2025-L23A - ECE-2025 Spring-2009 Info: Lab and HW Lab #12-B...

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ECE-2025 Spring-2009 Lecture 23-A Amplitude Modulation (AM) 13-Apr-09 Info: Lab and HW ab 2 uring the last week ± Lab #12-B during the last week ± Interference Removal from Electrocardiograms ± Done completely in-Lab ± GRADES: ± T-square is the OFFICIAL gradebook ± Quiz #3 will be 17-April (Friday) ± Coverage: HW #10, 11 and 12 ± Chapters 9, 10, and 11 ± No Z Transforms on Quiz #3, but will be on Final ± Review Session, 16-April, Thursday @ 6:00pm 4/12/2009 ECE-2025 Spring-09 jMc 2 Lab 12: Interference Removal: EKGs 4/12/2009 ECE-2025 Spring-09 jMc 3 Lecture The way communication ystems work systems work ow do we share How do we share bandwidth ? 4/12/2009 ECE-2025 Spring-09 jMc 4
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FDM Block Diagram (Xmitter) cos( ω t ) ( c 1 Spectrum of inputs s( must be bandlimited Need c 2 c 1 > 2 b cos( c 2 t ) 4/12/2009 ECE-2025 Spring-09 jMc 5 c 1 c 2 Frequency-Division De-Mux c 1 c 2 cos( c 1 t ) ( 4/12/2009 ECE-2025 Spring-09 jMc 6 cos( c 2 t ) andpass Filters for De ux Bandpass Filters for De-Mux c 1 4/12/2009 ECE-2025 Spring-09 jMc 7 c 2 Demo: 2-channel AM 4/12/2009 ECE-2025 Spring-09 jMc 8
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DSBAM Demod Phase Synch y w ( t ) v ( t ) x ( t ) ) cos( ) ( ) ( ψ ω + = t t x t y c cos( c t ) ) cos( + t c ? if what ) ( ) cos( ) ( 1 1 π = = j X j V ) ( ) ( ) ( 4 1 4 1 j j j X e j X e j W + = 2 2 4/12/2009 ECE-2025 Spring-09 jMc 9 )) 2 ( ( )) 2 ( ( 4 1 4 1 c j c j j X e j X e + + + Quadrature Modulator )) ( ( )) ( ( )) ( ( )) ( ( ) ( 2 2 / 2 1 1 2 1 2 2 / 2 1 1 2 1 c j c c j c j X e j X j X e j X j Y + + + + + = TWO signals on ONE channel: “out of phase” an you “separate” them in the demodulator ? 4/12/2009 ECE-2025 Spring-09 jMc 10 Can you “separate” them in the demodulator ? Demod: Quadrature System Qy 0 if ) ( ) ( 1 = = ϕ t x t v ) cos( + t c 2 / if ) ( ) ( 2 = = t x t v )) ( ( )) ( ( ) ( 2 / 2 2 / 2 1 1 2 1 j c j c j X e j X j Y + = ) ( ) ( ) ( 2 / 1 1 j X e e j X e j V j j j + + = )) ( ( )) ( ( 2 2 1 1 2 1 c c j X e j X + + + + 4/12/2009 ECE-2025 Spring-09 jMc 11 ) ( ) ( 2 2 / 4 1 1 4 1 2 4 1 4 j X e e j X e j j j + Demonstration of AM-modulated HDTV
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This note was uploaded on 01/27/2011 for the course ECE 2025 taught by Professor Juang during the Spring '08 term at Georgia Institute of Technology.

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2025-L23A - ECE-2025 Spring-2009 Info: Lab and HW Lab #12-B...

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