Error correcting codes are certainly a part of it (from simply looking up the definition of FT8), but what can also help generally is knowing very specifically

Error correcting codes are certainly a part of it (from simply looking up the definition of FT8), but what can also help generally is knowing very specifically the frequency range of your signal so that you can filter out the out-of-band noise. A lock-in amplifier is one example of this: https://en.wikipedia.org/wiki/Lock-in_amplifier https://en.wikipedia.org/wiki/Lock-in_amplifier