Hi there! I'm working on Pulse compression for radar signal using FFT, the echo is N points, and the length of match filter is also N points, then...

Hi there! I'm working on Pulse compression for radar signal using FFT, the echo is N points, and the length of match filter is also N points, then I use N points FFT to calculate the pulse compression result, it seems that I can indeed get the right result. I just get a little confused, since two N-points signals for linear convolution needs L(L> =2N-1) points FFT to get the right thing. Is there

Looking for a succinct example showing convolution processing (in the time domain) is notoriously computationally intensive; e.g., the...

Looking for a succinct example showing convolution processing (in the time domain) is notoriously computationally intensive; e.g., the typical reverberation time of a room is approximately 0.3 seconds which corresponds to 2400 samples, i.e., taps (filter coefficients), for an 8 kHz sampled sound. Because the sound is sampled at 8 kHz, the "delay steps" are each of length 1/8000 (0.000125 seconds)...

Hello I am new to this forum so at first I want to say hello to everyone :) I am trying to make a fast fft convolution (FFT_Blocksize=1024...

Hello I am new to this forum so at first I want to say hello to everyone :) I am trying to make a fast fft convolution (FFT_Blocksize=1024 samples) of an headpone related impulse response (L=512 samples) with an sine wave audio signal. Here you can see the plots of the time Signals: impulse response: http://fs2.directupload.net/images/150617/fc9j6cs7.png audio signal block: http://fs1....

Hi, I have a (for simplicity brickwall) bandlimited white Gaussian noise signal x[n]. Hence I know roughly its PSD. I would like to get an...

Hi, I have a (for simplicity brickwall) bandlimited white Gaussian noise signal x[n]. Hence I know roughly its PSD. I would like to get an estimate of ||x^3[n]||/||x[n]||^3 (||.|| l2-Norm of the discrete time signal x[n]). My idea was now to go to frequency domain (Parseval) and obtain the PSD of x^3[n] via 2-fold convolution of X[k]. If I would just approximate the PSD of x[n] as ...

Hi, I have a pretty trivial issue: I want to convolve a shifted rect function with an exponential: h(t) = 2pi/K e^(-2pi/K t) p(t) =...

Hi, I have a pretty trivial issue: I want to convolve a shifted rect function with an exponential: h(t) = 2pi/K e^(-2pi/K t) p(t) = rect(t-1/2) g(t) = (h*p)(t) When I do the convolution with a discrete-time approximation numerically in MATLAB (either conv or cconv) I get the blue line: http://snag.gy/ZOhp5.jpg When do the convolution analytically, I get g(t) = e^(-2pi/K (t-...

You know the problems you get at college - convolving a pulse with another pulse or a pulse with a triangular pulse etc. Loads and loads of such...

You know the problems you get at college - convolving a pulse with another pulse or a pulse with a triangular pulse etc. Loads and loads of such examples, many of them start with negative time (ie pulses go from -1 to +1 !). But although convolution as a classical method can be used for solving ODE's what practical use is it? I am not talking about digital or discrete-time convolut

Could anyone please explain how Cyclic Prefix in OFDM system converts linear convolution to the circular convolution? Thanks in advance! ...

Could anyone please explain how Cyclic Prefix in OFDM system converts linear convolution to the circular convolution? Thanks in advance! _____________________________ Posted through www.DSPRelated.com

Hi all, I want to implement a convolution with timing offset in Matlab. My continuous signal equation is: r(t) = sum over k of...

Hi all, I want to implement a convolution with timing offset in Matlab. My continuous signal equation is: r(t) = sum over k of (a(k)*h(t-k*T-k*0.1*T)), where a(k)'s are a stream of bits, h is the pulse shape, and T is the symbol period. My sampled h is [1 4 6 4 1]. Could you please guide me how to do this? Thanks, Elnaz

i am currently implementing the 'Undecimated Wavelet Transform' with the 'a trous' algorithm. See...

i am currently implementing the 'Undecimated Wavelet Transform' with the 'a trous' algorithm. See e.g. http://www.znu.ac.ir/data/members/fazli_saeid/DIP/Paper/ISSUE2/04060954_2.pdf, section II-A. As far as I understand, the implementation (in 1D) for the 'decomposition' and 'reconstruction' phase is very simple, it boils down to the convolution with a low-pass and high-pass filter (where for le...

I have implemented the basic overlap-add convolution using a standard complex FFT routine. This has lots of zeroes, first from padding data and...

I have implemented the basic overlap-add convolution using a standard complex FFT routine. This has lots of zeroes, first from padding data and IR (impulse response) to FFT size, then I have to copy data and IR to complex numbers (with zero imaginary part). Now I tried instead to replace the complex FFT routine with a real-valued FFT so I can skip copying all data and IR to complex numbers. ...

I want to write a Matlab code to convolve the two signals: x=[1 2 3 4]; y=[1 -1 3]. I want to do it through circular convolution. Please kindly...

I want to write a Matlab code to convolve the two signals: x=[1 2 3 4]; y=[1 -1 3]. I want to do it through circular convolution. Please kindly any body could help in guiding how to generate the code which should be in generic form that could be used for all signals. Thank you

Hi there. I'm going to implement circular convolution with zero latency, however here I'll simplify it to say 1024 points latency, because I need...

Hi there. I'm going to implement circular convolution with zero latency, however here I'll simplify it to say 1024 points latency, because I need to understand where is the problem. So let's say we have an extremely long kernel, like 1000 * 1024 points. Now this is the input: i1 i2 i3 .. i1000 (each 1024 points long). And this is the kernel: k1 k2 k3 .. k1000 (each 1024 points long). To...

Hi, I'm using FFT convolution for smoothing. Basically FFT kernel is exp(-x^2) and the signal is something positive. All of it is done in a...

Hi, I'm using FFT convolution for smoothing. Basically FFT kernel is exp(-x^2) and the signal is something positive. All of it is done in a single pass, so no need for overlap-add and stuff like that. Seems working fine, except now I tried it on quite long data - the FFT length was 262144, kernel being 32768 samples (zero-padded to 262144), calculated in 32-bit floating points, FFT implemen...

Hello, I have a discrete signal a(x[i]) = cos(2*pi*x[i]/L). I integrate analytically this cosine function from x[i-1] to x[i+1], I...

Hello, I have a discrete signal a(x[i]) = cos(2*pi*x[i]/L). I integrate analytically this cosine function from x[i-1] to x[i+1], I get exact[i] = L * (sin(2.0*pi*x(i+1)/L) - sin(2*pi*x(i-1)/L)) / ( 2.0*pi). Now, I want to calculate the convolution a * h where h is a rectangular filter (non causal filter). Doing that, I should recover for each node [i] the exact value of the integral (...

Quick (and dumb) question, but just wanted to make sure I understand. Supposed I have an input vector x of length N=500. And I also have a...

Quick (and dumb) question, but just wanted to make sure I understand. Supposed I have an input vector x of length N=500. And I also have a filter vector h of length M=3000. If peforming convolution filtering via FFT, what should I set the FFT sizes to be? I want the output signal to be the same size as the input signal (N) I assume it would need to be greater than N+M-1 to not cause circular c...

Greetings, I'm stuck trying to figure out how to use half length complex FFTs to implement the convolution of two real sequences and could use...

Greetings, I'm stuck trying to figure out how to use half length complex FFTs to implement the convolution of two real sequences and could use some advice as I feel like I might be missing something (relatively) obvious. I'm trying to convolve two real valued sequences (of length N, zero padded to length 2N) using two complex-valued FFTs (of length N). I'm doing this in C using FFTW thou...

Suppose I have A -------------------------------------- 10.000 10.000 B -------------------------------------- 10.000 ...

Suppose I have A -------------------------------------- 10.000 10.000 B -------------------------------------- 10.000 10.000 and C -------------------------------------- 100.000 200.000 100.000 where C = CONVOLUTION(A,B) Taking the FFT of each: A' -------------------------------------- { 20.000, 0.000 }, { 0.000, 0.000 }, B' ------...

Hi all, I want to filter out very narrow band signal, and thinking about using fast-convolution filtering. The input signal is real (not...

Hi all, I want to filter out very narrow band signal, and thinking about using fast-convolution filtering. The input signal is real (not analytic) and the output signal should be real. I wonder if there is any trick I can play to take advantage of real signal processing? Is there any saving on computation I can achieve since I deal with real signal? I have huge data to process, thus, even sma...

Suppose I add two noise signals y=x+v where x has a PDF Px and v has a PDF Pv What is the PDF of y?? I am led to believe that it is the...

Suppose I add two noise signals y=x+v where x has a PDF Px and v has a PDF Pv What is the PDF of y?? I am led to believe that it is the convolution of the two PDF's of x and v - is this right and if so why? Therefore if x and v are both Guassian, y must have a PDF which is the convolution of two Guassian PDF's - I assume that must be guassian too???

Hi I'm using fftw3 on ubuntu linux in a convolution of 1-dimensional data. for ( int k=0 ; k

Hi I'm using fftw3 on ubuntu linux in a convolution of 1-dimensional data. for ( int k=0 ; k