Questions tagged [sampling]

In signal processing, sampling is the reduction of a continuous-domain signal to a discrete-domain signal.

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Stability analysis of hybrid discrete-continuous systems

I'm trying to derive the overall state-space system model for a hybrid system, in order to plot its eigenvalues. The system is shown as follows: Which is originally from this paper: Modeling and ...
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How does the sample rate work on an SDR?

How can an SDR, which has a sample rate of about 32MHz record signals with a frequency of 1GHz? Shouldn't the sample rate be at least two times as high as the frequency or am i missing something?
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How to Calculate Frequency "X values" from a FFT/DFT Transformation

First of all I am totally new to the DSP field and I have no background in it whatsoever, but my work in biology has led me to data that would greatly benefit from DSP. Any answers devoid of specific ...
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Upsampling after S/P convertor in MSK modulation

I have found this post "implementation a S/P conversion: different length / in Matlab" In the given implementation, Tsym = 2*ovs. ...
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Sampling and Aliasing

What is meant to be explained in the section between the 2nd paragraph and the folding section in the Sampling sinusoidal functions section shown in this link? Why is $Nf_0$ written in $f+Nf_0$ ...
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Optimum sampling frequency for decoding analog PDM stream?

I have an analog value coded as an analog PDM stream, which has a toggling frequency $f_{PDM} \approx$ 100 kHz when the value is at midscale. I am demodulating this value into a 32 bit result with a ...
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What is the frequency representation of nonuniform sampling?

Uniform sampling can be thought of as multiplication of a function $x(t)$ with a Dirac comb function: $$\text{III}_T(t) = \sum_{k=-\infty}^{\infty}\delta(t-kT)$$ Multiplication of $x(t)$ with $\text{...
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Quadrature Detector with a single ADC

I have a quadrature detector, which provides I and Q baseband signals with 4 kHz bandwidth, set by detector's LPF. I digitiize them on two ADCs with sampling frequency 48 kHz, make Hilbert ...
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FFT to work out optimum number of samples to average

I have a magnetometer, a LIS3MDL to be precise, and I am taking readings from it every second. As expected there is variation in the readings. For example, if I take five readings I get: 1164, 1190, ...
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Sampling Frequency For Samples That Are Greater Than 1 Second

I understand that sampling @ X times per second is X Hertz. What if the sampling rate is given in minutes? 5 minutes for example. 5*60=300 Is that 1/300 Hertz or 0.003333~ Hertz?
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Convolve sinc trains

$$ \begin{align} & \mathrm{sinc}(As + .5)\sum_{n=-\infty}^{\infty} \delta (s - n/A)\ \star \\ & \mathrm{sinc}(Bs + .5)\sum_{n=-\infty}^{\infty} \delta (s - n/B) \end{align} $$ How to compute? ...
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Why would the emitted signal from repeating binary data over a wire appear at a frequency lower than the bit frequency?

I have a signal over which binary data is transferred over wire in a repeating 10 bit format. The wires that the data is send over are CML, DC coupled 3.3V twisted pairs, and the protocol of encoding ...
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How to maintain DFT symmetry for zero padding in frequency domain? [duplicate]

I am looking for a mathematically correct way of zero-padding in the frequency domain when we have an even number of points. (i) If we zero pad in the center of the DFT, after the Nyquist value, the ...
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What does the two following formulas mean?

I am a bit confused between the following two formulas: $$ f\le \frac{f_s}{2} \tag{1}$$ and: $$ f = \frac{f_s}{N} \tag{2}$$ Now I am given an ACF Plot of a sine/cosine wave and I am asked to find ...
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Does LPF limit the maximum sampling frequency of the input signal? [closed]

Consider the system where the signal passes through analog LPF with cutoff frequency of 50 Hz, so the maximum sampling frequency of the input signal could be 100 Hz (according to the theorem). But can ...
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Why aren't negative frequencies folded in reconstruction of the aliased signal?

I'm working on the problem 1.9 from the book Introduction to Signal Processing by Sophocles J. Orfanidis. The pdf version and solution is freely available here. This is the solution for part a of the ...
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Plotting the Frequency Response of Zero-Order Hold

I'm trying to find the frequency response and the DC gain, then plot the response and find the cutoff frequency from the graph. I start off with the impulse response $$h(t)= 1 ; 0\leqslant t\leqslant ...
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How does SDRs implement anti-aliasing filters, when the sampling rate can be fairly arbitrary?

I was looking at the schematic for the small USRP B205-mini SDR from Ettus. I can't seem to find any switchable analog anti-aliasing filter on the input of the chip, or anything resembling a filter ...
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How do we determine the required sampling rate of a closed loop control system?

Consider the controlled dynamical system $\dot{x}_t = f(x_t, u(t-\tau_{sd}))$, where $0<\tau_{sd}$ denotes the time delay caused by sampling. It is intuitively clear that the time delay caused by ...
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What make sample rate affect QspectrumAnalyzer output?

Use QspectrumAnalyzer to analyze signal,set sample rate as 8M and 32M. I get different output as below,32M sample rate cause ...
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What is the output signal's frequency when doing operations of two signals?

If I have two continuous time signals x(t) and y(t) of maximum frequencies Ω1, Ω2 respectively. I want to find the sampling frequency used used in continuous-discrete conversion of the following ...
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How do I determine the dominant frequency of a signal after sampling?

For example if I have a $10 Hz$ signal and I sample it at $19 Hz$ (less than the Nyquist frequency) how can I determine the dominant frequency of the output and why? If I then apply a lowpass filter, ...
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Strided unpadding energy relationship?

If x1 = x0[::2] is unaliased subsampling, then $E(x_1) = E(x_0)/2$, which can be proven via Parseval's theorem. For same $x_0, x_1$, however, ...
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Oversampling ratio ( factor) calculation

I study GMSK modulator. In its simulation we use an oversampling ratio if we implement gaussian filter or oversample the input signal. In my simulation I can test different value of the oversampling ...
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Stanford EE 261 HW6 Q1 - Sampling below Nyquist Rate

The problem (taken from here) asks for possible sampling rates that will not cause aliasing in the following frequency spectrum: The range of possible values after some math is given as $B_2 < f_s ...
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Given a signal that is not bandlimited, how do you properly take the FFT?

I assume that the Nyquist theorem doesn't apply, at least not in the standard sense, for a non-bandlimited signal. In my case, I sample the signal (in the time domain) above the Nyquist rate and then ...
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Given the Fourier Transform of a continuous signal how can I sketch the sampled signals discrete time fourier transform

I am given the frequency response for a continuous time signal X(jw) = 2 at w=0 and 0 at w = -10000pi and 10000pi. Looks like a triangle. I am told to sketch X(e^jw) the frequency response of a ...
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How does under sampling modify the spectrum of a signal in nyquist zones and BW?

I have two conflicting concepts when looking at the spectrum of a analog to digital signal that has been sampled. The nyquist zones. So any sampling frequency fs will make the spectrum replicate at ...
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How to convert discrete-time QAM pulses to a continuous-time signal using the IFFT (for OFDM)?

So I've run into some trouble in trying to plot the PSD of an OFDM signal. Specifically, I cant see how we go from the discrete domain to the continuous in time domain. I have a time vector, which is ...
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Inferring shape of information signal from its DFT?

I came across this question recently, and I am very confused by (b)(ii). b(i) gives $x_n$ = [0.5, 0, -0.5, 0]. My approach to (ii) was to recognise that $X_m$ represents the frequency content of the ...
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Calculate i. Sampling interval ii. Physical signal length ii)fundamental frequency of s iv. Maximum frequency tv. spatial distance (in mm)

Assume we have a 1D print pattern with a resolution (i.e., spatial sampling frequency) of 120 dots per cm, which equals approximately 300 dots per inch (dpi) and a total signal length of N= 1800 ...
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Can someone please explain to me how to sample in the time domain?

I am trying to understand how the Nyquist-Shannon theorem applies to sampling in the time domain. Suppose I want to sample a function whose time constants I know. From what I understand, the bandwidth ...
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What is the Fourier convolution theorem range of application (example of Dirac comb times rectangular window)?

$\DeclareMathOperator{\sinc}{sinc}$ I have questions regarding the Fourier transform of the product of functions or distributions and the range of application of the convolution theorem. Context When ...
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how can 16bit depth look like 10bit?

Recently I obtained some measurements using a consumer grade ECG device (wearable, thus designed for low power consumption). The device is claimed to have a dynamic range of 10 mV (peak to valley), ...
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Multiplication term $ \frac{ 1}{T_s} $ in sampling theorem

\begin{equation} X(\Omega) = \frac{ 1}{T_s} \sum ^{\infty}_{k=-\infty} X_a\left \lbrace \frac{\Omega /( 2 \pi) - k}{T_s}\right \rbrace \end{equation} What is the purpose of multiplying sampled ...
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Estimating quantification and sampling error

I have a signal sampled from $\mathbb{R}^2$ at a frequency of $2\text{Hz}$. It is quantized from $\mathbb{R}^2$ to $\mathbb{N}^2$, seemingly using the round operator. How can I estimate the error ...
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Signal flow for conversion of audio to Lzeq (sound pressure level time-equivalent)

I'm developing an embedded system which takes in digital audio from an ICS43432 MEMS-microphone via the I2S-bus to compute the sound pressure level over variable ...
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Channel impulse response vs sampling frequency

As part of my uni assignment I have to figure out what is the impact of sampling frequency on actual channel impulse response. One obvious thing is that the higher sampling frequency is, the more taps ...
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Effect of sampling a cont. stochastic process on the variance

I am trying to understand the estimation of the power spectral density of a continuous time stochastic process from it's samples. Consider a normal wide-sense stationary white noise process with ...
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Will or can a sampled signal with a limited sampling frequency have infinite bandwidth?

I know that a continuous-time digital signal with sharp edges (e.g. jumping from one y-Value to another discontinuously at the same x-value) will have infinite bandwidth. But what about sampled ...
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Resolution of phase measurement using cross Correlation

The setup is the following: I am using a RedPitaya board to measure the phase shift of two input signals. These input signals will sweep logarithmically from 1kHz to 100 kHz in 10 seconds. Currently, ...
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does T = 1/F always hold?

i just want to know if i use a sampling frequency of 100-110Hz and get a useful signal frequency of 50Hz (because of Nyquist–Shannon sampling theorem), is the period 1/50Hz or 1/100Hz? I've been told ...
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Sampling frequency vs Signal frequency

I've started recently working with the ADXL345 accelerometer with the goal of finding the velocity. And so far, I'm getting "okay" results after applying a second-order Butterworth filter to ...
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How does the RMS value of noise varies with sampling frequency?

I have been trying explore the background rates due to thermal noise (instrumental) through a simulation (python). So, what I have been essentially doing is the following ...
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Artifacts on frequency spectrum

I made a spectograpm in C that takes in a wav file (44.1kHz), converts it to 8bit pcm(can't go higher because of memory constraints) and does 1024 sample FFT on a number of bins, using Welch method. I ...
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Digital Up Converion and Digital Down Conversion

Description: I’m trying to use the standard sample rate of 61.44 MSPS on both sides of my digital transceiver(DUC and DDC), so I’ll upsample my data from baseband data rate 3.84 MSPS to 61.44 MSPS ...
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Reconstructing function from samples

Assuming I have sampled my function with frequency above nyquist frequency, using the sampling theorem I can reconstruct my original function from the sampled values. Let's assume though that I change ...
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Spectral function value of a frequency above the nyqist limit

this was the question on my today's exam on signals and systems: *We have a continuous function $f(t)$. Its value of the spectral function at an angular frequency of $8000\pi\ rad/s$ is $\frac{1}{...
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Sampling with Rectangular Pulse and Nyquist Condition

The classical Nyquist theorem assumes that the sampled signal is obtained by multiplying the signal with dirac-delta functions separated by width 1/f_sample or less. Given such sampling we can ...
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Oversampling for Synthesizer

I am in the early stages of learning DSP and am writing a simple synthesizer. I want to dabble in oversampling and am following this guide: https://www.nickwritesablog.com/introduction-to-oversampling-...
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