1. S. Mandayam/ ECOMMS/ECE Dept./Rowan University Electrical Communications Systems ECE.09.331 Spring 2009 Shreekanth Mandayam ECE Department Rowan University http://engineering.rowan.edu/~shreek/spring09/ecomms/ Lecture 7b March 4, 2009

2. S. Mandayam/ ECOMMS/ECE Dept./Rowan UniversityPlan Recall: Costas Loop QAM SSB Modulation Signals Systems Time Domain Complex Envelope Spectrum Power Performance Transmitters Receivers Standards Modulation Index Efficiency Bandwidth Noise

3. S. Mandayam/ ECOMMS/ECE Dept./Rowan University ECOMMS: Topics

4. S. Mandayam/ ECOMMS/ECE Dept./Rowan University Recall: Costas PLL s(t) v 1 (t) Product Modulator Baseband LPF VCO LPF -90 o Phase Shift X v 2 (t) Product Modulator Baseband LPF v 3 (t) v 4 (t) Phase Discriminator I-Channel Q-Channel

5. S. Mandayam/ ECOMMS/ECE Dept./Rowan University Quadrature Amplitude Modulation (QAM) Product Modulator Local Oscillator -90 o Phase Shift Product Modulator m 1 (t) m 2 (t)  s(t) Product Modulator Local Oscillator -90 o Phase Shift Product Modulator LPF Tx Rx I-Channel Q-Channel

6. S. Mandayam/ ECOMMS/ECE Dept./Rowan University Single Sideband (SSB) Modulation Recall: DSB-SC Spectrum USSB - Signal with zero-valued spectrum for |f| < f c LSSB - Signal with zero-valued spectrum for |f| > f c -f c -B -f c -f c +B 0 f c -B f c f c +B |S(f)| f

7. S. Mandayam/ ECOMMS/ECE Dept./Rowan University The Hilbert Transform -0.5 0 0.5 1 1.5 01234567 time, t in sec » t=0:0.1:2*pi; » w=sin(t); » plot(t,w) » hold Current plot held » H=hilbert(w); » plot(t,imag(H),'r'); » xlabel('time, t in sec')

8. S. Mandayam/ ECOMMS/ECE Dept./Rowan University SSB Generation Product Modulator Carrier -90 o Phase Shift Product Modulator -90 o Phase Shift m(t)  s(t) Sideband Filter Carrier Product Modulator m(t) s(t) Phasing Method Filter Method

9. S. Mandayam/ ECOMMS/ECE Dept./Rowan University SSB Generation: Weaver’s Method

10. S. Mandayam/ ECOMMS/ECE Dept./Rowan UniversitySummary