Questions tagged [sampling]
In signal processing, sampling is the reduction of a continuous-domain signal to a discrete-domain signal.
725
questions
0
votes
0answers
14 views
removing noise using Scipy.signal.butter:
I am going to remove the noise from a brain recorded signal. It was a continuous recording and with sample rate=30kHz, it was digitized. So now it is a digital signal.
I have written the code here ...
0
votes
1answer
45 views
Trouble with understanding moving average filter as an oversampling filter
I am struggling with understanding how an moving average filter can increase ENOB in a given sample.
I wrote a test for a simple MA (moving average) filter in matlab. The algorithm to create new MA ...
-2
votes
0answers
30 views
Analogue signal and bandwidth [closed]
An analogue signal has a bandwidth which extends from very low frequencies up to 12 kHz. Using the sampling theorem, what is the minimum sampling rate (numbers of samples per second) required to ...
0
votes
1answer
49 views
sampling a continuous time signal using MATLAB?
I have a continuous time signal $x(t)=cos(2 πft)$ where $0\leq t \leq 2$.
I want to plot discrete time signal $x(n)$ where $0 \leq n \leq 19$ for sampling frequency 100 Hz and signal frequency 10 Hz.
...
0
votes
1answer
37 views
Torque signal fft
I have the following torque signal picked up with a 10.240Hz sampling rate from a testbench.
I am studying its fft which I create on Octave with the following code:
...
0
votes
2answers
56 views
Why is the digital frequency highest at $\pi$ and what does it mean in terms of analog frequency? [duplicate]
I can't seem to comprehend why the digital frequency is highest at $\pi$. I know the relationship between the digital and analog frequency is given by:
$$\omega = 2\pi\frac{F}{F_s}=2\pi f$$
Where $F$ ...
0
votes
1answer
36 views
Build an inverse model for a train of gaussian pulses
I have a stationary signal from a train of Gaussian pulses.
My sampling window is too wide (cannot be reduced). In the example 1 ms. So it is not possible to clearly distinguish one pulse from another....
1
vote
1answer
64 views
relation between DFT to CTFT
The signal $$x(t)\;\;\;\;0\leq t\leq 0.2s $$
We know that the CTFT of $x(t)=0$ when $|w|>2*\pi*10^4$
We sample $x(t)$ in sample space of $$T=25\mu s$$ or $$F_s=1/T=40000Hz$$and we get a series ...
0
votes
2answers
49 views
find the maximum of the DFT of sampled signal
The signal $$x(t)=\cos(10\pi t+\phi)+\cos(20\pi t)$$ is sampled with a sampling frequency $F_s$ as $25 \mathrm{Hz}$ where the phase $\phi$ is unknown.
Sampling the continuous time signal $$y[n]=x(nT)$...
1
vote
3answers
60 views
Poisson summation formula and periodic summation of Fourier transforms
One of the forms of the Poisson summation formula is
$$
\sum_{n=-\infty}^{\infty} T\cdot x(nT)\ e^{-i 2\pi f T n}\;
{=} \;
\sum_{k=-\infty}^{\infty} X\left(f - k/T\right),$$
where $x(nT)$ are ...
1
vote
1answer
57 views
Discrete time aperiodic signal: Concept of frequency?
Is concept of frequency to a-periodic signal whether it is continuous or discrete time is valid?
I am bit confused, since discrete time sinusoids have frequency $-\pi<\omega<\pi$ or $-\frac{1}{...
0
votes
1answer
36 views
Choosing right cut-off frequency for a LP filter in upsampler
I'm implementing a upsample function in Matlab but it's not perfect right now,for reasons I'm not sure. Here is my code:
...
1
vote
2answers
41 views
How sampling aperiodic signal will result in periodic repetitions of the same
I am reading "Digital Signal Processing" - Proakis and often read that sampling guarantees periodicity (not exact as read)
But I wonder how sampling aperiodic signal will result in periodic ...
4
votes
1answer
46 views
Can the Nyquist sample rate be extended to stochastic sampling?
It appears there are lots of questions here about Nyquist, and a few questions about stochastic sampling here. But I haven't found any that address quite what I'm after. This is the closest I've ...
3
votes
5answers
1k views
A question about sampling rate of cosine signal
Given $$c(t) = \cos(2\pi\cdot 30 \cdot t) $$
If we sample this signal at the Nyquist rate 60 Hz and at a higher rate of 80 Hz, we get the following:
There is no aliasing as $f$ = 30 Hz is less than ...
1
vote
0answers
19 views
Calculate sampling lattice matrix in 2D
The pattern in which the sample points are distributed in 2 dims, is called a
sampling lattice, and can be defined by a generator matrix.. In 2 dimensions, the generator matrix consists of 2 vectors. ...
1
vote
1answer
80 views
How do I convert a sampled complex signal to a real signal?
I’m writing a Soapy SDR plugin for the FL2K-SDR. Soapy SDR expects plugins to produce and consume IQ samples. However, the FL2K-SDR driver consumes only real samples. I know you can convert a real ...
0
votes
1answer
32 views
Recoverable continuous function after average sampling
I have a personal interest in this question, but I don't know if it is unfounded.
Suppose I have a continuous function x (t), which is sampled using an average sliding window, which performs a ...
0
votes
3answers
72 views
confusion sampling vs quantization?
while converting analog signal to digital equivalent,we have a process that is called analog to digital conversion and it has two main steps/stages sampling and quantization? I am confused whether y ...
2
votes
2answers
221 views
Phase difference between signals sampled at different frequencies
I want to know that if it is possible to measure the relative phase difference between a signal that has been sampled at two different locations with different sampling frequencies? Also can that ...
0
votes
0answers
10 views
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?
1
vote
2answers
83 views
anti-alias filter of square pulses
I'm trying to determine whether or not an anti-alias filter is needed for sampling square waves. The goal is to sample square wave pulses from a video detector with an ADC, do some time-domain digital ...
0
votes
2answers
59 views
Nyquist sampling in image acquisition
I know that in the image acquisition stage, after obtaining the analog image from the sensors, it is sampled and quantized. How the Nyquist sampling is achieved? The sampling frequency must be at ...
0
votes
2answers
49 views
Sampling $x(t)=\cos(4\pi t)+\cos(2\pi t)$
Imagine that we sample the signal $x(t)=\cos(4\pi t)+\cos(2\pi t)$ with a certain sample frequency $f_s$ and we obtain $x[n]$. Now, by ideal interpolation, we get $y(t)$ from $x[n]$.
How can we know ...
0
votes
1answer
49 views
ADC sampling rate implications Matlab/Simulink M-PSK modulation
I am trying to find a way to evaluate what would be the minimum sampling rate used in a modulated waveform using matlab / Simulink.
The real scenario would be let say a M-PSK waveform of Y bandwidth ...
1
vote
0answers
31 views
How to generate Digital Sine Wave? [closed]
I am trying to generate a sine wave digitally. I am using LMS7200m RF chip from Lime microsystems. I want to generate a sine wave of 100KHz. The DAC on the chip has a sampling rate of 640 MHz with ...
0
votes
1answer
41 views
I/Q plane plot understanding?
I am experimenting with some signals. I ma generating a 2.47 Ghz signal from signal generator and receiving it by an SDR (LMS7002m Rf chip) with Rx frequency tuned to 2.47 GHz. Upon plotting the ...
0
votes
1answer
61 views
How to determine sampling frequency for an x(t) signal avoiding aliasing?
The antitransform of the function is given:
$ \hat{x}(f) = \frac{123 + i246\pi f}{246 - 24600 \pi^2 f^2 + i4920\pi f} $
I'm asked to determine which frequency can I sample using the function x(t) ...
2
votes
0answers
72 views
Lagrange Vs Sinc interpolation
I was wondering what is the practical difference between Lagrange Interpolation using Farrow Structure and Sinc Interpolation? Both require pre-computation of time offset coefficients using a lookup ...
0
votes
0answers
31 views
Nyquist sampling theorem / Nyquist - Shannon theorem evaluation over M-PSK
I am trying to simulate an M-PSK Tx-Rx System on Simulink and analyse what the effect of sampling rate reduction would have on it. More, particular I am trying to prove what Nyquist sampling theorem ...
0
votes
1answer
26 views
How to get RMS to Frequency chart for discrete samples of acceleration?
I’m reading a book on Motorcycle dynamics and want to compare the vibration profile of my motorbike against this chart:
I am not sure how to get the RMS of acceleration at different frequencies.
I ...
0
votes
1answer
65 views
Why is my filter unstable and self-oscillating in this case?
I am using resonant bandpasses to simulate modes of guitar/piano strings for audio synthesis. While attempting to introduce coupling effects I have encountered a problem.
I will illustrate with some ...
2
votes
1answer
70 views
Variance of a signal
How to calculate the variance of noise samples modeled as follows:
$n_a(t)$ is a
Gaussian zero-mean white noise process with (two-sided) power spectral density $\frac{N_0}{2}$. $n_a(t)$ is passed ...
4
votes
3answers
109 views
Digital to analog aliasing or mirror query… DAC can output negative frequency?
Using a clock Fs = 1 MHz.
The Digital to Analog (DAC) can make frequencies upto 500 KHz.
500 kHz to 1 MHz is an alias? Or is it called a mirror?? Is aliasing a concept only on the ADC and sampling ...
0
votes
2answers
61 views
how a signal for which calculate RMS can be filtered and have a fast settling time?
i designed a sinusoidal pwm amplifier (3KHz to 20KHz) that regulates its output voltage reading the RMS value of output current.
The RMS is obtained squaring the signal sampled by AD converter @...
0
votes
1answer
45 views
What is the difference between t=n*Ts sampling vs impulse train sampling?
I know that if I sampling with impulse train so I get in the frequency plane
X(f)*h(f)
(when x(f) is my signal, * means convolution and h(f) is fourier transform of impulse train).
what the ...
0
votes
0answers
30 views
Signal to Quantization noise problem
a full scale signal of bandwidth 5 khz is sampled by an 10-bit ADC at a sampling rate of 2 Msa/sec
calculate the Signal to Quantization noise of the resulting DT signal
repeat for a 14-bit ADC at ...
0
votes
0answers
32 views
FFT first frequency
I have some problems understanding FFT. If I know Fourier analysis frame (1024 samples) and sample rate (48 000 Hz), how can I find the first frequency of harmonic sines and cosines?
2
votes
1answer
49 views
How to describe correlated noise after the signal is oversampled?
The Gaussian noise in discrete signal models is usually assumed to be independent and identically distributed variables (i.i.d.). Does this mean that the signal must be sampled with the sampling rate ...
0
votes
1answer
61 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 ...
0
votes
0answers
16 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'...
0
votes
1answer
31 views
Band-limited signal recovery with finite bit depth
The sampling theorem tells us that a signal with no frequencies above $f$ can be completely described by sampling it a rate of $2f$. However, the theorem makes no reference to quantization, and so I ...
0
votes
0answers
47 views
Analog-to-Information Converters?
In Analog-to-Digital Converters(ADC), the signal is first sampled at a rate higher than or equal to the Nyquist, then quantized and encoded. In Analog-to-Informations (AIC), the sampling and ...
0
votes
1answer
70 views
1
vote
1answer
33 views
Sampling a signal with varying frequency
Question
I'm trying to figure out the sampling rate for my ADC to sample essentially signal essentially of the form:
$$y(t) = \sin(\max(t, \omega_{max})\times t) + n$$
where $n$ is noise.
Context
...
2
votes
1answer
60 views
FFT of white noise with different sampling rate
I have a question on how I should interpret the white noise power level (noise floor) obtain from FFT for different hardware sampling rates. I realized if I sample the same noise at different rates (...
0
votes
1answer
22 views
Perform frequency analysis on grouped pulses
I have a system which consists of individual pulses grouped in trains.
The trains have a frequency of 10 Hz, with a timing precision of sub ns.
The pulses have a frequency of 2.2 MHz with a timing ...
0
votes
1answer
72 views
with given Sampling rate, what max frequency human voice can be captured?
I'm new to signal processing and sampling rate, I was asked interview question related to this.
This is the exact question asked:
With 8Khz of sampling rate, whats the max frequency that human ...
1
vote
1answer
146 views
When calculating SNR, is noise included in signal?
Given a signal $x(t) = s(t) + n(t)$ where $s(t)$ is the desired signal voltage and $n(t)$ is the noise, should the signal to noise ratio of this signal be 20log(xrms/nrms) or 20log(srms/nrms)? i.e., ...
0
votes
1answer
32 views
$x[n]$ after sampling of $cos(16\pi t+\phi)$ at 12kHz
I'm not sure what the question really means, so this is just guesswork.
I think options 1 and 4 can be ruled out as $w_0<\pi$.
The CTFT of $cos(16\pi t+\phi)$ has two spikes at $16\pi$ and $-16\...
