analog digital signal difference

[p11]

please someone explain me that why digital signals are less noisy than analog signals ?? i , mean if noise affects then i think , both the amplitude of the digitaland analog signals should get change ..

 

[BradtheRad]

DIgital (or binary) communication is based on switching between two states.

The only way the two states can be easy to discern, is if you make them sufficiently different from the other so they overcome the noise.

This can be done by making them different amplitudes, or different frequencies, or whatever.

Sometimes you find there are tradeoffs between analog and digital.