0
votes
0answers
13 views

Autocorrelation and FFT : avoid zero-padding

Some posts evocate the computation of convolution or cross-correlation using FFT and zero-padding the temporal signal. I want to compute the autocorrelation of a 3D array using FFTW (2 dimensions are ...
-1
votes
0answers
15 views

Instantaneous power estimation by discrete hilbert transform - how far does it smooth?

In my research area, instantaneous power in a specific frequency band is commonly estimated by the following procedure: Apply a bandpass filter on the raw signal (e.g. 80-90Hz bandpass). Estimate ...
-1
votes
0answers
20 views

How to use reshape command for audio processing?

I have applied it: [Y Fs]= wavread('funky.wav'); A = reshape(Y,m,n) but this function is giving errors: Undefined function or variable 'm'. Now how ...
0
votes
0answers
16 views

Where is the energy goes in ANC (Active noise control)?

I just learned there is ANC technology in signal/audio processing domain. By my understanding, if two audio signal, whose phase is diff by 180, added the result will be silent. But from the physical ...
0
votes
1answer
14 views

float image to integer type image

I have a multispectral satellite image and I would like to "transform" each of the image bands into one with integer values. For example to stretch? the image between 0 and 255. Not sure how to ...
1
vote
0answers
19 views

Multiply filter kernel by sine

1)Suppose that we have low-pass filter with cf equal to 0.1. How frequency response would look like if I multiply filter kernel by sine with frequency say 0.3? How this is related to converting ...
-1
votes
1answer
37 views

Measuring the similarity of two waveforms

I have two approximately sine truncated waveforms of different amplitudes and I want a numerical measure of how similar they are to each other. I am sending a sonic pulse train whose multiple ...
0
votes
0answers
17 views

How to construct Polyphase(Frank) codes in Matlab

I have written a piece of code in Matlab to generate Frank codes - Pastebin link for pulse compression. I know that Frank codes are stepped frequency approximations to Linear Frequency ...
-2
votes
0answers
26 views

How to determine the frequency range of each channel of slantlet transform's filter

I have been using 2 scale slantlet transform (SLT) to analyze my data. For 2 scale SLT filter, it have four parallel filter channel, which are: 1) h2(n) - the first channel2) f2(n) - 2nd ...
0
votes
0answers
25 views

What are the foremost research areas in modern Statistical Signal Processing? [on hold]

I need to know what are some of the most research-demanding areas in today's Statistical Signal processing arena. I know, comprehensive-sensing is one such area? what may be others?
1
vote
1answer
35 views

correct for shift from butterworth filter?

I have implemented a python butterworth filter but it seems to shift the data a lot, the x location of my data is very important to me for my analysis. Is there a way to correct for this shift ...
2
votes
4answers
401 views

why Gaussian noise is usually used?

Gaussian noise with different SNR levels are usually used in research works to simulate a realistic environment. How can researchers guarantee that Gaussian noise can simulate the reality of a System? ...
1
vote
2answers
64 views

what is the unit of SNR?

SNR is defined as: $$SNR=10 \log_{10}\left(\frac{\sigma_s^2}{\sigma_n^2}\right)$$ When we say SNR of 10db is 10 times higher that 20db, it is higher in what? amplitude, power or what? also tell me ...
0
votes
1answer
27 views

How to change the start point of resampling process?

I'm trying to resample a digital communication signal in SciPy or Matlab. Suppose the signal was sampled at 3 samples per second, and I want to resample it to 2 samples per second, the thing is I also ...
0
votes
0answers
15 views

Testing whether instantaneous phase algorithm works 2D

I need to calculate the instantaneous phase $\phi$ of a 2D wave field $U$ in C which can be derived by one of two 1D Hilbert transforms $H$: $$ q(x,z) = H_1[U(x,z)] = 1/\pi \int_R U(x-\zeta,z) ...
1
vote
4answers
79 views

The reasons for filter explosion

Assume signal $x$, sampled at $f_s = 44100\; \mathrm{Hz}$. I tried to filter it using the Butterworth bandpass filter ( $30\; \mathrm{Hz} - 70\; \mathrm{Hz}$) of order $8$. However, as a result I get ...
0
votes
1answer
23 views

comb filter - attenuation

I have a signal and from 'standard information' I know the predominant frequency is at 1Hz and then there should be three harmonics at lower amplitudes. My signal however has a lower amplitude at 1Hz, ...
0
votes
1answer
21 views

variable length no-refrence filter algorithm

I'm searching for a an algorithm or an idea of implementation. I need to filter a signal in real time, and want to change the length of it (number of taps) in order to change the delay. In low ...
0
votes
0answers
21 views

How can I simulate a broadband ultrasound transducer in Matlab?

I am using a Matlab model to send a broadband acoustic pulse across a fluid. The centre frequency should be 50kHz with 100% bandwidth. It has been suggested that I apply a window the pulse to ...
0
votes
0answers
30 views

map two RGB images in Matlab

I wonder is there any algorithm or method that I can map two RGB images together in Matlab. I mean assume I have following images Is there any way I find what number I should multiply each ...
-1
votes
0answers
13 views

How do i get all the information regarding the header of an audio file? [on hold]

How do i get some human readable information from an audio file, (most preferably .wav file), like in the form of ascii values, so that i can further write a code to convert the file generated into a ...
1
vote
1answer
36 views

Sampling rate in Wifi 802.11 -> 20 MHz enough with a BW of 20 MHz?

In a Wifi 802.11n context, I'm looking to find the sampling rate to perform some processing on the signal and I've something I cannot understand : in the book Next Generation Wireless LAN's: 802.11n ...
0
votes
0answers
18 views

What are the advantages and disadvantages of the Ridglet transform?

I used continuous wavelet transform (CWT) in my research. Now a reviewer has put a comment, saying: Why the presented CWT algorithm is better than Ridglet transform? I thought it is better to ...
0
votes
0answers
12 views

Block matching based on correlation method for real time moving object tracking in large frames [on hold]

How can we make blocks in the images for block matching? How can calculate correlation value for each blocks between previous and current frame? How can we get maximum correlation value to match the ...
0
votes
0answers
21 views

Do eigenvalues shift with change in SNR

Let $H = \frac{1}{\sqrt{2}}M + \eta$ where $M= \frac{2}{\sqrt{15}}\left( \begin{array}{cccc} 3 & 2 & 1 & 3 \\ 1 & 2 & 3 & 1 \\ 1 & 2 & 1 & 1 \end{array} \right)$ ...
-2
votes
0answers
11 views

Steered Hermite Filter

if using Gabor filter with different scale and orientation, can remove the buildings edges, I believe Steerability of Hermite Kernel will also give the same result. I need opinions on this..?
0
votes
1answer
44 views

Fixed SNR with unitary noise variance

I've just one question : How can I write a model like y = x + w,( with w a white gaussian noise) with a fixed SNR and a noise variance equal to 1. What coefficient may I have before x ? Thanks !
-2
votes
1answer
77 views

Fourier transform properties. Spectral density function [on hold]

I have the following signal for which amplitude and phase spectrums have to be computed: This exercise also has a solution which begins by deriving the signal twice. Next, they say the spectral ...
0
votes
2answers
98 views

Plotting Real Amplitude of Sine Wave in FFT

Consider a sine wave having an amplitude of 9 and a frequency of 0.3 Hz. I wish to perform an fft and plot the frequency on the x-axis and the real amplitude (i.e. 9) on the y-axis. I am using the ...
0
votes
0answers
42 views

Understanding a mathematical statement in image processing

I am reading a document on Image processing and couldn't analyze a statement in it. For any $k \in \Psi_s$, the family of values $\{u[\varphi(p+l)+k-l]:l \in \Psi_s \}$ is representative of the ...
0
votes
0answers
34 views

Issue in crest factor

From Wikipedia: Crest factor is a measure of a waveform, such as alternating current or sound, showing the ratio of peak values to the average value. It is the ratio of peak amplitude of the ...
0
votes
1answer
40 views

Problem with a code of FIR Lowpass filter

I'm making an interpolator (filter) to remove aliasing but this doesn't work. I see also some strange behaviour: x[i - j], but what if ...
1
vote
1answer
21 views

How to decode speaker gender from spoken transcript

I have 20 audio recordings (raw format) of people reciting the same ~50 word transcript. I would like to use audio signal analysis to decode speaker gender from audio recording. Intuitively, it ...
-1
votes
1answer
31 views

Describing Function for non-symmetric Saturation Model

Let's talk about a standard saturation model: with bounds $bound_{lower}$ and $bound_{upper}$. So in this example the output $y$ will be: \begin{equation} y(u) = \begin{cases} ...
0
votes
0answers
16 views

Calculation of Heart Rate from Pulse Plethismography [on hold]

Can anyone tell me how can I calculate heart rate from the ADC data from a pulse plethismograph in Matlab?
0
votes
1answer
43 views

Matlab FFT keeps plotting mirrored values

My Matlab FFT plot keeps showing the mirrored values of my frequency of interest. In this example I am looking for 250Hz with a 3200Hz sampling freq. The FFT plots my value at 266Hz as well as 1330 ...
0
votes
1answer
37 views

Kalman Filter Estimate vs ACF Least Squares Estimate

I am currently reading Chapter 5, Applications to the Gas Markets, in Stochastic Modelling of Electricity and Related Markets by Benth, Benth and Koekebakker, World Scientific, 2008. In the ...
-1
votes
0answers
15 views

Difference between horizontal and vertical stereo vision [on hold]

Does anyone know the difference between horizontal or vertical taken photos for passiv stereo vision? Okay... the field of view is vertical aligned vertical bigger and horizontal aligned horizontal ...
0
votes
1answer
24 views

Effect of number of data segments in Periodogram-based PSD

In Welch or Bartlett method, original signal is divided into L segments, of D overlapping (D=0 in Bartlett method). Then FFT is done for each segment, and the result is the average of all segments' ...
0
votes
0answers
74 views

Get Mirrored FFT Results in Real part

Ok, I'm new to the whole Dsp thing, so sorry if the question is a lame one I'm trying to extract frequencies from a signal provided by a radio Device (Win Radio G31DDC- IFstream). The radio provides ...
0
votes
0answers
28 views

Equivalence of FFT and PSD based output based on the Frequency Response Function

Correct me please if I am wrong... I have just started working in the domain of signal processing using the Fourier Transform ($\mathbf{FFT}$) and Power Spectral Density ($\mathbf{PSD}$). I am trying ...
0
votes
2answers
38 views

Finding local brightness maximas with OpenCV

I want to find points (of a processed image) that are the brightest in their local region. Basically, I want all of the points whose 8 neighbors are all smaller but I want to have brighter maxima ...
1
vote
0answers
24 views

Interpolation methods for radar and acoustic imaging and potential pitfalls

A) What are the most common methods used to remap data for current generation imaging radars and acoustic sensors? B) What are some of the pitfalls in these methods? For example, in the past, at ...
0
votes
1answer
16 views

Is a change in colorspace needed when comparing colors only evaluated by the computer?

I am confused about the need to change color space for color comparison. I have read about delta E, the Lab format, and I do understand that comparisons in the RGB color space will not seem ...
2
votes
0answers
42 views

Designing a practical integrator

One way to describe a practical integrator ("leaky integrator") is $$ H(s) = \frac{g R}{1 + sRC} $$ I am trying to understand how to choose the values $g$, $R$ and $C$ because in practice, I will ...
0
votes
1answer
30 views

phase mod x freq mod equivalence

do any of you know how to convert a FM index to a phase mod index equivalent considering they both have the same carrier and modulator frequency? Is it even possible? This is in respect for sound ...
0
votes
1answer
42 views

Continuous speech recognition with HMM

I don't understand how this works. Help would be really appreciated. Let's say we have a 10 second sound input, we make a feature vector every 10ms - so we have 1000 vectors - $\mathbf{o}=o_1, ...
1
vote
0answers
44 views

Why is level of power spectrum dependent on FFT resolution?

I created a sinusoidal wave in some noise, and plotted the power spectrum of the signal using two periodogram estimates (welch procedure). One estimate is 'high resolution' - i.e. it uses a longer ...
0
votes
0answers
20 views

What filter should I pass to these signals to make them constant on every piece

I'm analysing the frequencies of something I'm recording (whistling), which is resulting like this (yes, it's super mario bros' beginning song: I'd like to filter it to make it remain like: in ...
-1
votes
1answer
36 views

Why does a gold sequence have $2^m + 1$ symbols while a single m-sequence has only $2^m - 1$

As explained in here: Gold sequences help generate more sequences out of a pair of m-sequences giving now many more different sequences to have multiple users. Gold sequences are based on ...

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