# Questions tagged [hilbert-transform]

Hilbert Transform is an operator of a function of time or frequency domain that, unlike the Fourier Transform, returns a function in the same domain. The Hilbert Transform of $x \left( t \right)$ essentially preserves magnitude and shifts the phase of all positive frequency components by -90° (Also shifts the phase of all negative frequencies by +90°).

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### Is it possible to implement a block-wise Hilbert transformer using FFT

I'm implementing a discrete Hilbert transformer and I know that an ideal Hilbert transformer is anti-causal and has infinite length so we can only make approximation. There are some FIR and IIR ...
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### Why does fourier transforming an analytic signal gives me negative frequency components?

I consider an array: import numpy as np from scipy.fft import fft from scipy.signal import hilbert a=np.random.rand(5) First I manually compute the fourier ...
• 103
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### How to determine which imf to use when calc a signal's instantaneous frequency?

I'm using pyhht and scipy and pyhht to calculation signal's instantaneous frequency.I had use EMD get the signal's imfs. But I don't know use which imf in this imfs to ...
1 vote
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### 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 ...
• 93
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### Best method to measure phase difference between acoustic recordings of sine wave?

I am using multiple digital MEMS microphones in an array which are 8mm apart. Now I recorded a sine wave of 20kHz for calibration (at angle 0°) and want to measure the phase difference over time ...
• 33
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### 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 ...
• 93
1 vote
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### Hilbert transform modifications for a non-sinusoidal waveform

I have recently been using the Hilbert transform a fair bit and its ability to return a instantaneous phase and magnitude estimate but it has got me thinking about the meaning of phase. From my ...
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### Why is there coherence below the cutoff frequency of two high-pass filtered signals?

I record surface EMG signals from two muscles at 1500 Hz. The following preprocessing steps are performed using basic MATLAB commands. First, I decimate both signals to 500 Hz (Lowpass filtering ...