Take 10 #40: Managing GNSS
Ten top tips for managing GNSS – and the absence of it
1 What is GNSS?
Global Navigation Satellite Systems (GNSS) are constellation of satellites providing signals from space to support mariners (and the rest of the world) with global positioning and accurate timing.
2 Origin story
GNSS are provided by different countries and include GPS (USA); Galileo (EU); GLONASS (Russia); and BeiDou (China).
3 Common weakness
Different systems have their own strengths and weaknesses; however, they share the common weakness of being fairly easy to jam and spoof.
4 Golden rule
Never trust a single positioning system – whether it’s visual, Radar, echo sounder, celestial or even GNSS. Always corroborate any position by other means – and be acutely aware of where the limitations lie.
5 Jamming
Jamming can be unintentional and caused by space weather or faulty equipment; or intentional, caused by individuals or governments. Due to the low power signal from space, jamming is fairly easy to achieve, and somewhat easy to detect.
6 Spoofing
Spoofing is the intentional fooling of a receiver in order to deceive the navigator. This can be harder to detect.
7 Risk assessment
The current geo-political turmoil around the world is making GNSS disruption and denial a lot more common. Disruption may affect many systems and ships in your area.
8 ECDIS
For navigation, it is essential that you can effectively use an ECDIS without GNSS input, using other manual plotting techniques as well as DRs (Dead Reckoning) and EPs (Estimated Positions).
9 Check your sources
Information sources about GNSS issues are being constantly updated. Ensure your company and crew remain aware of the latest advice, and seek further support from P&I Clubs, shipping associations, manufacturers, flag states etc.
10 Sharing is caring
Issues around GNSS disruption and denial and how to respond are complex. It is always good to share information and thoughts with the entire bridge team to enhance overall situational awareness.