ECEN 215, Principles of Electrical EngineeringDr. Mina RahimianLecture# 17 Date: 10/23/13Chapter 6, Frequency Response and Bode PlotsOne of the major branches of electrical engineering is signal processing. Signal processing is concerned with manipulating signals to extract information. Signal is a voltage or current that contains some information. For example, electrocardiogram (ECG) is an electric signal generated by human heart. Using circuits and computers one can extract useful information about the health condition of the patient's heart.Previousely we have learned to analyze circuits that are excited by either a dc or a sinusiodal source.However, most real world electric signals are not sinusoidal. How can we analyze circuits excited by non-sinusoidal sources? How can we express non-sinusoidal signals by phasors?Joseph Fourier (1768-1830) developed a mathematical technique to express the non-sinusoidal functions as the sum of a set of sinusoidal components having various frequencies, amplitudes and phases.For example using Fourier analysisa square wave has the following components:or, the components of this music waveform are: Spectrum analyzer is a laboratory instrument used to determine the frequencies, amplitude and phases of a signal.FiltersIn some applications we want to select a certain range of frequencies and discard the rest. This can be done using electric circuits called filters.Transfer
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