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Is there a way to make an inverse notch filter block in matlab simulink? I have found the peak-notch block, but I need to amplify the signal instead of attenuate it.

Thank you.

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  • $\begingroup$ So you want a filter that amplifies (or lets pass) a single frequency and suppresses all other frequencies? In practice you will need to implement a band pass filter, probably with a rather narrow passband. $\endgroup$ – Matt L. Jun 6 '13 at 12:30
  • $\begingroup$ No I need to amplify a frequency (50Hz) and leave the other as they are (gain = 0dB) $\endgroup$ – Daniele Vitali Jun 6 '13 at 12:47
  • $\begingroup$ One approach might be to bandpass filter to obtain the frequency of interest (at 50 Hz), then add the filter output back to the original signal. You'll need to account for the filter's delay when you add it back, but that should give you approximately what you want. $\endgroup$ – Jason R Jun 6 '13 at 12:53
  • $\begingroup$ Ok, but can I do that? I mean, how can I output the input signal for frequencies different from 50Hz? $\endgroup$ – Daniele Vitali Jun 6 '13 at 13:03
  • $\begingroup$ In audio this is called a peaking EQ filter. Transfer functions are on musicdsp.org/files/Audio-EQ-Cookbook.txt peakingEQ $\endgroup$ – endolith Jun 10 '13 at 16:34
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peak-notch block is a two-way component. You can set the response type to peak or notch. Here is the properties page:

enter image description here

int the link: http://www.mathworks.com/help/dsp/ref/peaknotchfilter.html

Using this filter you can obtain desired output by summing input signal and output of the peak filter.

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  • $\begingroup$ As I wrote in the question, I've already found the peak-notch block in simulink, but I need to get a filter that amplify a frequency and leave the other unchanged, kinda of inverse notch. $\endgroup$ – Daniele Vitali Jun 6 '13 at 16:15
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    $\begingroup$ @Daniele Vitali, Ok, I got it, The only thing you need to do is to sum the peak filter output and a copy of original signal $\endgroup$ – RonaldoMessi Jun 7 '13 at 12:53
  • $\begingroup$ Ok I've found another solution $\endgroup$ – Daniele Vitali Jun 8 '13 at 14:04
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Here is my solution. I don't know whether it is the best one but it works.

Simply, I created a transfer function with 2 resonant poles at 50Hz, and 2 zeros right after. In this way, the bode diagram is the opposite of the classical notch filter

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