The document discusses matched filtering and digital pulse amplitude modulation (PAM). It explains how a matched filter can be used at the receiver to detect pulses in the presence of additive noise. The matched filter impulse response is the time-reversed, conjugated version of the transmitted pulse shape. This maximizes the signal-to-noise ratio at the filter output. The document also discusses intersymbol interference in PAM systems and how pulse shaping and matched filtering can be used to eliminate ISI. It provides expressions for the bit and symbol error probabilities in binary and M-ary PAM systems.