# 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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### Discrete-time convolution response on matlab using for loop

An LTI system's Unit impulse response is defined as: > n = 1:100; h = 0.08*(0.9).^n; if we give input signal as: ...
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### Determine the haar wavelet function is linear or nonlinear

I'm looking for analytical justification of linearity or non linearity of the wavelet transform with the real Haar mother wavelet function. I have googling already. But I can't find and understand ...
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### How to calculate the coefficients of Auto regression model of multiple data?

I have ACF of a time series data, I want to interpolate the ACF using AR model for which I need to calculate the coefficient of the AR model The problem is I have (6000x6000) matrix of ACF and I cant ...
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### Wind turbine vibration analysis approach

This is going to be a bit of a long post. My questions are: Do the 5 signal processing steps look "correct"? Next steps could be to perform order analysis, and extract features from time, frequency, ...
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### Spectral kurtosis on non-stationary signal

I posted a question some weeks ago I still have not found an answer to. I updated the old question and am hoping someone could help. Link: Varying speed of shaft Spectral Kurtosis
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### Discretizing my continuous system in Matlab

I was hoping someone could help me with conducting my discretization in MATLAB. I have a linear system with known data: sampling interval $T$, system matrix $\mathbf{A}$, input matrix $\mathbf{B}$, ...
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### Time domain to angular domain approach

I have a rotating shaft where I need to move from the time domain to the angular domain to look for vibration faults. I have the data from a tachometer. From another post I found these steps: The ...
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### Strange FFT spectrum after resampling

I'm pretty new to signal processing and have encountered strange behaviour. I have a vibration signal from a non-stationary gearbox component that I need to resample to do order analysis. The ...
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### Why is it assumed that $x[n]$ is limited from $0$ to $N-1$ while evaluating DFT?

I am a total beginner in this topic of DFT. I get that the series must be finite for DFT calculation. But everywhere we are assuming that this series must be limited from $0$ to $N-1$. How to evaluate ...
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### Frequency change detection in step-wise frequency chirp

I am driving a system with a step-wise frequency chirp from 50-400 hz with a frequency step of 0.01 hz. I am having difficulty identifying the points of frequency change as the data collected has an ...
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### Varying speed of shaft Spectral Kurtosis

I want to perform Spectral Kurtosis (Kurtogram) on 10-second vibration signal of 25.6 kHz sample rate, where the shaft is varying in speed. Will a preprocessing step of resampling the signal be ...
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### What is the QPSK Constellation Diagram used in LTE

I think the question is pretty straightforward. I have to do a class project that requires me to modulate a signal, and one of the steps is Quadrature Phase Shift Keying (QPSK). It is to be done in ...
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### average value of modulated signal with Fourier Analysis

I am using an instrument that uses a modulated heating program. The instrument returns an average heat flow signal calculated from the modulated heat flow. I would like to understand how this average ...
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### Phase Difference offset when measuring phase difference between different FFT bins

In application where two sensors are used to calculate the phase difference of the incoming signal, what is the the phase difference offset which should be added when taking phase difference from ...
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### Smoothing a discrete function with point wise variances

In Stark's Introduction to numerical methods  it suggests fitting local polynomials to smooth discrete data before the Fourier transform using least squares minimisation. This gives the ...
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### Total Harmonic Distortion THD for the rectifier

I have a circuit with rectifier and this cause the non-linearity and consequently harmonic. I show it on the oscilloscope and then collect the signal from the oscilloscope to the computer by using the ...
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### Difference between Cepstrum and Spectral Envelope

I have no background in Signal processing and i don't understand the difference between cepstrum and spectral envelope. IDFT of the log magnitude of the DFT of a signal is cepstrum then what is ...
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### How to draw a finite-duration sequence

On page $359$ of the 2nd edition of the book "Signals & Systems", by Oppenheim and Willsky, the authors wrote the following words: "Consider a general sequence $x[n]$ that is of finite duration. ...
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### IID noise assumption at Matched Filter sample time

I read that at the correct sample times of a matched filter output the noise is independent assuming a Nyquist pulse. Can someone provide a proof of this or explain it more? Assuming your matched ...
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### Calculating average power of a discrete random signal with complex values

I have a Rayleigh channel that transmits discrete values according to the following: $$y(n) = h(n) * s_n + \omega_n$$ Where $y$ is the received message, $s_n$ is the symbol sent (constellation 2-PSM), ...
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### What is the difference between SFO (sampling frequency offset) and SCO (Sampling clock offset)?

What is the difference between SFO (sampling frequency offset) and SCO (Sampling clock offset)? I think they are essentially the same phenomenon?
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### Applying Wavelet on energy disaggregation as denoising technique to remove uncertainties

I would like to apply Wavelet in MATLAB as a denoising technique on Non-Intrusive load Monitoring data. The data was captured by sensors on each appliance and one sensor on the smart meter (Normally ...
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### Deep Learning based NDA Channel Estimation

I was wondering if it is possible to use Deep Learning to estimate the Channel Impulse Response for NDA synchronization? I understand Deep Learning is not normally used for regression problems but I ...
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### How to convert from Laplace Domain to Time Domain?

I want to convert the following equation from Laplace domain to continuous time domain: $F(s) = \frac{-2 m k v R}{2 m R s^{2} + m k s + 2 k R}$ m, k, v, R are all constants. If I can factor or put ...
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### Are discrete time functions expected to be this inaccurate?

I am attempting to test some discrete time functions against their continuous counterparts and I am surprised by how inaccurate the discrete versions are coming out. I am modeling the displacement, ...
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### (Frequency Offset): Relationship between Normalized Carrier Frequency Offset (normalized CFO) & ppm in OFDM system

How can I change a normalized carrier frequency offset (CFO) to ppm? And If the DAC sampling rate is 30GS/s, and the clock frequency is 15GHz, then should I use 30G or 15G when I calculate ppm? ...
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### inverse discrete FFT in python, multiple times?

I was wondering what really happens when taking the inverse discrete FFT on some set of numbers, for 3 times? Because looking at it, it looks like we're getting an output that is identically with the ...
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### How modulate and shift in frequency?

I have a 16-QAM constellation, then I divide it into imaginary part and real part. I convolve both by Srrc pulse and multiply by cos(2*pifct) and -sen(2*pifct). Let's say fc equal to 40 MHz Now, we ...
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### Impulse Response of a Moving Average System

According to Discrete Time Signal Processing by Al Oppenheim 3rd Edition, the impulse response of a moving average filter is as below My question is that shouldn't h[n] be having the dirac delta ...
A have a time signal: The associated DFT spectrum of this signal: The time signal can be considered as a non-symmetrical rectangular window function multiplied by a cosine signal with a frequency $... 0answers 21 views ### decouple signal from environmental effect Sensor signal depends on environmental factors such as temperature, relative humidity. Temperature compensation is relatively straightforward. But I am not entirely sure how to model the effect of ... 0answers 19 views ### Cross-correlation, spreading out the error I'm looking for a method to determine the most likely offset of a measured 1-dimensional signal to a reference signal. The reference signal does not need to be generalized and always has a similar ... 0answers 45 views ### Some confusion about calculating spectrogram I am new to DSP and i have a question because it is not the same as theory. I need to get spectrogram of wav file and feed it to CNN. I have used scipy.signal to get spectrogram. I know spectrogram ... 1answer 70 views ### Reconstruction of sampled band-pass signal I am pretty new to signal processing. I am currently trying to reconstruct a sampled band-pass signal created with the filtfilt and ... 0answers 17 views ### DTFT based Frequency Sampling H($e^{jw}$)= 1, |w| <$\pi/2$and 0,$\pi/2$<= |w| <=$\pi$I took M equally spaced frequencies from 0 to$2\pi$. If we assume h[n] to be causal,$H(e^{jw})$should have some phase and it'... 0answers 88 views ### Rigorous proof of the convolution- Sum Representation of LTI Systems We've started learning LTI systems and I have confusion regarding the convolution sum representation of a system. My problem stems from insufficient mathematical formalism in signals and systems ... 1answer 80 views ### Sampling period I started it but didn't how to continue , any help ? 0answers 20 views ### Which frequency bins give the best interpolation for the derivative of a function? A function$u:[0,2\pi]\to\mathbb R$sampled over$N$equidistant points$\theta_j=(2\pi/N)j,\, j = 0, \dots, N-1,$can be interpolated by a set of functions$\{u_{k_0}\}$enumerated by integers$k_0\...
When computing the energy of a NON-STATIONARY (transient) random discrete-time signal $x(n)$, does it make more sense to compute the energy as $E=\sum_1^N{x^2(n)}$ over all the $N$ samples or does ...