Questions tagged [phase]

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

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Finding the right phase offsets for minimizing the highest absolute value of a sum of sinusoids

suppose I have a sum of cosine waves. Their frequencies are 500 Hz, 501 Hz, 502 Hz and so on, all the way up to 900 Hz. The important thing here is that the amplitude of the slowest one and of the ...
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Time delay vs phase ramp, group delay and phase delay

I need to apply a phase ramp in the frequency domain to a signal in order to apply a delay to it in the time/digital domain. However, I am confused by the fact that if I convert the phase ramp into ...
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Linear Phase in equiripple filters

How come equiripple filters are symmetric/anti-symmetric in time, but do not posses linear phase, but only piecewise-linearity? Do not all FIR+symmetric/anti-symmetric have Generalized linear phase?
Processor48's user avatar
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How to recover carrier frequency from pm signal

I have a signal $$x(t)=\sin(\omega t + g(t))$$ where $\omega$ is carrier frequency and $g(t)$ is message signal. Given that message bandwidth is much less than carrier frequency, how do I extract ...
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Iterative GA algorithm For Antenna Pattern Matching

The following code creates a cosecant squared radiation pattern. There are phases and an amplitude_norm_V vector which are the coefficients of an Array Factor (AF) expression as the response of an ...
user70731's user avatar
2 votes
3 answers
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Wideband phase vs time delay beamforming correction

I am studying a 1D beamforming for wide-band signals, so that applying only phase weights to each individual antenna would steer the beam for the central frequency. For other frequencies the steering ...
Albert's user avatar
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Does calculating the phase margin when the phase is positive has any meaning?

I want to calculate the phase margin and the gain margin of my transfer function to have an idea about the system's stability. The transfer function is quite complicated since it contains an ...
Bilal abu kamal's user avatar
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Array factor phased array beam steering problem

I have created exactly the array factor formula in matlab . But when i add the beam steering delta member it does nothing to the main lobe. Why it stays the same? Thanks. ...
user70731's user avatar
1 vote
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Why in 2D Fourier Transform phase seems to be more "useful" than magnitude?

In 1D signals f(t) (e.g. a sound signal - independent variable t-->time) when we want to use informations from the Fourier transform F(ω) in order to reconstruct the signal, using the magnitude |F(...
user1198483's user avatar
1 vote
2 answers
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In the frequency domain of a phase modulated signal, why there are are prominent frequency components which are multiples of sampling frequency?

In the frequency domain representation of a digital phase modulated signal, why there are prominent other frequency components which are multiples of the sampling frequency, other than the main ...
Kiran Gunathilaka's user avatar
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What exactly is the carrier phase in a RINEX file?

RINEX files are containers for preprocessed data in GNSS receivers. I want to know what exactly the 'carrier phase' means. As far as I can tell, the carrier phase is simply the phase (that is, a value ...
requiemman's user avatar
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Minimizing maximum instantaneous magnitude by applying phase shift

Suppose I have the following sum, where all the input variables are positive real numbers while the output is complex-valued data $$a e^{i \left( x + y \right)} + a e^{i \left( x - y \right)} + a b e^...
5-limit_JI's user avatar
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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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5 votes
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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
4 votes
1 answer
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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
1 vote
2 answers
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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 ...
Philip's user avatar
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3 answers
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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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1 answer
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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
1 vote
2 answers
279 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
1 vote
1 answer
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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
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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
1 vote
1 answer
102 views

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
1 vote
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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
4 votes
1 answer
856 views

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
136 views

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 ...
matt's user avatar
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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 ...
Teena's user avatar
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1 vote
1 answer
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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
309 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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1 vote
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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
206 views

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
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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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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
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2 answers
521 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
345 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
161 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
0 votes
1 answer
48 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
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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
113 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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