Questions tagged [sampling]
In signal processing, sampling is the reduction of a continuous-domain signal to a discrete-domain signal.
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Which of the following sampling methods can be used to sample x(t) such that this signal can be uniquely recovered from its samples?
Assuming that a continuous-time $x(t)$ having its frequency content in the frequency band $1612\leq|F|\leq2015(Hz)$ is sampled with the sampling rate $Fs=806$ samples per second. Which of the ...
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How do I detune an audio sample by 1 hertz up or down from a copy of it
I have a program that can take a waveform, such as a sine wave or sawtooth wave and detune it with another waveform that is slightly sharper or flatter. It takes the frequency of said waveform and ...
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39 views
Changing sampling frequency of SDR
Here is the block diagram for RTL-SDR which is taken from Software-Defined Radio Using MATLAB, Simulink, and the RTL-SDR:
I think it well explains the basics of RTL-SDR but I have multiple questions.
...
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4answers
301 views
Can we have an analogous sampling theorem for quantization?
Sampling theorem tells us how we can sample a continuous signal such that we can reconstruct it without any errors, or without losing information.
Quantization, on the other hand always results in ...
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1answer
23 views
What should be my sampling frequency for a peak detector output where it is extremely important for me to capture the first time the peak occured?
Following is the output of the peak detector:
The amplitude is not important to me, however the time when the peak occurs is extremely important. So my microcontroller will have an algorithm like ...
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2answers
218 views
Nyquist frequency isn't working
The situation is that I have a signal with linearly increasing frequency,
$$\text{sin}(2\pi\omega(t)t),$$ where $\omega(t)=a+bt$ for some $a$ and $b$, and we constantly sample at one point per second ...
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1answer
30 views
Signal to noise ratio (SNR) of a CW signal
I understand the formula SNR = 6.02N+1.76 for a N-bit ADC which quantizes a modulated tone sampled at twice the BW. I am trying to understand what the same equation would be for a unmodulated CW tones ...
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1answer
44 views
Mitigating high-frequencies after sampling
I have a dummy signal that I am sampling at $T = 100 \ \mu s$. According to the Nyquist frequency, I can identify frequencies up to $\pi/T = 31416 \ rad/s$, as we can see in the FFT of my signal (blue ...
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2answers
69 views
Can we use Gardner timing error detector for multi level QAM or OFDM systems? [duplicate]
Sampling frequency offset (SFO) between the transmitter and the receiver in any system causes a gradually increasing timing error which is seen as an increasing phase rotation (function of time).
In ...
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2answers
41 views
GNURadio signal degradation *above* Nyquist rate
I am going through the basic tutorials for GNURadio, and I have a question related to the sample rate tutorial. In it they demonstrate the degradation effects of sampling at too low a sampling rate.
I ...
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1answer
23 views
Does Sampling frequency come into picture in Samples generation for DAC to generate sinewave (analog signal with particular frequency & amplitude)?
I'm generating samples for dac in STM32.
sin(2pii /N)*4096/2.
This is the formula I'm using.
How to I come to know sampling frequency?
Whether sampling frequency comes into picture?
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1answer
42 views
How is sampling affecting this sine wave?
I am trying to create a sine wave in python, but when I graph it, it looks like this:
here is the code I used to make the signal:
...
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2answers
69 views
Does summing two audio samples affect sampling rate?
Original Post: Electronics Stack Exchange ("Why is my frequency being effectively doubled?")
I'll try to explain everything with detail as this is one will be a hard one to explain.
...
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1answer
53 views
Dealing with normalized cut-off frequencies larger than 1.0
I am trying to create an FIR bandpass filter in python using scipy with the following characteristics:
$$f_{c_{low}} = 310\,Hz$$
$$f_{c_{high}} =600\, Hz$$
giving me a bandwidth of:
$$Bandwidth = f_{...
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1answer
60 views
Sampling Noise Given Power Spectral Density
I am trying to write a Monte Carlo physics simulation which involves, given a power spectral density, sampling rate, and total number of samples, generating noise with such a power spectral density. I ...
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0answers
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2FSK implementation with VCO GNURadio
I am fairly new to GNURadio. I am trying to generate a 2FSK with minimum frequency shift. Instead of multiplying with a 8MHz complex carrier, I directly use VCO to generate two frequencies. One at 7....
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1answer
35 views
Where can I get the file l1eq_pd.m?
To recover the original signal when compressive sensing is used, we get an error, to avoid the error, we need to modify the l1eq_pd.m file. How to go about it? Where can I get this file in Matlab?
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1answer
90 views
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 ...
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1answer
62 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, ...
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2answers
67 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 ...
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1answer
71 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 ...
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1answer
34 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 ...
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0answers
24 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 ...
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1answer
43 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
.
...
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1answer
90 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 ...
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1answer
39 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.
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21 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 ...
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2answers
53 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 ...
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3answers
181 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 ...
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2answers
1k 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 ...
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1answer
94 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
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1answer
31 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
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1answer
59 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 ...
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0answers
47 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 \...
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2answers
60 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 ...
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0answers
29 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 ...
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1answer
42 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 ...
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1answer
57 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 ...
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2answers
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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 ...
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0answers
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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 ...
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1answer
39 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? ...
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0answers
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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
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1answer
29 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". ...
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2answers
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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 ...
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1answer
32 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 ...
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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 \...
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1answer
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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....
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2answers
56 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 ...
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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 ...
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2answers
399 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) ...
