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Questions tagged [amplitude]

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1answer
69 views

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

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 modulate it by 0.5 degrees, will this work?...
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1answer
43 views

Amplitude modulation in pure sine wave [duplicate]

I am generating sine wave in MATLAB with following code ...
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3answers
47 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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2answers
47 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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1answer
91 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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1answer
25 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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1answer
75 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
71 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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1answer
31 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
592 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
63 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
100 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
210 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
213 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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3answers
633 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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0answers
238 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
300 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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1answer
131 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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0answers
88 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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2answers
516 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
75 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
211 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
483 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
776 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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1answer
652 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
882 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
112 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
152 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
667 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
838 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
49 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
91 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
9k 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-...
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1answer
2k views

why butterworth bandpass filter changes signal in the passband?

I want to apply a butterworth bandpass filter to EEG signals and it's not working so I tried with a simple signal: t=[0:0.01:10]; s3= 9*sin(2*pi*4*t); Still ...
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0answers
85 views

How to convert multi-band Energy Time Curve (ETC) to Impulse Response (IR)?

I am running my own sound simulator. Now I have obtained the Energy Time Curve (ETC, expressed by energy) by physical simulation, and they are stored in 8 discrete frequency bands (because decay of ...
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2answers
450 views

Closest two frequencies that can be resolved

Forgive me if I misuse the terminology. I wish to transmit two slowly changing analogue signals by amplitude modulating two higher frequency sinusoidal carrier waves. I will superimpose the two AM ...
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0answers
78 views

Values (amplitudes) of the CWT and their relationship to waveform amplitudes?

I'm coding up a scalogram in C++. Right now it calculates a single row of the CWT matrix and immediately maps it to a line of pixels. Trouble is my colouring scales with the values of the transform ...
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1answer
534 views

How we do frequency shaping and amplitude shaping in hearing aid

My project name is Digital Hearing Aid with frequency shaping and amplitude shaping using adaptive noise cancellation DSKC6713 DSP kit . Almost I have done this noise cancellation using code studio ...
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2answers
658 views

Do DCT results contain phase spectrum?

I've been working much with numpy.fft lately where just like the documentation says: When the input a is a time-domain signal and ...
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1answer
149 views

Quadrature Amplitude Modulation: I and Q Same

I am trying to understand a previous design that uses Amplitude Modulation. Instead of just using the real part of the signal, the designers put the voice signal on both I and Q. Both I and Q have ...
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1answer
113 views

First-Order Hold Filter Gain

I want to know the amplitude of the first-order hold filter at the Nyquist frequency (the roll-off amplitude/gain). I know that the Fourier transform of the reconstruction is given by: $$\sum^\...
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1answer
143 views

Amplitude loss during resampling with IIR

I have a problem in that I am resampling a signal and loosing amplitude. The steps I do are the following, in c++: Upsample/interpolate signal by 16x by padding with zeros. Run an IIR Bessel 2nd ...
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3answers
355 views

Amplitude cutoff following FFT

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

Maximum Throughput of QAM system

Consider a QAM system designed to transmit over a bandwidth of $3 \ \mathrm{kHz}$. The channel's power constraint imposes a maximum $\mathrm{SNR}$ of $30 \ \mathrm{dB}$. The system can tolerate a ...
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2answers
4k views

Is there a function in python which returns the Amplitude/Sound Pressure Level of a sound file(like .wav) file?

I found a function called scipy.io.wavefile.read() which returns the sampling rate and an array. But in the documentation, it is not specified that whether the ...
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1answer
2k 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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1answer
758 views

When does the Amplitude Spectrum equal the Magnitude Spectrum?

I had the following question on edX: I'm failing to understand why the second signal has $M(\omega)=A(\omega)$. First I find the DTFT of the signal: $$\mathcal{F}\{\delta [n]+\delta [n-1]\}\ =\ ...
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2answers
179 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 ...