I’m looking for help on the following objective for a class. I’m looking for a m
ID: 2293360 • Letter: I
Question
I’m looking for help on the following objective for a class.I’m looking for a method in which we can assess the SNR (signal to noise ratio) before and after application of a digital and or analog filter.
Specifically we can look at fft of the audio signal before applying the filter and taking the avg signal and dividing it by the noise level to get the SNR. However after applying a bandpass filter We eliminate noise from the signal so there needs to be a way in which we can calculate the SNR after the filter and doing the previous method would result in the same SNR which is obviously not correct. Please provide a detailed method/explanation in which we can determine the SNR. It’s a huge part of my grade and it will determine whether I graduate or not. Thanks she the sem SNR es 2. then
Explanation / Answer
Hello,
Please find the answer attached below. If the answer has helped you please give a thumbs up rating. Thank you and have a nice day!
In order for you to calculate the SNR using any software, you should tell the software what the signal component is, and what the noise component is. If you just have one signal with you, Matlab or any software cannot give you any estimate of the SNR, becuase within that signal, it does not have the knowledge of the signal and the noise seperately.
Having said that, we can make certain assumptions to give you a rough estimate of the SNR. Since you are passing the signal through a filter, lets assume that the FFT components at the highest values are your required signal, and those at the lower values (ripple) are the noise. Thus, calculate the inverse FFT of both the cases, to recover the actual signal before and after filtering. Now, you will get a sinusoid component and a noise component, in both the cases, i.e. before and after filtering. Now, just execute the command r = snr(x,y), where x is the signal and y is the noise, to get your estimate of SNR in dB, in Matlab.
NOTE: Please attach your signal files in Matlab. Then I can show you the exact code which will work. Thanks !
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