Questions tagged [discrete-signals]
A discrete signal or discrete-time signal is a time series consisting of a sequence of quantities.
2,033
questions
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1answer
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Is the Schroeder Allpass implementation in Freeverb incorrect?
I've been looking into the venerable Freeverb and I see that CCRMA state that it uses 4 Shroeder Allpass filters in series, but when I look at the source code I see:
...
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2answers
54 views
Can we use Gardner timing error detector for multi level QAM or OFDM systems?
Sampling frequency offset (SFO) between the transmitter and the receiver in any system causes a gradually increasing timing error which is seen as an increasing phase rotation (function of time).
In ...
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2answers
48 views
Frequency response of discrete time system involving interpolation and resampling
I am working on a problem towards calculating frequency response of discrete time system(does interpolation followed by resampling) which looks like:
x(n) is fed to linear interpolator(h(t) = ...
1
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1answer
30 views
Mixed - Discrete and Continuous system Laplace domain stability - Effect of Sampler and DAC
I have a system whose the plant transfer function is continuous and the compensation is discrete. I have an ADC which allows to measure the output of the system and a DAC which allows to control the ...
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0answers
21 views
Random variation of Bit Error Rate (BER) with increasing SNR for QAM 64 System
I am simulating a communication system with a transmitter and a receiver, where the transmitting signal is in QAM 64 format. The transmitter is connected to the receiver (back to back) and at the ...
0
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1answer
49 views
Why is z (and not ω) the variable of interest for discrete time systems?
A continuous time domain system is well described by the Laplace transform. It allows to express any continuous signal x(t) as the integral sum of weighted complex and exponentially growing/decaying ...
4
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1answer
54 views
One Sided Waveforms in Discrete Time and Frequency?
Consider a discrete time waveform $x[n]$ with $n \in [0...N-1]$ that is zero for all samples $n > N/2$ and non-zero elsewhere. Is there a waveform such that its Discrete Fourier Transform $X[k]$ ...
0
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1answer
37 views
Ideal Allpass filter
Is it possible to implement an ideal allpass filter in Matlab?
The filter response should be like this:
Note: the photo is imaginary (I did it using paint).
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1answer
34 views
Identify out signal from in signal and impulse response
Hi there I am studying a course in signal processing and systems.
I was given an excecise which I am having a great deal of trouble solving.
I am allowed to solved using matlab, but for top marks I ...
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1answer
34 views
How can I add complex WGN to a complex damped signal for a specified SNR?
I want to add complex wgn to a signal for a specified SNR. I have been using the following lines:
...
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3answers
106 views
Some signals whose Fourier transform are a particular rotation of its self
Let $N\in \mathbb{N}$.
I am looking for a non-zero scalar $\lambda$ and a nonzero vector
$$f=(f(0),f(1),\cdots,f(N-1)) \in \mathbb{C}^N$$ satisfying the following equations for $l=0,\cdots,N-1$:
$$\...
0
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1answer
50 views
Apply FFT to positive spiky signal
I have a signal that looks like this
It has regularly occurring peaks 50 units apart, and offset from 0 by approximately 20. I thought I could apply the DTFT to this signal and extract the period (...
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1answer
53 views
How to compute convolution using the Discrete Hartley Transform
It's easy to compute the Discrete Hartley Transform of a 1D signal:
...
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1answer
89 views
1ppm Sampling clock offset in Matlab
How to emulate a sampling clock offset (between the transmitter and the receiver) of 1 part per million (SCO=1ppm) in Matlab?
Theoretically, I can upsample the signal by a factor of 1,000,001 (one ...
1
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1answer
53 views
Compare two Fourier transforms of two signals by calculating the coherence
My overall aim is to compare the edges of two images by comparing their Fourier Transforms (FFT) and to calculate one number as a key performance indicator that describes how much they are similar to ...
0
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0answers
29 views
fft result with the number of integer multiples of fs
With the cosine signal fc=3Hz and the fs=13Hz as below,
fc=3;
fs=13;
Ts=1/fs;
N=101*13; % 101 times of fs
n=0:N-1;
x=cos(2*pi*fc*n*Ts);
and then fft with the ...
0
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2answers
36 views
Discrete Fourier transform with negative frequencies
In the standard definition of Discrete Fourier transform, as in Wikipedia, only positive frequencies exist. I want zero frequency to be at the center of the spectrum. In such a case, how should I ...
0
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1answer
26 views
A discrete time signal $x[n]$ is defined in terms of unit impulse function.Express the signal $x[n]$ in terms of step signal
A discrete time signal $x[n]$ is defined in terms of unit impulse function as follow
$$x[n]= 1-\sum_{r=3}^\infty \delta[n-1-r]$$
If $x[n]$ is expressed in terms of unit step function as $x[n]=u[an-b]$ ...
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0answers
18 views
$Z$-transform of a multilinear function/ consecutive multplication of $k$ signals $y_1(n), \ldots, y_k(n)$
How should one go about calculating the $Z$-transform of a signal that is the multiplication of $k$ signals (i.e. a multilinear function with regards to signals $y_1(n) \ldots y_k(n)$ ? Namely, $\...
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0answers
18 views
I/Q Imbalance Correction using S.W. Ellingson Algorithm
Correcting I/Q phase and amplitude imbalance using S.W. Ellingson method.
https://www.faculty.ece.vt.edu/swe/argus/iqbal.pdf -- S.W. Ellingson Algorithm
When I try to use the set of equations to ...
0
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1answer
51 views
Discrete implementation of the PI controller
I have been implementing discrete PI controller in the incremental (velocity) form in C++.
I have been looking for the anti-windup mechanism. One idea which I have can be described by
following ...
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0answers
58 views
Problems discretizing a notch filter - Chebyshev Type I
I'm trying to implement and discretize a notch filter (Chebyshev type I) these specifications:
Ws = 2pi[2000 2500];
Wp = 2pi[1000 7000];
Rp = 0.5;
Rs = 40;
But when I try to use discretization methods,...
0
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0answers
36 views
How can I define x(t) in terms of n?(matlab)
I have a signal x[n], that is sum of two sinusoidal signals. $x(t)=sin(2𝜋100t)+0.7cos(2𝜋500t)$
...
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0answers
11 views
How to figure out frequency weightings on acceleration data using ISO 2631?
I'm trying to convert the raw acceleration data into frequency weighted acceleration data.
According to ISO 2631:
The acceleration signal may be analyzed and reported as either constant bandwidth or ...
4
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1answer
116 views
Is there mathematical relationship between the FFT and DCT transforms
I need to model the relationship between the DCT and DFT transforms (If it exists). I mean real signal $x \to y = \textrm{DCT}(x) \to z = \textrm{DFT}(y)$, so I need to get the relationship between ...
0
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1answer
46 views
If we take Z-transform of a signal & find its ROC. How to use this ROC? There are ∞ signals in ROC, suppose we choose any signal what to do with it?
If we take Z-transform of a signal & find its ROC. How to use this ROC? There are infinite signals in ROC, suppose we choose any signal from ROC, what to do with it?
1
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1answer
53 views
RF-Chain Signal Delay for Sensor Switching
Lets have a RF-chain as above with system bandwith from HP corner to the green line say 1 MHz.
The signal accumulates delay as it passes through this analog chain, and due to it being non-liner filter ...
1
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1answer
25 views
Is there a difference measure that is insensitive to shifts?
I'm trying to figure out a difference measure that is relatively insensitive to time shifts.
I have tried DTW (dynamic time warping.)
This is the result:
The signals on the left are clearly more ...
0
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0answers
21 views
How to determine STFT parameters as a function of desired resolution
None of the Q&As I've seen thus far have given a clear answer to what seems like a simple question: assuming I know the CenterFrequency, ...
0
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1answer
22 views
DTFT of $(-1)^{n}\frac{\sin((7\pi / 8 )n )}{\pi n}$
The DTFT without $(-1)^{n}$ is relatively easy but with $(-1)^{n}$ I am not sure how it would be solved. I hope anyone can help
0
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1answer
35 views
I tried two approaches and gained the different conclusions of judging the stability of the transfer function of the system
We want to judge whether the system is stable or not.
Given the below transfer function.
$$ H\left( z \right) =\frac{\left( 1+2 z^{-1} \right) }{\left( 2+z^{-1} \right) } $$
$$ H\left( z \right) ...
0
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1answer
75 views
How to take into account phase differences when doing Fourier Transform?
I apologize if the title seems very vague, I don't really know how to put it a different way.
From what I understand, the Fourier transform is essentially just doing a dot product between multiple ...
0
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0answers
30 views
What is the unit of the color axis on a Matlab spectrogram, and bandpower?
I am new to signal processing, but successfully made a spectrogram with Matlab. It is nice and working, showing the expected output on the graph, but I just cannot understand what the numbers mean on ...
1
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2answers
74 views
What is phase shift?
I'm reading about when a $H(z)$ system is min phase or max phase, and I get when a system is a min phase or max phase depending on the location of the zeroes. But I don't get at all the phase shift ...
1
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1answer
31 views
How to add complex WGN to complex damped exponential and compute SNR?
I am new to the Signal processing domain, So my question might sound basic. I am trying to reproduce the results from the paper Decimative subspace-based parameter estimation techniques by
Geert ...
0
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1answer
54 views
Why is $x[n]=\sin(\frac{12\pi n}{5})-\sin(\frac{2\pi n}{5})=0$
I was trying to find the period of $\sin(\frac{12\pi n}{5})-\sin(\frac{2\pi n}{5})$, each of the sinusoids has a period of 5 however their difference has a period of 1. It turned out that they're ...
0
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0answers
15 views
Log in MFCC vectors incorrect according to Source-Filter Theory
In the MFCC vectors computation given many in places and here we apply log after we average with the mel bands. However, the source-filter theory says that the source frequency is modified by the ...
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3answers
108 views
On what it means for a system to be minimum phase
From my undestanding I get that when a system's poles and zeros are all inside the unit circle then it means that it's minimum phase. But I don't get how the location of zeros and poles are related to ...
0
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1answer
30 views
Find response of discrete time LTI system given input and impulse response
For this question the guide says to use $Y(e^{j\omega}) = H(e^{j\omega}) X(e^{j\omega})$.
I have been able to find the discrete time Fourier transform of the impulse function as $$H(e^{j\omega}) = \...
0
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0answers
59 views
Let a LTI system be causal and stable with the transfer function being… show that
if the system is an IIR LTI causal and stable one, and the transfer function is
\[H(z)=\sum_{n=0}^{\infty}h[n]z{^{n}}= \frac{G}{1 -\sum_{k=1}^{p}a_kz{^{-k}}}\]
show that the cepstrum of this system ...
0
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1answer
45 views
What does frequency weighting an acceleration signal mean? And How do I frequency weight the raw acceleration data collected?
Disclaimer: I have very little knowledge in signal processing.
I'm trying to calculate a Whole Body Vibration(WBV) measure called Vibration Dose value(VDV).
$$VDV = \left(\int_{0}^{T}a(t)^4\,dt\right)^...
0
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0answers
42 views
Frequency response of chirp signal changes when extracting burst from repeating chirp waveform
I hope i can make myself clear enough, even though i might not be familiar with the right terms.
Using GNU Radio, i created a chirp signal with a sawtooth signal source into a frequency mod block, as ...
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0answers
48 views
Short Time Fourier Transform has different frequencies than Fourier Transform?
The reason we do the STFT is so that we can analyse for short segments of time how much of the components in the frequencies of the FT are present. However, it may be possible that completely ...
0
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2answers
57 views
Periodicity of complex exponential in continuous and discrete time (Eq 1.51, Signals and Systems by Oppenheim & Wilsky)
Hi All: This is very basic but I've always wondered about it and now I see it in print in a textbook so I may as well ask. In Signals and Systems on page 26, it says
$$e^{j(\omega_0 + 2\pi)n} = e^{j2\...
0
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1answer
104 views
Is there a Python method to calculate moving RMS of a signal? How to calculate the moving RMS using the discrete signal formula? [closed]
I'm trying to calculate a moving RMS of an acceleration signal.
One of the answers in the post, shows the formula for calculating moving RMS for discrete signal.
The formula they suggest:
I have a ...
0
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1answer
62 views
Frequency response of a long signal
I am trying to get the frequency response of a system, so, in theory I would need to do:
H = fft(y)./fft(x);
I have measured the system with a long stepped sine ...
1
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2answers
60 views
Best temperature compensation equation?
I'm looking for the correct temperature compensation equation to use on our project.
We are measuring the output of a detector who's signal is very sensitive to temperature drift.
Any external ...
0
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1answer
34 views
How to compute dBFS from rms-values if the samples exceed 32bits
For a first approach on audio-sampling I'm currently working with the raspberry pi's pcm pins and MEMS-microphones, using the ALSA library.
A problem arises when I want to calculate dBFS from a buffer'...
0
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1answer
59 views
Output power of a signal passing through an IIR filter
suppose I have the following discrete time signal
$x\left(n\right)=0.7\sin\left(2\pi \times 623\:nT\right)$
where $N=4000$ and $T=\frac{1}{f_s}$, where $f_s=40$ kHz
I pass this signal through a simple ...
0
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1answer
33 views
Time scaled version of discrete time signals
I have a confusion regarding time scaling of discrete time signals.
Let u[n] be the discrete time unit step signal(or sequence)
Now if i plot u[n/3] i know there will be two zeros added between each ...
