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1500 questions
8
votes
1 answer
Scipy resample, "fourier method" explanation
I am seeking explanation of what "Fourier method" is that is described for resampling in documentation of resample() method. I want to downsample an array. I know what decimation is and how it works, I also know what fourier transform is. I cannot…
chess
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8
votes
2 answers
How Is Laplacian of Gaussian (LoG) Implemented as Four 1D Convolutions?
I am trying to understand the four 1D convolution operations involved in implementation of Laplacian of Gaussian(LoG). I have read the answers to What Is the Difference between Difference of Gaussian, Laplace of Gaussian, and Mexican Hat Wavelet?,…
skr
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8
votes
1 answer
How to Check Separability of 2D Filter / Signal / Matrix
Given:
x(n1,n2) = {1 ,n1=0,n2=0 ;
2 ,n1=1,n2=0 ;
3 ,n1=0,n2=1 ;
6 ,n1=1,n2=1 }
How could one prove it is separable?
Nilesh Padhi
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8
votes
2 answers
Extended Kalman Filter (EKF) for Non Linear (Coordinate Conversion - Polar to Cartesian) Measurements and Linear Predictions
I'm new to Kalman filtering and state estimation and I'd like some guidance on EKFs.
Currently, I'm trying to use a linear prediction model coupled with nonlinear measurements to estimate the state of an object. My state vector ($\bar{x}$)…
bparikh
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8
votes
1 answer
How to determine where to sample for demodulation of BPSK signals?
I have a simple BPSK demodulator. Very simply, the signal comes in and is split into two branches, one for I and one for Q.
The I branch is mixed with a sin wave of the carrier, and the Q branch mixed with the cosine wave of the carrier.
Then,…
Spacey
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8
votes
2 answers
How Can I Remove Flickering Background in a Video?
I have a black and white video taken with a high speed camera and I notice a background flickering coming from my LED light. The images alternate from dim to bright and it makes the videos quite disorienting.
Besides getting a different light, is…
user19960
8
votes
2 answers
QAM constellation slicer with unknown carrier phase
As shown in the image, I have a 16QAM constellation that is misaligned due to a phase rotation. In this case you can see that rotation amount is approximately $\theta = \pi/4$, but this won't be the case in general. For real-world data the phase…
user827822
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8
votes
3 answers
Are there any open source biomedical signal processing projects?
I'm in a biomedical engineering master's program and am mostly interested in signal processing. Unfortunately, I feel that I'd like to get deeper into the subject, and my university can't accommodate that request -- there's a limited number of…
Andreas
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8
votes
3 answers
Why does signal averaging reduces noise levels by more than $\sqrt{n}$?
I have an electrophysiology signal, which is time-based. It basically measures neural activity in the form of potential differences over time.
The noise in this signal is assumed to be a random background noise caused by the device electronics and…
AliceD
- 298
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- 13
8
votes
2 answers
Initial conditions for systems described in state space - LTI or not?
Suppose we have some system given by
$$\begin{aligned}
\dot{x}(t) &= Ax(t) +Bu(t) \\
y(t) &= Cx(t)+Du(t)
\end{aligned}$$
where $x(t)$ are the state variables, $y(t)$ is the output and $u(t)$ is the input. All matrices are constant. The same question…
Tendero
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8
votes
1 answer
Least Squares Re Synthesis of Short Time Fourier Transform (STFT)
Working with my own MATLAB implementation of the short-time Fourier transform (STFT), I've managed to write code for the analysis step where a 1D time-domain signal $s[t]$ is progressively windowed, taken into the Fourier domain and arranged in a 2D…
Nicholas Kinar
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8
votes
1 answer
Open access signal processing journal?
Signal processing is Elsevier, so it's not open access, and IEEE Transactions on Signal Processing is also not open access. I was wondering if there's any decent journal on par with those that's open access.
I'm trying to submit a paper on discrete…
Memming
- 193
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8
votes
1 answer
Differences between OpenCV Canny and MatLab Canny?
does anyone know why the MatLab Canny (MLC) is so different compared to the OpenCV Canny (OCC)?
ML-C delivers precise and more connected edges than the OCC, but how is that possible?
The reason why I ask is, that I need to implement my protoype of…
mchlfchr
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8
votes
1 answer
Which digital modulation scheme would be suitable for transmitting digital data through the output of a PC soundcard
I need to output a data stream at $40\textrm{ kbit/s}$ or faster out of a computer system whose only accessible output peripheral is the audio interface. This interface has reasonable specs, $96\textrm{ kHz}$ sample rate, with $24$-$\textrm{bit}$…
pichenettes
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8
votes
3 answers
Is the system $y(n)=x(n^2)$ time invariant?
According to my solution,
$$y(n) = x(n^2) \tag{1}$$
for $y(n,k)$ i.e output for delayed input $x(n-k)$
$$x_2(n) = x(n-k)$$
so $$y_2(n) = x_2(n) = x\big((n-k)^2\big)$$
and for delayed output signal $y_1(n)$, replace $n$ by $n-k$ in equation (1), so…
Niyam Shah
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