Questions tagged [discrete-signals]

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

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How to implement an improper discrete-time transfer function into Simulink

I am trying to model a discrete-time control system in Simulink. The control system contains an inner loop that utilizes the inverse of the plant model. The plant in question takes the form of: $P(s)...
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1answer
1k 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. ...
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56 views

How to get cofficients in DFT?

In my recent study of signal processing I came to know that we can compress images/signal using DFT/DCT. If we consider the lossy compression of audio or any image then it follows the same steps: ...
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Confusion in understanding the Proof of DTFT

While understanding the proof of DTFT from Signals and Systems by Oppenheim, I have confusion in understanding few steps. $$ x'[n]=\sum_ {k=<N>} a_ke^{jk(2\pi/N)n}$$ $$ a_k= \frac{1}{N} \sum_ {...
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88 views

Approaching the response of an RC circuit via y=ifft(fft(x)fft(h)). Why is this valid?

Some textbooks like (Numerical recipes the art of scientific computing) derive the DFT as a Riemann sum of the CTFT. With this in mind it would be natural then to approximate the identity $$y(t)=x*h=\...
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60 views

Estimating the power consumption of an arbitrary, real-time DSP algorithm

Consider a digital signal processing algorithm that operates over a block of $L$ [samples], with a real-time constraint $\tau$ [s] (i.e. its throughput must be $L/\tau$ [samples/s]). The theoretical ...
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91 views

How to take IFFT of Connes Window?

The Connes Window function is defined as : w(f)=$(1-(\frac{f}{ \Delta f})^2)^2$ for $f<|\Delta f| $ w(f)=0 otherwise The inverse fourier transform of this function can be analytically ...
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53 views

How accurate is Wavelet packet decomposition for emg signals with frequencies from 10 to 40 Hz?

I have an electromyographic signal sampled at a frequency between 10 and 40 Hz in a time window of 300ms. Is wavelet packet decomposition adequate in order to perform features extraction for ...
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121 views

how to find the distance of the root from the origin?

Good Day, I have 9 polynomial roots. i have plotted the roots. my problems are: 1)how to find the distance of the roots from origin? I want to find the distance of all the roots from the origin. 2) ...
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133 views

PID Control - process variable / setpoint

I'm trying to design a PID controller but I have a problem in the following case: The process variable can only be between 0 and 1. The setpoint can be close to one, for instance 0.97. Hence the ...
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174 views

MATLAB, recover a signal that has a cosinusoidal interference and that has been AM modulated

I have a signal which has been AM modulated but the channel also added a cosinusoidal interference A cos(2 * Pi * f0 * n * Tc + Phase), at the same ...
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909 views

Finding if a signal is periodic

Hello I just started learning Signals and Systems and I have a question regarding periodic signals. For instance: $x(t) = \cos(3.2t) + \sin(1.6t) + e ^{j2.8t}$ is periodic because of the HCF of the ...
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39 views

Approximating the fourier coefficients from a discrete time signal

Suppose I have a discrete time signal $x_t$ sampled with a frequency $f_s$. I know that if I take the discrete fourier transform of the signal and compute the power, I can easily (by visual ...
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150 views

Sub-clock FPGA delays on output line

I am trying to include the ability to have sub-clock delays on an FPGA system's data bus without the need of fractional delay filters. I am using a Xilinx V6 part, and could utilize its IODELAYE1 ...
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162 views

What is the preferred method of aggregating audio FFT data given variable-size frequency bins?

I am coding a program which uses a FFT to process audio data. I need to aggregate the FFT output into three bins ("bass", "mid", and "treb") determined by two arbitrary frequency values. The end-goal ...
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3k views

Generate time-domain random signal from PSD

Given an analytical description of the PSD, for example (MATLAB "pseudocode"): ...
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179 views

Adaptive Line noise removal using IIR notch filters

I'm trying to filter out line noise(60Hz and 120Hz) from a EEG signals received over a bluetooth link. I'm proposing to use a IIR notch filter to filter out the line-noise which varies w.r.t to ...
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97 views

How to simulate two OFDM Users with low complexity FFT/IFFT?

have two User one of them sending over freq (0-B] and the other transmit over (B-2B]. Both of them are using OFDM and each one has Nc subcarriers. I wanted to simulate the received signal using Matlab....
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569 views

For discrete signals, why does phase change not correspond to time shift?

I'm going through a Signal Processing lecture where the professor mentions this fact and the argument given is: Suppose you have a sinusoidal signal: $Acos(\omega t)$ Now if you change the phase of ...
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168 views

generating a waveform in matlab for rohde and schwarz signal generator

We are doing a test which consists in sending a waveform from Matlab to the signal generator SMB100A and sending it through a cable to the r&s spectrum analyzer just to have a channel. We set the ...
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314 views

Fast Walsh-Hadamard Transform frequency spectrum?

Can the Fast Walsh-Hadamard Transform be used to find a Walsh-Hadamard frequency spectrum which some how relates to a Fourier frequency spectrum? Is the Fast Walsh-Hadamard Transform more accurate ...
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993 views

CWT for filtering / feature extraction

I had asked a question last night in regards to how to process my data (Noise rejection / feature extraction) but I have a more specific question now that I hope someone can answer. As mentioned in ...
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120 views

Describing a time delay at a maximum for maxima and minima but tends to 0 elsewhere

I have two force-time signals obtained from a couple of force plates, corresponding to input/output signals for some system. Plotting the two together one of the first things I noticed was a time ...
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562 views

Online FFT of simulated signal

it is a couple of weeks that I am thinking about the following: I have a tool which is able to simulate the dynamic behavior a steel tower exhibites due to the coupled action of wind and waves. ...
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241 views

Determining Valid DTFT's

Are the following frequency domain signals valid DTFT's (Discrete Time Fourier Transforms)? Answer yes or no, and justify your answer. a) $X(\omega) = \omega + \pi$ b) $X(\omega) = i + \pi$ c) $X(\...
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37 views

Operaion on Simple Discrete Time Signal , Very Simple Question

I got this simple Discrete time signal question on which i have to perform shifting and multiplication.But I have some Doubt regarding the answer this book shows. Please see the uploaded image.
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266 views

Why the number of poles and zeros for a RHS signal in the Z domain is equal?

I can not understand the reason why the following sentence is true: If we have a Right-Hand signal(RHS) x(n), X(z), the Z-transform of x(n), has the same number of poles and zeros except at z = ...
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107 views

How to add 2 MFCC extracted features to a variable?

I am working on signal processing for speaker verification. I have extracted MFCC features for few wav files using GMM algorithm. Now, i want to add any 2 MFCC features to another variable. How can ...
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67 views

Common mode noise from two ADC results

I am sampling two sinusoidal analogue signals that are phase separated by $\frac{2\pi}{3}$, and there appears to be a significant amount of common mode noise in my samples. What, if any approach can I ...
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852 views

Similarity of signals

I have a question concerning methods to find different aspects of "similarity" of signals. So, first, I'd like to characterize the signals to be dealt with: We have a number of close to rectangular ...
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34 views

decorrelating two image maps — reflected images from laser scattering

I am stuck on a research problem and do not know what kind of methods to use. I hope people in this forum can give me some good ideas, I've always had good brainstorming sessions here. My problem is ...
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141 views

How to measure the short-time change in an audio signal?

The choice of frame length for calculating the Mel Frequency Cepstral Coefficients of a signal, depend on the how much the signal change over a small time scale. I guess that human speech change ...
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1answer
43 views

MMSE- Channel estimated based - DFE Equalization

For HF ionospheric channels ( frequency range 3 up to 30 MHz), I Want to make channel equalization in time domain, using MMSE criterion. I have to do it using the channel estimation. I have some ...
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1answer
414 views

Is inverse matched filter useful?

I am aware of matched filter and its application. Now, wondering if there is any application of inverse matched filter? What I mean my inverse matched filter is that convolution of matched filter and ...
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26 views

Discrete Time convolution calculation error

i'm trying to find the convolution among this three signals : $$ h1= \delta(n)-\delta(n-4) $$ $$ h2= u(n) $$ $$ X= ({1}/{2})^n * u(n) $$ If i try to do $$ x*h2 $$ i get : $$ 2-2^{-n}*u(n) $$ ...
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1answer
91 views

noise floor estimation

I want to estimate noise floor in the spectrum. I tested many methods using journals, but I couldn't find a stable method. Suggest that we have a spectrum consist of many signal and we want to ...
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1answer
27 views

How to extract two signals from one signal by selecting right index?

Assume that we want to solve $$AX=B$$ Where both $A, X, B$ are matrices. I solved this by using ordinary least squares: $$X = (A^TA)^{-1}A^TB$$ And I got this result for one column in $X$. Here ...
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1answer
25 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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1answer
254 views

integral filter

Assume we have a time domain signal: s(i), i=1:N. To apply a derivative filter to it, i.e. D*s, where ...
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1answer
402 views

edge detection of 1-D signals

Would you please introduce me to some methods (or references) to do edge detection on some pulses (rectangular pulses embedded in noise). At first I apply some filters to smooth the signals, then I ...
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1answer
34 views

Frequency component not filtered properly

Are frequency components other than wanted signal present in the output? If yes then why does it not disturb the original signal? I think all practical filter responses are not ideal, so all frequency ...
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1answer
48 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 ...
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1answer
73 views

Calculating phase only component of a signal in MATLAB

I am working in the field of digital signal processing. Recently I read a paper that tells about phase only component of a Signal. It is given that the phase only component is calculated as $r_{phase}=...
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1answer
369 views

Problem executing Hilbert transform on $x$-$y$ plot in MATLAB

I have a wav signal I have imported into MATLAB, and I would like to find its envelope. I want to do this via the Hibert transform. But whenever I try to find the Hilbert transform of the signal I ...
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1answer
353 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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2answers
331 views

Shift-Invariance of Dirac Comb?

Is a dirac comb a Linear and a shift Invariant System? I could prove the linearity, but I do not think it is shift invariant. How do do I prove it is shift variant?
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1answer
239 views

How to convert an analog signal to an impulse signal?

I have several analog signals with constant amplitude in time. What I want is a way to convert these analog signals to an impulse signal i.e. a signal that consists of impulses occurring at different ...
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1answer
82 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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3answers
688 views

How we decide sample rate and number of samples while doing discrete Fourier transform

I solved a differential equation numerically and I want to find the frequencies present in the solution but I am not able to figure out sample rate/frequency and no. of samples that I should take.can ...
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4answers
3k views

Trying to recreate sawtooth and square wave in Matlab

I've been asked to recreate the square and sawtooth wave shown below: And I've managed to recreate the square wave form but I can't seem to get my sawtooth wave to match. ...

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