Calculation of Noise for a given SNR

Started by Steve Thomas in Matlab DSP14 years ago

Hello All, I am trying to find the right method of finding the noise power to extrapolate from the SNR value. I have a signal in a variable y...

Hello All, I am trying to find the right method of finding the noise power to extrapolate from the SNR value. I have a signal in a variable y which is a second derivative Gaussian pulse: I normalized to make it 2v peak to peak Fs=5E9;%sample rate-10 times the highest frequency t=[(-25E-9):ts:(400)*1E-9)]; ts=1/Fs;%sample period y = SEC_GAUSN[x] % y is a second derivative gaussian p...


Using fft to obtain power spectral density of a gaussian distribution

Started by Anonymous in Matlab DSP20 years ago

Hi, I am currently writing this programme to simulate the AWGN using the rand function in C and the polar box muller algorithm. I...

Hi, I am currently writing this programme to simulate the AWGN using the rand function in C and the polar box muller algorithm. I managed to simulate a series of random numbers of gaussian distribution with variance 1 and mean 0. I would like to now test using fft the power spe


Re: Colored Noise in Matlab

Started by rizw...@yahoo.com in Matlab DSP13 years ago

Hi tarang .. i need a bit more elaboration on colored noise .. can u please give a small code which can generate colored noise ?? thanx in...

Hi tarang .. i need a bit more elaboration on colored noise .. can u please give a small code which can generate colored noise ?? thanx in advance Ali Can anybody elaborate on this.if h(t) is the impulse response of the filter I have to send white Gaussian noise to it,in continuous domain .In matlab simulation I have to generate a vector of Gaussian random variables using randn and con...


Gaussian filter

Started by Giovanni Marino in Matlab DSP12 years ago

Dear All, I am trying to denoising some simulated images by using a Gaussian filter. I would check if my results are right by deconvolving the...

Dear All, I am trying to denoising some simulated images by using a Gaussian filter. I would check if my results are right by deconvolving the output images in the frequency domain. Suppose that Image_out is the output of my filter, in the frequency domain we should get: F(Image_out)=F(Image_inp)*F(Filter_Gaus), where F() represent the Fourier transform. As a consequence the deconvolution re...


Gaussian Filter in signal processing

Started by Bavithi in Matlab DSP16 years ago

Hello, I would like to investigate the effects of filters on a signal. I have tried different nyquist filters like Sinc and RRC. I would...

Hello, I would like to investigate the effects of filters on a signal. I have tried different nyquist filters like Sinc and RRC. I would like to work with non-nyquist filter such as guassian. However, I am not sure of the choice of 'sigma' for the filter. The signal is a complex gaussian signal and has a certain variance, say v1. I normalize this variance, so that the variance of real...


construct gaussian white noise with particular SNR

Started by biswasengupta in Matlab DSP13 years ago

hi there, My issue is as follows: consider I have a low-pass filtered version of a white noise signal (fc=300 Hz, LPF) as my signal. I would...

hi there, My issue is as follows: consider I have a low-pass filtered version of a white noise signal (fc=300 Hz, LPF) as my signal. I would like to add different Gaussian white noise having different SNR referred to the LPF signal. I do the following. 1. I get the power of the signal using = mean(original_signal.^2) -> {say P_s} 2. standard deviation of the required noise = sqrt(P_


Reference that shows the kurtosis of a Gaussian signal is 3

Started by Adrian H in Matlab DSP14 years ago

Hello, I am looking for a reference that shows analytically how the kurtosis of a Gaussian signal is 3. Thank you, Adrian

Hello, I am looking for a reference that shows analytically how the kurtosis of a Gaussian signal is 3. Thank you, Adrian


Doubt in Belief Propagation

Started by maha devi in Matlab DSP11 years ago

Hi all, I am currently working on Belief Propagation. I have a doubt while estimating my beliefs. I need to estimate the r.v "xj's" of a ...

Hi all, I am currently working on Belief Propagation. I have a doubt while estimating my beliefs. I need to estimate the r.v "xj's" of a vector "x" i - function node j -variable node With some approximation, Message from function to variable node: Pi-> j is Gaussian and I have calculated its mean and variance. Message from variable to function node: Pi


how to generate a Gaussian matrix with each matrix component having unit variance?

Started by Maha devi in Matlab DSP11 years ago 1 reply

Hi all, I want to generate a matrix A with i.i.d zero mean Gaussian components such that the variance of each component in the matrix (a_ij)...

Hi all, I want to generate a matrix A with i.i.d zero mean Gaussian components such that the variance of each component in the matrix (a_ij) need to have unit variance. I used randn (M,N). But each matrix component in this case does not have unit variance. Could someone tell me how to generate such a matrix. Thanks a lot ! Regards, Mahadevi


Introduce correlation into wireless fading channel

Started by cash...@gmail.com in Matlab DSP14 years ago

Hi experts I need to simulate wireless MIMO fading channel in both Gaussian and Rayleigh random variables. I have implemented the channel...

Hi experts I need to simulate wireless MIMO fading channel in both Gaussian and Rayleigh random variables. I have implemented the channel matrix H = h11 h12 h21 h22 where h11 h12 h21 h22 are independent Gaussian or Rayleigh random variables. Could somebody teach me how to introduce correlations among thoese random variables in terms of correlation coefficient? Thanks for any he...


Average Contrast in DoG image

Started by twinklingstars88 in Matlab DSP11 years ago

Hi All I'm doing a project on region of interest detection. I need to find the average contrast given the maxima and minima of the...

Hi All I'm doing a project on region of interest detection. I need to find the average contrast given the maxima and minima of the difference-of-Gaussian images are detected by comparing a pixel to its neighbouring 26 points. The implementation has to be in matlab.Can someone help me with this? Thanks. Shanmugavalli


8PSK modulation for EDGE

Started by sylv...@yahoo.fr in Matlab DSP15 years ago

Hi everybody I\'ve got a problem in matlab when generating bits With my short program, modulus of bits pass by 0 which is not required of course...

Hi everybody I\'ve got a problem in matlab when generating bits With my short program, modulus of bits pass by 0 which is not required of course even if i rotate then of 3*pi/8 Can someone help me please? %%%%generation and rotation of bits%%%%%%%? for(l=1:n) q=floor(8*rand()); a(l) = exp(i*pi/8*(2*q + 3*l)); end %%%%gaussian filter thanks to http://www.tropian.com/tech/tech_doc...


Gaussian Distribution Power Spectrum

Started by imageprocessingx in Matlab DSP18 years ago

I'm trying to plot the power spec of a set of normally distributed random values. I'm told it should look like a straight line. ...

I'm trying to plot the power spec of a set of normally distributed random values. I'm told it should look like a straight line. However, I'm not seeing this. I'm seeing a 'spike' at the beginning, or at the end, depending on the shift. Any thoughts? As you can see, I'm a begin


how to make a "fading"?

Started by brunomaggi2002 in Matlab DSP19 years ago 3 replies

Hi I'm getting into radio channel simulations and I've come across the following r = t * c + n r (received) t (transmitted) ...

Hi I'm getting into radio channel simulations and I've come across the following r = t * c + n r (received) t (transmitted) c fading n (noise) where, books say, c is a complex gaussian variable with mean 0 and variance 0.5 per real dimension. My question


random variable of desired pdf

Started by nammi sairamesh in Matlab DSP17 years ago 16 replies

Hi, I am modelling a wireless channel, I want to model the channel as mixture of two guassians which is suitable for my...

Hi, I am modelling a wireless channel, I want to model the channel as mixture of two guassians which is suitable for my applications. i.e. f= a*f1+b*f2; where f is the pdf of the noise signal. f1 and f2 are gaussian pdfs with mean 0 and variance =1, a and b a


curvature calculation

Started by Anonymous in Matlab DSP20 years ago 1 reply

I have an image which i had smoothed using Gaussian smoothing technique. I had also detected the edge of the object in the image. ...

I have an image which i had smoothed using Gaussian smoothing technique. I had also detected the edge of the object in the image. Next, I would like to calculate the curvature of the edge. How can do this using Matlab ? anyone got any idea ?? thanks..


zero mean random variables

Started by mohan prasad in Matlab DSP19 years ago 1 reply

Hi, Am trying to generate complex gaussian random variables using the randn function but when I calculated the mean of those...

Hi, Am trying to generate complex gaussian random variables using the randn function but when I calculated the mean of those random variables it is not giving zero as answer.Can anyone tell why this is happening? mohan


Realtion between SNR and Eb/No

Started by sairamesh90 in Matlab DSP17 years ago

Hi, I am modeling a communication channel, where the noise is colored Gaussian noise whose variance is periodic in nature. I...

Hi, I am modeling a communication channel, where the noise is colored Gaussian noise whose variance is periodic in nature. I modeled that, but my problem is that to see the system perforamance(The standard method is to plot BER perforamce against Eb/No). But in my case,


Gaussian white noise: variance-power relation

Started by narv...@datamars.com in Matlab DSP16 years ago

Hello: I am simulating a transmission channel with simulink. I want to add gaussin noise. I need to know which is te realtion between the...

Hello: I am simulating a transmission channel with simulink. I want to add gaussin noise. I need to know which is te realtion between the variance of the noise signal and its power. Thank you. nac


Probabilistic Adder

Started by Anonymous in Matlab DSP16 years ago 1 reply

hi all, I would like to know if probabilistic adders are possible in matlab. Meaning that I want to make an adder which gives correct...

hi all, I would like to know if probabilistic adders are possible in matlab. Meaning that I want to make an adder which gives correct results ( adding of two nos) with certain probability, say 0.9. or would like to assign certain probabilistic distribution for the adder...might be gaussian....according to which the adder should behave. Any suggestions are welcomed an