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

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12 views

How to create and divide a signal envelope? Alternatives welcome

I'm very new to signal processing (still a student) and I'm trying to process a wav file in a certain way. I want to: Create an envelope of the signal (using absolute values of the amplitudes) ...
2
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3answers
51 views

Why do we use discrete-time sampling?

I have been reading Signals and Systems (2nd ed.) recently. Chapter 7 is about sampling. Oppenheim uses discrete-time signals and continuous-time signals to explain sampling. But why do we need ...
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1answer
28 views

SNR problem with different sampling rates using innerproduct

I'm trying to measure the amplitude of a sinusoidal component in a noisy signal. Since the signal frequency is known beforehand, I'm calculating scalar product with a sine and cosine base function ...
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1answer
57 views

$\mathcal{Z}$-transform of $\frac{1}{n^2}$

This is a Question asked in IISC ( Indian Institute of Science,Bangalore,India) interview for MS admission. What is the $\mathcal{Z}$-transform of $\dfrac 1{n^2}$ ?
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11 views

Is it possible compare 'the shape' of audio(voice) signal?

Here is an example: Record very low-tone voice guy saying, "Nice to meet you" Record very high-tone voice girl saying, "Nice to meet you" (they are saying almost same speed, it's like the second ...
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2answers
62 views

What should be the correct scaling for PSD calculation using $\tt fft$

I would to calculate the PSD of a signal using FFT however the result do not match with periodogram command. What did was as follow : ...
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1answer
35 views

How does scipy.signal.deconvolve work?

The deconvolve(signal, divisor) function of scipy ...
1
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1answer
66 views

Signal enhancing algorithm (deconvolution??)

I need an algorithm (preferably Pascal-like, but anything else will do it also) that will make the "signal" (actually a series of data points) in left look like the one in right. Signal origin: ...
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1answer
42 views

Zeropadding and amplitude scaling

Could somebody tell me what is the DFT scaling of a $N$-length signal which is padded with $M$ zeros ? Is it $1/(M+N)$ or $1/N$, i.e. $$ Y_k=\frac{1}{N}\sum_{n=0}^{N-1}y(n)e^{\frac{2\pi nk}{(M+N)}} \...
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1answer
38 views

How does summation over time samples influences DFT?

In case of DFT where we have following $$ Y_{k}=\frac{1}{N}\sum_{n=0}^{N-1}y_ne^{-j{\frac{2\pi nk}{N}}} $$ What happens in case when we change summation, e.g., increase or decrease number of $n$ ...
0
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1answer
27 views

Upsampling and comb function

Could somebody explain how upsampling works with comb function. How comb function looks for upsampling process? (if it possible I would appreciate if answer would be related to DFT)
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1answer
11 views

What's this discrete latch operation called?

I have a picture in my head of a specific DSP operation, but I don't know what it's called or how to google for it. I'm pretty sure it's a fairly common operation, however I have no idea what to call ...
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1answer
18 views

Raw signal to short for DWT

The algorithm i use to apply a discrete wavelet transform only accept raw-data with a certain number of samples (2,4,8,..128..). I have to either interpolate the raw signal or padding it with zeros (...
4
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2answers
75 views

Zero-padding the middle of a signal

I sample a signal at a certain frequency for a finite amount of time to get a sequence $$(x_n)_{n=1}^N = (x_1, x_2, ... , x_N)$$ with the intention of analyzing its power spectral density by ...
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0answers
22 views

Understanding extraction of MFCC from non-accoustic data

Although a lot of readings (also some advanced explanation in this forum - thank you -) I still have some questions. The sensor captures only one value per time.. So instead of $Time\rightarrow ...
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0answers
29 views

The graph obtained from my deconvolution routine seems to be shifted, is that supposed to happen that way?

So I'm writing a piece of code to deconvolve pseudo-data obtained from a (slightly)blurry particle-detector, using the gold algorithm of deconvolution. But the strange thing is, the graph I obtain ...
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2answers
72 views

Why is $\sin(t)$ a stationary process?

I am trying to understand the meaning of the term Stationary Process. For example, I was told that $\sin(t)$ is a stationary process. Could someone try to explain, in simple words, why is $\sin(t)$ (...
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0answers
20 views

All-pass filter

I know that I can write an all-pass system as: $$H_{ap}(z) = \frac{z^{-1}-a^*}{1-az^{-1}}$$ because it has magnitude $1$ (or magnitude = constant) And I can also write it like: $$H_{ap}(z) = \frac{1-...
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1answer
32 views

GCC-PHAT (Generalized cross correlation MATLAB)

I've been trying to implement generalized cross correlation with a PHAT weighting function for a while now, and cannot get it to work. I have tried correlating using MATLAB's xcorr.m file, and it ...
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3answers
55 views

Is the filter described by specific difference equation time independent

Is the filter described by $$y[n] + 2 y[n-1] + y[n-2] = x[n] - 2 x[n-1]$$ time invariant? ($x[n]$ - input, $y[n]$ - output) Theorem of Foures-Segal says no (?) When I asked about Foures-Segal I ...
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1answer
24 views

How to prove main-lobe side-lobe ratio in hann window is $-32\textrm{ dB}$?

I found that the value of the main lobe is about $N$, when I try to calculate the value of the sidelobe I got $0$, I assumed that the peak is at $\theta=\frac{6\pi}{N}$. How can I find the size of ...
3
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1answer
51 views

Define comb function in terms of exponential function

I have one signal with $N$ samples and I want to downsample it by factor of $M$. Essentially my downsampler is comb function which takes every M$^{th}$ sample while others are set to zero, i.e., $$ \...
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1answer
26 views

Alignment of signals for ensemble averaging? Something else?

I have been applying ensemble averaging (adding signals of different trials to obtain one signal) to improve Signal to noise ratio in my data. I have achieved good results in terms of classification ...
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1answer
28 views

What is the link between equation of a continuous signal versus equation of its sampled form?

I have just started DSP self-learning. I am a little confused by this 'end of the chapter' exercise question from Chapter 2 of "Understanding Digital signal processing" 3rd edition by Richard G. Lyons....
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42 views

Autocorrelation of a $L$-point moving average system

The $L$-point moving system is: $$y[n]=\frac 1L\sum_{k=0}^{L-1}x[n-k]$$ $x[n]$ is a Bernoulli random signal with $\beta=0.5$ (equal probability) The autocorrelation of $x[n]$: $\psi_{xx}[m]=\delta[...
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1answer
33 views

Bode plot of discrete-time transfer function $H(z)$

$H(z)$ is the transfer function of a biquad filter as described here. I would like to plot the Bode plot of the magnitude response of $H(z)$. Scipy has a bode method (...
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1answer
46 views

DTFT and Inverse DTFT Homework Problem

I'm trying to solve this signals homework problem: So for part a, since multiplication in the time domain is convolution in the frequency domain, I just used a DTFT table, found the DTFT for $\left(...
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2answers
69 views

autocorrelation for time-frequency analyses

Given a signal $x(t)$, how do I implement a form of autocorrelation function defined as $a(t,T) = x(t-T)x(t+T)$, where $T$ is an arbitrary constant? (a fast implementation would be ideal) Edit: ...
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1answer
59 views

Bandpass general equation to difference equation

I know this is a very basic question and I am coming out from a quarter of DSP. I want to create a function in Java which can taken in two parameters, either ...
3
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1answer
61 views

Is there a strategy for discrete control of a system with dynamics near sample rate?

I'm trying to control a system where the controller sample rate is physically fixed and the plant has significant dynamics on the same order as the sample rate. I understand that one would prefer to ...
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1answer
52 views

What can we understand when we increase the $N$-point DFT for a given signal?

I have an input sequence $$x(n)=\cos(0.48\pi n)+\cos(0.52\pi n).$$ I am determining its spectrum (amplitude of DFT values) based on the finite number of samples. For Example : Taking the first $10$ ...
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1answer
38 views

How is the energy of $x_1\cdot x_2$ related to the energies of $x_1$ and $x_2$?

Let's say first signal x1 = [1 2 3 4], second signal x2 = [0.08 0.77 0.77 0.08] (Hamming window), third signal ...
3
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2answers
247 views

Is my tranform the essence of DFT?

I'm someone just learning DSP, and want understand its essence. My transform is the simplest possible. Input signal is just one frequency: $256\textrm{ Hz}$. Sampling frequency is $2560\textrm{ ...
0
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1answer
38 views

A digital feedback network question

I saw the following digital network in a technical journal. I think the network's processing cannot be implemented because there is no delay element in the feedback path. How can we compute the "...
0
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0answers
34 views

Data reduction for a data collected from micro controller?

I have been given a project where I have to collect data reduce its size and send the data via bluetooth to some other storage. At first I thought it is simple data compression and used zlib and ...
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1answer
74 views

How is quadrature mixing done?

I've a Gaussian modulated signal whose quadrature and in phase components are separated. I'm multiplying these components with quadrature and in phase components of a signal of 10MHz frequency, ...
3
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1answer
48 views

Difference equation with complex zero

Let's assume I have the following transfer function: $$ H(z)=\frac{z-\left(\frac{1}{\sqrt{2}}+i \cdot \frac{1}{\sqrt{2}}\right)}{z} $$ It looks like a first order highpass-filter with a complex zero ...
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2answers
84 views

The mathematical interpretation of DFT [closed]

We have the DFT(matrix form) $X = Wx$ ($W$ is the Fourier basis matrix, $x$ is the original signal in time domain, $X$ is in the frequency domain). In mathematics, $x$ represents the coordinates of $...
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1answer
32 views

Classifying Discrete time filter

So let's say i have this frequency response of a digital filter: My question is how can i classify this type of filter ( low pass, high pass,...)?
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2answers
78 views

Method of reconstructing a band-limited signal from discrete samples

I understand current cell phones use digital communications. Given that this industry brings in billions of dollars each year, there is much incentive to get the best performance possible. So what ...
0
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1answer
17 views

Relating phase shift to the ROL/ROR operations

Is phase-shifting in continuous-time analogous to the rotate-left (ROL) and rotate-right (ROR) operations in discrete-time?
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1answer
15 views

Stability of the summation function

Stability of the below function was asked. $$ T(x[n]) = \sum_{k=n_0}^n x[n] $$ I understand that $x[n]$ shouldn't exceed $M$ value. $x[n]\le M$. I mean, we are looking for if the input is bounded, ...
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1answer
34 views

Simple discrete time transformation $x[(n-1)^2]$

If I want to do the following transform $$x[(n-1)^2]$$ I have thought about substituting each value of $n$ in $x[n]$ according to $x[(n-1)^2]$ i.e at $n=0, x[0]=1$ to put it in $x[(n-1)^2]$ $x[(...
0
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2answers
42 views

Very simple question about signal periodicity

$$x[n] = u[n]+u[-n]$$ Is it periodic or not? My answer is $$u[n] = {1 , n\geqslant0}$$ $$u[-n] = {1 , n\leqslant0}$$ which means that the signal $x[n]$ is always equal to $1$ from $-\...
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0answers
22 views

Inverse Discrete Wavelet Transform - partial reconstruction

I'm pretending to approximate a time series/vector usind dwt , with haar filter, in R. I can apply the full ...
0
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0answers
29 views

How to implement PLL blocks in MATLAB

I want to implement a PLL in MATLAB with individual components as Phase Detector, LPF and VCO. My problem is in implementing the LPF. I have determined the values of the pole and zero for the Laplace ...
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1answer
48 views

Adaptive Piecewise Constant Approximation (APCA) with wavelets/DWT

I am trying to approximate a vector or a time series, in order to have as little changes as possible. To do so, I pretend to apply the Adaptive piecewise constant approximation (APCA) algorithm. ...
0
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0answers
63 views

DFT of a continuous quasi-periodic signal

If I have a continuous quasi-periodic signal and I want to do a DFT of signal then what could be appropriate length of continuous signal that I should consider for sampling? I want to do DFT of the ...
1
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1answer
40 views

Wavelet transform in MATLAB

Suppose I have a wave with $20 \textrm{ kHz}$, $100 \textrm{ kHz}$ and $300 \textrm{ kHz}$. Sampling frequency used is $1000 \textrm{ kHz}$. I apply the discrete wavelet transform on the wave like <...
2
votes
1answer
61 views

Implementing Welch's method for Power Spectral Density

I want to implement Welch's method for PSD calculation in MATLAB. I do not want to use built in MATLAB cpsd function, such that I can change the FFT implementation ...