Questions tagged [amplitude]

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87 views

number of samples and Amplitude accuracy,what's the solution to this problem

I'm colleceting data samples from a device (temporal signal) in order to analyze it with FFT function in MATLAB R2015b,first i get N=4063 data points with (delta_t=0.000015s) so my frequency ...
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41 views

frequency amplitude asymmetry

I want to calculate the frequency amplitude asymmetry between two signals, EEG signals in particular. As a result, I expect a value ranging from 0 to 1. I have some references regarding that, but it's ...
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1answer
29 views

Decimation with IIR filter altering amplitude of signal

I'm downsampling a signal through decimate (scipy implementation), but the result has a different amplitude than the original signal, which if I understood correctly, shouldn't happen. The original ...
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1answer
32 views

Normalizing white noise to match pink noise's amplitude at a given frequency?

I have a pinking filter which I am running white noise through to get pink noise. I would like to then mix the white noise with this pink noise, where the amplitude of the white noise will match the ...
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1answer
553 views

When listening in to an AM signals of various frequencies, how do we exactly tune in?

Alright, so I read on AM and Double Sideband AM, but I don't the more fundamental idea - the frequencies. Frequency is just: $ \frac{1}{T} $, where T is period So difference between 5 Hz and 30 Hz ...
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1answer
1k views

Calculating SPL from pressure signal - Amplitude vs Power method

I have a pressure signal from a Fluent FFowcs-Williams Hawkings acoustics analysis. I converted this pressure signal into the frequency domain in order to get SPL values, using Matlab. I used the ...
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3answers
778 views

How do I calculate peak amplitude of the signal components after zero padding and FFT?

I am learning about DFT and trying to apply it to some audio processing. I am new to DSP but experienced in programming and have some background in math and physics. The FFT algorithm I use (lomontFFT)...
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2answers
2k views

What is the right way to extract particular frequency phase information from FFT?

Signals acquisition: Two proximity sensors are positioned Orthogonal to each other. These would be measuring the vibrations of a rotating shaft. Problem: Each of these 2 signals has two dominant ...
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5answers
8k views

Equal power crossfade

I am working on an audio system where I need to implement an equal power crossfade between two signals over a specified number of samples. Initially I implemented a linear fade but this creates a dip ...
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2answers
3k views

Help me understand how Pulse-Amplitude Modulation (PAM) works

Reading on the Internet i learned that PAM is basically a sampling technique which converts an analog signal into a discrete signal. It modulates a train of pulses by varying the amplitudes of the ...
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0answers
17 views

Cross location Cross frequency coupling

Let's say there are 2 sensors recording data at some sampling rate. I'd like to know, how to calculate Cross frequency coupling (Phase amplitude coupling, for now) between these 2 channels ? I have ...
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1answer
434 views

Amplitude of an Image

If I take a two dimensional image and conduct a fourier transform on it, I would get a two dimensional matrix of complex values. If I want to find the amplitude of each value, is that the same as ...
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1answer
57 views

Amplitude estimation of sinusoid in known spiky spectral noise

What is the "best" way to estimate amplitude of a known-frequency sinusoid in the presence of known spiky spectral noise (i.e. noise comprising a few spectral peaks at known frequencies)? By "best", ...
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0answers
54 views

How accurate is Python's FFT?

I am getting started with Python's FFT. I tested it on a signal that is a sum of three signals, two of which have an eigenfrequency of the grid, the third one does not (but due to large no. of data ...
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0answers
19 views

Is there a way to filter out low volume content in an audio sample?

Imagine you are listening to a digital file that contains some random speech. Now, while you are listening to it, you also hear in the background (spatially) some low volume content, either noise, ...
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1answer
175 views

Amplify a signal and phase shift it by multiplying by a complex number

Still need help 25th October 2019 I have a real time domain signal contained in an array, it's just two different frequencies summed together. If I want to amplify this signal by 10 and phase ...
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1answer
50 views

Amplitude modulation in pure sine wave [duplicate]

I am generating sine wave in MATLAB with following code ...
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2answers
50 views

Estimate amplitude of signal between 45 Hz-60 Hz

I have to estimate the amplitude of vibration of a real world robot. The signal is originating from a laser distance measurement, and the vibrations are somewhere between 45 and 60 Hz. I'm using ...
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3answers
48 views

Characterization of transfer functions with no local peaks

Assume that you are giving an arbitrary amplitude frequency response $A(\omega)=|H(j\omega)|$ Is there a characterization that ensures that $A$ is monotone? i.e, $A$ has a global maximum at $\omega=0$...
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1answer
11k views

Converting raw I/Q to dB

I am getting I/Q data from a software-defined radio. I want to do some stuff on signals in the data, but only if it exceeds a certain range. What is the general procedure to get dB (dBm, or anything)...
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1answer
172 views

MATLAB FFT Amplitude

I am trying to understand FFT, DFT through Matlab and I am fairly inexperienced in all of these. I have a time vector t and a corresponding simple sine wave x = 0.25*sin(t). Now I would like to view ...
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2answers
569 views

Is phase and amplitude information necessarily lost when undersampling?

Is phase and amplitude information necessarily lost when undersampling if you have a constant periodic single frequency sinusoidal? My second question is: How can one determine the undersampling ...
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1answer
33 views

Diode demodulation for AM

What is the capacitor and resistance at output of LPF meant for in the document it was mentioned that it is DC blocker I don't get it can't message contain DC value.
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2answers
213 views

Lock-in amplifier

From what I have studied so far I have understood that the benefit of a lock in amp is its ability to resolve the amplitude of a signal which is deep into noise. I was wondering if the same concept ...
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1answer
109 views

How is the decay of a signal exemplified in a Fourier Transform?

Is there any way to tell if a signal is decaying from its fourier transform?
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1answer
45 views

Relationship between spectral efficiency and PAR

Low PAR means less fluctiations in the magnitude of a signal and hence analog signal processing (e.g., power amplifier) is tremendously reduced. For example, constant envelope modulation schemes like ...
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1answer
49 views

are Ultra sound signal amplitude dangerous? [closed]

First sorry if this question if it's out of topic but I'm very intrigued The human ear can hear a specific range of sound waves frequency. and huge amplitude of those sounds can damage the ears but ...
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3answers
641 views

What is the (approximate) function for amplitude of a plucked string over time? Does it differ between string types?

Impetus: I'm currently working on my first synthesizer, after many years of playing with them. I've just added an ADSR envelope to modify the gain, but for some reason it sounds wrong to me. I've ...
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1answer
70 views

frequencies in sound: multiple possibilities?

First, I am by no mean a sound engineer (as you will guess later). I was just wondering something while looking at the waveform of a .wav for a given shape of waveform on a duration of 2 sec for ...
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1answer
114 views

What is the name of this very simple spectral subtraction technique?

Let $S = X + N$ be the sum of two audio signals $X$ and $N$ which are both stationnary (let's think X is a constant volume 440 Hz sinusoid and N is constant volume noise). If the sum S has a -20 dB ...
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1answer
245 views

How to measure acoustic pressure level under water with a hydrophone?

this is my first post here and I am also new in signal processing. Let's say I have a hydrophone with amplifier which is connected to a sound card plugged in to a computer. I gather the sounds to a ...
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1answer
303 views

Find Amplitude of each period of time series

I would like to determine the of each period amplitude of a time series (e.g. the amplitude of each day). The time series has a constant period of 1 day and varies only in amplitude. I have tried ...
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0answers
90 views

How to generate the amplitude of a signal with a certain power spectral density?

I am a newbie. If I posted a question someone else already asked, please forgive me. Thank you! Now, I have a power spectral density named $P(f)$ as a function of $f$. Let's say this function is ...
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0answers
272 views

FFT amplitude vs IQ amplitude

I'm very new to digital signal processing, so please let me know if my question doesn't make sense. I calculated the amplitudes (using the formula : $10 \log_{10}(i^2 + q^2)$) for some IQ data ...
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2answers
373 views

How to assess perceptual volume from FFT

So far I could estimate signal volume from FFT using amplitude information, then adding all amplitudes together and divide this number by the number of frequencies. But I think this method does not ...
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3answers
413 views

Amplitude cutoff following FFT

suppose I have a noisy sine wave (as R code): ...
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1answer
154 views

Measuring Amplitude of sound wave FFT

Please, pardon my ignorance. This may be a simple question, but I am still unable to explain what is happening. I am using a turtlebot to listen to sound emitted from a stationary sound source. My ...
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2answers
647 views

Bandwidth of product of two signals

POINT 1: According to convolution theorem, if g1(t) has a bandwidth B1 and g2(t) has a bandwidth B2, then product g1(t)g2(t) has a bandwidth = B1 + B2. POINT 2: Now, consider an AM waveform s(t)=g(t)...
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2answers
87 views

Estimation of step amplitude using the CUSUM algorithm

I used the CUSUM algorithm to detect steps in data. Basically the data looks like this, the data has a constant amplitude and then there is a rapid variation or a step. For example, the signal has a ...
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2answers
260 views

Amplitude in frequency domain not as expected with discontinues time domain signal

I'm having a problem where I cannot explain why the amplitude in the frequency domain not is as expected. The scenario: I have a time domain signal of consisting of two sine waves. on at 5Hz with ...
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1answer
727 views

Extracting the carrier signal from AM

I am new to DSP and leaning about amplitude modulation. I am trying to demodulate a 5 Hz signal that is modulated by a 50 Hz carrier. I am trying to extract the carrier, not the the 5 Hz signal. A ...
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1answer
1k views

Bits - symbols mapping in M-PAM beginner question

I am trying to implement a M-PAM modulator in Matlab without using the built-in functions. I am confused when it comes to the symbols-bits mapping. Say I have a sequence of bits: ...
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3answers
1k views

Get frequency and amplitude from an audio sample [closed]

I'm wondering how can i get the frequency and the amplitude from a 16 bits sample. I have actually an array of 16 bits signed int and I would like to get the frequency and the amplitude of each sample....
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1answer
127 views

Improving template with instantaneous amplitude

Given some recording (containing both the signal of interest and some Gaussian noise), can we improve our template (or model) of the signal using the analytic signal of the recording? For example, a ...
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1answer
179 views

AM modulated signal not centered at carrier frequency [closed]

I am trying to modulate the signal bl_msg_time (this is a speech signal) using DSB-SC modulation however the signal doesn't appear centered at the carrier frequency....
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1answer
775 views

Digital 16-bit PCM audio signal scaling and STFT spectogram amplitude

I'm sampling a 16-bit PCM audio signal at 44100 Hz and I'm trying to understand the amplitude level of both the digital audio signal and its corresponding spectrum. The final goal is creating audio ...
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2answers
1k views

Why is there an amplitude difference in Matlab and Python?

I've been trying to read an audio file in Matlab using this code -- q = audioread('C:\Users\DELL\Downloads\cha1.wav'); figure; plot(q); Translated to Python, ...
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1answer
58 views

How to find out amplitude of harmonic after diff type of FT?

I am new in DSP, so I apologies if it's dump questions but I didn't find needed information on the Internet. So the questions is: Assume that we have simple harmonic signal described by next function ...
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1answer
104 views

How i can create ghost on wavelet or seismic trace and then Deghosting that in MATLAB? [closed]

I want to model a seismic trace or wavelet and then create ghost on them, at the end Deghosting in MATLAB. Can anyone help me please?
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1answer
11k views

Difference between single sided and double sided amplitude spectrum

I've recently gotten stuck with a small issue. I was asked to plot the single sided amplitude spectrum of the signal $x(t)=\cos(2\pi\cdot20000t)$. I know that $X(f) = \frac{1}{2}\cdot\left[\delta(f-...