5.2 Pulse amplitude modulation sm()=Angr(t)cos2πft 5.2.1.PAM:passband signals BASK=Binary Amp-Shift- Keying 州M州 00K=0n- Off-Keying "11 ”01 "00 2PAM Antipodal Baseband signal:its freq band is close to zero, often used in wire-line transmission. 2PAM Unipolar Passband signal:its freq band is away from zero, a cos-like waveform, M and widely used in wireless transmission. 4PAM A=1 E UESTC-Digital transmission through the AWGN channel Prof李晓峰 14