# Questions tagged [fourier]

Anything related to Fourier series, Fourier transform and similar mathematical tools used to analyze the frequency content of a signal.

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### FSK Modulation in Python

I am currently writing a script that uses I/Q data to do FSK modulation. My question is about the FFT plot. I expected to have a peak at 1Hz and 2Hz which are the frequencies that represent binary 0 ...
70 views

### Finite-duration signal in the time domain, means what exactly in the frequency domain?

I'm trying to understand exactly what restrictions a finite duration time domain signal has on its Fourier transform. I found a helpful table in The Fourier Transform and its Applications by Ronald ...
76 views

### Why does a cosine function have a non-infinite Fourier coefficient?

I took my signals class a long time ago and have gotten used to using Fourier tables for a lot of things. I'm reading a textbook on communications and I stared at the Fourier transform equation for a ...
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### Pulse Doppler radar system simulation using MATLAB

How to code this project in MATLAB I'd tried coding this project (prob. 3-2, third paragraph) in MATLAB through this tutorial : https://www.mathworks.com/help/phased/ug/doppler-shift-and-pulse-doppler-...
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### Vanishing of Gibbs Phenomenon in MatLab

I was trying to represent a square wave with its Fourier series in Matlab. But as I increased the number of terms in Fourier series expression, the Gibbs phenomenon vanished and the edges of the ...
1 vote
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### Discrete Fourier transform for musical analysis

I am a senior in highschool and am currently trying to conduct an exploration on Fourier analysis, specifically using the discrete Fourier transform to analyze a chord played on my piano. Basically I'...
1 vote
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### A DFT-based phasor estimation

I have the sample set of ideal and real secondary current during CT saturation, need to apply the DFT analysis to samples and estimate the fundamental phasor (magnitude and phase angle) of samples (...
1 vote
138 views

### Numpy giving the wrong Fourier transform of sine functions

I'm using numpy's FFT to calculate the Fourier transform of $\cos(\omega_0t)$ and plot it. By using the definition we can derive its Fourier transform as below: X_3(j\omega) = \pi (...
1 vote
106 views

### Frequency domain analysis when sampling a switched (gated) integrator

I would like to use AC analysis (e.g. in spice) on a non-ideal op-amp integrator where the reset switch is open, and then apply a shaping function to the result of the AC simulation (in the frequency ...
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1 vote
229 views

### Fourier Transform Time Scaling Property using f (frequency) or w (omega - angular frequency)

The time scaling property for a fourier transform is as follows: My book shows this property in terms of $f$; however, my instructor likes to use $\omega$. I have also seen this property written ...
1 vote
59 views

### Interpreting Fourier transform of Images

I'm new to image processing and am learning about the Fourier transform. I've read that FT decomposes a function to its constituent frequencies. However, I'm not sure how to tell which is a low ...
1 vote
485 views

### Raspberry Pi and FFT (Fast Fourier Transform) -- Using MCP3208

EDIT: I've made adjustments based on your answers, while I couldn't get it to be evenly spaced, I managed to get a better curve with more samples per cycle. Turns out I need to remove the print ...
1 vote
309 views

### Total harmonic distortion and DFT

I am trying to understand a design that would enable us to measure/determine the total harmonic distortion. Key points: The system is microcontroller (TI, C2000, dual-CPU) driven electronic It has a ...
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1 vote
215 views

### Apparent lack of rigor in Phasor domain analysis of steady state AC circuits

so I have encountered a hitch in my understanding of analyzing steady state AC circuits. I have looked everywhere for the answer to my question and I can find nothing. Usually when we analyze ss AC ...
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1 vote
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### What exactly does the frequency spectrum represent?

The signals in the image represent a low pass signal and its Hilbert Transform. I know that a plot for a signal's magnitude with reference to frequencies can be found by applying a Fourier Transform. ...
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1 vote
128 views

### Spectral analysis of spectrum analyzer

Using measures from a spectral analyzer, I am a bit confused on how to properly compare the power of each spectral line with the fourier coefficients (Parseval). Take this signal: Take its spectrum: ...
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1 vote
110 views

### Calculating real part of a square wave

i'm trying to understand how Bruno putzey in Globally Modulated Self-Oscillating Amplifier with Improved Linearity in section 4.2 Analysis comes to the equation in presented in (2), see snapshot below....
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1 vote
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### Fourier series and Fourier transform of signals which can be generated in real world

Let first remind on Dirichlet conditions: In mathematics, the Dirichlet conditions are sufficient conditions for a real-valued, periodic function f to be equal to the sum of its Fourier series at ...
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1 vote
992 views

### Application of Fourier Series in Circuit

I am trying to find $v_o(t)$ in the circuit below, where $$v_s(t) = 3 - \frac{6}{\pi}\sum_{n=1}^{\infty}\frac{1}{n}\sin2\pi n t$$ The correct answer is v_o(t) = \frac{3}{2} - \frac{3}{\pi}\sum_{n=...
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930 views

### How to get fourier series of 8-bit character to be transmitted?

I have been reading this in a book, but can't understand how he used the 8-bit in fourier series equation to get the result below. The transmission of the ASCII character ‘‘b’’ encoded in an 8-bit ...
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### Z transform and the magnitude of Fourier transform

Would like to know if the graph of the magnitude in the picture I added is correct. Should I address the other pole?
85 views

### Sketching fourier transform after sampling

I'm having trouble understanding how this system is supposed to work. My sketch (all my sketches are for fourier transforms) for $X_b(jw)$ are two pyramids centered at 7pi and -7pi with height 1/2. ...
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### How to properly take the discrete Fourier transform of a signal as well as calculate the power spectral density of the DFT?

I'm getting conflicting answers on how to properly represent a DFT and normalize the results as well as calculate the normalized PSD of the time series. For background, I typically work with voltage ...
60 views

### Need help on signals and systems, Fourier representation of a signal

I've got a homework question for my signals and systems class. In the question, we're given the graph of the magnitude and the phase of a continuous signal. Here are the graphs: I have to find the ...
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### FFT analysis in LTSpice is giving wrong results during partial execution of time domain simulation (Details in body)

In LTspice, while computing FFT using waveform window (View-> FFT), the results seems to be wrong if FFT is computed after partial execution of simulation ( eg: if simulation is paused in between)...
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