# 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 ...
51 views

### 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 ...
1 vote
62 views

### 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 ...
62 views

### 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 ...
1 vote
68 views

### 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=...
43 views

### 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 ...
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,...
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 ...
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 ...
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....
40 views

### 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 (...
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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 p–p) is the change between ... 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@ |𝑐𝑘(𝜔=3,5,7,...)|/|𝑐𝑘(𝜔=1)|∝𝜔^𝛼 where I've already calculated ...
1 vote
133 views

### 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 ...
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 ...
1 vote
2k views

### 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 ($N=100$), ...
1 vote
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 ...
1 vote
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 ...
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&...
957 views

### 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 ...
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 $A$ ...
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 ...
81 views

### 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 ...
27 views

### 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 ...
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:  ...
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 ...
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 ...
1 vote
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)?
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 ...
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 ...
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?
1 vote
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: ...
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 ...
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 ...
1 vote
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 ...
1 vote
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 ...
1 vote
42 views

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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 ...
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. ...
788 views

### Amplitude of the fft is less than what is expected

This is my MATLAB code ...
1 vote
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 ...
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 ...
1 vote