A discrete signal or discrete-time signal is a time series consisting of a sequence of quantities.
0
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0answers
7 views
Understanding wavelets via 1-D PyWavelet example
I have been reading about wavelets for few weeks now and I have bumped into subjects like scaling functions, wavelet functions, filter banks and multiresolution analysis. Despite reading and getting ...
0
votes
0answers
16 views
Correlation between elements of a video
Should there be an expected correlation between the audio signal and the frame pixel data, considering the frames of a video?
If so, what is the reason for such correlation? Pondering over the topic ...
0
votes
2answers
47 views
Conversion from stationarity to non-stationarity
Is there any way to convert a non-stationary signal to a stationary one, perform operations on it meant for a stationary signal and then convert it back to the non-stationary one?
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votes
0answers
43 views
What does the output of a DFT really mean?
I've computed the DFT twice on the function:
$$
f(t) = 2 + 2\cos(2\pi t) + 2\cos(4\pi t)
$$
Once between $t=0\to 3/4$, hence taking 4 readings, and once between $t=0\to 15/16$. The first plot has ...
0
votes
1answer
33 views
Finding the transfer function of a discrete signal described by two equations
A discrete time system is described by the following system of equations.
$$q[n] = \big(x[n]-\frac k4q[n-1]\big)$$
$$y[n] = \big(q[n]-\frac k3q[n-1]\big)$$
Find the systen function and then find the ...
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votes
1answer
28 views
Convolution of discrete time signal
I'm given a discrete time signal which is as follows:
$$ x[n] = \alpha^n u[n],\\$$
$$ h[n] = u[n],\\$$
Why is unit function neglected in the following step:
$$ y[n] = \sum_{k=0}^{n} \alpha^{k}\\$$
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0answers
13 views
Question on stationarity of a time series
The whole foundation of discrete Wiener theory for estimation of signals, leading to the Yule-Walker equations assumes stationarity of the time series.
But, financial data, in general, may not be ...
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votes
1answer
33 views
How does an IIR system affect magnitude and phase of a sinusoidal signal
Consider an IIR system with impulse response $h[n]=\left( \frac{1}{\sqrt{3}} \right)^n u[n]$. If I apply $x[n]=\cos(n \frac{\pi}{2} + \varphi)$ at the input, how can I determine the change in ...
1
vote
1answer
53 views
Are two jointly stationary white noise processes independent?
I am currently dealing with a problem concerning beamforming, where two "jointly stationary zero-mean white noise processes" form the input of an adaptive system. One of those processes resembles the ...
0
votes
0answers
21 views
Plot Bit-Error-rate (BER) vs Eb_N0 of a discrete BPSK signal passed through integrator in MATLAB [closed]
I am a novice to communication systems but I am in need to solve this question. I would appreciate inputs in this regard. Apologies if you my question lengthy.
I have a BPSK signal such that the ...
0
votes
1answer
14 views
Difference between these two integrators
I am an electrical engineering student but new to digital signal processing. However while searching references for my senior project I came across following two different discrete integrator blocks ...
0
votes
0answers
12 views
Changing BCJR algorithm to work on all trellis states
I am using the BCJR algorithm for channel equalization (simple ISI channel + AWGN).
The algorithm assumes that zeros are transmitted in the beginning and in the end, but I would like to change it not ...
-1
votes
0answers
11 views
I keep getting error messages on FFT Signal with two sinusoids (100 Hz and 200 Hz) with -10 dB
I am new in matlab. This code supposed to show 2 graphs - magnitude spectrum, and phase spectrum. The problem is it wont show anything and keeps getting error messages. In this code, I want to make ...
0
votes
1answer
37 views
Why must the angle contain $\pi$ for $\cos$ be periodic?
The $\cos(\frac{n}{6})$ is aperiodic, and $\cos(\frac{n\pi}{6})$ is periodic, why? What role does the $\pi$ play? By the way, $n$ must be integer
I have seen this question,Why is cos(n/6) aperiodic? ...
-2
votes
0answers
19 views
Is this a memory system? [duplicate]
I have a following expression:
$$y(n)=(2x(n)-x^2(n))\,,$$
Now if I take $n$ to be -1 I have:
$$y(-1)=-(2x)+x^2\,,$$
So it's a memory system. Right?
1
vote
2answers
36 views
What is a memory less system?
As far as I have grasped the concept is that if we are given the expression
$$y[n]=(2x[n]-x^2[n])^2\,,$$
it is a memory less system because even if we give negative values of $n$, we still get the ...
1
vote
0answers
11 views
artifact identification in irregular-samped data
There is a dataset combined by different datasets a,b,c,d,e. The time intervals are irregular(i1, i2, i3:intervals between a and b, b and c...), but the sampling rate SR in every single dataset is the ...
0
votes
3answers
53 views
How do I know if the given signal is discrete?
If I am given an expression of a signal then how do I know if it is a discrete signal or not?
If this signal is given how do I know if it's a discrete or continuous?
$$x(n) = e^{j (n \pi/2 + \pi/8) ...
0
votes
1answer
13 views
Optimising an input signal for a system to minimise distortion of output signal
I have a discrete time-series signal which I am able to process before passing it through a system which distorts said signal. This system cannot be altered and is non-linear, but a signal can be ...
0
votes
1answer
21 views
What does it mean that the normalized power of a received equals one?
I have read in that lecture, page 2, here that, the symbols are independent, and normalized to have power 1, which means $E(x x^H) = I$ .. what does that mean? could you please explain that for me?
2
votes
1answer
59 views
How does a digital filter work?
To introduce my situation: I'm developing a digital synthesizer in a form of a C++ library, working with low level APIs like WASAPI, ASIO, ALSA etc. It's probably not very practical and I'm mostly "...
1
vote
1answer
37 views
Reconstruction of a signal from non-uniform samples [duplicate]
So I'm having some troubles with a signal that's been sampled but where the samples don't have consistent intervals. I've been looking into the NFFT (in python) as a starting point but I'm a complete ...
1
vote
2answers
72 views
Carrier Frequency Offset, Rotating Constellation and Correlator
I have been further reading up on carrier recovery methods and something is not clear to me:
It's written that a carrier frequency offset results in a rotating constellation diagram but if you are ...
0
votes
2answers
49 views
Quantization level versus bandwidth [closed]
Why is it that increasing the number of quantization levels $L$ results in an increase in the signal's bandwidth?
0
votes
1answer
40 views
Using the compressive sensing mathematical concept in signal processing
I am new in the field of compressive sensing, I've read many papers explaining that compressive sensing is used widely in sparse signal reconstruction. I've tried to understand how compressive sensing ...
1
vote
1answer
23 views
Linear combination of DT unit impulse
Came across this example in class but I'm not sure how the expression $x(n)$ was derived.
0
votes
1answer
62 views
Impulse response from Frequency response: why using $e^{j\omega}$ as an input?
Every resource that I can find uses this identity when deriving impulse response:
$h[n] = IDTFT \Big\{H(e^{j\omega}) \Big\}$
Suggesting that the input signal was $e^{j\omega}$. But by definition ...
2
votes
1answer
66 views
How to Check Separability of 2D Signal / Matrix
suppose
x(n1,n2) = {1 ,n1=0,n2=0 ;
2 ,n1=1,n2=0 ;
3 ,n1=0,n2=1 ;
6 ,n1=1,n2=1 }
then, how do i prove it is separable.
2
votes
1answer
53 views
A general conceptual understanding of moving average
I have a conceptual question here. I understood how to calculate a Moving Average(MA).
For example :
x(n) = 0, 1, 2, 3, 4, 5
MA = 0, 1/2, 3/2, 5/2,7/2, 9/2, where for calculation of the MA we only ...
2
votes
2answers
77 views
How to get around the circular shift property of Discrete Fourier Transform?
I understand that when we introduce a linear time shift using DFT on a finite sequence, the algorithm assumes that the signal repeats itself outside of the given range. Here is an example explaining ...
0
votes
1answer
48 views
Band limited signals that are sparse
I am looking for examples of signals that are band limited but also sparse. For instance, the spiking of the neurons can be modeled as banded in frequency domain and sparse in time domain. What other ...
1
vote
0answers
13 views
graph display problem [closed]
I have a problem with the end of my code. I would like to display the last two curves, the problem is that at the beginning the size of YY is 288 and then after the equality with diff, my size goes to ...
2
votes
4answers
38 views
Bandlimiting and OFDM spectrum - what is considered “bandlimited”?
I have been reading about OFDM modulation, it's not clear to me how you can have band-limited OFDM but given its prevalence in wireless communication there must be some designation of approximately ...
0
votes
1answer
43 views
Extracting positive frequencies of discrete-time signal
Convolution in the time domain is the same as multiplication in the frequency domain.
My data is sampled at 200 Hz, which means that the Nyquist frequency is 100 Hz, and all frequency content is <=...
0
votes
1answer
112 views
How to measure acoustic pressure level under water with a hydrophone?
this is my first post here and I am also new in signal processing.
Let's say I have a hydrophone with amplifier which is connected to a sound card plugged in to a computer. I gather the sounds to a ...
0
votes
1answer
91 views
Discrete Fourier transform of an exponential decay
I have a vector with an exponential decay, using Numpy:
t=np.arange(128)
k=0.1
decay=np.exp(-k*t)
I would like to compute the discrete Fourier transform (DFT) of ...
0
votes
1answer
49 views
What's the difference between Channel shortening and time-domain equalizer
I'm asking about the difference about channel shortening and time-domain equalization. I have checked on-line and tried to get something clear but I couldn't.
What I found is that channel shortening ...
0
votes
1answer
24 views
Equation Derivation: Help with intermediate steps
As per the attached image above, I don't know how the equation in the first line transformed to the form in second line.
I tried solving it by multiplication but the result was different.
0
votes
0answers
26 views
Implementing Fractionally Spaced Equalizer
I have been searching for robust algorithm that can be implemented for avoiding the ISI (Inter-Symbol interference), I came across two types of channel equalizations are there. One is data Aided (...
1
vote
2answers
69 views
Software PLL tracking of carrier frequency in bandlimited transmission
My understanding is that a PLL(either in hardware or software) can recover the carrier frequency(or be used to correct the frequency offset) of a system. My question is how does this work when the ...
0
votes
0answers
47 views
What is the relationship between FFT size and demodulation in OFDM
As I mentioned in the title of the question, how can we demodulate the data in order to get the same number of subcarriers with different FFT size.
For example,
10 MHz LTE can be sampled with 15.36 ...
0
votes
0answers
26 views
Noncoherent Burst Detection
I am interested in developing a noncoherent receiver for a burst signal in an SDR. One of the first problems is developing a signal-detection method. I am wondering what is the standard way to go ...
0
votes
0answers
33 views
How can I oversample OFDM received signal in MATLAB
I need to oversample a received signal in OFDM by MATLAB, according to the below diagram, but when I oversample, I finally get the same number of samples however that should be double. !! The ...
0
votes
1answer
30 views
transfer function and 'causal' signal - evaluate transfer function or use z-transform of input?
From my studying difference equations and transfer functions, I understand that when a complex exponential input $x[n]=z_1^n$ is applied to an LTI system with transfer function $H(z)$, determining the ...
0
votes
1answer
45 views
Estimating variance in arbitrary, periodic signal
I have a periodic signal $x[m], m \in [0;M-N+1]$ made of modulated templates $s[n],~ n \in [0;N-1],~ N \ll M = NK$ of finite energy and support (i.e. zero outside of its defined interval, which does ...
0
votes
2answers
32 views
Reconciling Continuous and Discrete Complex Domains
Having taken some courses in Systems and Stability dealing mostly with continuous time signals, I am accustomed to thinking about the Laplace and Fourier transforms dealing with complex and pure ...
-3
votes
2answers
48 views
Is there a specific preferred order of operation on signals?
Basic Signal Operations Performed on dependent variables-- The periodicity of the signal is varied by modifying the horizontal axis values, while the amplitude or the strength remains constant. These ...
0
votes
1answer
50 views
What is the impulse response of SIMO channel and its equivalent in oversampling?
1- According to the below paragraph :
Could someone explain, What mean M here? I mean when saying with Order M ?
2- On the other hand, When performing Fractional sampling, for example sampling ...
2
votes
0answers
69 views
Why is channel estimation done after synchronization and why does it work?
I am interested in Software Defined Radio communications where almost all processing is pushed to the digital domain.
I'm wondering why is channel estimation done after frequency and phase ...
1
vote
1answer
53 views
How to convert DFT to DCT
I've been trying to find a fast 16 point dct2 and dct3 implementation, however I could only find it in literature expressed as mathematical equations, which honestly I couldn't understand.
However I ...
