All Questions
2
votes
1answer
29 views
Detecting the original bandwidth of upsampled recordings
I have a set of recordings sampled at 16khz, but some of them are upsampled from 11khz and some from 8khz. Quite some of the recordings are noisy. What is the best way to classify the recordings ...
0
votes
1answer
17 views
Cascade Transfer Function; Odd or Even Transfer Function
suppose we have a cascade realization of a transfer function of a higher order.
What difference does it make if the order of the transfer function is an Even or an Odd number?
0
votes
0answers
21 views
problem with inveres FFT
I try to change complex fft to polar fft but when I compute FFT of a wave, the IFFT is not the same before !
I have wrote following code :
...
0
votes
0answers
17 views
FM synthesis using phase accumulator
I'm attempting to implement an FM synthesis operator with feedback using a phase accumulator in C. In Tomisawa's original patent, the phase accumulator going into the adder counts over both negative ...
0
votes
0answers
28 views
How to correct for inperfect 90 degree phase shift before doing IQ demodulation?
I want to sample two signals, S and R and later do IQ demodulation on these.
I am multiplying S with R and I also want to multiply S with a 90 degree phase shifted version of R by shifting the ...
0
votes
2answers
49 views
Sampling at subnyqvist frequencies
I went through this material on Sampling theorem. http://www.wescottdesign.com/articles/Sampling/sampling.html
It uses a powerline signal example and concludes that if a signal is cyclic and ...
1
vote
1answer
44 views
Power or Energy Signal?
Can you tell me whether the following signal is a energy or power signal?
$$
x(n) = e^{j (n \pi/2 + \pi/8) }
$$
I've solved it and found it as it was neither power nor energy signal was that right?
2
votes
1answer
55 views
matlab How to design lpf\bpf\hpf without builtin functions
related to Filtering voice signal from randomly added frequencies
I'm trying to create a simple low pass filter but i'm not sure what is wrong.
my code:
...
3
votes
2answers
34 views
Mahalanobis vs Normalization+Euclidean
I'm using a set of features extracted from a signal for classifying the data window with KNN algorithm. Since the features have different value ranges, their influence on distance calculation is ...
0
votes
1answer
15 views
Extract not blurry images from video
I need a tool or code for extract not blurry images from video (it can be used for panorama of SFM building from video)
something like
...
3
votes
2answers
67 views
Where can I find a table of $z$-domain coefficients for Butterworth filters?
The primary source lists Butterworth polynomials in s-domain and provides a link to bilinear transform for digital implementation. But, who needs analog specification in our digital world? Why should ...
4
votes
2answers
44 views
How do I go about detecting whistles, pops and other sounds in live audio input?
I've read many questions on SO, and frankly, each one of them is not describing any particular way to go about it. Some say "do fft" and some say "zero crossing" etc.
But I've only gone as far as ...
0
votes
1answer
49 views
How did Scientists Capture First Images of Molecules Before and After Reaction?
"Using a state-of-the-art atomic force microscope, the scientists have taken the first atom-by-atom pictures, including images of the chemical bonds between atoms, clearly depicting how a molecule's ...
1
vote
1answer
34 views
How to choose one among different types of LPF?
My signal graph is as follows
I have < 10 reputation, thus cannot post the photo...
The graph are simply roughly the series of -5, 0, +5, 0, -5, 0, +5, 0.... but with sawtooth-like small peaks ...
0
votes
1answer
43 views
Impulse and step response of a system that contains cascaded second order sections
I have to design an 8th-order IIR filter with the following transfer function magnitude response as a specification:
I use "ellip" function from matlab to calculate the unquantised coefficient set:
...
0
votes
1answer
11 views
trainCascadeObjectDetector seems to be missing from MATLAB R2012b
I wish to use trainCascadeObjectDetector to train on new objects (other than faces); I have the Computer Vision Toolkit installed; but this function trainCascadeObjectDetector seems to be missing from ...
2
votes
3answers
53 views
How to pick coefficients for Fractional Delay Filters?
I have a Virtex 6 FPGA running at 200MHz with ADC/DACs on it. I have been converting a WiFi signal (2462MHz) down to a more reasonable IF of 25MHz, sampling, running the signal through taps, tweaking ...
1
vote
1answer
83 views
Separating waves of very close wavelengths
I'm new to wave problems, so excuse my simplified words.
I have a signal consists of high range of frequencies . I applied a Band-pass filter to this signal and I have been able to separate it to ...
0
votes
1answer
14 views
data for panorama stitching testing
I want some data (images that have only shift) to test on xuvtools or Microsoft ICE and my own software.
Is there any available?
1
vote
2answers
42 views
NAudio real-time equalizer
I have designed 9 IIR bandpass filters (chebyshev type 1, order 4) using fdatool in Matlab. Then I use a and b filter coefficients to apply it on differential equation. So, my question is how to apply ...
1
vote
0answers
20 views
Building a Low-Pass FFT filter for a noisy current pulse signal
I have some (well lots) of data signals which are measurements of current pulses. The current pulses are the result of spark breakdowns (20 kV + 700 pF capacitor so quite energetic) and my problem is ...
0
votes
0answers
15 views
Spectrum analyser and resolution bandwidth
For the preliminary part of a lab I had to do, I was asked the following question:
I get how to do 1.1, but with 1.2, I really don't get what's going on; I really would've thought that the ...
0
votes
0answers
39 views
What's the best method to extract vocals from music?
I want to achieve something like this https://soundcloud.com/user7421656/sonicworx-isolate-preview .
I've researched it and a few papers mention the use of "descriptors" on the audio and use ...
3
votes
1answer
57 views
What does the uncertainty principle say about recursive filters?
The uncertainty principle is usually stated as a relationship between a continuous signal and that signal's Fourier transform, and says that
$$
\int_{-\infty}^{\infty} \! x^2 f(x) \ \mathrm{dx} ...
0
votes
1answer
30 views
A 3x3 image kernel takes 9 multiplications and 8 or 9 additions for each pixel?
I doubt because you have 9 multiplications and you are adding 9 numbers together, when using a 3x3 convolution matrix.
Adding 9 numbers: 1+2+3+4+5+6+7+8+9
We are performing 8 additions as we repeat ...
2
votes
1answer
43 views
Transfer Function from input to node
From the IIR filter flow graph below i don't understand how the transfer function is calculated in every node:
The circles contains 'X' inside are multiplications.
The circles contains 'Σ' inside ...
-3
votes
1answer
59 views
How to combine similar signals to generate another one?
Assume there are 11 signals. These signals are very similar to each other in both time and frequency domains. (And the similarity between them is not random; they are similar because they have somehow ...
1
vote
0answers
18 views
Finding areas covered by features
I have an image as attached
The blue to yellow to red points are the points of interest the algorithm found, while the pink points are the radius per point. This maps pretty fine, but the issue I am ...
4
votes
2answers
58 views
Is there a way to reduce the covariance matrix of several source signals to the dominant source signal?
The problem I have can be seen in the context of DoA estimation or blind source signal separation and similar fields, where several source signals are observed by several antennas (or by an antenna ...
5
votes
3answers
89 views
How do I get started with Wavelets
Our current project requires us to do some analysis using Wavelet Transform. Can anybody suggest me a practical book, preferably with MATLAB or C examples.
I am currently reading some tutorials, but ...
3
votes
1answer
50 views
Trying to understand WAVELET TRANSFORM Frequncy-Time diagram
I am reading
The Wavelet Tutorial
Part III
MULTIRESOLUTION ANALYSIS
&
THE CONTINUOUS WAVELET TRANSFORM
by
Robi Polikar
The author explains about the following fig and says;
Note that ...
0
votes
1answer
28 views
obtain the position of an object in an image
I would like to compare the positions of the same object in 2 different pictures and get the difference between the positions in in terms of x and y coordinates.Suppose I have a picture with a square ...
0
votes
2answers
39 views
How to express linear convolution using positive frequencies from channel and symbol DFT vectors?
Sorry for the long question, but I'm struggling to implement something related to this question. Your help would be appreciated.
Background
Notation: In the sequel, the uppercase letters represent ...
0
votes
0answers
19 views
Association of multiple measurements to multiple objects
In every cycle I obtain measurements from which I initiate and later on update objects. I want to match properly measurements to objects. For this purpose I create a matrix of M measurements by N ...
-2
votes
0answers
33 views
similar matrix implementation [closed]
I am trying to separate music from song in my search I find something called similar matrix but it is solving my problem in math and I haven't a big information about this equations in this paper ...
8
votes
2answers
84 views
practical wideband digital beamforming for large arrays in radar applications
I do understand the mathematics behind digital beamforming but I am not sure how such systems are practically implemented. For example, in a typical wideband FMCW radar operating in S-band, the ...
0
votes
0answers
23 views
Meshes vs. Raw Point Clouds for 3D Object Recognition
I am trying to answer the question of whether it is better to use a raw point cloud or to mesh the point cloud prior to calculating local descriptors for the purpose of 3D object recognition in ...
0
votes
0answers
32 views
uncertainties in estimated transfer function
is there any method to estimate the uncertainties of a transfer function between two signals, using n blocks? Similar to the one in [1], which is for the squared coherence?
I used the tfestimate ...
5
votes
1answer
102 views
How one apply correctly FFT in image denoising
I'm writing program (Qt widgets/c++) for removing noise from images. As denoising method, i selected non local means method. This method has incredible quality of restored images (that's why it's the ...
-1
votes
0answers
24 views
Convert mouse coordinates to bitmap coordinates in DICOM imaging [closed]
In my aaplication rendering dicom image in picturebox. During the process, I felt the need of calculating Hounsfield Units.For that, when I move mouse over the image, It should get automatically ...
1
vote
0answers
61 views
Coherence of a single function given a single frequency
I have a signal sampled from a hardware, s. I would like to compute the coherence of the sampled signal given a single frequency, ...
0
votes
1answer
146 views
Sampling Frequency Math
The Nyquist formula for digitally sampling and recovering a continuous waveform is well known. Are there any mathematical formulas that show that it is computationally infeasible (or impossible) to ...
1
vote
0answers
56 views
How does Image Search on Google + work
I found out today about Google +'s image search feature. It allows users to perform a text-based search for objects within their picture library. I was instantly curious to know how this feature ...
0
votes
1answer
57 views
Lossless algorithm for hyperspectral imaging
I am looking for Lossless compression algorithm for hyperspectral imaging. The only one that I found was LPVQ.
Do you know other algorithms? I am looking for pseudocode or matlab code.
Thanks
2
votes
1answer
55 views
Gain function calculation (frequency response)
Define moving average process $y_t := 0.5 x_t + 0.5 x_{t-1}$ where $x_t := e^{i2 \pi t}$. Its frequency response is then:
$$H(f) = 0.5 + 0.5 e^{-i2\pi f}$$
Recall that the frequency response in ...
3
votes
0answers
46 views
What is right and full Frobenius canonical form?
I'm having a trouble here. I'm supposed to learn Frobenius canonical representation form for finding statespace matrices, but I found many different forms.
Let's suppose we have a system with this ...
1
vote
0answers
38 views
Errata Corridge in Gabor Filter Documentation and Frequency Response
I have a really simple question regarding this tutorial I found on Gabor filters.
Check the very beginning section, equations (1), (2), (3) and (4). Is there any chance that equation (4) is missing ...
-4
votes
0answers
18 views
Basic Idea About ECG Dicom Image [closed]
having an ECG Dicom image from this ecg image want to draw a ghaph for all waveform Data Tag I dont know to do this please give it me in detials
2
votes
2answers
80 views
What are Lumped and Distributed Systems?
What is the exact difference between Lumped and Distributed systems? Also, Lumped systems are said to be ordinary differential equations while the latter is said to be partial differential equation. ...
-2
votes
0answers
24 views
How to know what spectrum image layers are in eCognition? [closed]
This might be a really newbie question, but my teacher is an idiot so hopefully you guys can help me out:
I'm learning to use eCognition (8.1) and my teacher has provided me with some example tif ...
