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FFT - How to calculate real phase shift

When I calculate from FFT the phase shift like that: atan2(fft.imag(),fft.real()) * 180 / M_Pi It always gives me the value between -180° and +180°. And when ...
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12 views

Algorithm for “Signal => STFT with reassignment => masking => ISTFT => Output signal”

It is well known in DSP that this is a successful method to modify audio signals: Signal => STFT => masking => ISTFT => Output signal For example, ...
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12 views

Analytical Calculation of the Phase Contribution

I'm willing to analytically calculate the phase contribution of the complex singularities. So far, I'm using $\ b(\Omega) = -arg\{e^{j\Omega}-z_{0,1}\}$ equation for calculating phase contribution, $\...
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2answers
87 views

What exactly is a 90 degree phase shift of a digital signal in FM demodulation appraoches?

I am working on an FSK demodulator (1200/2200Hz, 1200 baud) featuring a 90 degree phase shift operation. I don't exactly understand what 360 degrees mean for a digital signal. My sampling frequency ...
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1answer
54 views

Phase shift problem in Fast Fourier Transform

I try to make graph/print for magnitudes and phase shifts for impulse response calculated by FFT. For magnitude everything works perfect, but for phase shift I get some strange curve for higher ...
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23 views

FFT phase spectrum not correlate with DSA

I am trying to use an USB DAQ to replace DSA 35670A (Keysight) as the instrument is going to be discontinued the end of this year. I am measuring target vibration response by driving chirp signals ...
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1answer
45 views

OFDM: How to do the carrier recovery of the quadrature(I/Q) demodulation

For an OFDM system, after the OFDM modulation, the quadrature modulation is used to move the signal from the baseband to the pass-band. But when it comes to the receivers, I can't find any way to make ...
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2answers
56 views

Relating phase difference in a signal with its frequency

I have a 134 point complex signal. Using MATLAB, I have observed that the phase difference between any two adjacent samples of this signal is 2 radians i.e. the phase increases linearly from 0 to 268 ...
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1answer
12 views

Is the phase difference between recorded sounds from left and right ear the same as the phase difference between their HRTF?

Pardon my ignorance if my question is silly. Lets say I did a binaural recording and found the phase difference between right and left channel. If the recording was done in anechoic chamber, where ...
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1answer
45 views

Phase wrap when computing impulse response from frequency response [closed]

Short: I have the frequency response of a system as a set of complex numbers. I want the impulse response for that system. Problem: The phase of my frequency response wraps around 2pi multiple times....
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2answers
171 views

Can the instantaneous frequency be always derived from an analytic signal?

Instantaneous frequency can be defined as a derivative of an instantaneous phase of an analytic signal which can be nicely seen in practice in this example from Scipy's documentation. But it seems ...
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0answers
46 views

Hilbert transform “pass band”

I sample a human speech at 24kHz, to make the Hilbert transform using FFT and iFFT. What are the minimum and maximum frequencies (or range of frequencies), which will be 90 degrees shifted? Maximum ...
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1answer
36 views

Phase of a signal with multi delayed windowed (rectangular window) signal with different amplitudes

I have a signal $x(t)$ which is composed of multi delayed linear chirps with different amplitudes and phases but they share the same $w$ and $\alpha$, the signal can be expressed as follows: $$\...
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32 views

Simulating Phase Noise: How to do it?

I have a system that I am simulating, and I want to add phase noise to the process. I didn't know how to do it, so I have been conducting an literature review. I found a good reference with an "easy ...
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1answer
56 views

About phase unwrapping

I am not too familiar with phase-related problems so I need some suggestions or corrections in a problem that might be an old but easy one. Here is my problem: given a complex signal: $$y(t) = e^{j\...
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3answers
40 views

Phase response of a FIR Hilbert transformer

The graph below shows a linear phase response of FIR Hilbert transformer with a constant diff of -0.06135923. I am not sure if I understand the concept of the phase response correctly, but as the ...
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0answers
29 views

How to know whether numerical roundoff error or not in MATLAB?

This is result of real and imaginary parts of cos fft. I think e-13 number is numerical error but, I don't know how to know they are real numerical error. If I have to try change primitive types, ...
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1answer
40 views

Phase and Amplitude estimation

Context: I have used FFT many times, but for real, non-periodic signals I consider it a poor estimator. For most of my applications I am only interested on the power spectrum, so I use the Welch's ...
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1answer
53 views

Why MATLAB fft cos makes imaginary parts?

The cos fourier transform has no imaginary parts, but in this code it has imaginary parts that little big. %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% figure(7); fs=128; t=-4*pi:1/fs:4*pi-1/fs;...
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30 views

Passband filter before Hilbert transform

I have a .wav file of human speech sampled at 48kHz. Before making the analytic signal with: hilbert(s_real) lets say in range 200 - 3,500 Hz, I probably need to do pass-band filtering, say 300 - 3,...
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1answer
29 views

Converting Time Shift to Phase Shift

I have just started taking signal & systems lessons and here is my question: If we say that x0(t) = A.cos(w0t). (a cosine signal with zero phase shift, w0 ...
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3answers
139 views

Phase change rate of human speech

I have a .wav file of human speech, sampled at 48kHz, with useful signal up to 5kHz, and almost no noise. If I do Hilbert transform in MatLab, I get the Analytic signal: $$ s_\mathrm{a}[n] = s_\...
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0answers
50 views

Cosine Fourier Transform and Phase

If we do FT of cosine wave, then sine wave will be orthogonal. So, the imag parts of FT will be 0. This is my think. But, the result isn't show that. Like this. Figure 1. Real and Imag parts (Y label ...
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39 views

Bandpass Fractional Delay Filter

I am designing a fractional delay filter, I found this code for lagrange FIR fractional delay filter, The fractional delay filter acts as a low pass filter, it passes low frequencies from 0 to 0.25*fs....
2
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1answer
125 views

Discrepancies between FFT-based Hilbert Transform and FIR filter results

I compared the results of Hilbert Transform as provided in scipy.signal.hilbert() (which is uses I/FFT as you can see in the source code) with its approximation implemented as FIR filter using coeffs ...
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2answers
51 views

Phase ambiguity in QAM modulation

I'm currently studying a decision directed carrier recovery scheme. Basically a PLL try to estimate the phase error in the current received symbol, the phase detector compensate the incoming symbol's ...
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2answers
41 views

Why the angle of a real signal in frequency is continuous?

This original signal is shown below (time domain): It is a real signal. According to the signal processing theory, the form part of the angle is conjugate to that of the latter part. That is, $\...
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1answer
91 views

extracting ultra accurate phase and frequency with FFT with real world data

I was doing some experiments in Matlab, and write this code to experiment with it. I want to know if it's possible to extract accurate within -+0.01° phase info from samples of an ADC, the matlab FFT ...
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0answers
29 views

How does the M-law Synchronizer work?

Relatively new to DSP, I've came across the approach for phase-estimation of PSK-Signals x(k): My question is: What do we get by exponentiating the Baseband-Signal?
7
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2answers
404 views

QAM constellation slicer with unknown carrier phase

As shown in the image, I have a 16QAM constellation that is misaligned due to a phase rotation. In this case you can see that rotation amount is approximately $\theta = \pi/4$, but this won't be the ...
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0answers
68 views

Phase Noise in OFDM simulation

I am trying to simulate phase noise in OFDM and in search of a mathematically tractable model. So far, I have managed to get phase noise by multiplicating $e^{j\phi(n)}$ in frequency domain where $\...
0
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1answer
74 views

Measuring acoustic phase difference between two receivers

I am trying to measure the acoustic phase difference between two sensors 30cm apart each other. The sampling frequency is 20kHz, and my interest frequency is about 1700 Hz. The below is how I ...
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1answer
50 views

Adaptive filter to scale and phase shift two sensors output

One way of separating downgoing and upgoing wavefields in offshore seimic processing is to add signals from hydrophone and vertical component of the geophone (they are co-located). Hydrophone only ...
3
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1answer
101 views

Phase Modulation and Intermodulation Anomaly ? (Spectrum plots inside - **Updated**)

I have a MATLAB script for modelling a two tone signal (a sum of two sinusoids) going through a non linear transfer function (such as an amplifier). The amplitude of a signal is amplified non linearly,...
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2answers
80 views

Adding phase to a signal that has multiple frequencies

An amplifier changes the phase at different amplitudes of asignal. I am using amplifier data in a MATLAB model. I have constructed a signal that is a sum of sinusoids of different frequencies with ...
0
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1answer
52 views

temporal high-pass filtering to approximate phase derivative

I am currently following the algorithm as based on a previously published research article "A Motion Detection Algorithm Using Local Phase Information" by Lazar et al. The basic overview of the ...
0
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3answers
86 views

How to calculate arbitrary phase shift in discrete signal?

When I have digital audio signal, represented in samples, I can easily phase-shift the signal by 180° by simply inverting the value of each sample. But what if I want to phase shift an arbitrary ...
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0answers
47 views

Oscillator resynthesis with interpolated phase in sinusoidal model

I'm implementing a sinusoidal model based on the STFT of an input signal: Analysis occurs at evenly spaced hops of S samples; spectral peaks are tracked and the peaks of analysis frame m are matched ...
0
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2answers
139 views

How to “rotate the phase”?

I have problem, not sure how to call it but I think it's something called "phase rotating", but not sure. I make fast Fourier transform on simply square wave, and then I make inverse fast Fourier ...
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0answers
17 views

Linear distortions in transmission systems [duplicate]

I am quite new in Signal Processing and I do not know even the basics. In my lecture slide notes, I came across with the following sentence: Phase distortions happen if the phase function b(f) of ...
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0answers
85 views

Removing I/Q phase rotation

What is the most reliable and agnostic way to correct for a phase rotation of I/Q downconversion - without time alignment of the signal and support different lengths of transmitted and received data? ...
3
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2answers
191 views

Phase function of filter

I have a filter with the transfer function $$H(z) = 1 - 2z^{-2} + z^{-4}.$$ The task is to find the phase function $\theta (\omega).$ My attempt is to start by expressing the frequency response \...
0
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1answer
76 views

FFT phase spectrum to suppress noise?

All that I heard so far about phase spectrum - that it is very hard to process. Are there any methods to do that, and is it possible to extract information about the noise from phase spectrum?
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79 views

multiplication of two signals with phases

I need to multiply two discrete signals in the following form $$(a(t)+i b(t))\exp{(i \phi(t))},$$ where $a(t)$, $b(t)$ and $\phi(t)$ are real smooth discrete functions along $t$. I need to obtain the ...
0
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2answers
53 views

Phase information from product of complex conjugate transfer functions

For an input signal $x(t)$ and output signal $y(t)$ through an LTI system I $H(t)$ I have found and interesting property that concerns signals' power spectral densities: $${\lvert H(\omega)\rvert}^2 =...
0
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1answer
72 views

Phase of FMCW linear chirp

I'm doing a project involving FMCW linear chirp signals. Given the phase $\phi = 2\pi\frac{k}{2}t^{2} + 2\pi f_{c} t + \theta$ where $k$ is the frequency increase rate. When transmitting ...
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2answers
138 views

What does the Phase part of a FFT of a received signal represent?

Imagine we've receive a signal, $R$, at a distance of $L$ from a transmitter. Then, we do FFT on the received signal. This is what FFT gives us: \begin{align} R(f) &= A e^{j\phi} \tag1\\ \ \...
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1answer
104 views

Could you please confirm my method or correct me on computing the phases of my signals?

I did some measurements, and I have two received signals in two different distances. By doing the fft on the signals, I have the spectrum, then by using the angle() function in MATLAB on my fft, I ...
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1answer
129 views

How to smooth (or interpolate) phase of FFT and reduce data points

I am writing some code for audio analysis, and have currently got two signals with FFT performed on them. I get the phase of my complex array by using: ...
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1answer
56 views

Question regarding DTFT of a complex signal

I have been doing DTFT practice problems for my DSP course, and I encountered this problem in the textbook that completely stumped me. The question asks to find the DTFT of the shown signal and to ...