Questions tagged [discrete-signals]
A discrete signal or discrete-time signal is a time series consisting of a sequence of quantities.
1,391
questions
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Sampling rate issue in microcontroller
I am using 3 axis LIS2D12H accelerometer interfaced with NRF51832 with SPI interface. The sensor has sampling rate from 1 HZ to 5.376 KHz which is happening at sensor only. I am taking sensor data at ...
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1answer
26 views
Measuring group delay through a linear phase filter
I'm having a difficult time wrapping my head around a phase/ group delay problem and it corresponding to where you start sampling so I built up a system to test some of these issues. The system passes ...
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1answer
32 views
Ways to differentiate three respiratory signals
I have three 1-min respiratory signals I derived from ECG signals. I am wondering if you guys have any suggestion on differentiating those three? The red line represents the experimental signals and ...
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0answers
6 views
wavelet packet decomposition in python
i want to write a code for wavelet packet decomposition in python. i don't understand how i ll proceed.i am trying pyWavelet library but don't understand how to save the output coefficients in each ...
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1answer
22 views
Is fft2 in MATLAB unitary? Some differences happen
I meet a problem when implementing fft2 in MATLAB.
The question is I try to simulate the realistic measurements $Y = |FCXF^H|^2$ - the intensity of Fourier domain of object $X$, where $F$ denotes ...
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2answers
51 views
PSD of modulated signal
I know this question has been previously asked just saw it and tried to do myself but reaching an expression which is different from expression of PSD which I remember for modulated signal
Actual ...
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1answer
30 views
DFT of an audio signal stored as a multi-dimensional array
I'm using the Python scipy library to get the data of a particular .wav file into array format. Now, I'd like to find the Discrete Fourier Transform of that signal. The formula for the DFT is,
$X_k = ...
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2answers
44 views
Independence of Functions of random Variable
Consider I am given two functions of one random variable each for example x=cos(at),y=rect(bt) where a and b are random variables.And I am given Probability density function for a and b then if I am ...
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2answers
71 views
What is the difference between y[n] and y(k) (using square brackets)?
Can I modify y[n] = αy[n-1] + x[n] the same way I would do it with y(k) --> Y(z)?
I need H(z), but I don't know what is the difference between using (k), and (n). I often encountered [k] notation, ...
2
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1answer
16 views
Zero State and Zero Input Responses from Steady State Response
Let a linear, time-invariant, causal discrete linear system be described by the following difference equation:
$$y[n] = 0.9y[n-1] + 0.1x[n]$$
Assuming that $y[-1]=2$ and $x[n]=20\cos(\Omega n)u[n]$, ...
2
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3answers
73 views
How to determine if an IIR filter is causal or non-causal?
It may sound impractical, as only causal system are passively realizable, but what I am facing is a general statement made regarding recursive digital filters: for them to be stable, the poles should ...
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2answers
56 views
Intuition about independent signals
Given is this Wiener filter:
From this we take \begin{equation}
x[k]-a x[k-1]=v[k]
\end{equation}
$v(k)$ is assumed to be a white gaussian noise.
In the textbook it is then stated that
The ...
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0answers
37 views
Can I find FFT for signals with odd number of element
I am said to divide signal into two parts even and odd numbered {index/value of n} .What if number of elements in x[n] is odd out will I divide into two networks?
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40 views
DFT truncation of signals
How can I calculate 8 point DFT of signals whose length is less then 8 ( say 2,4) then what will I assume other members in formulae "0" or rotation or keep repeating the same two numbers
Consider I ...
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2answers
60 views
Digital Equations problem - The fundamental ones that everyone should know
I think I am looking at conflicting equations from a few sources, or maybe I just dont understand it. But please can someone help me with these fundamental equations that everyone should know
$ \...
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0answers
10 views
How can I find inverse Z transform using synthetic division method when Region of convergence is bounded rather than right sided or left sided?
Explanation of synthetic division method
Above example has region of convergence of type mod(z)>mod(a)
I want to solve problems when region of convergence of type mod(e)>mod(z)>mod(d)
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0answers
31 views
Is there a filter to deal with spectral leakage?
Consider we know that our medium is dispersive and we are transmitting/expecting a signal around 10kHz at receiver, as we do not get only 10 kHz, the input has a sligh spread as well. Due to ...
3
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3answers
270 views
How to Prove a System Is Invertible?
what i know is that for a system to be invertibel it should be one-one ,
but I am confused that if i am given a transfer function of a LTI system how can I prove or verify if it is invertible.
...
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0answers
17 views
What is definition of cross correlation function?
I mean there are three different formulas for cross correlation that I have studied f and g are two functions whose correlation has to be found
1.For Energy signals
2.For Power signals
3.For ...
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0answers
20 views
Detecting changes in signal due to server delay
I'm currently working on an application that can be used to determine when a signal changes due to a server delay. Essentially, I have an API that is used to output data to a UI. However, for reasons ...
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0answers
30 views
How to calculate Eb/N0 for a digital BPSK modulated multicarrier waveform
Suppose that I have a BPSK modulated multicarrier carrier waveform $L$ samples long at a sampling rate of $f_{s}$:
$$ x_{tx}[l] = \sum\limits_{n=0}^{N-1} A \cdot \cos\left(2 \pi \frac{f_{n}}{f_{s}} ...
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0answers
15 views
Finding the differences(using features, not subtraction) in order to find differences in signals
I have a question. Let’s say I have two signals (discretely represented as arrays), $S_1$ and $S_2$ as shown below. $S_1$ has a similar form to $S_2$. If the signals are subtracted, $S_2-S_1$, they ...
1
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1answer
54 views
Discrete Kalman filter for a continuous system
The question is related to the implementation of a discrete kalman filter given a description of the system model in continuous time.
I will give an example. Suppose we have a mass, spring and damper ...
0
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1answer
56 views
Does $y[n] = x[n] \star (u[n]-u[n-2])$ have memory or is it memoryless?
$y[n] = x[n] \star (u[n]-u[n-2])$, by its definition is has to be a system with memory since it is depended from a fraction of time in the past, but if we calculate the difference $u[n]-u[n-2]$, it ...
0
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1answer
65 views
Real signal from I,Q, sample rate and center frequency
I am given a recording of an ionosonde sounding. The signal $S$ is represented as a series of I/Q pairs at a sample rate $F_{sr} = 10\,\text{MHz}$. I am told that the center frequency of the ...
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1answer
21 views
What happens when the frequencies of the signal does not lie within the reconstruction filter passband?
Assume we have an analog signal that has frequency components between 40Hz and 50Hz and 0 otherwise. If we sampled this signal with 100Hz sampling frequency then passed to DAC with the same sampling ...
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0answers
21 views
Discrete Frequency Equation and Relation
I think I am looking at conflicting equations from a few sources, or maybe I just dont understand it.
$ \Omega $ is Discrete frequency
$ N $ is Discrete Period in number of samples
$ \omega $ is ...
0
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0answers
50 views
Python FFT outptut
I have a (real) array of data and am trying to analyze its frequency components. I've been using NumPy's FFT routines, but I realized there is something I don't quite understand: why does the output ...
0
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1answer
82 views
Amplitude demodulation of sinusidal signal in matlab
AM-demodulation task and I was asked to demodulate the signal in MATLAB and the result should contain three pictures.
plotting the $fft$ the (frequency spectrum)of the signal i was able to determine ...
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0answers
34 views
How to crop a song and mantain the same values in the sample vector?
Does anyone know how can I crop an audio signal and maintain the same values in the sample vector?
I am working on a audio signal processing project for song recognition in Python and I wanted to ...
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1answer
34 views
Discrete vs discretized signals
Ive heard both of these terms and i am still having trouble to understand what is the difference between these two. As far as i understood, the only difference between discrete and discretized signal, ...
2
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1answer
136 views
Comparing arithmetic complexity of FFT radix-2 and convolution
Let's assume we have a discrete linear time invariant system and we have a real signal $x[n]$ with length N=50 as input for the system.
The impulse response $h[n]$ of the system is considered to be ...
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0answers
16 views
MFCC parameters for gunshot recognition
I'm writing a gunshot detector software. I'm using this article as reference:https://arxiv.org/ftp/arxiv/papers/1706/1706.08759.pdf.
For now, my software is able to recognize an impulsive sound. Now, ...
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0answers
24 views
Correlation/anticorrelation as a function of frequency
I am tracking the values of two fluctuating quantities as a function of time and am trying to analyze possible correlations between the two as a function of frequency. The application is experimental ...
2
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1answer
46 views
Missing delay in heavyside step function
I found the following task that was inspired by an example in the book A. V. Oppenheim and R. W. Schafer, "Discrete-Time Signal Processing", 3rd Edition, 2014.
Task:
Consider the 2nd-order IIR ...
0
votes
2answers
64 views
Convolution property
Is the convolution of two equal signals the same signal?
I have this system:
and i have to find $h_1[n]$ (which i've been struggling for a while), given
$$ h_2[n] = u[n] - u[n-2] $$
and $h[n] = ...
1
vote
1answer
41 views
fftshift in MATLAB with even number of data points in double sided spectrum
I have a question with reference to this Table.
With even N, the frequency axis extremes should be $\pm$Fs/2, where Fs is the sampling frequency. However in the array we have only one value ...
0
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1answer
61 views
Frequency Axis of Discrete Fourier Transform (DFT) with Odd Number of Data Points
I am trying to understand the logic behind making a frequency axis in DFT. I am using for time based light absorbance. When we have even number of data points (N= even integer), collected over a ...
2
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2answers
68 views
DFT: a function of $n$?
I‘m a high school student and I haven’t studied physics or anything.
Why does the DFT depend on an integer, say $k$ or $n$ (it’s usually expressed like $F(n)=...$ or $F(k)$ or $F_k$, etc.) if it is ...
0
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1answer
24 views
What does kchip/s datarate mean? [closed]
I am working in w mbus and came across this term kchip/s in datarate like 37.768 kchip/s what does the unit specify?
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0answers
27 views
Correctly interpret Butterworth filter frequencies
I am using the butter function from the signal package in R to filter my data.
The data is Fourier-transformed (complex numbers) - and I want to filter out specific frequencies (I have a 256Hz ...
0
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0answers
19 views
Frequency selective channel modeling using rayleighchan object in matlab
I intend to model a frequency selective channel using matlab "comm.RayleighChannel" object. Consider the following command, which sets the parameters of Rayleigh channel :
...
9
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1answer
1k views
Why doesn't sampling a periodic continuous-time signal yield a periodic discrete-time signal?
I have been studying signals and systems lately and I have came across the following claim:
The uniform sampling of a periodic continuous-time signal may not be periodic!
Can someone please ...
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2answers
63 views
How to deal with the mirrored components of a FFT? And another question
I'm trying to simulate the behavior of my FFT spectrum analyzer, I am using Mathematica, but my questions are more conceptual than technical implementation of code...I hope.
If we consider a simple ...
0
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1answer
45 views
Conversion from continuous to sampled signal?
I am bit confused regarding sampling as i read different types of statements in different texts
Forexample i have a continous time signal $x=sin(t)$ defined for $t=0:10$
and i want to sample it with ...
3
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1answer
43 views
How to match two signals that have similar shape but are scaled and expanded?
I have two signals A and B in time domain as follows:
Visually both signals look very similar; however the X and Y axis range are different for both the signals. Signal B is basically a "stretched" ...
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0answers
27 views
Angular velocity of discrete time exponentials, increasing and then decreasing over 0 to 2 pi [duplicate]
So, the differences between:
$$
x(t) = e^{j(\omega_{0} t) } \,\,\,\,\, \textbf{Vs.} \,\,\,\,\, x[n] = e^{j(\omega_{0}n)}
$$
Are:
For $x(t)$ the $\omega_{0} \to \infty $ means the oscillation rate ...
2
votes
1answer
89 views
When Two Sampled Sinusoidal Are Orthogonal?
If two analog sinusoidal are orthogonal with duration T, their minimum frequency difference should be 1/2T in case of no phase offset between them.
And if there is phase offset, the difference is 1/...
0
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0answers
20 views
why we use time step only in continuous convolution in MATLAB? But not in discrete convolution?
I am studying convolution from book of alex palamides but i am confused because he uses time step(in this case 0.01) in his code for continuous convolution as shown highlighted in attached photo but ...
0
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2answers
39 views
Frequency Domain Correction of Frequency Offset or Doppler Frequency in LTE
We are working on LTE Uplink CFO Correction for 3 MHz band. The time domain CFO correction is easy, which depends on the processing of 3840 samples step by step multiply by $\exp(-j 2\pi f_\text{...
