Frequency in signal processing is the number of cycles (of the signal) per second.

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How to calculate the frequency of a signal without knowing the sampling frequency using Matlab

I have a signal and I am using Matlab command pwelch to calculate the frequency of the signal, but the frequency I obtained is changed as I changed the sampling frequency. For example, when using ...
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12 views

What is the method to group frequency values into EEG Bands (delta.. theta..)?

I have a raw-EEG signal (time domain) I did the fft then I have the frequency values of the signal. I want to group them as different bands (delta, theta, alpha, beta, gamma) for example .5hz to 4hz ...
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37 views

Frequency Shifting in MATLAB

I am currently attempting to demodulate an audio file using MATLAB. After taking the fft of the signal, I receive this: After some more coding, I found the following values: Fs = 44100; Window ...
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35 views

Filtering with filters without even or odd symmetry in the fourier domain

I am doing a project where I have to use the fourier domain for convolution. I have been reading Digital Image processing by Rafael Gonzalez but I unsure about one thing, and I could not find anything ...
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1answer
96 views

Why is the magnitude of the second component of my FFT spectrum always the largest one?

While working with FFT, I have a strange case with a current experimental setup. I am working with beat frequencies (intermediate frequency output) and using a standard FFT algorithm (complex to ...
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24 views

Why sonar not used as radar?

When we want to do ranging and detection in air the first idea comes to mind is of RADAR. Sonar is mostly related to underwater stuff since it has less attenuation as compared to EM waves used in ...
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25 views

Curve fit for fft dplot

I have data from accelerometer (time domain) and convert it to fft using Fourier Transform. However, I need to do the curve fit to the plot. Can somebody share with me the coding.I don't know how to ...
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34 views

Very high SNR BPSK modulation

I am using BPSK modulation to modulate a signal in continuous time (making rectangular waveform, multiplying by a carrier). The channel is band-limited and frequency-selective, and has the following ...
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1answer
38 views

Real-time frequency recognition in python

I'm a newcomer to signal processing, so forgive my ignorance. I'm working on a project in Python that will play a .wav file and pick out the dominant frequency as it plays. I've found a few examples ...
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3answers
73 views

Calculate and interpret the instantaneous frequency

I'm new to the principle of calculating the instantaneous frequency, and came up with a lot of questions on it. You find them all in a bullet-point list at the end of this text. The text might be a ...
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30 views

How to calculate the frequency of the analog information signal? [FM] [duplicate]

How to calculate the frequency of the information signal from the follow spectrum diagram (it contains only one frequency)? Information signal is also called as original signal but i'm not sure.
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28 views

Carrier frequency estimation - dependency on symbols rate

I am working on the problem of estimating the carrier frequency of some PSK modulation around a carrier. The PSK symbols are unknown (Non-data-aided) and I do not wish to estimate them (considered ...
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1answer
11 views

Cannot recreate a simple Nyquist series in Matlab

a Nyquist series should look something like {...-1, 1, -1, 1, ... }, which i think means it is a sine wave sampled at the peaks and valleys exactly. Now, given a sampling rate of 48 Hz, the Nyquist ...
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3answers
71 views

Zero-frequency response of an IIR transfer function

I have a question about the zero-frequency (DC) response of a IIR filter. The coefficients of the 3rd order IIR filter are as follows, ...
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2answers
57 views

Find Stopband Edge Frequency

I tried to find the stopband edge frequency.I know that the signal amplitude falls to -3 dB below the passband edge frequency.I examine a lot of DSP books so i don't any information about how to ...
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0answers
55 views

Getting the frequency of a 0.33Hz to 3Hz signal

I read a noisy signal from an accelerometer which is attached to the pedal of a stationary bike and need to find the frequency of the signal/ speed of the person cycling. I taught of the following ...
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2answers
60 views

Am i performing Sinesweep correctly?

I am bit unsure whether i am doing i sine sweep correctly. I am feeding my system a sine wave with f hertz within a given time interval and log its output. And then i do the same for another ...
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1answer
54 views

Parallel Goertzel filters in C# [closed]

I have 2 frequencies in my application: $12000\mathrm{Hz}$, $13000\mathrm{Hz}$. I want to set a parallel Goertzel filters and every 100ms I want to take the bigger magnitude for detecting the tone ...
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1answer
42 views

FFT peak estimation: Zero-padding vs signal repetitioon

I am working on obtaining the vortex shedding frequencies behind a 2D square using CFD. Time-varying data is being extracted from a specific cell behind the square. I've written a little python script ...
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33 views

How to show the time history of a signal down-sampled ? under the rate of 25Hz & 40Hz and find its DFT analysis?

How to show the time history of a signal down-sampled under the rates of 25Hz & 40Hz and find its DFT analysis using Matlab ? The sample signal is in a data file (sensor_data.mat) its sampling ...
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4answers
138 views

Why every musical instrument sounds different than any other while listening?

This is soft question.I am not expert in music. We know that English language has 26 letters (which are again grouped into vowels and consonants) , while language of music is same all over the world ...
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1answer
28 views

nyquist fequency

simple question, but I cant seem to understand how they got the answer. I have $x(t)$ as a signal, and I'm told that its Nyquist frequency is $\omega_0$ I'm asked - what is the Nyquist frequency of ...
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1answer
38 views

What is the difference between upsampling and up conversion (done during signal transmission)? Also is upconversion different from modulation?

Up sampling is when you increase the sample rate of a continuous signal. Modulation is when you, by multiplying with a carrier, shift the base frequency of a signal. But what is up conversion? How is ...
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1answer
21 views

input output read/write frequency

I am trying to identify a system based on input/output response and thereby estimate a transfer function. I generated a frequency sweep function in Mathematica which gives me the discrete values of a ...
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2answers
52 views

Find the Differential Equation of an Analog Band Pass Filter

I don't even know how to start. We're supposed to find the differential equations that links $V_{in}$, $V_{out}$, and $V_{io}$, as well as the values of $C_1$, $C_2$ and $R$ so the filter works in the ...
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1answer
18 views

Frequency and amplitude estimation with missing samples

My input signal is given by $$ x[n] = A\sin(2\pi f n/F_s + \varphi)$$ The signal is uniformly sampled at a sampling rate of $F_s $[Hz]. However some of the samples are missing. Assume that there are ...
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2answers
99 views

Dominating frequency in a “clear” 50 Hz signal

I am trying to find out the dominating frequency of a signal with a frequency of 50 Hz (sampled at 200 Hz - every 5 milliseconds). The python code I am using to do this is the following (based on ...
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1answer
73 views

What is the maximum frequency that can be captured by a given sampling rate?

Let's say that we want to digitally sample an analog signal and have a sampling frequency of 8000 samples/second. Usually the maximum frequency that can be captured is the half of the sampling ...
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2answers
79 views

Frequency spectrum of signal - Matlab

Here is the code I use to plot a function in frequency domain in Matlab: ...
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3answers
51 views

what are frequencies in a digital image? [duplicate]

I don't completely understand the term " frequency" with respect to digital image processing. for 1D electrical signals , its pretty easy to understand , visually too. higher the frequency - more ...
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26 views

Fit a plane on a 2d picture

My supervisor gave me the hint, to fit a plane on a 2 dimensional image and substract it from it before doing the fast fourier transformation to reduce low frequencies. I get the low frequencies ...
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2answers
30 views

Frequency modulation of audio signals. Does increasing the pulse width of frequency tone result in larger operating distance?

I have a simple frequency modulation scheme where in I am sending simple textual data by encoding it into specific frequencies(for example 'a' is converted to ASCII value of 97 and I use 10 ...
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2answers
142 views

How compute frequency of signal from zero crossing? [duplicate]

I need to compute frequency of a signal from zero crossing.It's possible to compute to frequency from zero crossing of a signal. Plz anybody help me about this with matlab .
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179 views

FFT bin interpolation for low frequency with DC offset

I have a noisy signal in I/Q format with a peak frequency that constantly changes between 0.5Hz and 4Hz. The sample rate is 64Hz. I want an output showing the current peak frequency with a maximum lag ...
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32 views

How to scale fundamental frequency to [0,1]?

[Sorry for the noobish question...] I have a signal which is known to be generated by a process operating at some known rate $f$ Hz and the sampling rate is also know to be $K$ Hz. Now I do a ...
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76 views

What is the minimum sampling duration to capture a given frequency?

Due to the Nyquist rate, you need to sample twice as fast as the highest frequency you want to measure. Then when you do a FFT the number of samples determines the number of bins and thus the ...
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2answers
122 views

Instantaneous magnitude

I was reading this thread: How to get Instantaneous Magnitude for a Instantaneous Frequency From FFT? I have basically the same question, but I'm curious about more detail about the Hann window ...
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70 views

How do I identify CUTOFF frequency from my audio signal? [closed]

I was able to recorded an audio signal through the MIC and i applied FFT and Hanning window function to it. Now I want to know how do I identify CUTOFF frequency from it to apply the High Pass Filter. ...
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1answer
65 views

Signal Sampling

I am new in this field (junior year) and I have a question may a little lazy for the majority of the forum. I have a speech signal $ x(t)=0.4\cos(100πt)+0.3\cos(1800πt)+0.2\cos(980πt)$ and I know ...
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37 views

Determine Frequency Resolution samples

Can someone tell me if the way I solved this problem is right? Suppose I have a signal $X_a(t)= 0.5cos(700πt)+0.6cos(720πt)+0.1cos(780πt)$ where $F_s=8000Hz$ I want to determine the minimum samples ...
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1answer
59 views

Magnitude value of filter frequency response

Can someone help me with this problem: Suppose we filter signals with the below pre-emphasis filter: $$y[n]=x[n]-0.8x[n-1]$$ I have to calculate the impulse response of the filter (ok easy) and ...
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2answers
68 views

FM demodulation amplifier with saturation

I'm trying to understand how FM demodulation works. I read a lot on the internet and as far as I understand, the main process is to extract the phase difference (that is also the output) between a ...
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2answers
68 views

Fundamental frequency

Can someone help me: I have a signal which consist of three frequencies; for example, $f_1=800\,\text{Hz}$, $f_2=1050\,\text{Hz}$, $f_3=1600\,\text{Hz}$. How can i compute the fundamental frequency? ...
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1answer
138 views

PLL and zero crossing detection

Is there an Algorithm which can give un the frequency and phase of a three phase signal (three phase voltages) without using the zero crossing detection. I mean an algorithm which is done in open ...
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1answer
48 views

how to write a frequency modulation formula in FooPlot? [closed]

I have tried to write a Frequency Modulation of a sine by another sine, and i can't manage sin(x*sin(x*10)) please can you write the formula for me?
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26 views

How to transform one graph to a spectrum?

Recently, I studied a paper called "What Does Your Chair Know About Your Stress Level? It can be download at the link below. ...
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1answer
128 views

Beat Detection with Arduino

I'm trying to make a robot dance on several songs using Arduino. I need to understand how to get the rhythm from the songs, something like detecting the beats, calculating the bpm.. I'm not expert but ...
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1answer
51 views

Frequency of a noisy signal with fixed width pulses

My electricity meter has a front panel LED which pulses in proportional to the current energy rate. The frequency changes but the pulse width is set at 250ms. Due to environmental conditions there's ...
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29 views

What is the relationship between signal and its analytical version?

Hilbert transform is used to transfer signal into analytical signal. But why after the transform, the envelop and instant frequency (if the signal is monogenic) can be calculated. What is happened in ...
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144 views

Confusion in the spectrum of FSK modulated signal by using matlab fskmod module

I want to do a comparison of power spectral density of BFSK, 4FSK and 8FSK by using matlab baseband module "fskmod".Following is ...