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It is usually a combination of a Bode magnitude plot, expressing the magnitude (usually in decibels) of the frequency response, and a Bode phase plot, expressing the phase shift. As originally conceived by Hendrik Wade Bode in the 1930s, the plot is an asymptotic approximation of the frequency response, using straight line segments .
The following Python code can also be used to calculate and plot the root locus of the closed-loop transfer function using the Python Control Systems Library [14] and Matplotlib [15]. import control as ct import matplotlib.pyplot as plt # Define the transfer function sys = ct .
The magnitude plot indicates that the moving-average filter passes low frequencies with a gain near 1 and attenuates high frequencies, and is thus a crude low-pass filter. The phase plot is linear except for discontinuities at the two frequencies where the magnitude goes to zero. The size of the discontinuities is π, representing a sign reversal.
The short-time Fourier transform (STFT) is a Fourier-related transform used to determine the sinusoidal frequency and phase content of local sections of a signal as it changes over time. [1] In practice, the procedure for computing STFTs is to divide a longer time signal into shorter segments of equal length and then compute the Fourier ...
A Nichols plot. The Nichols plot is a plot used in signal processing and control design, named after American engineer Nathaniel B. Nichols. [1] [2] [3] It plots the phase response versus the response magnitude of a transfer function for any given frequency, and as such is useful in characterizing a system's frequency response.
Nichols plots graph magnitude and phase parametrically against frequency in rectangular form; For the design of control systems, any of the three types of plots may be used to infer closed-loop stability and stability margins from the open-loop frequency response. In many frequency domain applications, the phase response is relatively ...
A related goal is to find a relation between the magnitude and phase of a complex response function. In general, unfortunately, the phase cannot be uniquely predicted from the magnitude. [ 9 ] A simple example of this is a pure time delay of time T , which has amplitude 1 at any frequency regardless of T , but has a phase dependent on T ...
The phase cepstrum (after phase spectrum) is related to the complex cepstrum as phase spectrum = (complex cepstrum − time reversal of complex cepstrum) 2 . Related concepts