real-time refers to processing done with a strict set of time constraints in a deterministic manner.

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2answers
50 views

Filtering a digital signal online in real-time using python

I am currently trying to apply a bandpass filter to a signal in real-time. There are samples coming in with a constant sampling rate and i would like to calculate the corresponding bandpass filtered ...
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1answer
38 views

Computes velocity from sampled position

My system is : A step by step wheel returns its position each 150ms. I want to pilot an horizontal infinite scroll bar with the wheel. The scroll bar needs velocity as input to move. Moreover the ...
0
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0answers
20 views

Is there a way to go from a set of (F/D)FT values to FIR coefficients?

I'm not yet well educated on the DSP subject, but I've initiated a project where I will do some audio filtering. My intuition tells me that there is a link between the coefficients of a FIR filter and ...
0
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1answer
43 views

Cascaded one-pole sections and relationship to time constant

I have implemented a typical one-pole lowpass filter to smooth out some control signals. The form of the filter is: $$ y1 = x0 + b1\centerdot(y1 - x0) $$ x0 is the current input sample. y1 is the past ...
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0answers
31 views

Estimating the power consumption of an arbitrary, real-time DSP algorithm

Consider a digital signal processing algorithm that operates over a block of $L$ [samples], with a real-time constraint $\tau$ [s] (i.e. its throughput must be $L/\tau$ [samples/s]). The theoretical ...
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1answer
146 views

How do real-time convolution plugins process audio so quickly

Okay, so in Logic Pro I can load up a Space Designer plugin (convolution reverb) with an impulse that's 9.1 seconds long, turn my mic on, and get real-time convolution reverb as the mic records ...
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2answers
83 views

A 10-seconds digital reverb with very few memory (64KB)

I'm currently thinking about the design of a low-cost digital reverb guitar pedal, using a Teensy or Arduino. My goal is to achieve big 10-seconds long reverb. If I implement reverb with a mix of ...
3
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1answer
79 views

Optimal windowing strategy for filtering live signal

I have a stream of 250 samples per second arriving at a pipeline stage which looks something like this simplified example. ...
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1answer
62 views

Convolution reverb using a frequently updated frequency dependant impulse response

I am implementing a software to auralize a virtual scene but am kind of a newbie to DSP. The focus should be the calculation of the IR which is frequency dependant. But this means that the renderer of ...
0
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0answers
57 views

Audio block-processing discontinuities

I have an algorithm that looks at an audio frame, calculates a threshold in db-rms, and decides to filter the frame whether or not the threshold is crossed. However, filtering each block is producing ...
0
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0answers
20 views

reverse engineering - RT frequency estimation

I need to maintain code I inherited. The code is for RT frequency estimation. There is not a single line of comment in the code. I was hoping someone here will recognize which technique is being used ...
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1answer
87 views

Computation Costs of Filters

Is there any general knowledge regarding the costs of computation time (computation complexity) of filters? Like what types are "generally" less/more costly than others.
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1answer
60 views

In speech recognition applications, how are different voice amplitudes handled? (i.e loud vs. quiet tones)

I am doing some research related to real-time voice/hotword recognition engines. In most current implementations, input is divided into frames (overlapping or not), and audio features are extracted ...
0
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1answer
139 views

Detecting FSK near real time with c#

I try to detect some FSK signals made by audio in near real time. I know that I will get some latency. In the start I try to detect some tones of 10Khz in a duration of 75ms. That is achieved by a ...
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3answers
286 views

Pre-processing EEG signals

Good Afternoon Everybody. I am developing filters for EEG signals in these days. During the Develop I find some problems: The filter is FIR (band-pass using a convolution of low-pass filter and ...
0
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2answers
85 views

Authoritative DSP book/reference material on Psychoacoustics

I am an auto didactic Electrical Engineer currently pursuing a goal to design a custom application targeted at deeply embedded linux(think BBB or even Raspberrypi-2) type device. My DSP background is ...
0
votes
1answer
149 views

Real time fft/ifft processing

when manipulating a live stream of audio data in the frequency domain, I've heard you need to do fft / ifft in small chunks, say 256 samples at a time. I've also heard you need to somehow employ a ...
0
votes
1answer
21 views

How to accurately count the time period (hardware)?

Input : Square wave which sweeps over time domain. (about 1 MHz) Output: The time period of high/low value. Like the timer does, I would like to know the actual time (in sec) when the input goes high ...
0
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2answers
404 views

Resample an array in real-time (application: pitch-bend)

I'm working on a sampler software (that plays .WAV files, when notes are played on a MIDI keyboard). In order to implement pitch-bend feature (i.e. you have a "pitch bend wheel" on the synth and you ...
2
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1answer
85 views

Implications of $X( -j\omega ) = X^*(j\omega)$

What are the implications of: If $x(t)$ is real and $x(-t) = x^*(t)$, then $X(-j\omega) = X^*(j\omega)$ and $X(j\omega)$ is real. I am trying to understand it and I would like to research it ...
0
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2answers
153 views

Guitar Effects/Filters in real time using low cost DSP?

I have an c5502 texas low cost DSP. I can capture sound trough its P2 input and process every separated sample after sending it to the P2 output. Im trying to implement some kind of effect in the ...
0
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0answers
98 views

Reducing latency due to FFT windowing for a real-time signal

I need to compute the amplitude of a certain frequency band as the input to a PID algorithm. My system looks like this: ...
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2answers
260 views

Working with the DCT

I am having a very hard time to implement the DCT algorithm. I have quite a few requirements like it has to work with NxN matrix or at least power of 2, it has to be 2D, it has to produce same output ...
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1answer
99 views

What does “real time” signal processing mean?

I thought this was supposed to be an obvious question, until I finally set up my real time system. So basically I have a transmitter that sends 128 samples/second to a receiver. The transmitted ...
0
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1answer
716 views

Reconstructing time domain signal with Hanning window

I am currently working on a frequency domain real-time application on a digital signal processor. Currently for one time frame of my algorithm I read in time domain data into a buffer, perform a ...
3
votes
1answer
82 views

How is a realtime BiQuad/IIR possible?

I was thinking, if a realtime system is one in which the processing time is shorter than the sampling period, how does a feedback filter such as a biquad perform the computation without waiting for, ...
3
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1answer
1k views

YIN Pitch detection Algortithm ( how do I improve my results )

I am using YIN algorithm in a school project of mine which uses pitch detection on guitar sound. I when I play a note I get random frequencies at the beginning until they stabilize. I am thinking ...
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1answer
94 views

Can SIFT run in realtime?

What is the best possible runtime for extracting SIFT keypoints and Descriptors? I know it depends on #keypoints extracted. So, say for image of size 640x640, the code that I have been using requires ...
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2answers
43 views

Upper bound for realtime application

I have developped an application for image inpainting. Now I want to claim that it can be used for realtime purposes. Does somebody know a paper which gives some boundaries for realtime applications? ...
3
votes
2answers
78 views

Need to calculate $\frac{E\left[|x(n)|^4\right]}{E\left[x^2(n)\right]}$

I need to calculate $\frac{E\left[|x(n)|^4\right]}{E\left[x^2(n)\right]}$ in real time, where $x(n)$ is complex. For $E\left[|x(n)|^4\right]$ I plan to take the absolute, raise it to the power $4$ ...
0
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2answers
133 views

Audio distortion while implementing a low-pass filter

I attempted to implement a real-time audio filtering in a callback function using the simplest moving-average filter with coefficients [0.5 0.5] : ...
3
votes
1answer
161 views

Ultrasound Signal Processing Methods

I am sending 6.6Vpp square wave across a narrow-band, 40 kHz Transmitter to a narrow-band, 40 kHz Receiver. I want to find a very accurate distance between the two (sub millimeter). My assumption so ...
0
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1answer
43 views

How do I estimate the derivative of the current position, when I have only values from past to present?

If I have a discrete real-time signal $x[n]$, with its latest value $x[i]$ and all its past values $x[i-t]$, how can I estimate the derivative at $x[i]$?
0
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1answer
367 views

USB microphone & interface selection

As a part of my thesis work -in which I am using both acoustic and visual information- I am looking forward to implement a real time sound source localization sub-system. From the geometric ...
0
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0answers
817 views

Sample accurate real-time pitch shifting algorithm

I am trying to implement a phase vocoder overlap-add pitch shifting algorithm for part of a plugin I'm writing. I have done this kind of thing offline before and I understand the theory, but this is ...
2
votes
3answers
1k views

Conceptually, how does real time convolution reverb work?

I've got an impulse response of a hall, it's 10 seconds long. Now say I want to apply this reverb to a wav file of some singing. I would perform a convolution of the data in two wav files and that ...
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1answer
111 views

Basic Convolution Reverb Question

I'm surveying for feasibility techniques for a potential future project that's rather out of my past areas of expertise, and I have a fairly basic question. Of course if it looks feasible I will have ...
1
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1answer
1k views

Hilbert-Huang Transform Implementation

I am looking for a implementation of Hilbert-Huang Transformation. Ideally, in Java, but any language with similar syntax would prove useful. Could someone point me to a specific implementation, ...
0
votes
1answer
1k views

SINR calculation

I would like to calculate the total SINR of a IQ modulation system in time domain. $$ SINR = \frac{P}{N+I}$$ The blocks of the system are. Bit generation QAM modulation pulse shaper (sq root ...
2
votes
2answers
546 views

12 bit ADC to 8 bit DAC

A bit of background information: I plan to start experimenting with digital signal processing on microcontrollers. The particular microcontroller I plan to use (TI Stellaris LM4F230H5QR, from the ...
2
votes
2answers
137 views

Implement a software PID for the first time in real time software, I can find P what about I and D?

Here we have the basic formula of a Proportional Integral Derivative controller. This is the formula from the Wikipedia page on the subject I want to implement this type of controller in my system. ...
0
votes
1answer
180 views

Calculating the gain for adjusting sound level to X db

I have a sound signal, and I would like to implement a simple realtime level control (for info, I am using Pure Data, but I'd like to know about the general case). For this I thought of using the ...
3
votes
1answer
649 views

Online filter for EEG

My goal is to build a real-time filter for EEG data. The data are being recorded in 512Hz and I wish to filter it (in a real-time, from 0.5Hz to 30Hz in the most optimal way). Unfortunately I'm not ...
2
votes
1answer
103 views

A filter for for a realtime system?

Apologies if this is too basic. I need to implement a band-pass filter, for a realtime system. Not sure what to use. FIR? IIR? Something else ? Any tips would be highly appreciated.
4
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0answers
225 views

Detect human speech in realtime audio on mobile phones

I am looking to develop an Android app. As part of the functionality the app would require to randomly sample 3-5 seconds of audio and classify it as containing human speech or not. I understand that ...
2
votes
1answer
334 views

Signal Processing in Amateur Radio Astronomy

I am an amateur astronomer and I took recent interest in Radio astronomy and I am also new to Digital Signal Processing. My team is trying to build a radio telescope. I am interested in the data ...
4
votes
5answers
2k views

Computing the derivative from a set of real-time data?

So I have an array of say 25 samples and I would want to be able to note the trends of whether it's decreasing n or increasing from those 25 sample time interval(basically 25 samples array is my ...
8
votes
4answers
6k views

Most efficient way to extract frequency components of audio signal with near-human accuracy in real time

I'm trying to work out how (if possible) to extract the frequency components of an arbitrary audio sample (typically music) in an FFT-like manner, but in my research on the FFT algorithm, I'm learning ...
10
votes
3answers
979 views

How to detect “fast” changes in signal processing

I'm working on a project where we measure the solderability of components. The measured signal is noisy. We need to process the signal in real time so that we are able to recognize the change that ...
3
votes
1answer
92 views

Characterizing real-time sampled signal

I have a signal which is sampled in real-time. At every time interval I receive a value. I need to characterize this signal as active or inactive (to take priority in the control actions). By active ...