Questions related to implementation of various algorithms under software environments and programming languages.

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Well-regarded C/C++ General-purpose DSP libraries

I am looking to transition some of my MATLAB algorithms to C/C++ for deployment on target (PowerPC and/or ARM). Mostly 1D FIR/IIR filter in this instance. In other domains, there are well-regarded ...
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0answers
23 views

Motion Blur Filter

I want to implement Motion Blur Filter in C# using Emgu CV, what is the correct way to do this in fourier domain. I am currently stuck at how to perform multiply of Motion Blur filter and my Complex ...
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0answers
38 views

2D FFT vs 2 Pass 1D FTT

We know that the 2D FFT can be performed by taking the FT along the rows and then taking the FT along the columns. I'm wondering how theoretical performance compares to the direct 2D FT case, which ...
0
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1answer
41 views

Wav file scale factor

I seek a scaled audio file format for my dsp output. I'd like to produce "scaled wav files", when I've done my pre processing. Eg. if the amplitude is 15.5 (of whatever unit), you should be able to ...
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0answers
38 views

Python implementation of multidimensional power spectral density with Welch method

I have done my best to write Welch method implementation for python for multidimensional time series and still in the case of one dimensional time series I am getting inconsistent response compared to ...
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0answers
36 views

Python module request: Spectral density estimation for multivariate time series

I have worked with scipy.signal.welch and spectrum.pptm to calculate power spectral density with Welch and Multitaper methods. However as far as I can see these functions are meant for one dimensional ...
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0answers
60 views

Implementation of the constant Q transform + property questions

I'm reading up on fourier theory, especially the transforms. I implement the math as spectrograms in C++ to get a better understanding of what is going on. I've made an implementation of the short ...
0
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1answer
70 views

Design and implementation of causal band-pass filter for biosignals - what to consider? [closed]

I currently work in a project of clinical software (C#) which deals with clinical biosignals, specifically EMG and other low-frequency signals (load-cells, goniometers, and other biomechanical ...
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0answers
29 views

Comparing two signal outputs from two clients on a networked computer game to identify lag

Basically, I'm running a server and two clients of the Unreal Engine and trying to figure out if there is lag in player movement on one of the clients (the clients are different in way that's not ...
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2answers
66 views

What do cloud-based speech-to-text services upload to the cloud?

Services like Siri and Google Now perform speech recognition (speech-to-text) on mobile phones by doing part of the computation on a server in the cloud. What do they upload to the cloud? Do they ...
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0answers
98 views

IIR filter SOS and Direct Forms doubt

I have below doubts, so confusing! As I don't want to assume from what I read, I am asking for help here! Are Second Order Sections another name for biQuads ? If I have 2 single pole transfer ...
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0answers
34 views

Sample rate synchronization [closed]

I'm currently working on a digital audio OFDM project and found that even if I explicitly specified the same sample rate (11025 Hz), the transmitter and receiver still differ slightly in it(lesser ...
2
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2answers
243 views

Using Total Variation Denoising to clean accelerometer data

I know this is maybe a very basic question but I am doing this as a hobby and I can't find a solution to this problem. Basically I am trying to remove some noise from data I am reading from an ...
0
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1answer
116 views

How is the MATLAB filter function so fast?

How is the filter function implemented in MATLAB? How is it so fast? What's the fastest implementation of a FIR filter?
2
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1answer
98 views

Software-based sound card OFDM

I'm trying to implement an sound card-based OFDM modem. A paper says: ...A serial to parallel converter is applied and the IFFT operation is performed on the parallel complex data. Say I have ...
3
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1answer
63 views

OFDM DA conversion problem

I'm working on a sound card based OFDM system and ran into some problems: How can I perform DAC on the real and imaginary parts of the IFFT? I think they are real numbers instead of 0 and 1. ...
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0answers
56 views

Use of USRP SDR to process sonar?

I have ordered a USRP kit to do radio signal processing in software. Is there a way to use the same device to process sonar data? What would I do upconvert the sonar to 50 Mhz?
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1answer
106 views

Modeling Load Modulation

I'm trying to create a simple NFC/RFID software simulator and am having a hard time understanding the math fully. I know that NFC tags respond by load modulating the 13.56 MHz wave that the reader is ...
1
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1answer
267 views

How would sigma-delta modulation work in software?

I've recently come across this YouTube video that shows a PCM stream being played back via the 1-bit internal "PC Speaker", and after hours of googling I've come to think this is done via Sigma-Delta ...
0
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1answer
79 views

Is my accelerometer precise enough?

I have a device with an accelerometer and I want to make it as precise as possible (using algorithms). Currently no DSP algorithm is running - I am reading values as they are. I've made 3 tests - in ...
2
votes
3answers
127 views

What is the most computationally efficient way to generate 100 sine waves layered on top of each other?

Right now I simply do this (pseudocode) for freq in freqs: for i in len(samples): samples[i] += sin(...) Is there a better way? This is for ...
1
vote
1answer
749 views

What is the most efficient type of software bandpass filter?

I'm writing a C++ application to extract four modulated carrier signals at four separate frequencies, from a single input signal. I've designed four FIR filters at t-filter.appspot.com but they run ...
1
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1answer
194 views

Amplitude calculation

I've got an array of different values representing the y-values in a plot: ...
4
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1answer
479 views

How does filter bank work in image processing?

I read a paper about directional filter bank in image processing and I don't understand clearly about the process. It says they use '2-band structure' like this image: could someone here please ...
4
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2answers
258 views

Qualitative Evaluation of Interest-Point-Detectors and Descriptors in Computer Vision

I'm writing on a qualitative evaluation study of interest-point-detectors and descriptors. I've read all Mikolajczyk papers as well as most of the surves from Datta et al. etc. Now I'm implementing an ...
7
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5answers
1k views

When to consider double (64 bit) floating point for Audio

When synthesizing and processing audio on modern processors, when would one consider using something other than single precision (32 bit) floating point? Obviously, the audio coming in and going out ...
7
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1answer
206 views

Convolution involving turning each pixel value to the most represented pixel value of the neighbourhood

In order to correct gradual changes of intensities in the background of grey-scales images, I have been blurring them and then subtracting the original images from the convolved one. In some cases, I ...
4
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1answer
3k views

How do I implement the Structure tensor (in Matlab)?

I am trying to figure out the details on how to implement the structure tensor in Matlab and need some advice! For an image $\ I(x,y) $ the structure tensor S is given by: $$ S=\begin{pmatrix} W ...
4
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2answers
340 views

Is it possible to transmit and/or receive multiple types of signals at the same time?

Using an inexpensive SDR (such as the USRP or Per Vices Phi), I want to process two or more communication protocols at the same time (e.g. WiFi and GSM). Is it possible to Tx (or Rx) both at the same ...
3
votes
3answers
775 views

Demodulation of a BFSK frequency hopping signal using FFT

I am not very familiar with DSP techniques, and I am currently working on my research project to develop the firmware of a DSP processor, using C/Linux. It involves the modulation and demodulation of ...
3
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0answers
208 views

What is EAQUAL ? How does it relate to PEAQ?

This wiki post on wiki.hydrogenaudio.org says that it is very similar to PEAQ and also a part of ITU-R BS.1387 recommendation ? How reliable it is for determining audio quality. Are there any other ...
4
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1answer
829 views

Why can Quadrature Demodulation demod a Frequency Modulated Signal?

I use a Quadrature Demodulator in my SDR application, which is defined as: $\angle (S_n, S_{n+1})=arctan(S_{n+1}*\overline{S_{n}})$ So practically its amplitude is the angle between two Samples ...
5
votes
3answers
2k views

Help with equations for exponential ADSR envelope

With application code, I have implemented a linear ADSR envelope for shaping the amplitude of an oscillator's output. The parameters for attack, decay and release duration as well as sustain level ...
8
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1answer
934 views

Tutorial on 2nd generation wavelets (with lifting)?

For some denoising and deconvolution experiments, I'd like to apply a 2nd generation wavelet transform (using lifting steps) to images. I know that there are several implementations available, but ...
5
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1answer
322 views

Help with algorithm for modulating oscillator pitch using LFO

I am developing a software emulation of an analog synthesizer. I am trying to modulate the pitch of an oscillator using an LFO. For each sample fed to the computer's sound system, I am calculating ...
5
votes
2answers
769 views

How can I break a filter down into second order sections?

This is a follow-up question of How do I apply a Chebishev filter? I designed a filter in Scipy: ...
1
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1answer
158 views

How to calculate the gain in a bivariate fft in R?

In Statistica gain is defined as follows: Gain. The gain value is computed by dividing the cross-amplitude value by the spectrum density estimates for one of the two series in the analysis. ...
6
votes
2answers
425 views

How do I apply a Chebishev filter?

I read a paper about a brain-computer interface. In this paper the authors reported "each signal has been filtered with an 8-order band-pass Chebishev Type I filter which cut-off frequencies are 0.1 ...
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2answers
1k views

how to extract features from this image ? what are the suitable features to be selected?

I have this image: After many preprocessing operations, I obtained this image my goal is implementing one to many matching on my images for recognition purpose,i have 250 image for 50 persons (5 ...
10
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3answers
2k views

“Low-pass filter” in non-EE, software API contexts

I am an experienced software engineer and am working on smartphone sensors. I've taken fundamental EE classes in DSP and am trying to apply my knowledge. I believe that I understand convolution, ...
9
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1answer
1k views

System identification packages

I've been hunting around for an alternative to Matlab's System Identification Toolbox, but the commonality of the terms "system" and "identification" are confounding the search. Are there any ...
4
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2answers
3k views

How does MATLAB handle IIR filters?

MATLAB has a butter, which constructs a Butterworth filter given an order and relative cutoff frequency. The filter created can be used to ...
12
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1answer
781 views

Removing Glare from Image

Disclaimer: I am in NO way engaged in signal processing. Just very curious... Ny question is, very simply: is it possible to apply software processing to an image to remove or reduce headlight ...
10
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3answers
1k views

How to implement a digital oscillator?

I have a floating-point digital signal processing system that operates at a fixed sample rate of $f_s = 32768$ samples per second implemented using an x86-64 processor. Assuming that the DSP system ...
13
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6answers
2k views

Where can I get an open source implementation of the Parks-McClellan optimal FIR filter design algorithm?

Background: Often times I am doing some sort of signal processing task that requires a unique filter. Usually at this point I go to Matlab and generate a new unique filter using firpm(). The Matlab ...
13
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2answers
1k views

Are there any standard implementation forms for tunable Butterworth filters?

One of the standard ways to implement a Butterworth filter is with a cascade of second-order sections, each corresponding to a pair of complex-conjugate poles. For a fourth-order filter, for example, ...