Stack Exchange Network

Stack Exchange network consists of 174 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.

Visit Stack Exchange

Questions tagged [discrete-signals]

A discrete signal or discrete-time signal is a time series consisting of a sequence of quantities.

1
vote
1answer
56 views

Moving average algorithm that conserves integral

Suppose I have point array $y_i$ of size $N$. How to implement moving average algorithm that conserves quantity $$ I = \sum_{i=1}^{N}y_i $$ NOTE: I don't want time shift so I would prefer to use ...
-1
votes
1answer
37 views

How to solve this question by using convolution?

I had previously posted this question but my method was wrong in it. Two signals are given: $$x[n]=2^nu[n]$$ $$h[n]=u[n]$$ I have to find $y[n]$. I have spent hours on this question but I am unable ...
2
votes
3answers
77 views

Maximum Magnitude Deviation between DFT and DTFT

Let $x[n]$ be a finite-length discrete-time signal with length $N$. The continuous DTFT $X(\omega)$ is then $$ X(\omega) = \sum_{n = 0}^{N-1} x[n] e^{-j \omega n}. $$ The length-$N$ DFT of $x[n]$ is $...
1
vote
1answer
28 views

What is the value of last sample of a discrete sinewave

I have a simple question. If I compute N sample values of a single cycle of a discrete sinewave (whose initial phase is zero radians), will the value of the last sample be equal to zero?
1
vote
2answers
83 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?
0
votes
1answer
40 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 ...
0
votes
1answer
35 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: $$ y[n] = \sum_{k=0}^{n} \alpha^{k}\\$$
0
votes
1answer
46 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
83 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
1answer
55 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
1answer
43 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? ...
1
vote
2answers
86 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
15 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
57 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
23 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
35 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
109 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
114 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
120 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
152 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?
1
vote
1answer
59 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
57 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
82 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
232 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
58 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
432 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
51 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
53 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
58 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
175 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
240 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
57 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
26 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
35 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
112 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
62 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 ...
1
vote
0answers
61 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
59 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
71 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
39 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
53 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 ...
1
vote
1answer
55 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
83 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
117 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 ...
1
vote
1answer
180 views

What is the noise whitening process?

I came across this process when working on OFDM in wireless communication. It's mentioned if we have two copies of a signal resulted from SIMO system (Single Rx Multiple Tx), we can process the noise ...
0
votes
1answer
18 views

How do you estimate necessary dynamic range?

Say I have a signal (1D in my case, but could be an image, etc.) that has been captured adequately on nice equipment with sufficient resolution and range to get all the details of the signal that are ...
0
votes
1answer
62 views

Band pass filter (digital resonance)

Q1:  Consider a discrete-time band-pass filter (BPF) that uses only two poles as $$ H(z) = G \frac{1}{\big(1-r \, e^{j \omega_0} z^{-1}\big)\big(1-r \, e^{-j \omega_0} z^{-1}\big)} $$ where this ...
0
votes
2answers
39 views

multiplying the received signal by carrier, in OFDM system

Sorry for this question, I'm still new in signal processing area. In OFDM system, let $x$ be the received signal, what do we call the process of multiplying the received signal $x$ by $e^{-j2\pi F_c ...
0
votes
1answer
94 views

What's the relation between the sampling rate and FFT size in OFDM

In OFDM system, Is there relationship between Sampling rate and FFT size? For example, if we downsample or oversample the received signal, Should we decrease or increase the FFT size accordingly? ...