Amplitude Modulation (Large Carrier)

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1 Department of Electrical, Computer, and Biomedical Engineering Ryerson University ELE 635: Lecture Four Handout Condensed from Lathi Amplitude Modulation (Large Carrier) Amplitude Modulation ϕ AM (t)= A c cos ω c t + m(t) cos ω c t =[A c + m(t)] cos ω c t If m(t) ←→ M (ω), then we have: ϕ AM ←→ (1/2)[M (ω + ω c )+ M (ω - ω c )] + πA c [δ (ω + ω c )+ δ (ω - ω c )] For envelope detection: A c + m(t) 0 for all t. Which is the same as: A c m p

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C:/Users/Sepali/Documents/SubforNNandLS/Lecture635handouts/ELE635LectureFour.dviAmplitude Modulation (Large Carrier)
If m(t)←→M(ω), then we have:
AM ←→ (1/2)[M(ω + ωc) +M(ω − ωc)] + πAc[δ(ω + ωc) + δ(ω − ωc)]
For envelope detection:
Ac +m(t) ≥ 0 for all t. Which is the same as:Ac ≥ mp
Whenµ > 1 only synchronous detection is possible.
Tone Modulation
Modulating signal is a sinusoid:m(t) = B cosωmt. Find the spectrum.
= [c cosωct+m(t)]
Demodulation of AM Signals