Questions tagged [scaling]
The scaling tag has no usage guidance.
46
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STFT normalization
In Scipy's implementation of STFT, an argument allows to scale the result as a spectrum or as a psd :
...
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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 (...
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Understanding the multiply by 2 factor in scaling the DFT magnitude
I have seen a number of answers on various forums for why we need to scale the magnitude of DFT output by 2 (e.g. 1) to account for discarding negative frequencies, or 2) due to the 2 in the ...
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Fixed point scaling; float -> Q31 -> float
I am new to DSP and I am trying to understand how to work with fixed point operations and in particular the Q31 format.
In floating point (full range) I am doing some multiplications, it could be for ...
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Discrete Time Signals - Time Scaling and Time Reversal
On the top graph, we can see a discrete-time signal $x[n]$.
I don't understand how for the signal $x[3-n]$, the impulses with magnitude $1$ still are at the positive indices $n = 1, 2, 3, 4$. Why ...
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Scaling factor in DFT: pure math or bandwidth issues?
I'm trying to match the amplitudes of a signal before performing DFT and after. So, let's consider a 64-point sine signal with amplitude of $1$:
The DFT of such a signal will give us the amplitude (...
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160
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Fourier transform of time-scaled signum function
I have the signals $x_1(t)=\mathrm{sgn}(9t)$ and $x_2(t)=\mathrm{sgn}(t/5)$, where $\mathrm{sgn}$ denotes the signum function: $-1$ or $+1$ depending on the sign of the argument. I computed their ...
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Algorithm that enlarges the image to a resolution of $2N \times 2N$ using DFT operations
I'm trying to solve the following question:
Given an image at a resolution of $N \times N$. Describe an algorithm that enlarges the image to a resolution of $2N \times 2N$ using DFT operations.
As I ...
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Building the low pass filter in the wavelet scattering transform
In 1, analyzing the equivalence between MFCC and wavelet transform, the scaled wavelets are truncated for $\lambda < 2\pi Q/T$ to fit the time spread of the wavelets within the length $T$ of the ...
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How to interpret a break in linearity when performing detrended fluctuation analysis?
I have time series with 1048 values and when I perform detrended fluctuation analysis on this time series (using the windows or scales of 2^4 to ...
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Calculate ScaleVlues of IIR Filter manually from sosMatrix of MATLAB
while using "design" in matlab to design filters, at the output we can see a ScaleValues matrix that is used to compensate for overflow problem. my question is that how this matrix is ...
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How to evaluate fixed-point implementation of LMS filter is correct?
I am having an LMS block with 6 filter coefficients.
The value of filter coefficients are
0.0001
0.00045
0.2535
0.546536
0.0000243
0.3423
I have tried to ...
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3
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506
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What's the minimum decibel value?
I'm trying to scale wave amplitude (0-1) to perceived loudness (still 0-1). The decibel scale seems to be unbounded. For my audio, the amplitude 1 represents a decibel $d$ - i.e. the audio is being ...
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Time scaling of a shifted function
When we have say Delta at time $t_0$ on continuous time: $\delta(t-t_0)$.
If we want to move it $t_0/2$, can we scale the time and squeeze by 2 instead of shifting?
How does scaling in time of a ...
- 174
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1
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Software-Emulated Amplifier: Cracking while change Volume
I'm developing a software emulated analog synthesizer in the style of Euro Rack Modules. I have a problem with the volume amplifier.
Whenever I control the volume button via mouse/hand/manually ...
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How to improve accuracy while converting floating point coefficients to fixed point in the case of an all pole IIR filter
I am having an all pole IIR filter of order 5 with floating point filter coefficients
...
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2
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395
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Impulse response of a time scaling system
Assume a bandlimited signal $X(t)$. Given that the output for this signal is $X(t/2)$, what will be the impulse response $h(t)$ of such a system?
\begin{array}{l}
X( \omega ) \ =\ \int ^{\infty }_{-\...
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Time scaling and shifting of delta function
Learning signals and systems.
Solving time scaling and shifting problems.
For the question
$$x(t) = u(2t - 1)$$
First we shift by 1 to the right side and then we do time scaling , i.e divide by 2 ...
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Scaling of a rect function,drawing of signals
Im trying to understand on how the drawing of signals (time shifting,scaling...) works. This one example is confusing me, and a bit of help would be much appreciated. This is the starting Signal
We'...
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Audio time scaling using a phase vocoder
I've implemented audio time scaling using a phase vocoder approach because I wanted to answer this question here (and learn something in the process). Since that question has been closed, I may as ...
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Pixel Binning: Effect on SNR for Hardware vs. Software Binning
Is there a difference in SNR (or any other measure of image quality) between using 2x2 pixel binning in the camera and shrinking the full resolution image in software (cv::INTER_AREA) to the same size ...
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Whether $y(t) = x(t/3)$ is a memoryless system?
I am a newbie in signal and system, and feeling confused about the memoryless property, it says at the definition, if a system gives output only depends on present input, then its memoryless. So if at ...
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Math.Net and alglib returning different FFT outputs by default
I am developing an application in C# with spectrogram drawing functionality.
For my fist try, I used MathNet.Numerics, and now I am continuing to develop with alglib. When I changed from one to the ...
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why should I scale the fft using 1/N?
I am writing a report, and my advisor asked me to explain why I scale the fft by a factor 1/N (where N is the length of the array).
I used to use the scaling convention of multipling the fft by the ...
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492
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Correctly scaling FFT of different lengths
I have been looking at using two FFTs of different lengths and displaying the output magnitudes on the same graph (a shorter length window for the higher frequencies, and a longer one for lower ...
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237
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Inverse Fourier Transform Dirac impulse with scaled argument
Currently, I am dealing with the sampling problems and I don't understand how to calculate inverse Fourier transform of a scaling impulse function
$\textrm{IFT}\{\delta(\Omega T)\} = ?$, $T$ is ...
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Scaling issue after doing manipulations in FFT
I have two filters which must apply (in series) to same input data $x[n]$ e.g of length 256 (real time asio input buffers). One filter is e.g. an impulse response $h_1[n]$ of a speaker and other one ...
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393
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What's the right scale to represent a frequency spectrum?
To represent a 16 bits temporal spectrum, it's "easy" : my scale is going from -32000 to +32000. But What's the scale for a frequency spectrum ?
I made that try : I calculated a pure single frequency ...
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Overlap/add time-domain audio frames: How does normalization/scaling work with overlap greater than 50%?
I am attempting to overlap-add time-domain audio frames in a real-time context (with a continuous stream of data coming-in). Each frames consist of 1024 samples and have been previously "Hann" ...
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what is multiresolution
I have gone to wavelets course and up to my knowledge, changing the scale and translation of wavelets produces multiresolution images.
is this correct or can someone tell me what is multiresolution ...
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How to scale a signal to get desired variance [duplicate]
I am new to dsp, and I'd really appricate it if someone please help me with this problem. I guess it's a basic simple question, but I cannot get it write. Here is the question:
The variance of a ...
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Correctly scaling Power Spectrum and Correlation Function of Galaxies from Mock Catalogues
I'm currently writing a code to compute the two-point correlation function of a set of galaxies. As I work with a loooot of galaxies, it was suggested to me not to do it in real space, but to compute ...
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Most natural interpolation to simulate increasing distance?
Background: I'm generating multiple datasets with varying scales of resolution to simulate taking pictures from varying distances and then comparing image classification performances. For example ...
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Theoretical Maximum of DFT
For any discrete input signal between +1 and -1, what is the theoretical maximum DFT?
If the input is a cosine of $N$ samples with amplitude $A$, the peak spectral magnitude is $A*N/2$. But what ...
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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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How to upscale an image without affecting pixel aspect ratio?
For example, if we upscale an image from 100 x 100 to 400 x 300 then we see the pixel stretch in the image which I want to eliminate.
The easiest way I could think is to crop the image to maintain ...
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How to "scale" the FFT when using it to calculate discrete convolution?
As you probably know, the discrete convolution $ H = F \ast G $ of some $ F \left[ x \right] $ and some $ G \left[ x \right] $ can be calculated using the Fast Fourier Transform (FFT).
To do this, ...
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signal saturation [duplicate]
My signal is an actuator displacement signal. It is a sinusoidal signal with the max amplitude of 10cm. I want to clip amplitude at 7 cm in Simulink. But with saturation block, I will get flat ...
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What is the relationship between scales and frequency in a Morlet wavelet transform?
I'm using PyWavelets, with a complex Morlet wavelet. Its complex wavelet transform function requires scales as one of its parameters, rather than frequencies. However, I don't understand the ...
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Factor $|a|^{-1/2}$ in definition of mother wavelets
The mother wavelet is defined as
$$\Psi_{a,\tau}(t) = \lvert a\rvert^{-1/2}\Psi\left(\frac{t-\tau}{a}\right)\tag{1}$$
in which the factor
$$ \lvert a\rvert^{-1/2}\tag{2}$$
is supposed to serve ...
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How do scaling of the coefficients for the poles of a biquad filter affect the gain?
Given a digital filter consisting of a chain of digital biquad filters.
Given a digital biquad filter with a normalized Direct form 1 difference equation: $ y_n = b_0x_n + b_1x_{n-1}+b_2x_{n-2} - ...
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Scaling factor of Discrete Fourier Transform [duplicate]
I am going through DFT basics. I found somwhere it is represented by the equation
$$ x[n] \ \triangleq \ \sum_{k=0}^{N-1} \ X[k] \ e^{j 2 \pi nk/N} $$
$$ X[k] \ = \ \frac{1}{N} \sum_{n=0}^{N-1} \ x[...
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Library/strategy for rotate & scale image alignment/registration
I have two raster images of maps, A and B. I know that B contains A but I do not know the scale or rotation. There should not be any other distortions between the image but there may be noise. ...
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Implementation of IIR Filter in dsPIC 33EP - Scaling
I have to implement an IIR controller in dsPIC 33EP (16-bit, fixed-point, two's complement, wrap-around, 40-bit accumulator, 32-bit multiply, 12-bit ADC) and I am using cascaded, Direct Form I second ...
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Digital RF signal vector resize algorithm
I'm searching for an algorithm for resizing a RF sampled signal in order to draw it without losing any important maximum or minimum values.
The values of the vector are negative/positive around zero.
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