Adding high frequency noise..

How can we add a high frequency noise to a sinusodial signal in matlab.Is there any process to generate a high frequency noise in matlab.

[pietro]

What is the amplitude of the noise? do you need any special noise properties such as: guassian noise?

[Marben]

sir i have seen in many coding that only gaussian noise and imnoise is used to add noise.i have never seen any other noise to add with a signal in matlab code. So how can we add another noise(high or low frequency) to a signal? sir you can take amplitude randomly....Please help

Answer 1

[Image Analyst]

Hint: one way to do it is to take the fft of your signal and add random numbers ONLY to frequencies higher than whatever you consider "high" to be. And there will be no noise at lower frequencies. Then, after you've added noise, inverse Fourier transform to get back to the "x" (spatial) domain.

[Marben]

sir, will you explain with a code....still i am confusing in high frequency...

[Prajan Pradhan]

With your explanation there are imaginary terms while doing ifft. When used absolute value i.e. abs(fft_data), there is error in the audio which is not filtered.

[Sowmya Dasari]

can u please answer the doubt asked by prajan pradhan i too got a similar error ?

[Image Analyst]

Post your code and audio file so I can try to fix it.

[Daniel Russell]

Great idea, that worked perfectly (doing image processing demo). Thanks.

Answer 2

[Jan]

Yes. You can create any kind of noise in Matlab and add it to your signal.

For a more detailed help, please explain the details of your problem.

[Marben]

for eg. i have a sinusodial signal x = -pi:.1:pi; y = sin(x) Now i have to add high frequency noise with y. How can we add?I am unable to generate high frquency noise?

[Jan]

@Marben: Please provide any information. Do you need a general "high" frequency, than use simply rand(). If you have a defined frequency spectrum, explain it with all required details.

[Prajan Pradhan]

If I need to insert noise of frequency over 20 kHz to an audio signal. How can I do that?