# Questions tagged [octave]

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

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### What is the sos simplification that octave does?

I am comparing sos (cascaded 2nd order IIR) coefficients from my own implementation of a textbook method versus the coefficients that octave generates. Here is an snip of the octave code: ...
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### problems changing SSB Modulation frequency on Octave

i'm trying to implement SSB Modulation on Octave. i based my code on this: https://www.mathworks.com/help/signal/ug/single-sideband-modulation-via-the-hilbert-transform.html it works ok, until i ...
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### FM0 (bi-phase space) decoder

I'm looking for the solution for decoding FM0 (bi-phase space) encoded signal from RFID tag. Response from the tag starts with preamble and then followed by 16 bit random number. Link rate is 40kHz. ...
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### Octave specgram: How do I plot negative frequencies

I have a complex signal and I'm trying to use Octave to plot a spectrogram. I found the specgram function, and it's close to what I want, but I can't figure out how to get it to display negative ...
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### How can I convert a 1/3rd octave spectrum into a linear spectrum for use as a frequency response?

I have a one-third octave spectrum with 23 frequencies, and I want to use it as a frequency response to filter another spectrum, however that spectrum is specified linear with 2049 points. I know I ...
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I have an audio signal $g(t)$ composed by the sum of my original signal $f(t)$ and a delayed copy of itself: $$g(t)=f(t)+f(t+\varepsilon)$$ My goal is to recover the original signal $f(t)$ knowing: $... • 103 1 vote 1 answer 141 views ### Peak locations in Hz with findpeaks() (log spaced bins) I have resolved peak locations using Octave findpeaks command: ... • 917 1 vote 1 answer 154 views ### Filter IIR, 1/3 Octave Corner with 2 Octave BW I'm trying to design a new filter with IIR to filter out specific bands. Basically it's a bandpass filter with 2 Octave or 3 Octave bandwidth but the filter order should be equal to 1/3 Octave filter. ... 1 vote 0 answers 417 views ### How to plot the STFT of a .wav file in GNU Octave? I'm quite new to signal processing and am trying to find the short time fourier transform of an audio sample and plot it (I believe the best way is as a spectogram?) using Octave (similar to this ... 3 votes 1 answer 428 views ### How to obtain filtered impulse response from frequency response? I am trying to find the reverberation time of a room using the Schroeder method (i.e., Reverse-time integration method). Therefore, impulse responses should be measured first. There are many ways to ... • 61 0 votes 0 answers 58 views ### What is the dominant frequency of recurring symbols spaced in time by X samples using an FFT? I'm not an expert so I'm not sure if this has a name associated with this phenomenon or not, so I'm not sure what to search for; Perhaps this can be answered by pointing to some literature which I am ... • 121 1 vote 1 answer 151 views ### How to remove the unknown intervention from the signal (Octave)? we have a signal recording and there are always interventions, I think it is not a noise, since it is not continuous but occurs in intervals, with 25 Hz (please see below). It is not affected by the ... • 11 1 vote 2 answers 552 views ### How to calculate frequency of a periodic signal? I know there are similar topics but I can not find any solution in my situation. I have an accelerometer sensor and a basic microcontroller. Accelerometer data is collected in an array via i2C. I want ... • 21 2 votes 1 answer 103 views ### Combining two wave generation formulas does not work as expected (MATLAB/OCTAVE) I'm trying to convert sawtooth wave calculation formula to Octave/Matlab language. Here are the original formulas. My Desmos take is here. I've got formulas for triangle wave and square wave working ... • 917 0 votes 1 answer 32 views ### Indian Space Research Organization - Extent of spectral spread 1/3rd Octave Analysis [closed] I am a scientist at Indian Space Research Organization (ISRO) and will be representing my team. We work on Telemetry and Data Handling units for our Launch Vehicles. We are preparing for our upcoming ... -1 votes 1 answer 91 views ### Visualise/compare numpy arrays from Matlab/Octave to matplotlib I'm new to python and matplotlib, and I'd like to visualise / compare 3 mfcc files stored as numpy arrays in txt format. I have the Octave code below, and I'd like to know how it can be done using ... 1 vote 1 answer 125 views ### Output of IIR filter not matching the frequency response - Proximity to fs/4 After not having dealt with digital filters for a long time, I have now been playing around with filter design in octave and I am observing a behavior which I do not understand. After designing a low-... 1 vote 0 answers 2k views ### Alternative function for MatLab iztrans to Octave? I am trying to compute the reverse Z transform on Ocatve and I get the following error: error: 'iztrans' undefined near line 1, column 1 The code I am running is ... • 125 2 votes 2 answers 1k views ### Autocorrelation and Spectrum Density Wiener–Khinchin theorem states that autocorrelation function and power spectral density are a Fourier-transform pair - see Wikipidia (and lots of other resources). That means autocorrelation should be ... • 155 0 votes 1 answer 669 views ### Speech recognition algorithm in GNU Octave to convert speech to text (and vice versa) Recently, I am building an application in Octave and I saw some algorithms about speech recognition spread around the net, but most of them were implemented in Python, MATLAB, C++ and no one in Octave.... 1 vote 2 answers 262 views ### How to use Octave ellip() coefficients for 3-band C++ crossover I have been working on making a 3-band audio crossover in C++, with the goal of activating/deactivating a different device depending on whether the low, mid, or high range of the input is above a ... 0 votes 0 answers 288 views ### Normalize two or more sound signals in order to let them with the same duration time and amplitude I am very new in signal processing area and I am trying to solve the task in order to make an experiment with audio files from different languages, so, I am trying to let some ogg audio files with the ... 1 vote 0 answers 103 views ### Octave demodmap function - simple assist I'm a beginner with Octave. I'm trying to de-modulate a simple FSK file (wav file of alternating 2KHz and 4KHz tones at 500 bits per second, into an array of 1s and 0s. I read the documentation for ... • 13 2 votes 1 answer 348 views ### How do I create a polar plot from a multi-channel sound file? I have a multi-channel sound file from a microphone array. I want to get the polar plot in Matlab in order to get the directivity patter of the sound source. How do I do this? I did the FFT on the ... • 21 0 votes 1 answer 196 views ### What is the unit for power spectrum of acceleration signals in log scale I have a signal recorded by an accelerometer in m/s^2. It is basically accelerations over a period of time. I have calculated the power spectrum of the signal over in a certain frequency band and then ... • 103 1 vote 1 answer 320 views ### Frequency response of FM modulation/demodulation chain with phase derivative demodulation Frequency modulating a carrier by white noise and then demodulating the complex signal using discrete derivative of phase it appears that the discriminator is acting as a low-pass filter. How do I ... • 237 1 vote 2 answers 1k views ### IQ signal FM descrimination using phase derivative I'm trying to demodulate an FM signal recorded as IQ samples from RTL-SDR at 2.4Msps with RTL-SDR centered on an FM station's frequency. So the input signal is 8 bit IQ baseband at 2.4MSps. The data ... • 237 0 votes 2 answers 360 views ### FFT error when number of samples growth - Matlab/octave I see when I increase number of samples, the imaginary error part of the FFT growth due to the error of sin(n*pi)!=0 where n is the index of the sample in Matlab or octave. Is there anyway to force ... 0 votes 1 answer 557 views ### Alternate Octave Commands for Matlab can you tell me how to write video data to file.. what is the alternate of these 4 commands in octave ... 0 votes 1 answer 67 views ### Basic question regarding third octave filters I would like to use third octave filters on a time signal. Do I have to apply all third octave filters to a single frequency or do I only need to apply the one that has its center frequency the ... • 11 2 votes 0 answers 405 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 ... • 121 1 vote 1 answer 509 views ### Octave - freqz strange results I wrote octave code to find transmittance based on zeros and poles: ... • 13 2 votes 0 answers 253 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.... 1 vote 0 answers 164 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, ... • 165 1 vote 1 answer 97 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 ... • 917 1 vote 0 answers 253 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 ... • 917 1 vote 0 answers 2k 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, ... • 19 1 vote 1 answer 1k 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 ... 3 votes 2 answers 597 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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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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### 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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### 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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### 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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### 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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### 1st order filter output

Two 1st order filters : ...
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### 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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### 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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### 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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### 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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