S. Mandayam/ECE Dept./Rowan University Digital Communications / Fall 2002 Shreekanth Mandayam ECE Department Rowan University Lecture 8 October 28, 2002

S. Mandayam/ECE Dept./Rowan University Plan Bandpass Data Transmission Recall: QPSK  /4 QPSK or 4-QAM Basic QAM Structure M-QAM QAM Simulation BER for QAM and QPSK

S. Mandayam/ECE Dept./Rowan University Digital Communications Transceiver Anti- aliasing Filter SamplingQuantization Data Encryption Encoder Source Encoder Error Control Encoder Channel/ Line Encoder Modulator MUX Audio Amp Source Decoder Data Encryption Decoder Error Control Decoder Equalization / Decision Circuits Demod- ulator DEMUX Reconstruction/ DAC ADC CODEC MODEM Analog o/p Multiple access channel Analog i/p

S. Mandayam/ECE Dept./Rowan University Quadrature Phase Shift Keying (QPSK) IQ Diagram I Q 

S. Mandayam/ECE Dept./Rowan University M-ary Phase Shift Keying (M-PSK) I Q Octophase I-Q Constellation

S. Mandayam/ECE Dept./Rowan University  /4 QPSK or 4-QAM I Q 11 IQ Diagram s(t) = A c cos(2  f c t +  (t)) t  (t)     

S. Mandayam/ECE Dept./Rowan University Basic QAM Structure Binary Data -  /2 Phase Shift Transmitting Filter Balanced Modulator Transmitting Filter Balanced Modulator Oscillator f c  QAM Signal Matlab script: qpsk.m Serial- Parallel

S. Mandayam/ECE Dept./Rowan University M-QAM I Q 16-QAM I-Q Constellation

S. Mandayam/ECE Dept./Rowan University Symbol Error in M-ary PSK Systems Matlab script: dignoise.m

S. Mandayam/ECE Dept./Rowan University Symbol Error in M-ary QAM Systems Matlab script: dignoise.m

S. Mandayam/ECE Dept./Rowan University Summary