Questions tagged [phase]

The tag has no usage guidance.

Filter by
Sorted by
Tagged with
5
votes
1answer
4k views

Phase synchronization in BPSK

In BPSK for demodulation at the receiver end we do phase recovery between received wave and carrier wave. We can find the phase difference between the carrier and received waves using : PLL And ...
22
votes
1answer
6k views

How to circularly shift a signal by a fraction of a sample?

The shift theorem says: Multiplying $x_n$ by a linear phase $e^{\frac{2\pi i}{N}n m}$ for some integer m corresponds to a circular shift of the output $X_k$: $X_k$ is replaced by $X_{k-m}$, where ...
41
votes
5answers
55k views

What is the difference between phase delay and group delay?

I'm studying some DSP and I'm having trouble understanding the difference between phase delay and group delay. It seems to me that they both measure the delay time of sinusoids passed through a ...
13
votes
1answer
10k views

How to perform carrier phase recovery in software?

What are the options for recovering the phase of a BPSK signal in software? The only resources I can find online contain circuit diagrams – there seems to be no one willing to explain this to people ...
11
votes
2answers
1k views

How to build a phase shifter with arbitrary phase shift

Fred, a DSP engineer, goes to his favorite DSP store to do some shopping. Fred: Hi, I'd like to buy a phase shifter. Shop assistant: Hmm, what exactly do you mean? Fred: Well, you know, if you put ...
3
votes
2answers
342 views

Should the phase coefficients of the DFT of a real, even input signal all be zero?

The phase coefficients of a real, even input signals should all apparently be $0$ or a multiple of $\pi$. That's a property of the DFT I've learned about in the Audio Signal processing course on ...
0
votes
1answer
2k views

once again,confusion between phase and group delay [duplicate]

Despite,reading up on this I'm unable to find crystal clear clarity on the differences b/w phase and grpdelay functions and interpretation of grpdelay's output. I have designed a low pass butterworth ...
2
votes
1answer
965 views

Minimum phase FIR method

I am trying to make a minimum phase filter (in wxMaxima) according to these steps: first create a "normal" FIR (a simple sinc, wc=0.4, random example, but in the pictures a remez with Octave) ...
1
vote
2answers
202 views

Understanding the phase in DFT

Although using regularly the FFT algorithm to compute DFTs, I don't really understand how the phase part works. e.g. in Matlab: ...
0
votes
1answer
80 views

Binary and Quadrature Phase Shift Keying [duplicate]

I was learning Modulation Techniques and was on the topic Phase Shift Keying (PSK). As far as I have understood, In Binary PSK we encode a single bit on a one signal element and we differentiate ...
0
votes
2answers
3k 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 ...
9
votes
3answers
9k views

baffled by fft phase spectrum!

A very simple MATLAB experiment: f = 200; fs = 1000; t = 0: 1/fs : 1; x = cos(2*pi*f*t); plot(angle(fftshift(fft(x)))); And here's the output: Now, made ...
3
votes
1answer
630 views

proving that a log gabor filter has 0 DC offset

I have read somewhere online that the log gabor filter has an advantage over the gabor filter, in the sense that it has 0 DC component. How do you prove this property mathematically? Thanks in advance....
9
votes
4answers
5k views

Can a causal filter without phase shifts exist?

When I was studying dispersion of refraction index in semiconductors and dielectrics, my professor tried to explain that if a filter (like a dielectric absorbing some light frequencies, or an electric ...
8
votes
3answers
8k views

How important is it to use power of 2 when using FFT?

Here is the problem. I have a 2D array of data, first column represents the time data and the second column represents the sinusoidal response data, based on the time data. I apply fft and I get my ...
8
votes
2answers
7k views

Phase Correlation - Poor Performance on Noisy/Blurred Images?

I have successfully tested 1D phase correlation algorithm to determine vertical shift between two synthetic images. When I moved to real images, however, it is not able to detect translation at all (...
5
votes
5answers
14k views

What is an Intuitive Explanation of the Phase of a Signal

I understand that the meaning of the phase response of a system is simply how much the system delays a frequency component. However, I do not find an intuitive explanation for the phase of a signal. ...
2
votes
3answers
237 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_\...
4
votes
3answers
5k views

Converting from a phase response to a group delay response and vice-versa

I'm trying to figure out how to convert any phase response to the corresponding group delay response. Is there a way to do that, and vice-versa if possible?
0
votes
2answers
2k views

Why does a pole close to the unit circle result in an enhanced Q-factor?

I have the following pole zero plot (in Z-domain) of a digital filter, where its poles lie far away from the unit circle, with its corresponding frequency response: On the other hand I have this one:...
5
votes
1answer
770 views

Phase Locked Loop Basics

I am trying to better understand discrete-time PLLs. I drew a picture of a simple feedback system here: I want to be able to describe and understand the system at v(t) and y(t). I found a fairly good ...
2
votes
5answers
16k views

Best method to extract phase shift between 2 sinosoids, from data provided

I have been asking around if the way I was extracting phase shift (lag) was correct, and I ran into some trouble. So in general, given 2 arrays of data of the same length, representing: the input ...
2
votes
1answer
542 views

Transform linear-phase FIR to minimum-phase FIR

Given a FIR filter (non-causal) with phase zero and real coefficients given by $$H(z) = \sum_{n=-M}^{M}h[n]z^{-n}$$ with ripple $\delta_2$. How can I obtain a filter $H_{{\rm min}}(z)$ of minimum ...
1
vote
2answers
143 views

DCT vs DFT why do we need/want phase?

Why do we use complex exponentials in the Fourier transform, why do we want the phase part? As opposed to in DCT where there is no phase and only magnitude? Moreover, what does this phase concretely ...
4
votes
2answers
5k views

Extracting accurate phase and amplitude information from FFT with an arbitrary number of samples

This is a followup question to one I asked earlier based on the chat after the answer given by @hotpaw2, and cross-posted from stackoverflow since it was suggested it is more relevant to DSP. I have a ...
4
votes
1answer
108 views

Group Delay for Hilbert Transformer and Resulting Dispersion

An ideal Hilbert Transformer shifts the phase for all positive frequencies by $-\pi/2$ and all negative frequencies by $+\pi/2$ while maintaining constant magnitude everywhere. Group Delay is the ...
3
votes
1answer
5k views

How does time shift correspond to phase change in a discrete signal?

I was watching this video where the presenter remarks: For a discrete signal, time shift corresponds to phase change in a discrete signal but not vice versa. I was trying to figure out how this ...
2
votes
0answers
491 views

How to find the phase lag between a sinusoidal input force and the response?

I have a system that is forced by a sinusoidal function with specific amplitude, phase and frequency. I get a deformation of sinusoidal form as well, and I would like to find the phase lag. I use FFT ...
2
votes
1answer
528 views

Signals cross-correlation

I am trying to measure phase difference between two received waves which are recorded by two separate PC's (microphones). The two PC's starts recording at the same time, then I make a sine wave sound ...
1
vote
0answers
596 views

Hilbert Transform, filters - two different phase graphs

Relationship between magnitude response and phase response for minimum phase is: Phase plots are obtained from Hilbert transform of real magnitude values. Input to Hilbert transform was a vector (...
1
vote
1answer
1k views

Phase difference between two sinuisoidal signal

Currently, I have two signals, the main components of both signals are 60Hz, but both also have weaker response at 180Hz + small amount of noise. As shown in the photo below, I want to find the phase ...
1
vote
3answers
3k views

What does the term phase actually mean?

I am new to seismic data processing and I really have no understanding of the term 'phase'. So, could anybody give me a simple explaination of the term? Thank you
1
vote
0answers
39 views

How to deal with phase incoherence issues after manipulating a signal in the frequency domain?

Let's say that we want to manipulate a signal in the frequency domain using a short time Fourier transform and once we're done , we use an inverse STFT (plus overlap and save) to convert the results ...
1
vote
1answer
180 views

Periodically-varying phase between transmitted sound and received sound

I have a function that can find the phase difference between two signals, this function uses Hilbert transform to do so. Here is the python code for it ...
0
votes
2answers
207 views

Phase response of FFT in practice

As I know if the impulse response is symmetric around sample zero phase response should be entirely zero. The code below just set a rectangular window for vector "in" ...
0
votes
1answer
372 views

How to find phase difference between 2 signals, one has an unknown function

I have a system that is forced by a sinusoidal function with specific amplitude, phase and frequency ( all these are known ahead of time). I get a deformation of sinusoidal form as well (think of a ...
0
votes
1answer
142 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 ...
0
votes
1answer
92 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 ...