Planes are having their GPS hacked. Could new clocks keep them safe?(www.bbc.com)
11 pointsby justin662 days ago2 comments
  • thesh4d0w2 days ago
    I don't understand this article. If the GPS signals are jammed, what purpose does it serve to have an atomic clock on board your plane? You still need accurate signals with time data to measure against.

    Am I missing something?

    • touisteur2 days ago
      You can get a very accurate timestamp from GNSS. What lots of people do then is slave a PLL based on a local oscillator, to be able to get time between two GNSS captations. Or to be able to extrapolate when they have no GNSS signal.

      Now suppose someone is spoofing your GNSS signals, it's pretty hard to replace a constellation with another one whilst maintaining time consistency for you. One way to detect spoofing is comparing what a local clock is saying to whatever the GNSS is giving. A local, unfudgeable, stable, accurate clock is a good reference for this.

      • thesh4d0w2 days ago
        Ahhhhh, that makes sense. Treating this as security mechanism rather than an anti-jamming one.
    • simne2 days ago
      As I read from book about gyroscopes, most sensitive achieve so fine accuracy, they detect daily Earth rotation and even yearly Earth rotation.

      But when they speaking about near zero temperatures, looks like they talking about something like Rydberg atoms - extremely sensitive matter, which could be considered as nuclear scale gyroscopes, or quantum gyroscopes, or read more about quantum accelerometer.

      And current inertial navigation could be used to calculate relative coordinates like automobile odometer, but from integrating accelerations. But classic accelerometer is just not fine enough, and at this place appear quantum accelerometer and quantum gyroscope.

      And I agree, article is terrible. I don't know why they use so abstract language, when could just say, navy already tested quantum navigation.

      • simne2 days ago
        To be more concrete, space rockets nearly all fly with inertial navigation, but they are extreme case, because most use only inertial navigation just few minutes (so all those classic gyros/accelerometers integrated errors are small enough to successful enter stable orbit, and then using some sort of radio or optical fine measurements and making corrections with fine engines).

        Planes flights are much more lengthy than rockets - I think, typical ~40 minutes or more (most long I hear 20 hours), so INS could integrate huge mistake.

    • BenjiWiebe2 days ago
      I didn't read the article, but: a GPS receiver must calculate/find both it's time and position to get a fix. So maybe by having the time already available really accurately it makes the job of finding position easier?
  • anovikov2 days ago
    So this pertains to jamming so strong that traditional jam-proof GPS that uses signal phase shift to weed out GPS signals coming from "wrong" directions, are insufficient? 100db attenuation of jamming signal has been achieved around 15 years ago with those.

    In the air, there are always more GPS satellites visible than necessary. So jam-proofing through signal processing methods is the way to go.