5 ms·

Reddit had AMA with engineers from this mission, IIRC last week. They provided good info on different aspects including how they were able to get video over low

• asaddhamani 6y ago
  Do you have a link to this AMA?
  • kgrimes2 6y ago
    https://www.reddit.com/r/IAmA/comments/lpzbzo/were_scientists_and_engineers_working_on_nasas/ https://www.reddit.com/r/IAmA/comments/lpzbzo/were_scientist...
• eCa 6y ago
  https://old.reddit.com/r/IAmA/comments/lpzbzo/were_scientists_and_engineers_working_on_nasas/ https://old.reddit.com/r/IAmA/comments/lpzbzo/were_scientist...
• jdmichal 6y ago
  Others have posted links to the Reddit thread overall, but I think this is the specific question being referred to: https://old.reddit.com/r/IAmA/comments/lpzbzo/were_scientists_and_engineers_working_on_nasas/godr2t7/ https://old.reddit.com/r/IAmA/comments/lpzbzo/were_scientist... EDIT: Apparently the rover has an antenna that can directly communicate with Earth at 10 bits per second! That's obviously not useful for pictures or anything, but it's an amazing capability for emergency comms.
  • londons_explore 6y ago
    Very low bandwidth, very low power, very long distance comms are really cool. The limiting factor tends to be the clock frequency precision - if you have precise enough clocks at both ends, there isn't anywhere in the universe you couldn't communicate with, as long as you're happy to go slow enough.
    • magicalhippo 6y ago
      Given self-clocking signalling[1] exists, why is clock frequency precision the limiting factor? I would imagine signal-to-noise would be the limiting factor, ie how strong is your transmitter and how sensitive is your receiver. [1]: https://en.wikipedia.org/wiki/Self-clocking_signal https://en.wikipedia.org/wiki/Self-clocking_signal
      • londons_explore 6y ago
        It is possible to send a signal weaker than the noise floor. The maximum information you can send is defined by shannon's channel capacity formula, which clearly says a signal can be weaker than the noise. If you use a self-clocking signal, then effectively the information you are sending consists of both the clock timings and the information you're really trying to send. If your channel capacity is very low, you will find there is no channel capacity for even the clocking information, let alone the information you really want to send.
      • tremon 6y ago
        Noise, by definition, doesn't have a qualifying characteristic. It just means "all signals we're not interested in". That means your ability to filter out noise is strongly dependent on having pre-existing knowledge about the shape of the signal you're interested in. Self-clocking signals are useful when the ambient noise level is low with respect to the signal, but if your signal is just "these two droplets in an ocean" you will not be able to filter out enough of the signal to detect the edges of the original signal. Having a very reliable clock frequency means you can apply a very exact filter to lock on to the signal you want, thereby making the transmission less sensitive to interference from other radio signals. Just having a sensitive receiver isn't enough, because a sensitive receiver will also pick up more of the other radio signals.