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Questions tagged [octave]

An octave is the interval between one musical pitch and another with half or double its frequency.

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1/3 octave analysis and convert dB/Hz to m/s^2 / Hz

I am new to this type of analysis.I have Labview with addon Sound and Vibration and have stuck with my program. I have uff file with vibration data. In this file I have data in m/s^2(t) units. And i ...
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60 views

Practical implementation of IIR/biquad filters following non-textbook transfer function of real-wold analog filter

I am trying to program a DSP filter to study prototypes of loudspeaker filters, which will be implemented as passive analog circuits in the final speaker system. This process involves simulation of ...
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1answer
60 views

Octave - freqz strange results

I wrote octave code to find transmittance based on zeros and poles: ...
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24 views

Octave filtfilt converted to R code

R has a function called filtfilt that performs zero-phase digital filtering by processing the input data in both the forward and reverse directions. But it suffers from having steep transition bands....
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39 views

Smoothing of Log Data Plots in Octave

I have some frequency based data that I'm plotting with Octave's semilogx that looks like this: The amplitude of peaks does not increase with frequency over the linear scale. But with a log scale, ...
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1answer
56 views

Problem with 1st order Massberg LPF [duplicate]

I'm trying to implement this filter in title by following the book "Designing Audio Effect Plug-Ins in C++" By Will Pirkle Problem I'm facing is the magnitude response error when comparing against ...
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104 views

Issue with the Massberg Analog-Matched Low Pass Filter

Implemented the filter mentioned in title using Octave and couple sources Vicanek and Zeitlin (LPF.cpp). Got filter working otherwise but, ... when tested the responses against 'analog model' of the ...
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344 views

Cocktail Party Problem — audio source separation

I am trying to solve the Cocktail Party Problem. I am trying to separate these two mixed audio files: mixed 1 [WAV] mixed 2 [WAV] into 2 separate audio files that contain the 2 original sources, ...
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51 views

Comparing Octave/Matlab FFT results against CPU FFT

I wrote a program which runs FFT from Intel MKL and am trying to compare its results with that of Octave, but things don't quite match. The program does: Populates a 1D array of, say, 1024 elements, ...
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152 views

SNR from noise and 0dB reference only

I'm using the following Octave script: ...
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1answer
327 views

Create a third octave spectrum from a time signal

I have to create a third-octave spectrum from a time signal on Octave GNU. I found some code on the net to help me but I don't have all the parts of the algorithm. I have a .csv file which contains ...
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1answer
97 views

How to prevent Octave Jumping in ACF of Speech Signal?

I'm working with speech signals and my aim is to estimate the fundamental frequency $\ F_0$ of this signal often called as "pitch". The main idea is taking small blocks of the speech signal such ...
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1answer
62 views

Octaves vs Decades Fractions

At this USGS very good site about rms noise in sensors, a phrase regarding third octave bands (the original topic) appeared. The figure displays the minimum vertical seismic noise directly as rms ...
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1answer
312 views

different solutions in matlab / octave using dft and fft

i am new here in dsp.stackexchange and I am trying to do my first basic steps with fourier-transformation. Some years ago I learned the basic theory in university and also developed a fft ...
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2answers
1k views

Calculating 1/3 Octave Spectrum from FFT / DFT

I am not often on this forum and I am not an expert on the subject. I struggle with the theory of FFT / DFT and the 1/3 octave spectrum. Assume I have a DFT analysis of a given signal. It (the DFT ...
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2answers
116 views

How to make bode plot when output signal changes amplitude?

When I do frequency analysis on my feedback controlled system and the controller is really tightly tuned, I get a frequency response that looks like this: Blue is excitation signal and green is ...
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807 views

How to find out z-transform in Octave?

How can I find out z-transform and inverse z-transform in GNU Octave? I didn't saw any built-in functions like ztrans, iztrans as seen in MATLAB. But I saw a built-in function czt(chirp z-transform)in ...
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1answer
90 views

AM modulated signal not centered at carrier frequency [closed]

I am trying to modulate the signal bl_msg_time (this is a speech signal) using DSB-SC modulation however the signal doesn't appear centered at the carrier frequency....
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1answer
170 views

1st order filter output

Two 1st order filters : ...
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1answer
145 views

wavwrite with 32 bits per sample seems to overflow?

I am trying to generate a 32bit PCM wav file with octave, the file shall contain a single full-scale sample (0db impulse). I am getting the expected result when using 24 bits per sample: ...
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1answer
685 views

How to create a swept / chirp signal between a given starting audio signal and a given ending audio signal

I can create a swept / chirp signal using matlab / octave with the code below (also see spectrum taken). But how can I create a swept / chirp signal between a given starting audio signal and a given ...
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1answer
101 views

Least squares FIR for type II

Following this paper (see the Matlab example at the end), I am trying to make a least-squares algorithm in Octave, but for type II (I know about firls). For type I ...
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1answer
118 views

Why do Octave and MATLAB both automatically shift the gray values in this image?

Edit: I found this other question that actually addressed a separate but possibly related problem I was experiencing. However, in the below case the image is in ...
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3answers
2k views

Impulse response to frequency response in octave

Having an impulse response of an audio system recorded as a wav file, how to calculate the frequency response of the system with octave?
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1answer
256 views

Digital Camera Spectroscopy?

Would it be possible to use a conventional Canon DSLR camera to do some kind of vaguely meaningful spectrum analysis with GNU Octave? My niece needs to do a biology science project for school so I ...
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231 views

Image Stitching using Octave

Assume you have an A3 size white sheet. It is divided into 10 sections with different amount of overlapping. So this image has no edges or corners to detect. So what would be the best approach to ...
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1answer
217 views

Testing filter code w/ Octave

I want to test some code generated by this site. I selected Bessel LP 1st sample rate $600\textrm{ Hz}$ corner $8\textrm{ Hz}$ long $10\textrm{ bit}$. If I adjust the code for octave to be: ...
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1answer
46 views

Smoothed image produces contour-like ripples, yet it disappears in saved image?

I smoothed a grayscale image using a size 10 gaussian filter and display it in Octave (imshow) which resulted in ripples which appears to be contours for image intensity. Yet if I save the image (...
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1answer
305 views

How can I read PCM linear file in Octave? [closed]

I have a pcm linear file (16 bits) collected with a sampling rate 8000 Hz. I want to read the file in octave. Whenever I read it using: ...
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442 views

Method for determining IIR filter stability

I have a function which takes some parameters for notch filters (gain, centre frequency, Q) and returns coefficients for a high-order IIR filter equivalent to placing the notch filters in series. It ...
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3answers
2k views

3dB and 6dB Per Octave Rolloff Digital Filters / Generating Pink and Brown Noise

So I would like to have a design method for filters with 3dB and 6dB per octave roll off -- for generating pink and brown noise respectively. I know the following 'pinking' filters exist: Filter to ...
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1answer
132 views

Looking for a better algorithm for finding the slope of an input signal

I've got an input signal that while sloping up, approximately bounces off an imaginary line. I'm looking for the equation to that imaginary line. I have a method, but is very brute force and it ...
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1answer
692 views

Averaging Different Length Speech Signal

I have around 10 wav audio files all containing same word spoken i.e. 'Hello' but all having different length. So lets say 1st file when loaded consist of 20000 samples, 2nd of 15000, 3rd of 18000 ...
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0answers
3k views

Verifying MFCC Final Result

I have created a Octave code for MFCC calculation for speech recognition, which takes a wav file as input and then gives the MFCC as the output. But the final results are a bit confusing, so I am ...
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1answer
555 views

Denoise Image with Gaussian Noise Using MATLAB / Octave

I want to remove a noise for an image using MATLAB, when the observed image is $$f=u+v$$ where $u$ is the restored image (is the image i want recovered) and $v$ is the gaussian noise. To restore $u$,...
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2answers
3k views

Is this code for doing a moving average correct?

Is this code for doing a moving average correct? y=conv(x, ones(1,100)/100); I want to filter my speech signal with moving average filter in code. I think that ...
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1answer
4k views

Noise removal from audio using FFT/Spectral editing

I have a noisy recording with some letters spoken out loud. I've noticed that the noise is easily recognizable when looking at a spectrogram of the audio. Is there anyway to set a power/frequency ...
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1answer
1k views

Calculating Affine Transformation matrix from 4 corner points

I'm trying to develop a sudoku solver, using image processing, ocr with neural networks and such. I've got the bare solver working, I can successfully interpret numbers and letters from a picture. All ...
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1answer
622 views

Measuring frequency response range of piezoelectric disc

How can I measure the frequency response range of a piezoelectric disc below. I don't have an oscilloscope but I do know how to program in matlab / octave I was thinking of creating a swept signal in ...
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1answer
6k views

How to plot the Hilbert Spectrum in Hilbert-Huang transform?

I'm working on integral transforms for a science initiation project and i got to do a work on the Hilbert-Huang transform. I've seen on the internet that, after one found the IMFs with the EMD method,...
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1answer
2k views

How to convert Third Octave data into single SPL quantity

I have a data vector which consists of calibrated pressure at each sampled point in time. I have also taken this signal, applied a filter bank to it using a butterworth filter with passbands according ...
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1answer
202 views

Is there two Types of Scale Space in SURF algorithm?

I couldn't figure out below paragraph on SURF paper and hope that someone can help me to understand it. Bay H., Ess A., Tuytelaars T. Van Gool L. - Speed-Up Robust Features (SURF), page 4, ...
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2answers
987 views

Compensate for phase shift of Hilbert transform

I'm using Octave and trying to use the "instfreq" function from the time frequency toolbox which requires an analytic signal input. To get this analytic signal I'm using the Octave function "hilbert" ...
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2answers
620 views

OCR (optical character recognition) for Indian languages - segmentation

Can any one help me in how to extract a table from the whole document image and segment it? I have done segmentation for the document image which has only text by using the projection profile. So ...
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1answer
1k views

How to get spectrum of an image?

I have an image : img = imread('pic.jpg'); Now, How can I get spectrum of that image?
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1answer
1k views

Obtaining beat histogram using Tzanetakis algorithm

I am working to make a music player with automatic genre classification application in Java. On Google searches I mostly found the works of George Tzanetakis who describe an algorithm from Music Genre ...
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1answer
90 views

adjusting swept signal equation

When I do a spectrogram in matlab / octave I can create a swept signal that looks like the RED plot line below. But how can I create a swept signal like the BLUE line in the 1st plot using the ...
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1answer
2k views

Exponential decaying Swept / chirp signal [closed]

I'm trying to create a chirp/swept signal that has it's frequency going down exponentially using matlab/octave. I can't use the built in chirp function because I'm trying to create a chirp/swept ...
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2answers
1k views

Is imadjust a Matlab-only library? If so, can it be replaced?

I want to apply a homomorphic process to an image, and one of the steps involves the imadjust function. The source of this code is http://www.csse.uwa.edu.au/~pk/...
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2answers
712 views

Equivalence of convolution through polynomial and matrix products

I am trying to understand the equivalence of convolution through polynomial (coefficient) multiplication, Fast Fourier Transforms, and matrix multiplication. I am using octave with the octave-signal ...