concept

Channel capacity

The absolute maximum rate at which a channel can carry error-free information, in bits per second. The Shannon-Hartley theorem gives it: C = B·log₂(1 + S/N), where B is bandwidth (Hz) and S/N the signal-to-noise ratio. Two harsh lessons live inside it: capacity grows linearly with bandwidth but only logarithmically with signal power - so bandwidth is the precious resource and "shouting louder" is nearly useless. Transmit below C and you can drive errors near zero; exceed C and corruption is mathematically certain.