I have a relatively low-frequency signal and want to calculate the peak envelope of it in Simulink. I tried some of filters but the envelope is not well precise. can anyone help, how can I do it?

Simulink diagram

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    $\begingroup$ Can you clarify what do you mean by "peak envelope"? $\endgroup$ – MBaz Jul 26 '17 at 18:50
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    $\begingroup$ peak envelope is picking the peak values of a signal $\endgroup$ – Wasi Jul 26 '17 at 19:05
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    $\begingroup$ Thanks for the clarification. Can you explain what you did and what was the problem? Standard envelope detection (say, with a Hilbert transform) should work pretty well with the signal in your plot. $\endgroup$ – MBaz Jul 26 '17 at 20:17
  • $\begingroup$ I used Hilbert transform, but the envelope has a bit higher amplitudes than signal itself, and also it has a delay, how can I fixed that? $\endgroup$ – Wasi Jul 26 '17 at 20:23
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    $\begingroup$ You're not using the Hilbert transform in that diagram (but it should still work; it's a square-law detector). I think your low-pass filter does not have enough rejection; you can still see a bit of the carrier in the envelope. $\endgroup$ – MBaz Jul 26 '17 at 21:08

The best reference that I'm aware of on Complex Signal Envelopes detailing definitions, some difficulties and workarounds is:

Nuttall, Albert H. Complex envelope properties, interpretation, filtering, and evaluation. No. NUSC-TR-8827. NAVAL UNDERWATER SYSTEMS CENTER NEW LONDON CT, 1991.

available at:


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