4 ms·

> All of the communications channels use the Reed-Solomonerror-correction protocol. I think you don't want to use Reed Solomon for this, but turbo codes or mos

> All of the communications channels use the Reed-Solomonerror-correction protocol. I think you don't want to use Reed Solomon for this, but turbo codes or most likely online codes. https://en.wikipedia.org/wiki/Online_codes https://en.wikipedia.org/wiki/Online_codes

Sporktacular 4y ago
Maybe it's because of RS codes superior performance during burst errors while the SNR involved isn't so low as to give convolutional codes a net advantage. Maybe it's Error Floor. Or maybe we should just assume that some of the world's most qualified RF and comms engineers behind these decisions did their homework.
- toolslive 4y ago
  maybe because online codes only came available after 2004, and the choice was already made and the picked solution sufficed so was never revisited. So the question becomes: when did they do their homework?
  - Sporktacular 4y ago
    Yes, there is a thread to that effect. Development was heavily delayed, certification and conservatism around space systems can slow down deployment to the point of just not being worth changing things. I am sorry to have been presumptuous. There's been a spate of recent armchair experts with some arrogant "they should just use a warp drive" type contributions lately.
    - toolslive 4y ago
      - The thing with online codes is that while they are quite efficient in data overhead (a few %) they only start working when you have enough data ( > X MB). (check!) - another problem is that since the system that you need to solve to get your data back is large and random, so in-place updates of the data are impossible. In other words: they only work for immutable data (check!) - The extra information to counter lost messages is scattered over all messages so the client doesn't need to figure out which ones are missing (and doesn't need to tell the server, in this case the telescope). This makes them highly suited for high latency communication (and storage which is in essence the same thing, but that's another story) (check!) They (online codes) were designed for this exact use case.
- toolslive 4y ago
  Sigh, I might not be top notch anymore, but I am the (co) author of some patents in the field. Questioning RS for this use case is legit.
- cle 4y ago
  > Or maybe we should just assume that some of the world's most qualified RF and comms engineers behind these decisions did their homework. I'd rather read an interesting discussion of the tradeoffs than a shallow dismissal of curiosity because "they know what they're doing".
  - Sporktacular 4y ago
    Of course, if it's phrased like a discussion. Assuming these guys "know what they're doing" is a pretty good starting point.

Sporktacular 4y ago

Maybe it's because of RS codes superior performance during burst errors while the SNR involved isn't so low as to give convolutional codes a net advantage. Maybe it's Error Floor. Or maybe we should just assume that some of the world's most qualified RF and comms engineers behind these decisions did their homework.

toolslive 4y ago
maybe because online codes only came available after 2004, and the choice was already made and the picked solution sufficed so was never revisited. So the question becomes: when did they do their homework?
- Sporktacular 4y ago
  Yes, there is a thread to that effect. Development was heavily delayed, certification and conservatism around space systems can slow down deployment to the point of just not being worth changing things. I am sorry to have been presumptuous. There's been a spate of recent armchair experts with some arrogant "they should just use a warp drive" type contributions lately.
  - toolslive 4y ago
    - The thing with online codes is that while they are quite efficient in data overhead (a few %) they only start working when you have enough data ( > X MB). (check!) - another problem is that since the system that you need to solve to get your data back is large and random, so in-place updates of the data are impossible. In other words: they only work for immutable data (check!) - The extra information to counter lost messages is scattered over all messages so the client doesn't need to figure out which ones are missing (and doesn't need to tell the server, in this case the telescope). This makes them highly suited for high latency communication (and storage which is in essence the same thing, but that's another story) (check!) They (online codes) were designed for this exact use case.
toolslive 4y ago
Sigh, I might not be top notch anymore, but I am the (co) author of some patents in the field. Questioning RS for this use case is legit.
cle 4y ago
> Or maybe we should just assume that some of the world's most qualified RF and comms engineers behind these decisions did their homework. I'd rather read an interesting discussion of the tradeoffs than a shallow dismissal of curiosity because "they know what they're doing".
- Sporktacular 4y ago
  Of course, if it's phrased like a discussion. Assuming these guys "know what they're doing" is a pretty good starting point.