Digital Communications 0909.402.03/0909.504.01 Fall 2002 Lecture 2 September 16, 2002 Shreekanth Mandayam ECE Department Rowan University http://engineering.rowan.edu/~shreek/fall02/digcomm/

Plan ECOMMS Review QUIZ Baseband Data Transmission Digital Signaling Orthogonal representation Vector Representation Binary and Multilevel Signals Baud Rate, Bit Rate and Bandwidth

Digital Communications Transceiver Anti- aliasing Filter Data Encryption Encoder Error Control Encoder Source Encoder Channel/ Line Encoder Sampling Quantization MUX Modulator ADC Analog i/p CODEC MODEM Multiple access channel Analog o/p Data Encryption Decoder Error Control Decoder Audio Amp Reconstruction/ DAC Source Decoder Equalization / Decision Circuits DEMUX Demod-ulator

Vector Representation of a 3-bit Binary Signal s(t) T T0=3T t 5V Digital signal p(t) T t 5V Bit shape pulse p1(t) t 5V p2(t) p3(t) 0 T 2T 3T Orthogonal set j1 s j2 j3 Signal vector

Multilevel Signaling Binary l-bit Source DAC Binary signal D symbols/second = R bits/second L=2l Multilevel Signal D symbols/second = R/l R bits/second Binary Source l-bit DAC

Summary