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Questions tagged [c]

C is a high level (i.e. not assembler) programming language often used to program DSPs and other embedded microprocessors as well as being used for systems programming. Features of the language make it especially suitable for programming hardware and writing device drivers.

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1answer
14 views

How to use Pffft FFT library

I am interested to use the pffft library, available here: https://bitbucket.org/jpommier/pffft/src/master/ I am currently using Intel MKL library, as well as a naive optimized reference implementation....
4
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2answers
115 views

How to set parameters of the PI controller inside the PLL?

I am going to implement in C++ software the synchronous frame phase locked loop (SFPLL) for estimation of angle and frequency of the three phase grid 220V/50Hz. For the internal PI controller setting ...
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1answer
94 views

Phase locked loop for three phase grid

I have been implementing a control software where one of its core functionalities is the ability to synchronize with the three phase grid. Basically I need to implement some form of the phase locked ...
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0answers
29 views

How to replicate/simulate experiments done on dsp kit 6713 without using hardware?

Due to covid, our university is now offering online classes to under grad students, even labs are conducted online. But we are bit confused regarding evaluation? We make videos of demonstration of dsp ...
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0answers
17 views

Mic input and speaker output

I currently have written a code which takes in a raw file as input and does some audio processing and writes it to another different raw file. The way I am currently inputting is ...
1
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1answer
29 views

Matrices of complex numbers multiplication

I'm trying to implement the multiplication of two matrices something like this picture in c langage. I want to read the numbers from a text file of x and store it later in an array the code that i ...
2
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1answer
54 views

How to optimally normalize filter coefficients?

I have designed an IIR filter in Matlab that comprises the following biquads ...
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2answers
242 views

Simulating a raised cosine filter

I am rewriting a simulation written in Matlab to C. I have a problem with a transmit data. The data is filtered by a raised cosine filter. In Matlab it was implemented by using the following function ...
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0answers
29 views

filter single radio station with sdr [closed]

I want to write a program to filter a single radio station using SDR. Not for any application just a stepping stone to learn. I am going to use C so it is easier for me to see the steps and things ...
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1answer
520 views

simple iir filter implementation in C++

I am programming the simplest way of implementing and IIR filter. However, I am struggling with the use of buffers. Do any of you have any simple implementation of an IIR filter implementing manually ...
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0answers
30 views

Implementing a beamforing algorithm for radar

I want to implement Real-time Radar Beamformer algorithm in C language, and the Conventional beamforming algorithm is as follow : ...
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0answers
122 views

FIR filtering with C++ to a sinewave

I am translating my FIR filter script from python to C++. My problem is that I am following a workflow which in theory should work but I get weird results. 1st. I create a signal from 1 and 50 Hz sine ...
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0answers
30 views

How to apply an offset to a complex exponential without chopping it off?

I am trying to encode a bitstream as offset in a complex exponential, but when I do, the sinusoids get chopped off. Do I need to apply a lowpass to the bitstream or is there a more elegant way? ...
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2answers
158 views

Fast algorithm for n-dimensional DCT

I need to implement an encoder which compresses a 5-dimensional structure of 10 bits values. Each dimension has between 4 and 12 elements. If a dimension ever has more than 12 elements, it is ...
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0answers
33 views

Are there any State Space Control C libraries?

I'm searching for a C library which implements methods needed for state space control (e.g. state feedback controller and state observer equations). Googling various terms only brought up a non-C (C# ?...
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3answers
79 views

Sampling a low-frequency sound doesn't work at some sampling rates

When sampling a low-frequency sound (like a 55Hz sine wave) I hear an additional high frequency sound at certain sampling rates, but not at others. This happens in Audacity and in my own program. For ...
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0answers
73 views

Problem with natural logarithmic function in fixed point notation

I am facing a problem with natural logarithmic function in fixed-point notation. Let's say $$x = 0.54, \qquad\text{then}\qquad \ln(x) = -0.616186, \qquad\text{a negative number} \tag{1}$$ Then in ...
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0answers
28 views

Changing Coherence function from float to fixed point

I want to calculate the coherence between two audio signals. After referring a few websites, I found that the coherence is calculated by using the equation $(1)$ which is as follows $$\rm Coherence = \...
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2answers
229 views

Coding an LFO in C

I want to know how I could implement a Low Frequency Oscilator on a simple synth I've coded in C. First in order to understand how to make this happen I would like just to modulate a sine wave by a ...
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2answers
335 views

Calculating the true values of biquad filter coefficients from normalized form

I have a C code in which the IIR filter(BiQuad) uses only 4 (normalized) coefficients per stage (a2/a0,a1/a0,b2/b0,b1/b0) instead of 6 coefficients (a0,a1,a2,b0,b1,b2). I know that the value of a0 is ...
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1answer
563 views

Comparison of results with Direct form1 and Direct form2 implementation of IIR filters

The results obtained from Direct form1 and Direct form2 implementations (in C language) of IIR (BiQuad) filters are a little different. In the implementation, i have made the b0 coefficient as 1. So, ...
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1answer
53 views

Carrier frequency offset in Bell 103 FSK system

This question is a sequel of the discussion that started in this question. Dan Boschen suggested some very nice solutions to decode a Bell 103 FSK signal. I am especially interested in decoding the ...
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2answers
53 views

What's wrong with this implementation of my IIR filter?

I posted this originally in the electronics stack exchange, as it's for an electronic purpose (digitally controlled boost) but it was pointed out to me that this would be the more appropriate place - ...
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1answer
208 views

Decoding a PCM BFSK signal (Bell 103)

A recent project requires me to get into some basic DSP, in C. I receive PCM samples of a BFSK signal (Bell 103). The sample rate is 8 kHz. The mark and space frequencies are 1070 and 1270 Hz. To ...
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1answer
101 views

Calculating Cross Power Spectral density between two complex signals

I have a small misunderstanding of cross power spectral density between two complex signals. I know that it is the Fourier transform of cross correlation between two signals. Let's say the complex ...
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1answer
81 views

dB SPL readings differ from external sound level meter?

I'm trying to write a program that takes values from a MEMS microphone and calculates the dB of the incoming audio data. The microphone i'm using is this: https://www.mouser.es/datasheet/2/218/...
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1answer
87 views

FIR Filter implementation without padding

Is it possible to implement FIR filtering action without padding the input and coefficients? i.e. Let's say if the input and filter coefficients are of size 4, then the output will be 7 samples. So, ...
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1answer
93 views

FIR Filter implementation vs Linear convolution implementation

I came across a C code for the FIR filter on one of the websites. It is as follows ...
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8answers
7k views

How can I generate a sine wave with time varying frequency that is continuous, in C?

How can I generate a sine wave with time varying frequency that is continuous? How can I resolve the following problem? I want a continuous graph. I'm generating this simply like this: ...
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1answer
47 views

Given a static time domain signal, why does the magnitude oscillate in the frequency domain after FFT?

I'm trying to: Generate a sine wave in the time domain (locally within my program at 500 Hz). Analyze it with FFT Print the results in the frequency domain. The expected results are that since the ...
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1answer
60 views

Kalman filter using only location information

I have never used a Kalman filter. Is it possible to implement a Kalman filter using only location information? In addition, if you can implement it, what kind of procedure should be used to program ...
2
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0answers
218 views

How to work with portaudio?

I am working in a project to record audio and process in real-time in C.For starting, I wanted to check how it works. I downloaded the pa_stable_v190600_20161030.tgz from here. I ran ,/configure and ...
2
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0answers
214 views

Understanding and converting Matlab's coarse frequency compensation function

I am trying to understand and convert to C Matlab's coarse frequency compensator the documentation for which can be found here: Documentation Matlab's design itself is based on this IEEE paper: ...
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1answer
105 views

Translating Matlab scrambler function to C

I am trying to implement the following matlab function in c: Mathworks scrambler Function Documentation This is the code I've written: ...
2
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1answer
4k views

How to design a digital filter in python that will run over an uC?

I am trying to implement a digital filter over a uC (it doesn't really matter which filter and which micro controller because I'm looking forward to learn how to do it in the future with different ...
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2answers
114 views

Hyperbolic sine “sinh” in fixed-point?

As part of an audio peaking filter calculation, I need to implement hyperbolic sine ("sinh") function in a fixed-point arithmetic (fixed-point DSP processor). What is the proper way to do this?
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2answers
1k views

Hilbert Transform in C provides possibly strange results

I am calculating some signals that depend on the Hilbert Transform and, after following various guides online and SO, my function looks like this: ...
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1answer
632 views

How to properly filter a BPSK demodulated signal?

I am new to this field and yesterday I began a project for BPSK modulation. So this is what i did: $\ x(t) = 0 $ or$\ 1 $ binary data $\ Fs = 15 $ sampling frequency kHz $\ Fc = 10 $ carrier ...
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0answers
79 views

BPSK demodulation [duplicate]

For experimental reasons i created a function that helps me to modulate a signal using BPSK, the input signal is {1,1,0,1,0} and it works fine ...
1
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4answers
180 views

Circular buffer wrap around with chorus effect

I am developing an embedded DSP audio processor and am trying to implement a chorus effect. To my understanding, the chorus effect is multiple delayed versions of the original signal, where the delay ...
1
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1answer
7k views

What exactly is “sparse representation”? [closed]

I saw a recommended topic for the final project in my university called "dsp and dip applications using sparse representation techniques (MATLAB, C, C++)". I consider taking this topic as my final ...
1
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1answer
434 views

how can I make a simple lowpass filter with this constraints? [closed]

I'm searching for a simple low pass filter code in C with this constraints a modulable frequency cutoff (how can I convert all these crazy coefficients into a frequency?) I could change with a slider....
0
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2answers
81 views

Pitch fluctuates unexpectedly in simple sine function

I wrote a very basic C program to play a sine of a user-specified frequency. In the interest of portability, I have it spit values directly to stdout, so hopefully you can reproduce my problem on your ...
1
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1answer
88 views

Difference between filtering using Matlab and filtering using C code generated by Matlab

hi,has anyone used Matlab coder to generate C code for a filter? Here is the thing: I tried to filter the same audio signal using Hamming window-based FIR bandpass filter, the filter is designed by ...
1
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1answer
487 views

How to convert floating point code to fixed point?

I am working on converting a floating point MATLAB code into fixed point C code. The code is to be run on a DSP platform, the specifics of which are yet to be decided. I'm new to floating point to ...
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3answers
994 views

IIR Lattice Filter in C programming

I would like to implement Lattice IIR filter in c, i can't defined the value of gN, i know that x(n) = fN(n), but how to initialize gN ?. you can find the algorithm here : n
1
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1answer
49 views

Finding a change in a signal

I am looking to some C algorithm(for MCU), where I have these signals : First graph you can see that there is an event in the middle and it goes back to normal, second and third there is some event ...
2
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2answers
900 views

Trouble with fixed-point arithmetic 2nd order IIR implementation in c

DSP newcomer here! I am tinkering around with a TI DSP and am trying to implement a second order IIR filter in C. Input is 16 bit 2's complement, as is the output, the accumulator is 32 bit wide. I ...
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1answer
696 views

How can i measure soundcard latency?

I want to write sonar/radar like sample application. For sake of simplicity (and not to use Arduino and specialized RTOS) - I simply used using audio in/out analog ports of a motherboard integrated ...
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3answers
2k views

Convolution and Deconvolution in C

I understand the theoretical foundations of convolution, but now that I'm trying to program it I'm having some issues conceptually. Say I have two blocks of 64 audio samples each. I also have access ...