Guys: I'm brushing up the mathematical side of my DSP brain. It's a bit dusty having spent the last few years doing implementation and device...

Guys: I'm brushing up the mathematical side of my DSP brain. It's a bit dusty having spent the last few years doing implementation and device control without regard for the underlying math. I'm trying to satisfy myself that vectors are a group under convolution. I've determined that there's an identity element: For any vector V, V*[1] = V (where * is convolution rather than multipl...

Hello, I have a gaussian kernel of size [192,192] to be convoluted with an image of size [512,512] for smoothing. Using the FFT property that...

Hello, I have a gaussian kernel of size [192,192] to be convoluted with an image of size [512,512] for smoothing. Using the FFT property that fft of a convolution is the product of the fft of the individual terms (fft(f(t) * g(t))) = f(w)g(w), i could say that smoothedimage = fftinverse(fft(image) fft(kernel)) the problem i am encountering is this: straightforward convolution is easy b...

Hi all, As the subject suggest, I would like to know if anyone know how to perform convolution in excel? In excel only have the Fourier...

Hi all, As the subject suggest, I would like to know if anyone know how to perform convolution in excel? In excel only have the Fourier analysis, but no convolution Function. Thanks in advance. Sulphox

I did a decimator FIR filter simply by doing the convolution only once every M' input sample. for example M=3: feed x0,feed x1, feed x2,...

I did a decimator FIR filter simply by doing the convolution only once every M' input sample. for example M=3: feed x0,feed x1, feed x2, convolution, feed x3,feed x4, feed x5, convolution, feed x6,.... Then I find many people talk about polyphase decimation filter, I wonder if it is more efficient than what I'm doing? What is the differrence? thanks mary

I refer to the method of overlap and add way of performing convolution of large input signals given in proakis. My question is, How is this...

I refer to the method of overlap and add way of performing convolution of large input signals given in proakis. My question is, How is this method of convolving the impulse response with the large input signal by dividing it into small blocks different from the normal way of convolution where we use the conv() function? I tried out the method in MATLAB and both gave the same result. But, I ...

I got a little problem when performing a FFT convolution. I try to have the output to have the same amplitude as it would with a...

I got a little problem when performing a FFT convolution. I try to have the output to have the same amplitude as it would with a time-domain convolution. To do so, I set the sum of the values of the samples of my kernel to 1.0, and after I FFT the kernel and the signal to convolve, I divide the values of both signals by the square root of the number of samples (which is the same since they...

By Multiply the amplitude spectra of the two input time series, and compare the result with the amplitude spectrum of the output series. Check the...

By Multiply the amplitude spectra of the two input time series, and compare the result with the amplitude spectrum of the output series. Check the rule "convolution in the time domain is multiplication in the frequency domain". When I subtract the amplitude spectrum of the convolution from the amplitude spectrum obtained by multiplying the two input amplitude spectra, I observed a difference. Wher...

This is just a curious doubt. What is the statistical significance of convolution? For instance, we define the auto correlation in terms...

This is just a curious doubt. What is the statistical significance of convolution? For instance, we define the auto correlation in terms of expectation as R(u) = E(X.Xu). Similarly, do we have any expression for convolution of two signals? Can I have it as something like (sorry, if it is completely absurd): Conv(Xu, Yv) = E(Xu-v.Yu) - Krishna

Hello! I'm searching for a method/class/package in JAVA that implements a linear convolution algorithm between two signals. For example...

Hello! I'm searching for a method/class/package in JAVA that implements a linear convolution algorithm between two signals. For example "public convolution(double[] signal1, double[] signal2)" that convolves signal 1 with 2. I've searched in many webpages, but I've found nothing. I think, I'm serching for any easy method, but I don't know why I can't find it. Somebody can help me? Me ...

Hi, I am deveoping a fec system. i am using convolution codes (K=7, code rate=1/2). i did some simulations in MATLAB to test...

Hi, I am deveoping a fec system. i am using convolution codes (K=7, code rate=1/2). i did some simulations in MATLAB to test convolution decoder's performance against burst errors. I took 128 bit frame of random data. Then used convenc function to encode it. and then introduced burst errors by selecting some bit randomly and making following bits zero (total number of consecutive bits which ...

I'm perusing the web and I suspect worse case I'll grab a few texts to further assist me, nonetheless, given two sequences ( radar application )...

I'm perusing the web and I suspect worse case I'll grab a few texts to further assist me, nonetheless, given two sequences ( radar application ) - reference and receive of length 1024. It was explained to me that the for linear convolution, I'll pad the sequences with zeros, then compute the FFTs. For circular convolution there's no need for padding. None of this makes sense to me as a re...

hi I'm a bit screwed up by the notation used in fourier transform, on convolution and product theorems. I'm drawing a blank with regard...

hi I'm a bit screwed up by the notation used in fourier transform, on convolution and product theorems. I'm drawing a blank with regard to what's the difference between: f1(t)*f2(t) F1(w)F2(w) [convolution theorem] f1(t)f2(t) F1(w)*F2(w) [product theorem] what's the difference between "f1(t)*f2(t)" and "f1(t)f2(t)" please give one example. Thanks.

Hello everyone: First of all, thanks to all those who have posted before and for saving the archives. As you know this is my first post here. ...

Hello everyone: First of all, thanks to all those who have posted before and for saving the archives. As you know this is my first post here. I searched the archives by terms and by circular convolution but did not find anything, hope I didn't miss a post. You see, I'm trying to implement a parallel cyclic convolution algorithm and was wondering if someone can point out the fastest cyclic con...

hello forum. convolution between the function x(t), with units of Volts, and h(t), the system impulse response. h(t) needs to have units of...

hello forum. convolution between the function x(t), with units of Volts, and h(t), the system impulse response. h(t) needs to have units of inverse time, in order for g(t), the output of the convolution, to have units of Volts: g(t)=summation {x(tau)*h(t-tau)}dtau Correct? 2) If correct, take the signal exp(i*theta) theta has units of radians. If theta=(2*pi)*rand(N)-pi (unif noi...

Hello, I am not sure if this is possible, but I have signals x(t) and y(t), and I need to find a signal z(t) that hold the following...

Hello, I am not sure if this is possible, but I have signals x(t) and y(t), and I need to find a signal z(t) that hold the following property: x(t).y(t) = x(t)*z(t); Multiplication of x(t) and y(t) equals to the cyclic convolution between x(t) and z(t). Is there any mathematical approach to find z(t)? Thank you.

Hi, I'm currently doing project on OFDM based. I want to transmit my signal through a Rayleigh channel. assume that the received signal should...

Hi, I'm currently doing project on OFDM based. I want to transmit my signal through a Rayleigh channel. assume that the received signal should be y(t)=x(t)*h(t)+n(t) or Y(f)=X(f)H(f)+N(f). I understand that in order to get y(t), we need to do a convolution between x(t) and h(t). let say, after IFFT in OFDM part, then I change the signal into serial where the data is in time domain. Now, I don...

Hello, Which of the following two definitions is correct for convolution of 2 complex signals? (1): x1(t) convolve x2(t) = int from -inf...

Hello, Which of the following two definitions is correct for convolution of 2 complex signals? (1): x1(t) convolve x2(t) = int from -inf to +inf [ x1(tau) x2*(t-tau) ] dtau (2): x1(t) convolve x2(t) = int from -inf to +inf [ x1(tau) x2(t-tau) ] dtau Here x2*(.) is the complex conjugate of x2(.). I would appreciate it if you could also point me to a textbook which confirms your...

In graphical convolution either the system impulse response h(n) or the input x(n) is folded/flipped and then slid across the other to...

In graphical convolution either the system impulse response h(n) or the input x(n) is folded/flipped and then slid across the other to determine the system response y(n). Why is this so? I have reasoned this as being necessary to align the "present" input to the "present" output of the system response to get the correct system time output. Is this reasoning valid? None of the several signals and s...

Hi all, I have some newbie questions for someone much more experienced than I. I am implementing a 6 band equalizer on the AVR32 processor,...

Hi all, I have some newbie questions for someone much more experienced than I. I am implementing a 6 band equalizer on the AVR32 processor, which has built in functions that do filtering by convolution of the input signal with the impulse response of filter. I have a couple of questions based on the AVR32 implementation of FIR filtering. In matlab I generated 6 bandpass filters and a hig...

http://www.youtube.com/watch?v=WNZCS-coZjY Well she *says* they do it with convolution, which makes sense. "Please try this at home, but not...

http://www.youtube.com/watch?v=WNZCS-coZjY Well she *says* they do it with convolution, which makes sense. "Please try this at home, but not with real guns!" ;) -- Eric Jacobsen Minister of Algorithms Abineau Communications http://www.abineau.com