GNSSjelek

GNSSjelek is an informal term used in some GNSS-related discussions to denote degraded performance of Global Navigation Satellite System signals, characterized by reduced positioning accuracy, reliability, or integrity. The term is not a formal standard but serves as a shorthand for observed problems in challenging environments or under interference.

Origin and usage of the term reflect ongoing concerns about GNSS reliability. The combination of the GNSS acronym with the colloquial word jelek, meaning “bad” in several Southeast Asian languages, signals a descriptive rather than technical label. GNSSjelek is commonly invoked when receivers experience unexplained errors, interruptions, or anomalous time and position outputs.

Description and scope of GNSSjelek encompass a range of phenomena. These include multipath effects in urban canyons, atmospheric delays in ionospheric or tropospheric conditions, and various forms of interference such as jamming and spoofing. Receiver limitations, including loss of lock or degraded signal quality in environments with weak signals, also contribute to GNSSjelek. It is distinguished from formal fault trees or standardized vulnerability classifications by its broad, situational usage.

Impact and applications: GNSSjelek can affect aviation, maritime, surveying, and autonomous systems, where accurate timing and positioning are essential. In practice, mitigating GNSSjelek involves improving receiver robustness, enhancing signal processing, and integrating supplementary sensors and systems.

Countermeasures and mitigation:

- Use multi-constellation receivers (GPS, GLONASS, Galileo, BeiDou, and others) to increase resilience.

- Implement anti-jamming and anti-spoofing technologies.

- Combine GNSS with inertial navigation systems and other sensors.

- Employ augmentation systems (SBAS/WAAS, GBAS) and cross-checks (RAIM) to improve integrity.

See also: GNSS vulnerability, GNSS jamming, GNSS spoofing, RAIM, anti-spoofing, inertial navigation.