Questions tagged [sampling]
In signal processing, sampling is the reduction of a continuous-domain signal to a discrete-domain signal.
885
questions
2
votes
2answers
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Aliasing in Doppler Radar
my book about RADAR says that:
If a Continuous wave radar sends a sine wave at frequency $f_T$ to a moving object (at speed V), a frequency $f_R$ is received. Their difference is called Doppler ...
1
vote
1answer
21 views
Why symbols have to be upsampling, if the symbol rate and sample rate is same what happen?
In digital modulation process, after constellation mapping and before pulse shaping, the symbols are upsampled with the number L(samples per symbol). At this moment, why symbol have to be upsampled, ...
0
votes
2answers
50 views
How to reconstruct original signal from sampled signal?
My original signal as
f1=2;
f2=5;
fs=100;
Ts=1/fs;
t=0:Ts:1;
xt=cos(2*pi*f1*t)+cos(2*pi*f2*t);
figure
plot(t,xt)
as shown below figure.
and my sampled signal ...
1
vote
1answer
38 views
Clock recovery using Mueller and Muller adds noise affecting EVM or SNR (Two cases - GNU Radio & Python code)
The implementation of the Mueller and Muller clock recovery that I am seeing adds a large amount of 'noise' or degradation to the Error Vector Magnitude (EVM) to the symbols on the constellation. This ...
0
votes
1answer
19 views
FFT requirements of real time signal from sensors
I have an electrical current sensor which generates measurements every second. I want to calculate the FFT of this signal. Since my real-time values are received every second, I think that the fastest ...
0
votes
0answers
23 views
Speed measurement calibration
I have a sailing yacht where speed is measured using a peddle wheel. It measures speed through water (STW). This measurement contains a measurement error whose magnetude is dependend on both speed (it ...
0
votes
1answer
36 views
How to perform a phase recovery for higher order modulation schemes
My objective is to demodulate the signals with different modulation orders and schemes. In particular, I want to recover the phase first.
Let us say, my signal looks like in the constellation below
.
...
0
votes
1answer
73 views
Sampling with an alternating phase offset
Suppose, I sample a signal $z=\mathrm{e}^{\mathrm{i}\omega t}$ alternatingly in $I=\mathrm{Re}(z(t))$ and $Q=\mathrm{Re}(\mathrm{e}^{\mathrm{i}\alpha}z(t))$. Thus my data array contains
$$\texttt{data ...
1
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1answer
35 views
Train of impulses in frequency domain
Why compressing a train of impulses in time domain produce a wide-spaced train of impulses in frequency domain and vice versa? i want to know the intuition behind that.
0
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0answers
20 views
Sampling and Demodulation question
if I have an analog modulated signal with a DSBSC modulation (modulation index 100%) as an input in my receiver and I want to convert it to a sampled signal, do I need to demodulate the signal (with ...
0
votes
1answer
40 views
Nyquist Frequency and Window Length
The Nyquist theorem states that the sampling rate must be twice the highest frequency to be observed. How does the length of the interval play into this relationship?
The main resource that I found ...
4
votes
3answers
170 views
How to find peak value of an analog signal efficiently after sampling in the digital domain?
I have a bandlimited analog signal for which I want to find the peak value in real time. The signal is sampled and processed digitally at just enough sampling rate. Since the peak of the analog signal ...
1
vote
2answers
996 views
Does the Shannon theorem not apply when the amplitude of a wave is changed faster than half the time period of the wave?
Shannon's version of the sampling theorem states that if a function contains frequencies all strictly less than $B$ hertz, then it is completely determined by giving its ordinates at a series of ...
1
vote
1answer
88 views
QPSK demodulation
My objective is to demodulate QPSK signal. At this moment, my constellation in the best case looks like in the picture below:
and the corresponding eye-pattern:
Eyes are completely closed, which ...
0
votes
1answer
30 views
What is the difference between sampling over $-4\pi$ to $4\pi$ and 0 to $8\pi$
I see no difference in magnitude, but the phase plots vary significantly while using NumPy and MatPlotLib to plot.
Looking at the phase plots, I feel like I'm missing something important. Also, I'm a ...
0
votes
1answer
56 views
Filter to eliminate a 60 Hz frequency range
I have a analog signal that is converted into a discrete-time signal with an ideal A/D converter with a sampling frequency $fs$. The bandwidth of the signal of interest is $1 kHz$. The resulting ...
0
votes
0answers
30 views
Rate transition block in simulink
My model is operating at a sampling interval of $\frac{1}{f_0 \times N \times L_{maf}}$ s, (using a fixed point iterative method), now i want the output of my model to be at a sampling rate of $ f_0 \...
1
vote
2answers
57 views
Understanding FFT for a vibrational analysis experiment
I am trying to understand how FFT works in order to measure the vibrations of a 3D printer. I will be doing this with an Arduino Nano and a MPU6050 accelerometer.
In order to program the Arduino ...
0
votes
0answers
28 views
K-Path sampling overall transfer function
I'm trying to derive the overall Z-transform for the K-path sampling system shown below. I numbered some of the equations that I'll reference.
I don't think I understand going from equation 3 to ...
1
vote
1answer
39 views
FFT sample ordering with odd N
I have series of $ N =133 $ data sampled symmetrically around the origin in an actual space at $ x(n \tau) = x_n $ with $ n \in \{ -(N-1)/2, \, ..., \, 0, \, ... , \, (N-1)/2 \} $. Now, I'm a bit ...
0
votes
1answer
47 views
Improving Main Lobe Width of FFT
It is common knowledge that the duration time samples are collected is inversely proportional to the width of the main lobe in the Fourier domain. The simple example is the rectangular pulse in time ...
10
votes
2answers
2k views
Does the Nyquist frequency of the Cochlear nerve impose the fundamental limit on human hearing?
The bandwidth of human hearing by empirical data is $20 \; Hz$ to $20 \; kHz$. A cochlear implant stimulates the auditory or acoustic or Cochlear nerve directly so that the hearing can be improved in ...
1
vote
0answers
30 views
Dynamic sampling of thermal images
My master’s dissertation subject is to analyze and implement an algorithm that would sample (store) thermal images from camera with different frequency rates to optimize database size and processing ...
1
vote
1answer
32 views
Question on PCM Sampling and Quantization order
I had a doubt in my mind regarding the orders of sampling and quantization in PCM. What is the impact if the order is reversed, that is, the continuous time signal is first quantized and then sampled? ...
0
votes
0answers
4 views
Doubt about sampling rate and spectrum with USRP and gnuradio [duplicate]
I have started working recently with software defined radio (SDR) as well as gnuradio. I have worked with digital signal processing for a while and one feature at one tutorial, which I saw for ...
0
votes
1answer
26 views
Why does applying RRC to the signal increase bandwidth?
Please see this question: Why samples per symbols $\geq 2$ in the GNURadio Constellation Modulator block?. The first answer here says "filtering the signal, you have bandwidth expansion". ...
0
votes
2answers
38 views
Wavetable and Nyquist: which size do I need?
I was reading this tutorial by the master earlevel, while trying to build some sort of wavetable.
He says First, let’s back up and figure out how long our tables need to be. Recalling that we need to ...
0
votes
1answer
28 views
does ifft of higher order equal upsampling signal
I have a signal with length 2000, and am taking an fft by 2048, after I perform analysis and some operation on signal in frequency domain I tried to convert it back to time domain. I received a signal ...
0
votes
0answers
30 views
How is sampling rate affect the Doppler spectrum? Textbook attached
I am studying FWGN model, in the textbook "MIMO-OFDM wireless communication with MATLAB", it says "When oversampled by a factor of $N_OS$, the bandwidth of Doppler spectrum becomes \...
1
vote
1answer
37 views
How to verify and plot expression for sampled signal is correct?
Given the signal $x_a(t)=4cos(2\pi\times40t+\pi/3)+10cos(2\pi\times160t-\pi/6)$, I am to sample it at $f_s=200Hz$ and find the expression for $x[n]$
My process:
$$x[n]=x_a(nT)=x_a({n\over f_s})=4cos(0....
5
votes
2answers
45 views
ADC sampling rate and signal bandwidth for FHSS
If i am correct; for a radio receiver the ADC sample rate will have to be higher than at least twice the BW of the data (disregarding sparse sampling techniques). So for frequency hopping spread ...
1
vote
0answers
33 views
Simulating Effects of Sampling after Butterworth Filter
Is there anyway to simulate the effects of sampling an analog signal with Python/MATLAB? I am trying to show what happens to the frequency domain (magnitude and phase) of the analog signal after it ...
0
votes
2answers
348 views
Minimum sampling frequency, quantization, and bitrate calculation
An analogue sensor has a bandwidth which extends from very low frequencies up to a maximum of 14.5 kHz. Using the Sampling Theorem what is the minimum sampling rate (number of samples per second) ...
0
votes
1answer
76 views
What is the Uncertainty or error due to sampling frequency?
If I want to detect the distance between two peaks in a signal sampled at 100 Hz. Then is it right to say that the first and second peaks occurred within 0.01 seconds of uncertainty? Therefore, the ...
0
votes
0answers
16 views
Dynamic sampling points based on the first order derivative of signal amplitude
Problem:
I need to measure an arbitrary experimental data set $x(t)$ where t = linspace(min,max,N).
However, the experiment is extremely time consuming and I don't ...
2
votes
1answer
40 views
Relation between continuous time transfer function and sampled approximation
Suppose I have some continuous time system and associated transfer function:
$$ y(n)=x(n)+x(n-1)$$
$$ H(j \omega) = 1+e^{j \omega (-T_s)} $$
Now suppose I create a discrete-time approximation of this ...
0
votes
1answer
173 views
I/Q sampling with just one ADC
Usually I/Q sampling is performed on two signals with a 90° phase shift using separate ADCs. Suppose I have only a single (fast) ADC available to perform I/Q sampling, which approaches do exist? Is ...
0
votes
1answer
58 views
What should be IQ sample rate at least?
As i read, IQ sample doesn't need nyquist criteria. What is the mathematical representation of this result? Why IQ sample doesn't need nyquist frequency? I know that can be set to nyquist frequency ...
4
votes
3answers
158 views
Under what conditions is there a one-to-one mapping between continuous-time and discrete-time signals?
As the sampling theorem dictates that the uniform sampling frequency must be at least twice the maximum frequency present in the bandlimited signal (Nyquist rate), a question arises about the ...
0
votes
1answer
45 views
How to measure correlation between 1 bit samples and theoretical original waveform?
I'm investigating quantization error.
I have an analogue waveform that looks like this and is of theoretically infinite resolution:-
I've sampled it as (8 bit oscilloscope readings & 0b1) to ...
4
votes
1answer
115 views
Recovering a signal after nonuniform sampling
Let $x(t)$ be a bandlimited signal such that $X(j\omega) =0 $ when $|\omega|>M$. Also $p(t) = p_1(t) - p_1(t-\Delta)$ is a nonuniformly spaced periodic pulse train where $$p_1(t) = \sum_{k = -\...
1
vote
2answers
93 views
Condition for aliasing
Which one of the following is the condition of aliasing?
(a) Tails of the replicas enter into the Nyquist
interval
(b) The tails of the replicas enter into the Nyquist
interval and add to the ...
0
votes
2answers
73 views
Question about aliasing
As far as I understand, you can have two different continuous-time signals with the same discrete-time frequency spectrum after they are sampled and it may be possible these shifted replicas in the ...
6
votes
2answers
224 views
Using oversampling to increase resolution of a DC-signal as input
Currently I'm working on a project which uses oversampling to increase the resolution of a 12 bit ADC to a maximum of 16 bits. My goal is to fully understand the theory behind oversampling and why it ...
0
votes
1answer
41 views
Sampling interval $T$ as a multiplier in digital processing of a continuous-time signals
[from: Discrete-Time Signal Processing, Oppenheim and Schafer, p.224]
Q: Why do we have $T$ as multiplier in $TY_a(j\Omega)$ in Eq.155?
0
votes
1answer
88 views
Multiple choice on sampling and aliasing
I found some multiple choices in a well known book . The problem is that I don't get the answers in some and I want to do so.
Question 1:
The signal x(t) with Fourier transform $X(j\omega) = u(\omega)-...
0
votes
1answer
160 views
Is this an error in Oppenheim and Schafer's Discrete-Time Signal Processing?
In Discrete-Time Signal Processing by Alan V. Oppenheim and Ronald W. Schafer (3rd Ed.), in Figure 4.47 the input of D/A converter is $\hat{y}[n]$ but later in Figure 4.64 the input of D/A converter ...
0
votes
1answer
60 views
What happens to the phase spectrum when I resample?
[An update is added at the end of the post after receiving first response]
I have an algorithm which is very sensitive to phase shifts. It works with signal sampled at 40MHz (it's a neural network so ...
0
votes
0answers
61 views
Optimal sampling rate for the HMM forward-algorithm
I have a system with a binary-state. The system state is estimated by an HMM forward-algorithm. Also, the system allows a varying sampling rate.
Considering that the system state transition takes a ...
3
votes
1answer
68 views
Sampling pure tone sine waves [closed]
What would happen if I am using the maximum frequency as the sample rate for sampling a pure tone sine wave?
For example, a $10\ \rm kHz$ sampling frequency for a $10\ \rm kHz$ monotone sine wave. ...
