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Fourier Series. Course Outline. Roberts, ch. 1-3. Time domain analysis (lectures 1-10) Signals and systems in continuous and discrete time Convolution: finding system response in time domain Frequency domain analysis (lectures 11-16) Fourier series Fourier transforms
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Course Outline Roberts, ch. 1-3 • Time domain analysis (lectures 1-10) Signals and systems in continuous and discrete time Convolution: finding system response in time domain • Frequency domain analysis (lectures 11-16) Fourier series Fourier transforms Frequency responses of systems • Generalized frequency domain analysis (lectures 17-26) Laplace and z transforms of signals Tests for system stability Transfer functions of linear time-invariant systems Roberts, ch. 4-7 Roberts, ch. 9-12
Periodic Signals • For some positive constant T0 f(t)is periodic if f(t) = f(t + T0) for all values of t (-, ) Smallest value of T0 is the period of f(t) • A periodic signal f(t) Unchanged when time-shifted by one period May be generated by periodically extending one period Area under f(t) over any interval of duration equal to the period is same; e.g., integrating from 0 to T0 would give the same value as integrating from –T0/2 to T0 /2
Sinusoids • Fundamental f1(t) = C1 cos(2 p f0 t + q1) Fundamental frequency in Hertz is f0 Fundamental frequency in rad/s is w0 = 2 p f0 • Harmonic fn(t) = Cn cos(2 p n f0 t + qn) Frequency, n f0, is nth harmonic of f0 • Magnitude/phase and Cartesian representations Cn cos(n w0 t + qn) =Cn cos(qn) cos(n w0 t) - Cn sin(qn) sin(n w0 t) =an cos(n w0 t) + bn sin(n w0 t)
Fourier Series • General representationof a periodic signal • Fourier seriescoefficients • Compact Fourierseries
Existence of the Fourier Series • Existence • Convergence for all t • Finite number of maxima and minima in one period of f(t) • What about periodic extensions of
Fundamental period T0 = 2 Fundamental frequency f0 = 1/T0 = 1/2 Hz w0 = 2p/T0 = p rad/s f(t) A -1 0 1 -A Example #1
Fundamental period T0 = 2p Fundamental frequency f0 = 1/T0 = 1/(2p) Hz w0 = 2p/T0 = 1 rad/s f(t) 1 -p/2 -p -2p p/2 p 2p Example #2