Questions tagged [discrete-signals]
A discrete signal or discrete-time signal is a time series consisting of a sequence of quantities.
0
votes
0answers
12 views
Is it customary to use the period as coefficient when sampling the impulse response?
I have an analog, continuous impulse response $$h_a(t)=u(t)\cdot\sum_{n=1}^4A_ne^{s_nt}$$, and by sampling it with the usual method I get $$h[n]=\Delta th_a(n\Delta t).$$ Now, that $\Delta t$ is a bit ...
1
vote
3answers
115 views
Measure Sine Wave Amplitude from ADC Signal
I'm trying to do some DSP that I have never done before and a nudge into the right direction would come in handy. The context is replication of this project.
The system architecture is the following: ...
0
votes
1answer
27 views
Sampling - Higher order harmonics
I have been studying about the sampling theorem and it seems that even though we sample at a frequency with the nyquist criterion, the harmonics (due to sampling process) remain within the nyquist ...
0
votes
1answer
42 views
Difference between the DTFT and DFT [duplicate]
I know this question has been asked before. It is, however, so confusing, that I'd like to give this another try:
I have come across the following 2 definitions of the DTFT:
So, the first line is the ...
0
votes
0answers
25 views
Is there a big data solution to analyses hydroacoustic data? [closed]
I'm looking for tools to work on hydroacoustic data, basically I want to measure biomass volumes from using the data recorded from echo sounders, the final product I´m aiming to is a biomass heat map, ...
-3
votes
0answers
24 views
0
votes
0answers
25 views
How to make function in time domain after fft fit with the corresponding function in frequency domain?
For example, I want to use fft to transform the simple function exp(-x.^2) defined in time domain. And the corresponding funciton in frequency domain is
sqrt(pi).*exp(-k.^2/4).
And I use the upper ...
0
votes
0answers
14 views
How does discrete spectral moment relate to continuous spectral moment?
It is said in discrete/digital signal processing that $r$th spectral moment of signal $x[n]$ is defined as:
$$\sum_{n=-\infty}^{\infty}n^r x[n]$$
But how does this relate to usual continuous $r$th ...
0
votes
0answers
10 views
Use 2D FFT to replace 2D Discrete Fourier Transform (MATLAB)
I met a problem. I ran a code to implement the 2D discrete Fourier Transform, here is the code:
...
-1
votes
1answer
22 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 ...
0
votes
0answers
24 views
Adaptive frequency discovery of binary signal
First of all, I'm not a signal processing expert. Actually, I'm trying to benefit from some concepts of signal processing theory in my computer science research.
My problem is that, I have to find ...
0
votes
1answer
35 views
Distortion in sound after multiplying frequency spectrum by constant
I make a simple sound equalizer that operates in frequency domain and lets user to adjust frequencies in sound by using 4 sliders. The first one responsible for 0 - 5kHz, the fourth one for 15-20kHz.
...
0
votes
2answers
64 views
Higher order harmonics during sampling
I am studying about the sampling theorem in conjunction for ADC. I got little confused while reading about aliased frequencies. I see that as per the Nyquist theorem, the sampling frequency (fs) ...
0
votes
0answers
20 views
Convolution with rectangular function
I have a system $h(t)=4e^{-4(t-4)}u(t-4)$ and I want to response of the system to $x(t)=rect(2(t+4))$.
I have followed those steps:
$y(t)=x(t){*}h(t)$
$=rect(2(t+4)){*}4e^{-4(t-4)}u(t-4)$
$=4[u(t)-...
0
votes
1answer
76 views
Compute time constant of discrete exponential decay pulses
I want to retrieve (within a FPGA) the time constant $\tau$ of incoming pulses of the form $$x[n]=Ae^{-n/\tau}u[n]+C$$
In addition to the offset, inputs are subject to noise.
To measure the integral ...
0
votes
0answers
13 views
Signals time fluctuation
I am following this paper.
I am lost in equation 3. What exactly is a signal's fluctuation? What does the $\delta$ here represents?
Also why does it's autocorrelation is represented as $\langle \...
0
votes
0answers
18 views
Removing outlier data points from frequency-domain signal
Hello signal processing stack exchange,
I have a complex frequency-domain signal representing the impulse response of a physical system over some range of frequency space. As an artifact of the ...
0
votes
1answer
34 views
Very basic question about filters in signal reconstruction
I am studying digital signal processing and I would like to ask a question about sampled signal -> original signal reconstruction filters.
Most textbooks use a box filter or a tent filter to show how ...
0
votes
1answer
28 views
Impulse response of a system from the input-output relation
I need to find out the recurrence relation and the impulse response of the following system.
The relation seems to be $$y[n] = \frac{2}{16} x[n] + \frac{3}{16} x[n-1] + \frac{6}{16} x[n-2] + \frac{3}{...
0
votes
1answer
41 views
Linear Combination of Two Signals
In my signal processing class I have some basic tasks working with sinus signals in Matlab. I have two sinusoidal signals with 1kHz and 3kHz and sampling rate of 16kHz. The next task says 'Create a ...
0
votes
1answer
31 views
Cramér-Rao lower bound
I have been trying to implement the Cramér-Rao lower bound from the paper - A reference-free time difference of arrival source localization using a passive sensor array (eq. 6 and eq. 7).
$$
\...
1
vote
1answer
31 views
What is exactly Power Spectrum Density? [closed]
In papers or textbooks, I have found several different definitions of PSD. I think I understand the meaning of PSD and all these papers or textbooks agrees that PSD and Fourier Series share a ...
-1
votes
0answers
37 views
Signal Processing
My question is related to the attached picture
What is the effect of the system on the input. For example if I have a simple function x[n] = A , then I would expect
y[n]= { [ B^(-n) x[n] ] * p[n] ...
-1
votes
0answers
14 views
Why is it my wavelet transform works for % returns but not for a price time series?
So im trying to apply wavelet transforms to denoise stock data just to get a feel for the methodology. My plot looks good when I reconstruct on a series of daily percent returns centered at 0, but ...
0
votes
1answer
57 views
Upsampling signal using convolution-based interpolation filters
I am currently reading this paper which discusses several image interpolation methods, such as nearest neighbor and linear interpolation, using convolution filters. I first want to do this in 1D with ...
0
votes
1answer
20 views
Discrete signal testing for periodicity
How would one go about determining if the following discrete time signal x[n] is periodic, and if it is, determine its fundamental period?
I understand that the ...
0
votes
1answer
62 views
Is there an example of an infinite signal? [closed]
In the real world, Is there an example of an infinite signal?
0
votes
1answer
13 views
What is the z-domain transfer function of variable delay?
Is it possible to obtain the transfer function of a signal that has a variable delay?
For instance, I have a signal consisting of 10 samples:
0,1,1,1,1,0,0,0,0,1
If I would apply a unit delay to ...
1
vote
1answer
52 views
Octave - freqz strange results
I wrote octave code to find transmittance based on zeros and poles:
...
1
vote
2answers
135 views
What is the DFT of DFT of discrete signal [duplicate]
What is the discrete fourier transform of the discrete fourier transform of any discrete time signal. Is result same signal? How?
-1
votes
0answers
30 views
How to filter a discrete waveform by having continuous domain poles and zeros
Let's consider we want to model a continuous time filter that has one zero at 30GH and two poles at 35GHz.
I also have a sampled waveform with sampling frequency of $f_s$, so the time interval ...
1
vote
1answer
67 views
State of the art algorithms for estimating noise variance
Suppose I have a signal $X[n]= f[n] + W[n]$, where $W$ is uncorrelated Gaussian white noise satisfying $E\{W[n]W[k]\} = \sigma^2 \delta[n-k]$.
What are the state-of-the-art algorithms for determining ...
1
vote
1answer
46 views
How to count the number of threads in a bolt or nut using image processing?
How can I count the number of threads in a Nut with image processing?
I know that I need to find the place of threads and count them. Ok, But how can I find the place of threads?
This is a sample ...
1
vote
0answers
19 views
How to count the up and downs [duplicate]
I want to count the threads of a bolt in an image. My solution is this:
capture an image
Find the bolt
Get one dimentional data from it's top to bottom
Find the thread count from signal
This is the ...
1
vote
1answer
64 views
Limitation on the shift theorem of DFT due to frequency resolution?
The shift theorem states that shifting a sine wave in time domain by t is equivalent to multiplying the corresponding DFT coefficient of the signal by a complex exponential e^(-jwt). Described by the ...
1
vote
0answers
69 views
Linear Predictive Coding example in MATLAB
I have some data that is highly correlated and I wanted to see if I could try and encode it using linear predictive coding (LPC). Here is how I've been understanding the process:
Encoding
Generate ...
2
votes
1answer
37 views
IDFT of $Y[k]=2X[k]$ for even $k$
If the 16-point DFTs of $x[n]$ and $y[n]$ are given as
$Y[k]=\begin{cases}2X[k], & k=0,2,4,...,14 \\ 0, & k=1,3,5,...,15\end{cases}$, where $x[n],y[n]=0, \forall n<0, n>15$, how can I ...
1
vote
1answer
28 views
Inverse DFT in terms of original signals for product of two DFTs
Given $x[n]$ and $h[n]$ that are zero for $n<0$ and $n>15$, their linear convolution being $y[n]=x[n]*h[n]$ and their discrete time Fourier transforms are $X(e^{j\omega})$ and $H(e^{j\omega})$, ...
-1
votes
0answers
25 views
Why are componets of Complex baseband noise uncorrelated?
Many articles and papers on digital communications use the assumption of an AWGN environment. They write that after the signal is converted to baseband the resulting In-Phase and Quadrature components ...
-1
votes
0answers
39 views
ECG signal with kaiser and butterworth
first sorry about my english. I'm trying to do treatment of an ECG signal with kaiser and butterworth to compare. When a did with kaiser it's looked like that:
Blue is before treatment.
and orange ...
1
vote
3answers
94 views
$e^{j\omega}$ on unit circle
I am new to DSP, and I'm self studying. I am confused about the magnitude of $e^{j\omega}$ - where $\omega$ is the normalized angular frequency - when we are on the unit circle.
According to the ...
-1
votes
4answers
99 views
Nyquist Theorem - Why unique frequencies upto Fs/2 and not Fs? f+Fs is start of Aliasing
If any frequency, f, displays an alias at f + Fs, This shows that unique frequencies have a range of Fs. Why does Nyquist theorem say that actually there is only half of this with unique frequencies ...
-1
votes
0answers
37 views
How to Code a lead lag controller?
I have been fascinated in controls and signal processing and enjoy it so much that I like reading and learning this on my own time.
So (to the point) my question is, how do you implement a lead or ...
2
votes
1answer
37 views
Forward Linear Predictor
I just need some advice on a project. I have an unwanted sinusoid that has time-varying frequency (its not sinusoidally varying) which is relatively constant over a small section. I've been advised to ...
1
vote
1answer
40 views
Symbol Timing recovery for modulation producing ISI
I am interested in understanding why the common timing recovery algorithms function for modulation schemes which produce ISI.
For example, suppose you are receiving at the output of a matched filter ...
-1
votes
0answers
21 views
Audio signal for each video frame
I have an mp4 video. Is there any way to extract the amplitudes of all the audio signals for each video frame in the available video?
That is, suppose there are 1000 audio samples corresponding to ...
5
votes
1answer
66 views
Is possible reach the DFT if I have the DTFT?
My teacher told me that DFT is DTFT sampled, i.e.:
$$X[k] = X(e^{j \omega})\Bigg|_{\omega = \frac{2\pi k}{N}}$$
But, if I have the sine
$$ x[n] = \sin(\omega_0 n) $$
the DTFT is:
$$X(e^{j \...
0
votes
1answer
27 views
Interpolation of missing audio signal in a video sequence
Suppose there is a video sequence and there are some frames for which the audio data is missing. I want to interpolate the missing audio data on the basis of the correlation of the audio signal with ...
0
votes
1answer
65 views
How to determine fundamental frequencies (beats/minute) of heartbeat? (matlab)
read = matfile('ECG.mat');
[cor, lags] = xcorr(read.ecg, read.ecg);
read.Fs;
So i have read.ecg (signal) and ...
1
vote
0answers
32 views
Understanding linear predictive coding in MATLAB
I want to test my understanding of linear prediction by running it on some test data in MATLAB. The way I understand it is if I have some data that is correlated, I can encode the signal with linear ...
