3 ms·

Interesting that they added the code (random noise) to the data rather than multiply (XOR). I assume this was safe to do since averaging won’t recover much si

Interesting that they added the code (random noise) to the data rather than multiply (XOR). I assume this was safe to do since averaging won’t recover much signal when the signal rate and code rate are the same. Also interesting that the basement in that department store went down 200 feet. Was this to get a good foundation? The link does not say.

Aloha 7y ago
Isn't an add much cheaper than a multiply?
- madengr 7y ago
  Sure, but typically bit-wise multiply by XOR is used, at least with spread spectrum and many forward error correction.
  - kps 7y ago
    They weren't using base 2.
  - ncmncm 7y ago
    Using base-6 signaling, modulo addition per digit position is a close equivalent to XOR for binary.
Someone 7y ago
”Also interesting that the basement in that department store went down 200 feet. Was this to get a good foundation?” It’s not as much as “below Selfridge’s” as “effectively in the cabinet war rooms”. https://en.wikipedia.org/wiki/Military_citadels_under_London#Cabinet_War_Rooms https://en.wikipedia.org/wiki/Military_citadels_under_London...: ”There was a telephone room down the corridor that provided a direct line to the White House in Washington, DC, via a special scrambler in an annexe basement of Selfridges department store.”