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Questions tagged [sampling]

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

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realistic sampling - where am I wrong?

I’m given a signal $x(t)$, it's convolved with $h(t)$ and sampled at rate T=1. The result is called $\tilde{x}[n]$. For $$h(t) = \begin{cases} 1 & -0.5<t\le 0.5 \\ 0 & \text{else} \end{...
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Sample rate of digital modems--how do they do digital filtering if sampling below Nyquist rate?

I can't find this answer anywhere. I have a couple satellite modem manuals and they refer to digital filtering functions that they do, but they say almost nothing about their sample rate. I always ...
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Signal recovery is based on the development of the Shannon sampling theorem?

One of the earliest extensions of this theorem was stated by Shannon himself in his 1949 paper, which says that if $x(t)$ and its first $(M - 1)$ derivatives are available, then uniformly spaced ...
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Discussion on the relationship between the FFT magnitude spectrum and the corresponding actual amplitude

This might be a bit long, but it's a question that has troubled me for a long time, and I hope to get everyone's help. When studying signals and systems, we usually only pay attention to the relative ...
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Frequency decomposition of forecast error variance

I think my question concerns statistical signal processing. I was referred to this site by a user at Cross Validated. I want to do a frequency-domain decomposition of generalized forecast error ...
Pavel Filip's user avatar
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What are some good questions for a graduate level signal processing course?

I am currently taking an graduate-level Advanced Signal Processing class and I have a midterm soon. However, the midterm is not only open-book but it is also open-internet and untimed. Now I have no ...
Sherlock Rozman's user avatar
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Does oversampling lead to colored noise?

Suppose we receive $R(t)=X(t)+W(t)$, where $X(t)$ is band-limited to $[-B/2, B/2]$ and $W(t)$ is white Gaussian noise with autocorrelation $R_W(\tau)=\frac{N_0}2\delta(\tau)$. If we filter $R(t)$ ...
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DFT Matrix Oversampled In Frequency?

Edit 2: I am trying to replicate results from this paper Compressed Sensing with Coherent and Redundant Dictionaries. On page 3 the "oversampled DFT" is mentioned as an example of an "...
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Why is sampling a signal equivalent with multiplying with a Dirac comb?

Given a continuous time signal $f(t)$, we can sample it signal by multiplying with a Dirac comb (impulse train) $$\bar{f}(t) = \sum_{n=-\infty}^{\infty} f(nT) \delta(t-nT) \tag{1}$$ where each impulse ...
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DAC/ADC sample rate selection for modem

So I have a very basic on which I couldn't find much details anywhere. I'll start with an example: I have to transmit 100Mbps of BPSK data. Roll-off factor is 0.25. This data will be processed at ...
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insights into making AR Burg extrapolate finite periodic signals

Following a past question, I'd like to extrapolate a periodic signal using AR Burg, but when doing so, it seems that I need to sample "enough" for that to work. For example, if I use the ...
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ADC output rate, undersampling and decimation

I have an ADC working with a sample rate of 960 Msps, my signal being located at the 3rd Nyquist region (I am undersampling). Input signal bandwidth is centered at 1200 MHz with a bandwidth of 120 MHz....
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Multiplication of function with Dirac impulses: sketch signal

I should sketch the signal below: I think I should use delta dirac function sampling theorem but I don't know how in this special case I know that $x(t)δ(t-t_{0})=x(t_{0})δ(t-t_{0})$ but I don't have ...
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Signal reconstruction of time domain data via transfer function of a quadripole

Dear signal processing community, I hope my question finds you all well. I have an electrical network, consisting of three complex impedances. These impedances basically form a simple voltage divider. ...
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How does the sampling rate of a digital filter limit the sampling rate that can be used for replay of filtered signal?

I need a band-limited white noise to characterize a biological sensor that senses mechanical movement. For that, I am generating a Gaussian white noise (MATLAB Communications toolbox) of length 10 ...
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Need help with DTFT transform (sampling and reconstruction)

Given the continuous time signal $$ x \left( t \right)= 2 \cos \left( 100 \pi t \right) + 3 \sin \left( 250 \pi t \right) \tag{1} $$ The signal is sampled in point sampling with sampling interval $T_{...
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Benefit of Anti-Aliasing for Wideband Finite Time Duration Signals prior to Sampling

Most literature about sampling explains the need for anti-alias filters in terms of periodic signals, preventing a periodic signal with frequency greater than half the sampling frequency from ...
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How to show that these two factors are related to frequency interpolation and extrapolation respectively

Consider two sequences $x[n]$ and $y[n]$ being simultaneously sampled from a real-world signal. Let $x[n]$ be a sequence of length $N$ sampled for duration of $T_x$ at rate $f_x$ $n = 0, ..., N-1$ ...
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What is the event that repeats itself in sinusoidal signals

I am studying medical imaging and it has been stated that it is sufficient for Nyquist Theorem to hold for the signal to be Bandlimited. I am trying to understand what is the wave in a signal. What is ...
George Ntoulos's user avatar
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Assumptions of Nyquist sampling theorem [closed]

Hoping I can save the question and it doesn't get migrated to philosophy stackexchange as Hilmar said in any case I don't think it is a different question the question was always meant to be ...
George Ntoulos's user avatar
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2D Fourier downsampling to even number of points gives incorrect modes in the last column

I would like to downsample an image in the frequency domain to an even shape, similar to what is described in this post. I have been able to do this successfully with a 1D signal to both an odd and ...
Jacob Helwig's user avatar
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Sample Use vs Sampling Frequency

I need to acquire an analog signal via an ADC and send it via a digital communication line (CAN bus) with a given frequency $f_{send}=100Hz$. If I understand correctly this means that this constraint ...
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ADC bias, noise and number of bits under Gaussian signals

I'm digitizing a zero-mean complex Gaussian white noise signal with certain variance, through independent I/Q baseband sampling (two ADCs). The noise variance (power) depends on the thermal emission/...
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Discrete Frequency representation for central frequency/ discretize up-converted signal in time and frequency

I want to analyze a signal after up-conversion in discrete time and frequency, for example: Let's assume a continuous up-converted signal is: $$e^{j2\pi ft} \cdot e^{j2\pi f_c t} = e^{j 2 \pi (f+fc) t}...
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How to get the original sample pitch knowing how the sample is interpolated at a given pitch?

I'm trying to "reverse engineering" a sample-based synth from the 90's (an Ensoniq SQ1, which uses a OTIS chip for the samples; if you're interested you can find the manual of both on the ...
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Triangulation by phase delay basic requirements

I'm trying to identify the relevant specifications/calculations for building a system (at least theoretically) to accurately triangulate the position of a 915MHz CW transmitter to within 1cm. I have ...
turdfergason's user avatar
1 vote
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Resolution after Oversampling, Filtering-Decimation

The ADC I am working on has a resolution of 24 bits and a Signal-to-Noise and Distortion (SINAD) of 108.4 dB. Assuming only quantization noise is present, the Signal-to-Noise Ratio (SNR) of the ADC ...
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How is the normalized power required for unipolar NRZ twice that of polar NRZ?

So, the normalized power for unipolar NRZ scheme is $\frac{1}{2}V^2$. According to my book, the normalized power required for polar NRZ is half that of unipolar NRZ. So, the power should be $\frac{V^2}...
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Plot amplitude vs freqency in DB

I have C++ App which wich plot 3 plot amplituede vs sample amplitude vs frequncey(used FFT for calculation) amplitude(in dB) vs frequncey I want plot 2 with y axis lable represent in DB, without ...
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Estimating spectrum with regularly missing samples from data

Suppose: $$ s(t) = \sin(2\pi{f_0}t) $$ Suppose I'm sampling the signal with a sample frequency $f_s >2f_0$ . However, every $M$ samples there is a dead-time of $L$ samples. Traditionally, the (...
Sammy Apsel's user avatar
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How can I plot a sinc function correctly?

I am generating a rectangular pulse using a piecewise function on Matlab. I have listened to some advice to use a normalization coefficient and the amplitude appears correct now. However, my issue is ...
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Is there a test/statistic for the reliability of my data given my sampling?

I'm in a situation where I'm sampling blood pressure data over time (unequal sampling) to capture potential peaks. On average, the frequency of circadian blood pressure would be 1. But in reality, ...
Gary Stu's user avatar
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Anomaly in Magnitude Spectrum plot of an ASK Signal

Following is a SciLab code and Plots for Modulation of ASK Signal: My question is : For these particular values of fm and t, I get two weird small spikes on either side of main lobe, which doesn't ...
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DAC sampling rate when using DSSS/CDMA

I'm currently not sure if I understood DSSS correctly. Following example: We have a shared RF network with around a thousand of users and we want to use CDMA. The RF link should allow the streaming of ...
Stefan Maier's user avatar
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When converting real samples to complex, how much energy does the signal lose?

Assertion: When converting real samples to complex, the resulting complex vector will have half the energy of the original real vector. Simulation in Python tells me this is true. However, my proof ...
Jonathan Williams's user avatar
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Partially undersampling effect on FFT

I am struggling to understand the effects that partially undersampling a signal would have on its FFT. I have a complex signal consisting on a sum of sinusoids of different frequencies, which I am ...
Carlos Ravelo's user avatar
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How does aliasing affect bits in an ADC?

I want to measure a signal whose frequency spectrum is infinite, but I am particularly interested in the frequency range $ 0 - 500 \ \text{Hz}$. I have a 12-bit ADC. The ADC has dynamic range $ 6 \ \...
Carl's user avatar
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Bilinear transformation with a high sampling rate (chebyshev filter)

I'm trying to design a digital Chebyshev filter of order 2. This gives the general transfer function If I transform this and simplify I get If I then expand the denominator and then normalize so ...
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Combining two time series with different cadences (different Nyquist frequencies)...?

If it helps, I want to do perform the below computation in python. Two time-series - 30-min cadence (Nyquist of 24 cycles / day) lasting 27 days, followed by 10-min cadence (Nyquist of 72 cycles / day)...
Prasad Mani's user avatar
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How to minimize RMS calculation error due to sampling?

Say I have a sinusoidal signal of 49.93 Hz, which is sampled at 16 kHz. A period of the input signal would then contain 16000/49.93 = 320.448 samples. Naturally, the number of samples has to be an ...
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Sampling a sinusoidal signal smaller than Nyquist rate

If we have a sinusoidal signal at 50 kHz and we sample it by an ADC with a sampling rate of 7 kHz. What would be the output of the ADC? Since the sampling rate is way less than the Nyquist rate (...
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Why am I getting 2 frequency spikes in a mono tone signal?

I have a single tone sinusoid, and its fft in scilab is giving me double spikes, why is that? Please explain me the concept of why is it happening. ...
Vibhav shivadeker's user avatar
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How does downsampling decrease the noise power?

I read one equation from a technical document, i.e., assuming the time-domain white Gaussian noise samples with variance $\sigma_{TD}^{2}$ in dB are sampled using ADC with sampling rate $f_{s}^{ADC}$, ...
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Noise variance of DT samples from CT track-and-hold signal

(I will be referring to info from these slides in this post, for your reference.) Consider first for comparison a typical CT low-pass filter, without any sampling, for example implemented by the RC ...
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Symbols to samples at the transmitter and samples to symbols at the receiver

Suppose I have the $N\times 1$ vector $\mathbf{x}$ that contains binary phase shift keying (BPSK) symbols each with power $P_s$ Watts. At the transmitter: I want to convert these symbols into samples ...
Math_Novice's user avatar
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Sample rate change using Lagrange interpolator

I'm trying to understand how to make Sample rate change by a non integer factor say $K=1.0012$ In real hardware I will be using cubic polynomial but for now I have chosen a linear interpolator. I have ...
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producing sine signal with few samples

I need to produce a signal of $\sin(2\pi\cdot 60\cdot10^6 t)$, where $t$ in sec, with sample rate of $2^{28}$ Hz. Since the signal has period of $\frac{1}{60\cdot 10^6}$ sec can I somehow sample only ...
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Sampling a pulse train with a controllable square wave

I have an issue regarding a sampling process of a pulse train in an image sensor based on events. Basically, these are a family of image sensors in which each pixel outputs a train of pulses, and the ...
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Choice of $N_{terms}$, frequency grid in Lomb-Scargle periodogram

I am completely new to signal processing! Please explain as if speaking to someone who knows nothing more than linear algebra and what a Fourier transform is defined as. I am working with an 8-month ...
Akash Dutta's user avatar
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Decoding an analogue signal for a given sampling and signal frequency that aren't in sync

I am trying to decode an analogue signal, that is intended to be converted to a digital one and decoded as USART communication. In the image shown the blue trace is the analogue signal, and the ...
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