working group or a similar testing process that ensures unimpeded coexistence of the modified Iridium terminals with the established RNSS systems.”

    Documents related to the case can be found here, on the FCC International Bureau website.