Questions tagged [amplitude]

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Spectrum and Fourier transform of a sine wave

Take for example: $x(t)=A\sin(2\pi f_0t)$. The Fourier transform of this signal is $\hat{s(f)}=\frac{A}{2i}(\delta(f-f_0)-\delta(f+f_0))$. If we want to represent the spectrum of the signal we would ...
fi-xgamex do's user avatar
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OFDM samples after fft show Amplitude Compression

I transmit OFDM signal with bandwidth 20 MHz via ADALM-Pluto SDR device. To study the effect of the wireless channel, I used the same device for transmission and reception. The maximum bandwidth of my ...
Walkürie's user avatar
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Relationship between fourier transform and fourier series

Let $$x(t) = A\sin(2 \pi f_0 t + \alpha)$$ its Fourier transform is given by $$ X(\omega) = \frac{A \pi}{i}(e^{ia}\delta(\omega-2\pi f_0) - e^{-ia}\delta(w+2\pi f_0)). $$ the Fourier series complex ...
MOHAMED SALHI's user avatar
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2 answers
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Plot amplitude vs freqency in DB

I have C++ App which wich plot 3 plot amplituede vs sample amplitude vs frequncey(used FFT for calculation) amplitude(in dB) vs frequncey I want plot 2 with y axis lable represent in DB, without ...
Haris's user avatar
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OFDM complex symbols have dynamic phase shift after the fft-block & before the BPSK demodulator at the receiver ,

I have transmitted and received an OFDM-signal using the same ADALM-Pluto-SDR's Tx/Rx Antenna. I have used BPSK baseband modulation with symbol freq=312.5 KHz, L (length of ifft)=64, fsampling=fsym*L=...
Walkürie's user avatar
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1 answer
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Recovering the Sign of a Sinusoid's Amplitude and Phase from the Complex Values resulting from a Frequency Transform (Goertzel)

It seems I've forgotten much of the details of signal processing theory when attempting to reconstruct algorithms for extracting FFT-like amplitude/phase information from examples online. I was ...
Jordan McBain's user avatar
5 votes
4 answers
2k views

What is the audible level for digital audio dB units?

What is the audible level for digital audio dB units? I was looking at a soundwave from an mp3 file. I am using the "Sonic Visualizer" app available on Linux. The amplitude is between ~ -0.1,...
user2183336's user avatar
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1 answer
79 views

Bandwidth of amplitude-modulated wave with triangular envelope

I have the following wave: I know that it is demodulated by an envelope detector whose source resistance is 0Ohm and its load resistance is 250Ohm. Now, I need to calculate a C capacitor in order ...
neil_huygens's user avatar
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1 answer
73 views

What is discrete in value/amplitude/magnitude?

A digital signal is commonly described as a signal which is discrete both in time and value/amplitude/magnitude. I understand what is "discrete in time" (say, the signal is received each 1 ...
hamza's user avatar
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6 votes
2 answers
423 views

What causes the mismatch between a calculated sine wave and a measured sine wave?

Note: this question has been edited to refer to a sample that does not use dithering. I recently asked my first question on here, about what I saw in an uncompressed audio file written out as integers....
Patrick O'Brien's user avatar
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What is the right scaling factor to get the amplitude after aplying a hanning window? [duplicate]

I have a waveform where I sliced the flat top so I can do some analysis on the amplitudes of each frequency. I have a dataset of N measurements each with M samples of current (A) over time (...
Typhaon's user avatar
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2 answers
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To create feedback, does the peak to peak amplitude of a signal loop have to have an amplification factor (gain) that reaches zero?

In technical terms, feedback occurs when the gain in the signal loop reaches "unity" (0dB gain). How to Eliminate Feedback Peak-to-peak amplitude (abbreviated pโ€“p) is the change between ...
user avatar
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1 answer
343 views

How to get amplitude of harmonics from amplitude relation?

I'm coding the amplitude spectrum plot of a square wave signal with the following relation@ |๐‘๐‘˜(๐œ”=3,5,7,...)|/|๐‘๐‘˜(๐œ”=1)|โˆ๐œ”^๐›ผ where I've already calculated ...
Navia's user avatar
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1 vote
1 answer
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How are discontinuities in quadrature modulated signal QAM physically produced?

In quadrature modulated signals, for instance: I am unclear how the "discontinuities" in the waveform at the junction of each data point can be physically produced? Taking a speaker as an ...
James's user avatar
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3 votes
0 answers
118 views

Are there algorithms to compare changes in signal amplitudes?

I am working on a project to reduce resonances caused by motors. The vibrations in the material are measured and sampled by ADCs. The measuring works as intended and the next step is to reduce the ...
ls.ptr's user avatar
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How to correctly get the amplitude and phase of the signal after applying the fast fourier transform to it

I am new at signal processing and was trying to understand the relation of the result of the FFT to the original signal. I generated a signal with a sampling rate of 100 Hz within 1 second ($N=100$), ...
bvl's user avatar
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1 vote
3 answers
321 views

How to interpolate the peak amplitude of an fft output?

I want to find the peak amplitude of an audio signal in a given frequency area. My problem is that if the signal has a strong resonating frequency between 2 fft bins, then both bins are way below the ...
Potheker's user avatar
1 vote
2 answers
228 views

Why MATLAB's abs(fft(X)) returns maximum amplitude first harmonic's while in signal maximum is second's?

Please let me ask you about my problem with Matlab code executing in R2022a release. A signal has 3 harmonics with amplitudes 170, 220, and 150 in that order. Matlab's function ...
George Theodosiou's user avatar
2 votes
2 answers
246 views

Why complex signal doesn't remove "beatings" while sampling?

My motivation to this post has arisen from the accepted answer to Amplitude modulation vs sampling rate? Sampling the signal with the frequency close to $f_s/2$ can lead to some kind of "beatings&...
Curious's user avatar
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1 answer
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How to calculate amplitude from a wav file?

I'm a beginner in audio signal processing, and trying to calculate the amplitude of a .wav file. I've read some documents from the web and some other questions asked about this topic. However, I still ...
Megan's user avatar
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-1 votes
1 answer
59 views

Adjusting pulse amplitude against fixed noise variance to achieve a given Eb/No

Given a short duration pulse of $n$ samples out of a frame of $L$ samples, and amplitude of each of these samples being $A$, and an AWGN channel with variance $\sigma ^{2} = 1$, how can I derive $A$ ...
Howard's user avatar
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15 votes
4 answers
5k views

When concatenating sine waves, how do I phase shift in order to prevent "pops" caused by sudden jumps in amplitude?

I'm writing a synthesizer using numpy and python. I've run into a problem where concatenating sine waves causes 'pops' or 'clicks' when they are outputted to audio, say, via ...
Tim's user avatar
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0 votes
1 answer
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How to modify spectrograms so that there is no effect of amplitude on their classification?

Is there any way to bring different classes of spectrograms to comparable amplitude levels so that when they are used for classification, the deep learning algorithm focuses on other aspects (like the ...
nasrin's user avatar
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0 answers
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What can I do to improve the sound of a signal?

I want to improve the sound of my signal, I know I can do it by increasing or decreasing the amplitude of the signal itself. Are there any other ways to do this? How can I apply the Fourier transform ...
Luca Leone's user avatar
0 votes
1 answer
70 views

How to compute data imbalance?

I have to compare amplitudes of two signal ("ideal " signal and "estimated" signal) and want to compute an amplitude imbalance For my calculation I used the following equation: $$ ...
FrimHart64's user avatar
0 votes
1 answer
31 views

Does different frequency signal cause different voltage from antenna?

When antenna received signal,antenna generate voltage,then SDR convert voltage to I=amplitude*cos(t)and I=amplitude*sin(t). When ...
kittygirl's user avatar
  • 175
2 votes
1 answer
222 views

Decrease of the signal amplitude and oscillation in the output of FIR filter (windowing method)

In order to truncate my signal in the frequency domain, I am applying a low pass filter with the windowing method. As a test, I chose the Hamming window. What is the cause of the oscillation at the ...
Amy 's user avatar
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1 vote
3 answers
272 views

Is digital necessarily discrete in both amplitude and time?

Is digital necessarily discrete in both amplitude and time? Or rather it is necessarily discrete only in time (but not necessarily in amplitude)?
yaraklis's user avatar
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0 answers
115 views

Should I use IQ data or power data to compare 2 signals through `similaritymeasures.dtw`?

I choose similaritymeasures.dtw to compare experiment signal exp_sig and reference signal ref_sig. Both signals are I,Q data ...
kittygirl's user avatar
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0 votes
2 answers
171 views

How do you find a specific frequency's volume corresponding to that signal's FFT?

I've been dabbling in FFT for awhile now and I came across a problem: We have a signal comprised of two different frequencies A and B. Frequency A is much louder than frequency B; frequency A's ...
Steve Mucci's user avatar
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0 answers
266 views

Extract amplitude values from a wav file

I would like to extract the amplitude value from a wav file. Using Python I can extract the raw data into an array. How do I go about extracting the amplitude value of each sample?
Hitesh Tewari's user avatar
1 vote
1 answer
36 views

0/1 dB normalization using clamp function

I would like to perform dB normalization on audio data to make less loud sound louder and to make unusually loud sound less loud, before feeding them into neural networks. I came across this function: ...
JXuan's user avatar
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0 votes
1 answer
380 views

Why does adding a high-pass or low-pass EQ increase volume?

The following three screenshots show the max volume levels (indicated above the VU meter) of Cuckoo by Tipper if played with: No EQ: -0.5db Headroom High Pass EQ: +2.5dB over Low Pass EQ: +0.4dB ...
Seph Reed's user avatar
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2 votes
4 answers
294 views

50Hz sine wave precise amplitude measurement

I have a 50Hz sine wave(mains voltage divided to the full-scale voltage of the ADC) sampled at 4kHz with not much noise in it. I want to measure precisely the peak-peak voltage of the sine. My first ...
Kristóf Tunner's user avatar
1 vote
1 answer
53 views

how make an equation of a procedure?

Good day to everyone, i have frequency spectrum i selected top 10 peaks of that spectrum i give weightage from 1 to 10 to top 10 frequencies by multiplying the corresponding amplitude by weightage ...
alexis texas's user avatar
1 vote
1 answer
60 views

FInd the amplitude function to a system

I'm studying a course in signal analysis and have come across an exercise where I find the analytical part a bit tricky. I am to find the amplitude function $|H( f )|$ for a system with the impulse ...
Aedrha's user avatar
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1 vote
1 answer
42 views

Amplitude-and phasefunctions for a system

I am studying a course in signalanalysis and have run into som trouble with a exercise. I am to dimension the circuit below in such a way that the DC-amplification is 1 and that the frequencies $\...
Aedrha's user avatar
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0 votes
1 answer
144 views

Can FFT tells us existance of same frequencies with different phases?

So I know that applying FFT on a time-domain signal, shows which frequency components exists and what amplitudes each frequency signal has. My question is, suppose the signal contains same frequency ...
Kadaj13's user avatar
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1 answer
88 views

Calculating power of brain signals

I have a dataset that contains EEG (or MEG) recordings of brain signals during some cognitive tasks. Each row, shows the source estimates of neurons in a particular region. source estimate contains ...
Kadaj13's user avatar
  • 149
1 vote
1 answer
276 views

How is sampling affecting this sine wave?

I am trying to create a sine wave in python, but when I graph it, it looks like this: here is the code I used to make the signal: ...
user57935's user avatar
1 vote
1 answer
433 views

Bandpass filter equivalent for amplitude

I have a signal where I am using a bandpass filter to limit the frequency range. I am also interested in filtering the remaining frequencies (after bandpass filtering) within the signal by their ...
connor449's user avatar
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0 votes
1 answer
124 views

Fine frequency correction : grouping and finding max amplitude inside a group

I work on phase and frequency estimation algorithm. Currently I am working on a derivation and determination of the Doppler shift( dF โ€“ frequency step). For each dF, The following algorithm was ...
LeeLeeYa's user avatar
0 votes
1 answer
88 views

Amplitude / gain of difference of 2 known FIR low-pass filters

Given a discretely sampled sinusoidal signal (frequency $1/40$), and 2 Simple Moving Averages (SMA), better known as FIR low-pass filters of order e.g. $10$ and $21$, it can easily be calculated what ...
MisterH's user avatar
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0 votes
1 answer
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RMS Amplitudes of voltage

I am looking here at the course of current fluctuations and have calculated the RMS values, but somehow it seems strange to me: with the black line there are small fluctuations, but the RMS value is ...
CB95's user avatar
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0 answers
127 views

Emulating tape distortion of low-level audio signals

I'm working on a tape echo emulation in Reaktor, and I've based the frequency response, tape speed warble, high-amplitude saturation and tape hiss on a paper I found about the Roland Space Echo. ...
Reaktor4's user avatar
3 votes
4 answers
788 views

Amplitude of the fft is less than what is expected

This is my MATLAB code ...
SeAlGhz's user avatar
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1 vote
1 answer
1k views

How to obtain the exact value of wavelength from a 2D FFT amplitude vs wavenumber plot like it is obtainable from 1D FFT amplitude vs wavenumber plot?

I have a two dimensional multi modal spatial signal generated from a MATLAB code using sinusoidal functions of different wave numbers, amplitudes and phases. What I want to know is that if I have the ...
Shataneek Banerjee's user avatar
0 votes
1 answer
121 views

Amplitude decrease in FFT at higher frequency for multisine

I am adding sine signals with different frequencies but same amplitude=100. Sampling frequency is 50MHz. I am not getting 100 in frequency domain for frequency 787KHz. At 1K, 3K I am getting 100 ...
user653241's user avatar
1 vote
1 answer
598 views

How to compute correct phase in FFT even after applying phase unwrap and zeroing round off error?

I am converting a time-domain synthetic 1D signal to frequency domain using MATLAB fft. In the frequency domain, the amplitude vs frequency plot is coming reasonable which means it is showing the ...
Shataneek Banerjee's user avatar
0 votes
2 answers
314 views

Amplitude spectrum (transfer function) of signal?

I have one question related to finding amplitude spectrum (transfer function) of signal knowing that output signal is time derivative of input signal. I have the answer graph but I don't understand ...
thecarefulone's user avatar