New answers tagged discrete-signals
2
votes
Accepted
Average of discrete periodic signal
It appears the OP would like to estimate the mean of the signal efficiently. A moving average will provide the best estimate under condition of white noise; assuming that is the case, the CIC (Cascade-...
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0
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Why is this Python implementation of trigonometric interpolation not working properly?
I strongly suggest using the Dirichlet interpolation. The basic idea is the interpolation via the Fourier transform:
$$f(x)=\sum_k \hat{f}(k)e^{ikx}$$
Here is an implementation for arbitrary chosen ...
1
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Accepted
Adding Fractional STO to an OFDM Signal using Frequency Domain Zero Padding
I believe the distortion is from using the FFT of the complete OFDM symbol including the CP to introduce time delay with a zero-padded FFT. Even before zero-padding is added the FFT result will no ...
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0
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Weird Pattern in the Power Spectrum diagram (i.e. the frequency domain of the signal)
Two possible reasons:
A low pass filter is active. The ripple looks like a typical filter stopband ripple.
It is due to the way the spectrum is calculated. Check the settings and play around with ...
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Does Zero padding cause noise in the high frequency region?
If you've got it in the frequency domain anyway, why not phase shift it by (delay)(frequency)? It may still do odd things (like, shift whatever's at the end of the sample to the beginning), but you'...
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3
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Accepted
Does Zero padding cause noise in the high frequency region?
Is that correct?
No. This zero padding just leads to interpolation with a (cyclic) sinc kernel. It affects all subcarriers the same (as you can see in your own DFT!).
So, this has to be a problem ...
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4
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Calculate the energy of x[n]
It's always helpful to write down the first few elements and check if you can see the pattern. You can quickly see that $\sin(\frac{\pi}{2}n)$ is simply ...
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0
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Are there any order analysis functions in Python?
I am not sure if you can find an implementation to those functions (you might do if you will look long enough). Main point, each of those functions might be implemented in several lines so there is no ...
0
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What is the difference between natural response and zero input response?
have a look at:
https://www.youtube.com/watch?v=isSFqzZwu38
time: 19:22,
he mentions that total= a) homogenous+particular,
b) force + natural
c) zero state+ zero input
and that force+natural are not ...
1
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Accepted
Applying a window to a signal
For regularly sampled data, windowing consists in multiplying a signal $x[n]$ or a portion of it by a window $w[k]$, sample by sample, as illustrated as follows (source NI). The result will be somehow ...
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When is the Fourier transform of a periodic discrete signal $\mathcal{F}x[k]$ the same as $x[k]$ up to a diagonal matrix
tl;dnr version: No nonzero vector can satisfy the requirement stated in the body of this question.
The rest of this answer is a long-winded proof of the assertion above.
The Discrete Fourier Transform ...
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2
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Applying a window to a signal
Windowing is commonly done to reduce spectral leakage in the result of a Discrete Fourier Transform (DFT). There are many other posts here that explain the finer details, but at the high level to ...
- 36k
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When is the Fourier transform of a periodic discrete signal $\mathcal{F}x[k]$ the same as $x[k]$ up to a diagonal matrix
Let $\newcommand{\F}{\mathbf{F}_{{}_N}} \F$ be the (unitary) DFT-Matrix of size $N$. Let $\newcommand{\x}{\mathbf x}\x$ be the vector $\x=(x[0],\ldots x[N-1])$. Your equation says:
\begin{align}\...
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0
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Why do I need to shift time for getting a response?
The impulse response has components at n = 0, 1, and 2, which means for any scaled impulse at the input at any given time m, we will get an output at time m, m+1, and m +2 as the scaled impulse ...
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Transformation of the independent variable of signals
The independent variable denotes here any of the locations or indices at which $x$ is defined. The symbolic name or notation of the independent variable does not matter per se, as long as is a valid ...
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Transformation of the independent variable of signals
As per my understanding, $x$ is a function of $n$,
Correct
so it is not possible to write lets say $x[n-n_o]$.
Why not ? The time variable can be transformed like any other variable so you can ...
- 30.6k
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calculate discrete time signal convolution example by hand
Just assume that $x[n]$ and $h[n]$ are zero for all sample times outside those that have been specified.
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1
vote
Accepted
Representing changing sample rate in block diagram and frequency response plot
This is how I would represent the processing described by the OP:
"MAF8" represents a moving average filter over 8 samples. Even though the OP is doing a block average, the result will be ...
- 36k
1
vote
Accepted
Find maximum of a square wave with variable frequency
An easy and robust solution would be to low pass filter with a post-processed "Zero-phase" filter, the result of this will be time aligned with the input waveform and provide an averaged ...
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