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# Questions tagged [envelope]

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### How to get a reliable envelope of a signal with clipped peaks?

I'm trying to compute the power per minute in the time domain of some seismic signals. I deal with signals sampled at 5 kHz characterized by random amplitude peaks emerging from low background noise ...
97 views

### The Hilbert transform is used to extract the envelope

I have a sine wave signal with a frequency of 1 Hz, and it is evident that there is low-frequency modulation. I want to compensate for it by extracting the envelope using the Hilbert transform. ...
• 11
1 vote
93 views

### Spectral Envelope in Python

i have a 192kHz sampled signal that has been measured using an ultrasound MEMS microphone and i want to visualize the spectral envelope. I have found here and here ideas on how to do it (mainly "...
• 131
56 views

### Hilbert Transform matches signal rather than envelope

I have an interferogram of a white LED. I am trying to extract the envelope of the signal. Shown is the interferogram, and the absolute value of the Hilbert Transform of the interferogram. I used <...
1 vote
83 views

### Does an analytic function composed with another stay analytic?

Assume $s(t)$ is analytic, such that it has no negative frequency components. Will $s(f(z))$ also be analytic, assuming $2≥f'(z)≥1$? Concretely, I work with audio data that is mapped through a time-...
943 views

### Does analytic signal have positive instantaneous frequency?

The Analytic representation of a signal has no negative frequencies. Does this mean that everywhere, it's instantaneous frequency is positive?
2k views

### Smooth envelope of an aperiodic signal

I have a signal that looks like this: Red line is the function I'd like to obtain somehow. Everything <= -60 is basically absent data (i.e. not low signal). If I understand correctly, Hilbert ...
• 163
141 views

### Bandwidth of amplitude-modulated wave with triangular envelope

I have the following wave: I know that it is demodulated by an envelope detector whose source resistance is 0Ohm and its load resistance is 250Ohm. Now, I need to calculate a C capacitor in order ...
42 views

### How do I find if my amplifier compressed the waveform?

I have a waveform that's modulated by a trapezoidal function. I fitted the envelope to the expected function to show if the amplitude is modulated correctly. I also plotted the difference of the fit ...
• 111
88 views

### Problem with starting values when recreating the matlab envelope function in python

I am trying to recreate the envelope function from matlab in python, but I have a problem with the initial values. I have a window of 1000 and the first 1000 values won't show up. Here is a snippet of ...
1 vote
192 views

### Examples of audio files that are challenging to cross-fade

What can be recommended as challenging tests for cross-fading/mixing of music? I am looking for examples of music-titles that exhibit severe volume dips when cross-faded or mixed. Ideally answers ...
• 133
1 vote
136 views

### Why is Envelope noisy even after filtering and achievement of SNR gain (-6dB SNR to 14dB snr)?

A noisy signal with 500 MHz bandwidth, with negative SNR, when filtered to 6 MHz bandwidth, should attain a theoretical SNR gain of 20 dB. So if the original signal has -6 dB SNR, after filtering we ...
969 views

### Envelope by using Hilbert not working in python [duplicate]

I'm trying to obtain the envelope of an audio signal by using the Hilbert method. My code generates the analytical signal in the same way as scipy.signal Hilbert() function does (I basically copied ...
• 23
439 views

### Filter type selection for signal envelope detection

Working on a signal envelope detection code in Matlab in which an RF signal envelope is to be created. The flow is such that filtering is performed according to the detected presence of a signal in a ...
• 488
171 views

### Standard method of smoothing (amplitude envelope) of continuous wavelet transform

My basic question is, "What is the standard way to post-process/smooth a continuous wavelet transform result to measure the wavelet's activation at a specific frequency?" When using wavelets ...
• 101
2k views

### Why Hilbert Transform is terrible choice for amplitude demodulation of broadband signals?

A reference answer empirically demonstrates that Hilbert envelope does not work well for the (amplitude) demodulation of a broadband signal. I am looking for the math which explains why...
• 1,211
201 views

### Need for rectification in cochlear implants

In cochlear implants, the input signal is fed to a set of bandpass filters and is then half-wave rectified and low pass filtered to estimate the envelope signal. What is the need for doing ...
• 325
467 views

### Envelope detection in MATLAB

I have a sine wave of peak value 1000, frequency 1kHz sampled at 16kHz. I need to find the envelope of this signal using hilbert transform in MATLAB.I have used the inbuilt function abs(Hilbert(input ...
• 325
2k views

### Envelope detection using hilbert transform

I have a sine wave of frequency 1kHz sampled at 16kHz. I need to find the envelope of this signal using hilbert transform in MATLAB.I have used the inbuilt function abs(hilbert(input_signal)) and got ...
• 325
418 views

### How to find complex envelope of a signal in MATLAB?

The transmitted signal $$x(t) = A_c \cos(2\pi f_c t+\phi),$$ I know mathematical expression of complex envelope and its derivation, but how to find its complex envelope in MATLAB? Assume that $A_c = 3$...
1 vote
340 views

### Calculation of Attack Decay Release durations of a signal

I want to write a program that can calculate the attack, decay, release times and sustain level of the audio signal coming from let's say an analog synthesizer. (the envelope which modulates the ...
234 views

### Envelope of a signal regarding shifts

Assume I have a Ricker wavelet. I can compute the envelope of this wavelet as shown below: This is the normal condition we usually see. However, if I shift the Ricker wavelet to be wholly negative, ...
98 views

### Is there a technical term for smoothing or flattening the floor of an amplitude envelope?

I am working with the speech envelope, and I have been trying to make it act a little more like a bilevel signal by exaggerating the peaks and flattening out the floor. I detrended and smoothed my ...
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1 vote
62 views

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403 views

### How does the power spectrum of the amplitude envelope depend on its underlying carrier frequency?

when looking at the amplitude envelope of an oscillation (see red trace in Figure below), it seems to me as if the frequency content of the envelope depends on the the frequency of the underlying ...
40 views

### How to change the shape of a function generator keeping the rate?

I'm making a sort of Envelope Function Generator. At the moment, I'm calculating only the the "rise" stage, which goes from 0 to 10 V; than, brutally, I back it to ...
• 45
582 views

### Bandpass filter that automatically adapts its bandwidth when a transient is detected (to avoid to smoothen the transient)

Let's say we want to isolate a band 1000 hz +/- 50 hz. Obviously, limiting the bandwidth by applying a passband filter will always destroy a bit the sharp transients (a Dirac or a rectangular ...
• 529
39 views

### how to robustly estimate low and up envelope of signal with trend, few level constant steps and noise

I am looking for robust estimation method of low and up envelope of the signal consisting from smooth trend component, constant steps between few fixed levels and additive noise (+ outliers of course)....
• 21
6k views

### What is a constant envelope modulation?

The Book "Digital Modulation Techniques" by Fuqin Xiong groups digital modulation schemes into two classes: "constant envelope" and "nonconstant envelope." However, I was surprised by the inclusion ...
• 842
1 vote
355 views

### Is it possible to get the envelope of a signal via FIR filter?

I was reading an article about ultrasonic signals, and I read in it that it is possible to get the envelope of a signal by using a band pass FIR filter. My question: Is it possible to get the envelope ...
• 117
1k views

### Extracted envelope via Hilbert Transform is tracking the signal

I am trying to extract the envelope of the signal shown in blue, which is the low-pass filtered output of a second-order system. Low-pass filtering was done in order to reduce measurement noise. To be ...
• 423
1k views

### Signal envelope

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?
• 1
1 vote
904 views

### Recover IQ samples from signal

I have a data acquisition device that provides me with an array of integers that represents a modulated signal (let's say QAM16). I would like to recover the I and Q samples from the raw time-domain ...
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