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Fourier Series. Engineering Mathematics – I Prepared By G.VANMATHI, M.Sc.,M.Phil., Assistant Professor / Mat hematics. Content. Periodic Functions Fourier Series. Fourier Series. Periodic Functions. The Mathematic Formulation.
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Fourier Series Engineering Mathematics – I Prepared By G.VANMATHI, M.Sc.,M.Phil., Assistant Professor / Mathematics
Content • Periodic Functions • Fourier Series
Fourier Series Periodic Functions
The Mathematic Formulation • Any function that satisfies where T is a constant and is called the period of the function.
Example: Find its period. Fact: smallest T
Example: Find its period. must be a rational number
Example: Is this function a periodic one? not a rational number
Fourier Series Fourier Series
A periodic sequence f(t) t T 2T 3T Introduction • Decompose a periodic input signal into primitive periodic components.
Synthesis T is a period of all the above signals Even Part Odd Part DC Part Let 0=2/T.
Orthogonal Functions • Call a set of functions {k}orthogonal on an interval a < t < b if it satisfies
Orthogonal set of Sinusoidal Functions Define 0=2/T. We now prove this one
Proof m n 0 0
Proof m = n 0
Define 0=2/T. Orthogonal set of Sinusoidal Functions an orthogonal set.
Proof Use the following facts:
f(t) 1 -6 -5 -4 -3 -2 - 2 3 4 5 Example (Square Wave)
f(t) 1 -6 -5 -4 -3 -2 - 2 3 4 5 Example (Square Wave)
f(t) 1 -6 -5 -4 -3 -2 - 2 3 4 5 Example (Square Wave)
Harmonics T is a period of all the above signals Even Part Odd Part DC Part
Define , called the fundamental angular frequency. Define , called the n-th harmonicof the periodic function. Harmonics
harmonic amplitude phase angle Amplitudes and Phase Angles