Yes ! Well , accept the modulation scheme is decided ahead of time , generally . But that is the birds eye view of a digital communication system . Side note , matched filters are really really easy to understand if you are familiar with inner product spaces , and specifically inner products over functions . And yeah , they are really cool . Also , you can compare that with the birds eye view of analog communications . You take the signal , and use it as the input to some invertible functions , pass it through the channel , and then invert the function . Whatever errors you incur , you are stuck with . The only interesting part is which function do you pick . If the signal is xt , and f is the modulation function , then fAM x xt cos w t , while fFM x coswxtt and fPM cosw t xt .