5 ms·
Celestial navigation is way easier than you think it is. We have accurate clocks now, and you can just take the measurements and feed it into the computer.
by SamReidHughes 11y ago
Celestial navigation is way easier than you think it is. We have accurate clocks now, and you can just take the measurements and feed it into the computer.
- toyg 11y agoThe point of this training today, I would expect, is that computers might not always be there.
- gavazzy 11y agoWe might have computers, but GPS signals can be spoofed: https://en.wikipedia.org/wiki/Spoofing_attack#GPS_Spoofing https://en.wikipedia.org/wiki/Spoofing_attack#GPS_Spoofing
- gruez 11y agoIs there a reason why the signals aren't digitally signed? I understand that GPS and GLONASS was deployed over 30 years ago, but surely Galileo, with its first satellite launched 4 years ago can have this?
- Nrsolis 11y agoSpoofing of GPS signals isn't generally the problem the US military is most concerned about. It's availability. The assumption is that in any significant event, US space assets will be unavailable either momentarily or for some extended period. Chinese Anti-SAT weapons are one indicator that this is a likely avenue of attack for any weaker actor seeking to degrade our capabilities. So, celestial navigation is a crude but workable substitute for GPS but it has the distinct advantage of being ancient and nearly impossible to impede unless you can change the weather or the positions of the heavenly objects.
- kevinchen 11y agoHere's a paper that proposes GPS authentication based on signing and statistics about the signals (lots of math): http://radionavlab.ae.utexas.edu/images/stories/files/papers/nma.pdf http://radionavlab.ae.utexas.edu/images/stories/files/papers... Paper from Los Alamos with a receiver-only implementation that would use: - abnormally high signal strength - abnormally regular transmissions - a secondary time source to double-check time (e.g. NTP on a smartphone) - dead-reckoning based on accelerometers/gyroscopes/compass to double-check position http://lewisperdue.com/DieByWire/GPS-Vulnerability-LosAlamos.pdf http://lewisperdue.com/DieByWire/GPS-Vulnerability-LosAlamos...
- maaku 11y agoGPS signals are weak. You simply jam them.
- knodi123 11y agoIf the people on a modern naval ship don't have access to some kind of basic computer, then they have bigger problems than navigation.
- deleted 11y ago[deleted]
- superuser2 11y agoGPS depends on satellites to stay in the right place, intact, and powered, as well as the ability to receive authentic RF signals from those satellites. Celestial navigation requires (the computational equivalent of) a graphing calculator.