Questions tagged [phase]

A quantity representing the fraction of cycle of a periodic signal, usually represented as an angle.

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Calculating phase difference between two vibration signals

The idea behind this question is for misalignment fault we say vibration signals across the misalignment are out of phase. If the signals are just sinusoidal signals with one frequency calculating ...
Genos's user avatar
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Interpolation of STFT between time and frequency bins

I am trying to identify and remove airplanes in a time series obtained at a radio meteor receiver. Here we have a spectrogram which displays the power content of my signal as a function of frequency ...
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Sliding Window correlation vs cosine of relative phase

I create two band limited signals having a specific time-varying covariance at each time point using cholesky decomposition. My aim for this experiment was to show a scenario where sliding window ...
Sir-Lord's user avatar
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FFT-based phase estimation better than CRLB in MATLAB simulation

I am trying to understand the concept of CRLB for a simple sinusoid in AWGN with a simulation in MATLAB. According to Kay (p. 57) the CRLB for phase estimation is: $var\{\phi\}=\frac{2(2N-1)}{SNR\cdot ...
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Is it possible to use np.fft.fft to pick out the Fourier coefficients from one timepoint, at a specific frequency?

I am trying to apply np.fft.fft on a 2D array of data of shape (98, 1024), where 98 is the number of trials and 1024 is the sampling rate in Hz. I am trying to find ...
Lisa Duan's user avatar
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What exactly is a frequency component, and what is the phase shift from the argument of the Fourier Transform relative to?

I'm an EE undergrad that struggles heavily with the intuition behind the Fourier Transform (most likely due to a shoddy mathematical foundation). Specifically: From what I understand, the real part ...
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Phase of a Complex Exponential

It is known that the discrete-time Fourier transform (DTFT) of a complex exponential $$ x[n] = e^{j\omega_0 n} $$ is $$ X(e^{j\omega}) = 2\pi \sum_{k = -\infty}^{\infty} \delta(\omega - \omega_0 + 2\...
Sami Al-Dalahmah's user avatar
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Method to extract a phase between input and output of a nonlinear system

I have a nonlinear (blackbox) system which gets a singular frequency (f) signal as input: input = A*sin(2*pi*f) + B And I get an output signal, which has ...
ValientProcess's user avatar
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2 answers
252 views

First-order allpass filter coefficient calculation

Given the first-order IIR allpass filter depicted below, I would like to calculate the coefficient $a_1$ such that a phase shift of $\frac{\pi}{2}$ occurs at a desired frequency $f_\mathrm{c}$ (the ...
wolframw's user avatar
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How to calculate Coarse & Fine Carrier freqeuncy Offset using Short and Long training Preamble respectively! Equations not understood

I am transmitting an OFDM signal. According to 802.11a Standards, I am using Short and long training Preamble each has length of 160 samples for time and frequency synchronization. According to Essam ...
Walkürie's user avatar
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How to convert the phase noise spectrum density to frequency spectrum density?

Following the answer in this post: Phase noise and frequency noise relationship, I can calculate the phase noise spectrum density with the unit from $\frac{dB_{c}}{Hz}$ to $\frac{rad}{\sqrt{Hz}}$. ...
Zhixing Lin's user avatar
2 votes
1 answer
72 views

Finding phase of frequency response as a function of frequency

I am trying to calculate manually the phase of the frequency response of an LTI system as a function of frequency and plot the results. The original system is described as $y[n]=0.1(x[n]-x[n-1]+x[n-2]$...
Samantha Garcia's user avatar
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Phase correction of a received signal

How is it possible to correct the possible phase distortion of a typical signal which has been received by an antenna and passed through different analog elements including an amplifier and a band ...
Fernando Sanz's user avatar
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How to get defect image from unwrapped phase image?

My problem is how to get the third and fourth image using first and second image. The first one is unwrapped correspondence image in x direction. The first one is unwrapped correspondence image in y ...
Uy Linux's user avatar
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Complex samples in OFDM signal, after fft-block at the receiver, have rotating amplitude towards zero even after phase correction

First of all, please consider my lack of experience/background in real time transmission using SDR especially if my explanation was expressed technically well.enter image description here I have ...
Walkürie's user avatar
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OFDM complex symbols have dynamic phase shift after the fft-block & before the BPSK demodulator at the receiver ,

I have transmitted and received an OFDM-signal using the same ADALM-Pluto-SDR's Tx/Rx Antenna. I have used BPSK baseband modulation with symbol freq=312.5 KHz, L (length of ifft)=64, fsampling=fsym*L=...
Walkürie's user avatar
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Why is the phase of the FFT not exactly 0 degrees for a cosine and 90 degrees for sine wave?

Let's say I have two signals. The first is a cosine wave and the second is a sine wave. Each oscillates at 0.01 Hz. The sample rate is 1 Hz and the length of time series is 1000 seconds. Each has an ...
Darcy's user avatar
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Extracting the phase using FFT without detrending

I'm trying to use FFT to extract the phase of the following signal: This is just a function in the form of: m*t + 5*sin(2*π*f*t - π/4) Is it possible to get the <...
ValientProcess's user avatar
1 vote
1 answer
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Does phase shift introduce high frequencies?

In PSK phase modulation scheme, the signal phase is shifted, hence it looks something like this: I cannot understand why this doesn't introduce a set of unwanted high-frequencies, as the steep ...
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PLL in noise-free and noisy channels

I'm trying to evaluate the performance of PLL in compensating the phase noise in the absence and presence of AWGN noise, and the counterintuitive result I consistently get is that PLL performs better ...
Math_Novice's user avatar
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How to compute the direction/bearing of a vector time series in the frequency domain (i.e. as a function of frequency)?

I have a time-domain magnetic field, $\mathbf{b}(t)$, with components $b_x(t)$ and $b_y(t)$ where $x$ and $y$ denote orthogonal coordinate directions (i.e north and east, respectively). At each time, ...
Darcy's user avatar
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Probability distribution of phase of fourier transform of white noise, colored noise (1/f noise in particular)--- Definitions and standards

What is the probability distribution of phase of fourier transform of white noise and colored noise (1/f noise in particular) ? Is there a standardised definition? Often, the colored noise is derived ...
vikram 's user avatar
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Variance of phase estimation using FFT as a function of SNR, frequency and signal length

I have looked at previous questions on this topic but I am still unsatisfied. I want to predict how accurately I can estimate the phase of a tone as a function of signal SNR, tone frequency, and the ...
LDPC's user avatar
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Is lock-in amplifier a correct approach?

I have a noisy signal which is the voltage output from a photodetector circuit. I have researched about extracting signals, and found that lock-in amplifiers are one of the main approaches for the ...
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1 vote
1 answer
189 views

Lock-in Amplifier: How to improve the output of lock in amplifier?

I tried to extract a pure signal from the noisy signal using a lock-in amplifier with the help of python code. The output is from a photodetector circuit. These are the reference signal, expected ...
Teena's user avatar
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1 vote
2 answers
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Averaging a Signal with a delayed version of itself

I am working on a problem that requires interpolating between two music files. One music file is very similar to a delayed version of the other. I would like the 'average' of the two signals to sound ...
Mason Wang's user avatar
2 votes
2 answers
269 views

How to calculate the phase difference between two squarewaves of same frequency but different dutycycle?

I have two squarewaves of the same frequency but with different dutycycle. How can I calculate the phase difference between the two? I know that for sinewaves one can use the correlation coefficient, ...
eeqesri's user avatar
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Loss of Resolution When Shifting Up With FFT / Phase Vocoder Pitch Shifter (Compared to Shifting Down)

I am working on a project writing a realtime FFT / phase vocoder based pitch shifting algorithm in C++. In development, I notice that shifting down has much better audible pitch tracking and ...
Emmett Palaima's user avatar
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1 answer
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How can I apply a phase shift to an LFM pulse?

I am modelling radar scenarios in python and am trying to make a model which retains phase information. To do so, I'm envisioning something which works like this: Generate samples of an LFM waveform ...
Jim's user avatar
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2 votes
1 answer
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Average of a set of transfer functions: how should I treat the phase?

I have a set of transfer functions obtained by impacting an instrumentation hammer against a mass, measuring the acceleration on a set of accelerometers; the result is shown below. I want to get a ...
Julio's user avatar
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1 vote
0 answers
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Phase rotation compensation in AOA

We are using $4 \times 4$ corehw antenna array with nrf52833 mcu as the receiver and nrf52833 as transmitter. When working on AOA Direction Finding, we found that each element in the antenna array has ...
user68463's user avatar
0 votes
2 answers
445 views

Low-pass Filter with constant phase response

I would like to design (e.g. in GNU-radio) a low-pass filter where up to the cut-off frequency the phase-response is constant (I do not mean a "linear-phase response"). The rationale is to ...
mabeco's user avatar
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1 vote
2 answers
305 views

Design a Real FIR with arbitrary Phase Response

Intro My question is related to this one: Correcting phase response of a signal. I need to design an FIR low-pass filter with real coefficients for data received from a sensor. An additional ...
Yair M's user avatar
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2 votes
1 answer
155 views

Why extracted minimum phase component have inverted phase?

I'm using Octave code to extract minimum phase, but this minimum phase has became inverted phase acording to original signal, What is goin wrong? Resault here I have shifted main signal about 48 ...
mohammadsdtmnd's user avatar
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1 answer
40 views

Introducing periodic jitter to a clock

This question is about the ideal digital clock. Lets consider an ideal clock with 0 raise time and 0 fall time i.e. perfect square wave. As shown in the diagram below. Let the original clock period be ...
arun's user avatar
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Calculate Phase Shift Using FFT

I'm not a specialist in this field and learnt FFT fairly recently. I want to calculate phase difference of between 1 MHz signals sampled at 4 MHz. The sample counts are both 144. I think the ...
Sukho Suh's user avatar
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0 answers
77 views

Phase Unwrapping Behaving Oddly For Optics Simulation

In short, I am coding an optics simulation for an experiment I am running. There is a point where I perform a Fourier transform on my incoming signal and want to extract the phase; however, I get ...
user68185's user avatar
0 votes
1 answer
100 views

Pitch tracking and phase

I wish to control a simple pitch tracker using my voice. So far I have experimented with fft and yin. I am extracting the frequency and amplitude in real time. I then feed these into: ...
Baz's user avatar
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0 answers
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How to compensate for rotational offset for Steering vector of a phased antenna array

I am working with antenna phased arrays for direction finding. According to the manufacturer of the antenna some elements of the uniformed rectangular array (URA) have a rotational difference. This ...
Yudop's user avatar
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1 answer
62 views

How to explain the ripple in this graph?

Hi everyone I need your help to understand this phase response would you please share your ideas?
ALI's user avatar
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1 vote
2 answers
561 views

Can someone explain the phase spectrum of a sinc function?

The Fourier transform of a sinc function will result in a rect function. Suppose I have a discrete time-domain sinc function with a frequency of $\omega_0 = 0.1$ Hz and amplitude of $A = 10^{-3}$: If ...
Darcy's user avatar
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2 votes
1 answer
150 views

Why is there a difference in the phase when using fft versus a manual DFT on a cosine signal?

Apologies if this is a duplicate, but I can't find a good answer anywhere. If I have a time-domain cosine signal of the form: $$x(t) = A\mathrm{cos}(\omega_0 t)$$ Then this will result in an Fourier ...
Darcy's user avatar
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how to log phase of NWC Australia 19.8KHz in a file in python

First I am very new in this field,and i am doing a college project and i stuck at determining phase of msk signal which is transmitted from a radio stations called NWC Australia 19.8Khz , so let me ...
Somen Das's user avatar
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0 answers
52 views

Modelling phase noise for self-heterodyne method

I am trying to model the phase noise $\phi(t)$ of laser used in self-heterodyne method using python code. The noise is time-dependent. The noise follows the condition that $$\langle(\phi(t)-\phi(t-\...
FearlessVirgo's user avatar
0 votes
1 answer
204 views

Phase Spectrum of Signals

I did fft of a fish's trajectory, because it looks periodic and I tried to find the frequency. However, I can't understand what does the phase spectrum below represent. Does this lower left to upper ...
wannastudycommunication's user avatar
1 vote
1 answer
199 views

phase unwrapping relative to a reference

I have samples of wrapped $(-\pi,\pi)$ phase from a bandlimited signal $A(t)\cos(\pi\omega t + \phi(t)+\theta_0 )$ Frequency is constrained by very regular physics and I know a preliminary guess $\hat{...
Eli S's user avatar
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3 votes
3 answers
927 views

Phase compensation using IIR allpass filters

As an exercise with IIR allpass filters, I am trying to compensate the phase of a lowpass Linkwitz-Riley filter using the Matlab integrated function iirgrpdelay. The code I am using is the following: <...
skateskate's user avatar
2 votes
1 answer
64 views

Filtering after a phase domain ADC

While researching receiver architectures for the demodulating constant envelope signals like a GFSK, I stumbled over the concept of phase domain ADCs, where after $$\boxed{\text{LNA}}{\longrightarrow}\...
njg's user avatar
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0 answers
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Integrating CWT around nominal frequency with amplitude and phase

I have a real signal f sampled at 96Hz composed of clusters of harmonics scattered tigthly around evenly central frequencies close to 1Hz and 2Hz (multiples of 0.966Hz) that I'll call features. These ...
Eli S's user avatar
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1 vote
1 answer
195 views

Finding phase of a received signal using spectrogram function

I am trying to find the phase of my dataset between a range of frequencies. I can't post my code or data but generally speaking, the frequencies range from 10 to 100kHz and I need the phase between 20 ...
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