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1500 questions
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methods of computing fixed point atan2 on FPGA
I am in need of computing atan2(x,y) on an FPGA with a continuous input/output stream of data. I managed to implement it using unrolled, pipelined CORDIC kernels, but to get the accuracy I need, I had to perform 32 iterations. This led to a pretty…
user2913869
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Deconvolving the measurement system from the system response
I'm preforming a system identification measurement, and would like to deconvolve the measurement system's response from the measured response.
The set up of the system is as follows; the signal is generated on a PC, the signal is then sent to the…
Lance
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Speech synthesis requiring very little CPU performance?
Back in the days of 1 MHz 8-bit CPU personal computers (Apple II, Atari 800, et.al.), there were software programs that could do comprehendible arbitrary text-to-speech synthesis on those PCs. What published speech synthesis algorithms might be…
hotpaw2
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14
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What is the relationship between the sigma in the Laplacian of Gaussian and the two sigmas in the Difference of Gaussians?
I understand that a Laplacian-of-Gaussian filter can be approximated by a Difference-of-Gaussians filter, and that the ratio of the two sigmas for the latter should be 1:1.6 for the best approximation. However, I'm not sure how the two sigmas in the…
visual-kinetic
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What bandpass filter design will yield the shortest impulse response?
Designing a simple 2nd order IIR bandpass Buterworth filter with a centre frequency of 500 Hz and a 1 octave bandwidth gives me the following frequency response ...
Now, if I take the impulse response and normalise it and convert it to dB, we can…
learnvst
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14
votes
1 answer
On using eigenvectors to estimate a signals' fundamental frequency, via MUSIC
Context:
(Disclaimer: This is NOT a comm problem).
I am trying to estimate the fundamental frequency of a real, periodic signal. This signal, was constructed by match filtering a raw signal, to that of a pulse. (the matched filter). The resultant…
Spacey
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14
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2 answers
How to match a drawn Chinese character to a database of stroke animations
I have a database of Chinese character stroke animations. Each entry is basically a set of points which shows how and in which order a character should be drawn.
To make lookup easier, I would like to allow the user to manually draw a character with…
laurent
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14
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5 answers
Fastest implementation of fft in C++?
I have a MATLAB program that uses fft and ifft a lot. Now I want to translate it to C++ for production. I used OpenCV but I noticed that OpenCV's implementation of fft is 5 times slower than MATLAB's. Then I tried armadillo but it was even slower.…
Saeid
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1 answer
Kalman filter - understanding the noise covariance matrix
What is the significance of the noise covariance matrices in the Kalman Filter framework?
I am referring to:
process noise covariance matrix Q, and
measurement noise covariance matrix R
at any time step t.
How do I interpret these matrices? What…
Raaj
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14
votes
5 answers
Identify Where Singing Starts in a Voice Only Recording
I have a little karaoke-style app where a user sings 4 lines of a song, with a one second gap between each line. There is no backing music, so it's voice only, hopefully making the problem easier to solve.
I am looking for the most robust way to…
Mike Hogan
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14
votes
2 answers
Is a high-passed signal the same as a signal minus a low-passed signal?
My question is, if I want to high-pass a signal, is it the same as low-passing a signal and subtracting it from the signal? Is it theoretically the same? Is it practically the same?
I have searched (both on google and dsp.stackexchange) and I find…
Fixed Point
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3 answers
What does it mean in image processing when a filter is called non-linear?
In image processing, what does it mean when a filter is called non-linear?
Does it mean the equation of the filter contains derivatives and if it didn't, it would have been called linear?
siddharth
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14
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1 answer
What does the normalization step of the Haar wavelet transform represent?
When you perform the Haar wavelet transform, you take the sums and differences, then at each stage, you multiply the entire signal by $\small\sqrt2$.
When taking the inverse transform, you multiply the signal by $\frac{1}{\sqrt2}$ for each…
bobobobo
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14
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3 answers
What Does It Mean Exactly When Two Parts of a Signal Are Correlated?
I stumble quite often upon the notion that two or more parts of a signal are correlated to describe semi-formally that they belong together. For example in image processing, two pixels on an edge feature tend to be correlated whereas two adjacent…
Lenar Hoyt
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14
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6 answers
What Approximation Techniques Exist for Computing the Square Root?
I have very limited resources as I'm working with a microcontroller. Is there a taylor-series expansion, common lookup table, or recursive approach?
I'd prefer to do something without using math.h's…
tarabyte
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