# Questions tagged [amplitude]

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### 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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### Amplitude cutoff following FFT

suppose I have a noisy sine wave (as R code): ...
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### 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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### 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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### 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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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: $$\mathcal{F}\{\delta [n]+\delta [n-1]\}\ =\ ... 2answers 208 views ### Lock-in amplifier From what I have studied so far I have understood that the benefit of a lock in amp is its ability to resolve the amplitude of a signal which is deep into noise. I was wondering if the same concept ... 2answers 2k views ### Envelope detector for non-zero mean signal (Matlab) I used hilbert transform to get an envelope signal. envelope = abs(hilbert(inputSignal)) This works for zero-mean signal: But, for nonzero-mean case, ... 2answers 2k views ### Quadrature modulation for FM and AM This might be a naïve question, are these correct statements? Both amplitude and frequency modulated radio signals nowadays use quadrature modulation and demodulation as a mean to transfer and ... 0answers 96 views ### When to use raw signal strength, vs. when to filter first I am collecting I/Q samples from an RTL SDR dongle. I notice the rtl_power utility provided for Linux filters and does other processing, before reporting signal ... 0answers 68 views ### ssbmod single sideband modulation artifacts clc; clear all; close all; [c,fs]=audioread('60hz.wav') r=ssbmod(c,160, fs) r=r/max(max(abs(r))) audiowrite('artifacts.wav',r,fs,'BitsPerSample',24) I am trying ... 1answer 261 views ### Why does QAM use two cycles instead of one per byte? If you look at this image, you can see that you have 256 possible binary values by modulating the amplitude (the radius of the trigonometric circle) and the phase (the degrees) of the carrier. ... 1answer 3k views ### Amplitude transfer function Given a LTI-system$$y[n]=x[n]-2x[n-1]+y[n-1]- \frac{8}{9}y[n-2]$$The transfer function H(z) is:$$H(z) = \frac{1-2z^{-1}}{1-z^{-1}+ \frac{8}{9} z^{-2}} $$How do I calculate the amplitude ... 2answers 4k views ### How do I calculate the frequency of the highest amplitude wave? I have a number of values retrieved from a sampled signal that is generated randomly for no specific purpose. The task I am presented with (Quoted below): calculate the frequency of the highest ... 0answers 58 views ### amplitude at exact frequency in wide band signal Could anyone suggest the most computationaly efficient method for finding amplitude of exact frequency having a noisy wide band signal. To be more specific about a task. I have some physical ... 0answers 220 views ### How do I find amplitude modulation effects in natural signals It is relatively easy to discover overlaid (additive) signals in natural phenomena using wavelet decomposition, Fourier Transforms, CEEMD, etc, because addition in the time domain is the same as ... 2answers 5k views ### Extracting accurate phase and amplitude information from FFT with an arbitrary number of samples This is a followup question to one I asked earlier based on the chat after the answer given by @hotpaw2, and cross-posted from stackoverflow since it was suggested it is more relevant to DSP. I have a ... 1answer 83 views ### DAPSK bit assignment for the amplitude difference I am studying DAPSK(Differential amplitude phase shift keying) at the moment. I have a 64-DAPSK. We are using 4 concentric rings and 6 bits per symbol. The first two bits contain the information of ... 1answer 1k views ### DFT normalization for amplitude estimation After an interesting recent answer, I'm doing some research on proper DFT normalization for sinusoidal peak estimation. It's clear that to get the correct amplitude from DFT peaks we need to normalize ... 3answers 93 views ### Logaritmic amplitude squarewave This morning i was experimenting with GNU Octave. I created several signals(Sine, Saw tooth, square wave and noise). After this i used the periodogram. in the periodogram the square wave weren't ... 1answer 553 views ### How do I calculate the autocorrelation of a train pulse having only the pdf? I have a pulse train of a fixed period, but a random amplitude following a Gaussian distribution (\mu=0,\sigma=1). I know how to work with a random period or delay, but how do I proceed to calculate ... 1answer 529 views ### Scale of Amplitude in FFT (Matlab) Using Matlab's FFT function, I am getting different Amplitude values in a particular frequeny, when I use different range of Bandpass filters centering around that particular frequency. What's wrong ... 1answer 90 views ### Why does the standard waveform from audio out get distorted when I reduce the amplitude? In my attempt to generate a standard sine wave out of a sound card, I started using matlab which has a function soundsc for scaling the output ... 1answer 416 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 ... 1answer 211 views ### In speech recognition applications, how are different voice amplitudes handled? (i.e loud vs. quiet tones) I am doing some research related to real-time voice/hotword recognition engines. In most current implementations, input is divided into frames (overlapping or not), and audio features are extracted ... 1answer 962 views ### What's the fastest way to get the phase angle and amplitude of a COSINUS 50hz signal? I'm not a DSP specialist.I'm working in transmission and distribution. I need to retrieve the amplitude and phase angle of a discrete 50Hz COSINUS signal as fast as possible. Right now I'm using a ... 0answers 666 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 ... 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 ... 1answer 80 views ### What is the reason for “random” spikes in amplitude of a guitar waveform? In the image below there is the waveform of a clean, strummed guitar note, where the absolute value of the amplitude values has been taken. At the point marked there is a momentary spike in amplitude ... 1answer 531 views ### Calculate amplitude of noise added Sine Gaussian signal from frequency domain How to calculate the time domain amplitude of noise added Sine Gaussian signal from corresponding frequency domain. Here time domain amplitude is 2. How to get this from frequency domain. ... 3answers 2k views ### Amplitude of frequency in MATLAB FFT I am trying to extract amplitude of specific frequency in Matlab FFT. Is it possible to use the abs(mag)... But I do not know in which sample to look for ... 0answers 52 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 ... 1answer 417 views ### Extracting amplitudes of components from FFT I have a 4096-point FFT of a continuous pipe organ sound (no windowing). I wish to extract the relative amplitudes of the various harmonically-related sinusoidal components for voicing analysis. I ... 0answers 40 views ### Amplitudes and phases of transform of an image I have recorded an image of a large macromolecule and after several types of image analysis, have obtained a rotationally averaged image, that is not quite perfect, but appears to show 6-fold symmetry.... 2answers 1k views ### A clarinet has no even harmonics. What would produce no odd harmonics? According to this link, the waveforms of clarinets do not have even-numbered components in their harmonic series: A closed cylindrical air column will produce resonant standing waves at a ... 2answers 3k views ### FFT Overlap in Matlab I am getting incorrect amplitude of my signal post FFT (90% error) and it does not improve after applying any of the window functions prior to FFT. After reading a number of articles, I believe FFT ... 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)... 1answer 390 views ### How to find phase difference between 2 signals, one has an unknown function I have a system that is forced by a sinusoidal function with specific amplitude, phase and frequency ( all these are known ahead of time). I get a deformation of sinusoidal form as well (think of a ... 0answers 78 views ### Phase difference betwen 2 signals, 1 signal with unknown function I understand this question may have been addressed however I have a major difference. I started out with a sinusoid of form A*sin(2 pi freq t + phase) and I know ... 2answers 3k views ### Relationship between Fs (the Nyquist frequency), and the frequency used with a sine wave Say you are given a vector t =[...] for the time to be used to generate a sine wave of a certain frequency say FHz. I have all the data for t so I can conclude what dt is (my dt = 1d-5). Now I am to ... 2answers 347 views ### Amplifying part of a signal If I want to amplify a certain frequency in a digital signal, can I just take the FFT, increase the real part of the value for the frequency I want (leaving the imaginary part alone), and then take ... 2answers 451 views ### Tuning a radio to a certain frequency I've a fundamental problem with understanding terminology used in DSP. What does it mean to tune a radio (for example, a software defined radio) to a certain carrier frequency f? The received signal ... 2answers 2k views ### What is the rate of change of amplitude? Frequency? I know that frequency is not the same as the rate of change of amplitude, but why? Surely a high frequency is when your amplitude changes rapidly. Does an FFT perform something similar to ... 2answers 6k views ### Why FFT does not retrieve original amplitude when increasing signal length I don't understand why FFT return different maximum amplitude as the signal length increase. I would except that with a large signal length according to the frequency, detected amplitude will be very ... 2answers 556 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 ... 1answer 4k views ### How is the symbol error rate for M-QAM, 4QAM,16QAM and 32QAM derived? How do you derive the theoretical symbol error rate as a function of E_\mathrm{b}/N_0 for 4QAM? I know that the result should be Q\left(\sqrt{2E_\mathrm{b}/N_0}\right) but I am ĺooking for the ... 1answer 156 views ### Amplitude Spectrum, Nyquist Frequency, mixed/min/max wavelets The problem is here. Now I know the definition of mixed/max/min phase wavelets, whether the roots lie within the unit circle or not. Starting from n = 1, let$$ x_t = ( 5, 6)  X(z) = 5 + 6z  ...
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I am using Matlab Simulink to analyse Amplitude Modulation in Noise. I attached my system below. My problems: 1)In the mixer I am using a bandpass filter and another one after the envelope detector ...