## Bessel Poles

Started by in comp.dsp7 years ago 1 reply

Hello, Just out of curiosity: I there actually a simple formula to determine the pole locations of a n-th Order Bessel Lowpass? In...

Hello, Just out of curiosity: I there actually a simple formula to determine the pole locations of a n-th Order Bessel Lowpass? In literature I've only seen tables which were obviously created by finding the complex roots of the Bessel polynomials... Thanks! Kind Regards, Joerg

## Kaiser window vs Kaiser-Bessel window

Started by in comp.dsp10 years ago 7 replies

Hi, I am trying to use Kaiser-Bessel window before FFT. However, I am a bit confused about what is the difference between Kaiser and...

Hi, I am trying to use Kaiser-Bessel window before FFT. However, I am a bit confused about what is the difference between Kaiser and Kaiser-Bessel window. There is a definition of Kaiser window: http://en.wikipedia.org/wiki/Kaiser_window and also definition of Kaiser-Bessel derived (KBD) window. According to this document, Kaiser and Kaiser-Bessel windows are the same: http://local.wa...

## image filtering using bessel function/filters

Started by in comp.dsp13 years ago 16 replies

Hi, I have been asked to design a program in Matlab which calculates the FFT of an image, then defocus the image using a Bessel filter, and...

Hi, I have been asked to design a program in Matlab which calculates the FFT of an image, then defocus the image using a Bessel filter, and reconstruct the defocussed image. Now, I find that only analog models of Bessel filters are available in Matlab, though i found a link to a pdf which shows values of the coefficients upto order 10. But, how do i construct a 2D-Bessel Digital filter? I a...

## bessel space

Started by in comp.dsp14 years ago

If I transform the image to bessel space before calculate it's derivative: x = -10:10; T = besseli(x,s,1); im =...

If I transform the image to bessel space before calculate it's derivative: x = -10:10; T = besseli(x,s,1); im = imfilter(im,T'*T,'symmetric','same','corr'); Can it(bessel filter) surpress the noise introduced by derivative filters?

## replacing 8th order bessel with FIR

Started by in comp.dsp7 years ago 6 replies

we use a filter chip we can't get any more, at least not reliably. it's an 8th order bessel. I want to replace it with an RC and then do...

we use a filter chip we can't get any more, at least not reliably. it's an 8th order bessel. I want to replace it with an RC and then do tight filtering in FIR in the uC, a 32 bit integer processor. I understand FIR is specified differently than analogue filters. Q: is there a rule of thumb to come up with an FIR that's "as good as" an 8th order bessel? Thanks, Jon.

## Bessel function simplification problem

Started by in comp.dsp15 years ago 9 replies

All, I'm trying to simplifiy the following equation for the zero'th order modified Bessel function of the first kind. I'm using...

All, I'm trying to simplifiy the following equation for the zero'th order modified Bessel function of the first kind. I'm using the approximation for the Bessel function as Io(z) = exp(z)/sqrt(2*pi*z) I would like to have the natural logarithm of this function log(Io(z)) = log(exp(z) / sqrt(2*pi*z)) = z + log(1/sqrt(2*pi*z)) but i don't want to have to ca...

## Bessel Filter (Digital)

Started by in comp.dsp9 years ago 34 replies

Hi, I want to implement a bessel filter (Digital) (in c++, well but that i can think of my own how to implement it in c++, right now i just want...

Hi, I want to implement a bessel filter (Digital) (in c++, well but that i can think of my own how to implement it in c++, right now i just want to know how to implement it!!). Can you please guide me? (I'll fetch you further details abt. the filter viz. 4-pole etc. , once i get started). I want basically the following info to get started: 1.> What all consists of a digital bessel filter? I

## bessel filter

Started by in comp.dsp16 years ago 5 replies

does any body know how to determine the analog prototype of a bessel filter??? thanks

does any body know how to determine the analog prototype of a bessel filter??? thanks

## Help me with bessel filter concepts

Started by in comp.dsp12 years ago 6 replies

I am implementing a Crossover in c sharp platform. I have already implemented 24th order Butterworth and Linkwitz Riley filters. Now I need to...

I am implementing a Crossover in c sharp platform. I have already implemented 24th order Butterworth and Linkwitz Riley filters. Now I need to implement 24th order Bessel filter with cascaded biquad sections. Can any of you help me with the procedure? Regards Gangadhar

## Accursed Bessel Functions!

Started by in comp.dsp10 years ago 7 replies

OK: I'm posting this because I'm lazy. I haven't even _tried_ to look this up yet, or to attempt to choke an answer out of Maxima. If there...

OK: I'm posting this because I'm lazy. I haven't even _tried_ to look this up yet, or to attempt to choke an answer out of Maxima. If there _is_ an answer, I'm sure it'll be a Bessel function, and those things always hit me like headlights do a deer. So, anyone feel like some math hand-holding? Here's the integral I'm trying to find an answer for: integral from -pi to pi, e^(-a +...

## FM Demodulation

Started by in comp.dsp11 years ago 15 replies

I have an application where I need to detect an unmodulated tone at a fixed baseband frequency on an FM carrier. The mod index of the tone is...

I have an application where I need to detect an unmodulated tone at a fixed baseband frequency on an FM carrier. The mod index of the tone is quite low, such that only the first Bessel pair of FM sidebands is significant. Can I demodulate the tone by directly detecting its Bessel components (the first two sidebands) at RF without first passing the composite FM signal through a discrimi...

## problem math bessel function

Started by in comp.dsp15 years ago 20 replies

All, I have a series of other questions, but before i get to those ones, i'm stuck on one part of an equation that appears on page 304...

All, I have a series of other questions, but before i get to those ones, i'm stuck on one part of an equation that appears on page 304 of Digital Communications 4th Ed, Proakis. It's equation 5.4-18 and i can't seem to understand how the equality between the integral of the exponential function and the zeroth ordered mod bessel function of the first kind works. The equation looks somethi...

## Approximation to Bessel Function in Integrand

Started by in comp.dsp10 years ago 22 replies

Hello, I am trying to find a closed-form solution (or reasonable approximation) to the following...

Hello, I am trying to find a closed-form solution (or reasonable approximation) to the following integral: integral(x^p*ln(x)*exp(-x^2)*besseli(0,2*x),x=0..infinity), where p is a constant and besseli(0,2*x) is the zeroth order Bessel function of the first kind. I have already looked through the traditional resources (Table of Integrals, Series, and Products by Gradshteyn and Ryzhik an...

## Is 'Bessel' digital lowpass filter standard?

Started by in comp.dsp2 years ago 64 replies

Hi, I'm trying to design a simple IIR lowpass filter with the following specs: fs = 2.4kHz fc = 150Hz order = 3 or 4 The most important...

Hi, I'm trying to design a simple IIR lowpass filter with the following specs: fs = 2.4kHz fc = 150Hz order = 3 or 4 The most important aspect is that the ringing (overshoot) shouldn't be higher than about 3%. When using a 3rd order Butterworth, I get about 9% overshoot, which is too much. Someone hinted my that a Bessel filter would be better suited. This program is a good start http:...

## Bessel filter: What am I doing wrong?

Started by in comp.dsp5 years ago 3 replies

Hi, A bessel filter should have nearly constant group delay up to a certain frequency. In my case, this should be fs=100MHz. What am I...

Hi, A bessel filter should have nearly constant group delay up to a certain frequency. In my case, this should be fs=100MHz. What am I doing wrong with this MATLAB code? set(cstprefs.tbxprefs,'FrequencyUnits','Hz'); fs = 100e6; [num,den] = besself(9,2*pi*fs); H = tf(num,den); f_axis = logspace(3, 11, 10000); bode(H, f_axis);grid on; The result is http://snag.gy/wweJj.jpg which sh...

## Parametric description of Transfter function for 4th order Bessel filter

Started by in comp.dsp15 years ago 5 replies

Hi, Does anyone know of a parameteric description for the transfer function (in Laplace domain) of a 4th order Bessel Thompson LPF, in terms...

Hi, Does anyone know of a parameteric description for the transfer function (in Laplace domain) of a 4th order Bessel Thompson LPF, in terms of its 3dB bandwidth? If not, is there an empirical way to scale the filter coeffs to get a specific 3dB cut off point? Thanks, Venugopal

## FIR coefficients for Bessel analog filter

Started by in comp.dsp13 years ago 3 replies

Dear all, I've only done a basic course in digital filters. But I'm required to implement a digial filter in FPGA to approximate an analog...

Dear all, I've only done a basic course in digital filters. But I'm required to implement a digial filter in FPGA to approximate an analog Bessel filter of order 5 and cutoff frequency of 15.5kHz. I used besself(5,2*pi*15.5e3) in Matlab to get the s-domain transfer function and plotted out the frequency response of the analog filter. I tried using the fdatool in Matlab to get the FIR coe...

## can the bessel filter be directly designed in digital domain?

Started by in comp.dsp10 years ago 3 replies

Can the bessel filter (of course IIR) be designed directly in digital domain? If so what would be the steps/process. Regards Bharat

Can the bessel filter (of course IIR) be designed directly in digital domain? If so what would be the steps/process. Regards Bharat

## Bessel Filter

Started by in comp.dsp9 years ago 3 replies

Hi I am trying to apply a bessel filter in C to data I pull from an oscilliscope. This is my first attempt at signal processing so excuse...

Hi I am trying to apply a bessel filter in C to data I pull from an oscilliscope. This is my first attempt at signal processing so excuse any idiocy that might follow. Is this the correct method; Take Z transform of data and find poles and zeros as its a discrete time signal Transfer to S domain Apply filter Transfer back to Z domain Inverse Z transform Result Cheers for an...

## Detection of Bessel components of a received PM signal

Started by in comp.dsp10 years ago 7 replies

Hi My current work involves estimation of modulation index for a PM signal with or without subcarriers. I have found articles to do the same...

Hi My current work involves estimation of modulation index for a PM signal with or without subcarriers. I have found articles to do the same without subcarriers, but I am yet to find something which might work when subcarriers are included. An important method to estimate the modulation index (which I believe can be extended for subcarriers later) is to detect the Bessel components and find cor...