8 votes
Accepted

Real time numerical differentiation of signals

Your original differentiator, which should be $x(n)-x(n-1)$, is called a "first difference" differentiator. That differentiator amplifies high-frequency noise. As a next step I suggest you try what's ...
Richard Lyons's user avatar
7 votes

Filtering a digital signal online in real-time using python

Do I have to filter the whole (or at least a huge bit) of the signal every time a few new samples came in or is there a way (like the sliding DFT) where it is possible to efficiently determine the new ...
Marcus Müller's user avatar
7 votes

Can deep neural networks achieve real-time video analysis?

Nvidia seems to have published some white papers comparing DNN inference performance between high-powered CPUs and (of course) Nvidia GPUs. (one example) Ballpark seems to be that some systems can ...
hotpaw2's user avatar
  • 35.2k
5 votes

Real time numerical differentiation of signals

In a 2003 paper in French, "Estimation par maximum de vraisemblance de la dérivée d’un signal bruité. Application à la caractérisation de vérins pneumatiques" (Maximum likelihood estimation of the ...
Laurent Duval's user avatar
5 votes

Real Time Partitioned Convolution Not Working

It seems you are implementing a uniform partitioned convolution, which is not very hard to realize. You should stick to the signal flow of Fig 5.2 from Wefers p110 and the stream processing on p111. ...
ZR Han's user avatar
  • 3,183
4 votes

what is the difference between buffering and queuing?

I think that, especially in the context of real-time DSP the terms are really talking about the same topic. Perhaps the most general Wikipedia reference about buffers would include both first-in-...
robert bristow-johnson's user avatar
4 votes
Accepted

Real-time modulated IIR filter

okay, using the snipping tool, i tried to put in just the 2nd-order IIR lattice in the following drawing. $x[n]$ is being input in the upper left. now the transfer function i get for this is $$ H(z) ...
robert bristow-johnson's user avatar
4 votes
Accepted

Real Time Partitioned Convolution Not Working

In step 5 it looks like you are implementing "overlap-save" not "overlap-add". In this case you DON'T zero pad the input, but do an FFT over two full frames of the input. Overlap ...
Hilmar's user avatar
  • 42.7k
3 votes

Two real time signals convolving

Convolution is what happens when a signal passes through an LTI system. $$y(t)=x(t)\star h(t)=\int_{-\infty}^{\color{red}\infty}x(\tau)h(t-\tau)d\tau$$ The keyword in this question is real-time. The ...
msm's user avatar
  • 4,225
3 votes

Filter Design - Step Response

For linear filters, binomial filters, which can be considered as FIR approximation to Gaussians, are very simple. Their coefficients are given by: $$ h_k=\frac{ \binom{n}{k}}{2^n} \,.$$ For instance, ...
Laurent Duval's user avatar
3 votes

Play IQ data in the soundcard

I'm replying to Oleg's recent comments here in an "Another Answer" block because the "add a comment" capability prevents me from providing a complete reply to Oleg. Here's my reply: You can indeed ...
Richard Lyons's user avatar
3 votes

Play IQ data in the soundcard

If the spectrum of your I/Q samples is centered at zero then you'll have to perform either AM or FM demodulation before routing any real-valued audio samples to a sound card. For AM demodulation you'...
Richard Lyons's user avatar
3 votes

Real-time wavelet decomposition and reconstruction for ECG feature extraction

Right now, I read the live ECG data into a 5 second buffer, and then perform the wavelet filter on the buffer (as described above). This seems rather inefficient, because I have to filter the entire ...
A_A's user avatar
  • 10.6k
3 votes

Do all real-time filters introduce phase lag, or can there be such a thing as "lag-less" or "zero lag" real time filters?

If a filter has any memory and that memory affects the current output, then that past data is lagged into the present. If that filter is time invariant, then a memory of the present can potentially ...
hotpaw2's user avatar
  • 35.2k
3 votes

How to detect real time sound onsets?

My guess is that the currently popular and new and likely robust way to solve this detection problem is to feed a sequence of audio fingerprints (such as MFCCs) to an RNN machine learning algorithm ...
hotpaw2's user avatar
  • 35.2k
3 votes
Accepted

Signals in real world?especially natural signals?

Eventhough most engineering signals are continuous, not all are such. For example, statistics of many kinds provide discrete data such as daily stock market indicators, computer network stats, hourly ...
Fat32's user avatar
  • 28k
3 votes

Can discrete wavelet transform for denoising purposes be implemented in real time?

Even though I'm not much of a wavelet expert, I can answer with a definitive YES!! Now, do you have any messy details to complain about, like the size of the box, the power that it consumes, or the ...
TimWescott's user avatar
  • 11.9k
3 votes

Confusion understanding digital signal processor?

The staple processor instruction of specialized DSP processors is a multiply-accumulate instruction. The vector multiplication and summation are performed in a single command fetch, it's a sort of ...
V.V.T's user avatar
  • 1,694
3 votes

Confusion understanding digital signal processor?

Real Time means having time-limit or time-constraint to complete assigned processing. For example : If you are using a DSP processor in the receive chain of a Communication system with certain Symbol ...
DSP Rookie's user avatar
  • 2,591
3 votes

Confusion understanding digital signal processor?

DSP algorithm implementations (software coding) are easiest when your microprocessor has an FPU hardware, but it's also possible with integer (fixed-point) ALUs too. This means that your ...
Fat32's user avatar
  • 28k
3 votes
Accepted

Removing cracking in real time audio filtering

Couple of things: You really can't print to the console in a high-speed context, especially not in audio callback functions. That printing has side effects, and it's slower than you think, I promise....
Marcus Müller's user avatar
3 votes
Accepted

Wigner-Ville Distribution (WVD) vs STFT for Spectral Analysis

I preface this answer with that I know little about WVD and never worked with it, but do know time-frequency, and synchrosqueezing, which shares similarities. Part of my answer will be for SSQ. Re: ...
OverLordGoldDragon's user avatar
2 votes

IIR biquad real-time filter just output noises

It looks like you got your a and b coefficients swapped. The feedback terms: b0,b1,b2, should be tiny (around 0.00x), and a0,a1,a2 can be close to 1 or 2 in magnitude.
hotpaw2's user avatar
  • 35.2k
2 votes
Accepted

IIR biquad real-time filter just output noises

I was unable to get a stable filter using your coefficients. You did not state, but am assuming this is a lowpass filter. Using the calculator here, I got: ...
Stephen Rauch's user avatar
2 votes

Can deep neural networks achieve real-time video analysis?

Here is a newly published paper and video example: https://www.youtube.com/watch?v=w2iV8gt5cd4 http://arxiv.org/abs/1411.4389
Kon Rad's user avatar
  • 21
2 votes
Accepted

Filtering a digital signal online in real-time using python

Real-time digital auido processing under a PC platform is based on double-buffering scenarios. [Note that it may not be a perfectly real-time solution, as the general purpose PC operating systems are ...
Fat32's user avatar
  • 28k
2 votes

what is the difference between buffering and queuing?

A buffer is a storage device for storing digital data. The mental image is that of a (long) shift register with data entering at one end and exiting at the other end and indeed once upon a time, ...
Dilip Sarwate's user avatar
2 votes

Do all real-time filters introduce phase lag, or can there be such a thing as "lag-less" or "zero lag" real time filters?

Consider the frequency response of a generic LTI system, written in split magnitude-phase form: $$\begin{align} H(f) &= \Big|H(f)\Big| \, e^{j\arg\{H(f)\}} \\ \\ &= A(f) \, e^{j\phi(f)} \...
Jason R's user avatar
  • 24.5k

Only top scored, non community-wiki answers of a minimum length are eligible