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

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Visualisation of bandwith of filter with sampling

I'm having some trouble visualising (and understanding) the filtering of a sampled signal. If I understand correctly, after sampling a signal, it is desired to have it go through a lowpass to ...
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19 views

Compressed Sensing vs Common Compression Approaches

I have a very basic question regarding common compressing approaches. Often, I have heard something like "The problem in our common way to compress data is, that we have to acquire a huge number of ...
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33 views

How to proceed with this convolution problem?

If $$\alpha_k = \sum_l a_l \ \ g((k-l)T-l\Delta T)$$ $$s_k = \sum_l \alpha_l \ \ q((k-l)T+k\Delta T)$$ where $a_l \in \pm1$ and $g(t) = \frac {\sin(\pi t/T)}{\pi t/T}$ and $q(t) = \frac {\sin(\pi ...
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46 views

Sample and reconstruct a real exponential (just one period)

I have a function with an equation: $$C = 1.6925\left( e^{-0.136t}-e^{-1.192t}\right) $$ Where $C$ is real and $t$ represents time in hours. Beneath is the representation of my function. I am ...
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32 views

Chip rate and sample rate

If a sequence of +1 and -1 with chip rate ($\frac{1}{0.57 ns}$) is being used for purpose of estimating channel impulse response with delay spread of 6ns. We decide to have a new rate change to rate ...
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57 views

Why isn't this AM Demod GNU Radio flow graph working with different sampling rates?

Please forgive me if this turns out to be a super newb question; I have spent some time (and also searched), and cannot find a solution. I am trying to demodulate an AM signal in GNU Radio, and I am ...
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17 views

what sampling rate and bit depth should i use?

I'm doing a simple mini project on FPGA board, electronic lock which open when a short track (the "password") is play next to the lock's mic. i want to save samples of the chosen song to an array ...
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26 views

Sampling rate of a sinusoidal Signal

What is the minimum sampling rate of a $\sin(\pi t)$ signal? When the sampling frequncy is twice that of the frequency, the spectrum is not present and in time domain all the samples we get is 0. In ...
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40 views

change function from continuous to discrete

I have function that I want to sample with sampleing rate 20 Msamples/sec. The funciton is the one below $w_T(t)= \left\{ \begin{array}{ll} \sin^2(\frac{\pi}{2}(0.5+\frac{t}{T_{TR}})) & ...
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38 views

24GHz FMCW Radar Signal Processing Questions

I am using the RFE-3400 (from Innosent) 24Ghz Radar Transreceiver in FMCW mode. The output of the radar module has 2 channels of I/Q signals from 2 receiving antennas. My objective is to find the ...
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33 views

Can an Delta Dirac function (not response) ever be sampled?

This is purely theoretical question but can an actual delta-dirac function ever be sampled? To make it clear again, I'm not talking about an impulse response from the impulse function. Lets say we ...
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41 views

Upsample - filter - downsample

Given a discrete signal $ r(nT_c)$ specified at a rate $T_c$, assume we want to resample with a 3/2 rate change to match the sampling rate of some other signal. We would like to upsample it by 3, ...
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34 views

Is Bernstein ever used in DSP?

In the early 1900s, Bernstein proved you could approximate any continuous function with the sums of polynomials. I know this is a bit weak for DSP because it isn't strictly periodic, but is Bernstein ...
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34 views

How to set sampling frequency of an acceleration data set

I have a set of accelerometer readings in X, Y, Z axes obtained from an android based smart-phone. The data (in X, Y, Z) was recorded at different time stamps and there is no uniform time period for ...
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27 views

transient response of simple digitalized RC low-pass filter

In http://en.wikipedia.org/wiki/Bilinear_transform#Example, digital version of simple RC low-pass filter is presented: $$\frac{1 + z^{-1}}{(1 + 2RC / T) + (1 - 2RC / T) z^{-1}}$$ where $T$ is ...
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41 views

How to apply a Butterworth filter to data of varying sample rate?

I am trying to apply a Butterworth bandpass filter to accelerometer data of my smartphone. However, the accelerometer samples I receive do not come at regular intervals. Sample frequency varies ...
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47 views

Spectral analysis of a time series with missing data points

I use a PC to record time series of some physical property. The problem is that, for some reason, I did not record the time series as a whole, rather I record first segment, then second, third, etc. ...
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72 views

What is the maximum frequency that can be captured by a given sampling rate?

Let's say that we want to digitally sample an analog signal and have a sampling frequency of 8000 samples/second. Usually the maximum frequency that can be captured is the half of the sampling ...
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68 views

how to solve the sampling rate conversion problem

I am trying to improve my DSP knowledge and this problem is too much for me. I am trying to solve following task: this is not a homework. any help will be appreciated.
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70 views

Why band-limit a signal?

A Band-limited signal is defined as a signal whose Fourier Transform is zero above a specified frequency. Shannon Sampling Theorem is also stated for a strictly band-limited functions,i.e, "For a ...
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18 views

Sending a Filtered vs Non-Filtered speech over a Communication Link

To send a $10 \, KHz$ bandwidth of speech (Non Filtered speech), Nyquist criteria says that sampling duration should be $50 \, \mu s$. While for a $4 \, KHz$ bandwidth of filtered speech, sampling ...
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39 views

Nyquist Criterion in higher dimensions

I was just wondering if there were any "obvious" resources, papers, or textbooks I should look into regarding the nyquist-criterion in higher dimensions. For example, this would be relevant if there ...
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26 views

How can I make the mean of samples be approximately equal to the mean of actual continuous signal?

Suppose there is signal $f(t)$ that is continuous and periodic. It is known that this $f$ is $T$-periodic. (but it's not necessarily a single cosine $f(t)$.( I'd like to make the mean of samples be ...
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37 views

What's the sampling frequency when synthetically generating data?

Say I am using matlab's random number generator to get an array of random numbers, which I will then, for testing purposes, find the spectral density etc. For that purpose I need to know the sampling ...
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199 views

Why is telephone audio sampled at 8 kHz?

When did we decide to sample telephone at $8$ kHz? Has this always been the case? Why did we do that? Is it because higher bit rates can't be transferred as quick? And do these reasons still count? ...
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230 views

A question about the sampling theorem

Let's say I have a signal, containing frequencies up to $30$ kHZ. I am sampling this signal at $40$ kHz with infinite bit depth (just for theory). Will I be able to recover exactly all the ...
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53 views

Playing back an audio file at an arbitrary rate with upsampling and downsampling

Background: My overall goal is to create an audio file player which can playback an audio file at an arbitrary rate. The rate can change continuously as the file plays. This means upsampling to ...
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41 views

Can sample aliasing of strictly white noise lead to random walk (drift) in the sampled signal?

Aliasing of tones higher than the Nyquist frequency, and where the tone may have some degree of nonlinear distortion can appear as low frequency 'drift' or even near static bias in the sampled signal. ...
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47 views

just getting started in Signal Processing - easy question

I am reading Cycle Analytics for Traders by John Ehlers and need help. in the first section "Transfer Response" he refers to: so if I had $4$ prices say $8+8+8+8$ then average would be $8$ and ...
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31 views

Image warping with subpixel accuracy

I am trying to test the sub-pixel accuracy of an optical flow method and need to generate some synthetic data to do so. I start with an image $I_0$, which is a Perlin noise image and a set of ...
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96 views

Oversampling and Aliasing

I am really confused about oversampling and upsampling. I know that upsampling means stretching our signal in time domain by a factor of K, then interpolating some values or using just zeros. As I ...
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23 views

Noise from quantization and sampling frequency

How to estimate if noise of sampled sound signal can be heard? I mean the noise that appear when an analog wave is sampled. Similarly if I use 16bits, 24 bits, and 32 bits resolution, how to ...
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34 views

What's the use case and explanation of frequency-domain subsampling?

In my solution to a certain problem I use subsampling in the frequency domain. Amazingly, it produces good results. Is it really that awkward to see subsampling in frequency domain? What the ...
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35 views

How does sampling and subsequent resampling affect aliased harmonics?

If I sample a signal with a harmonic higher than half my sample frequency I can predict the aliased frequency easily as $$|F_h-kF_s|$$ But what if after sampling the signal, I re-sample at a lower ...
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25 views

detecting position of lost samples

I have a pulse signal from which I sample N times of level changes (e.g. high->low). At undefined times the pulses in the original signal are completely missing. This leads to wrong number of ...
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11 views

Is a complementary filter usable with irregular readings?

I'm experimenting with a complementary filter for sensor fusion (the usual acc/gyro/mag). I've read whatever I could google, but two things are not very clear yet: (1) can a complementary filter be ...
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129 views

What is the sampling rate in this case?

A signal $x=\sin(\pi t/4)$ sampled at every $t=1$ sec. so $T=1$ sec Sampled signal is then $x=\sin(\pi n/4)$, What is the sampling rate in this case?, And according to Nyquist sampling rate what ...
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1answer
38 views

adequate sampling frequency in measuring acoustic emission

I am measuring acoustic emission signals. The ae frequency range is 20000 to 1000000Hz. The sampling frequency that i,set was 100000 Samples per second. I must be able to detect a maximum of 50000Hz ...
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141 views

What is meant by *sampling* in terms of the *sampling theorem*?

Let $y:\left(-\frac T2,\frac T2\right)\to\mathbb{C}$ be a square integrable function. The Fourier coefficients of $y$ are $$\underline{Y}(k):=\frac ...
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1answer
53 views

Processing 47-53 MHz signal sampled at 96000 Hz

I am fairly new to the topic of DSP and FFT and I have hit a mental block. For a project, I am trying to pick out frequency's with amplitude peaks in a 47-53 MHz signal. This signal is being put ...
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86 views

Sampling theorem and signals explained to a mathematician

Let $f:\left(-\frac T2,\frac T2\right)\to\mathbb{R}$ for some $T>0$. The Fourier coefficients of $f$ are $$\left\{\begin{matrix}a_0&=&\displaystyle\frac ...
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49 views

filter out an expected but not regular signal

I am stuck with a case where I need to get rid of a portion of sinusoidal signal that suddenly appears in my main signal (sine wave). my total signal will look like: $ s(n) = \begin{cases} ...
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41 views

Sampling rate effect on quantizer SNR

I am currently reading the 'Coding' chapter on Rabiner & Schafer's Book on speech processing. In one of its exercises, the reader is given a simple A/D converter using 16-bit uniform ...
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1answer
201 views

What is the difference between cubic interpolation and cubic “Spline” interpolation?. How to use it for upsampling purpose?

After considering a couple of advices and suggestions for upsampling techniques here, I finally converged to use the cubic interpolation technique to estimate the voltage values corresponding to ...
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2answers
60 views

How to choose sampling rate for non-band limited signal given as an expression?

I have a signal given as an expression $x(t)$. In frequency domain most of the information is around 0 and higher frequencies progressively get smaller and smaller compared to DC component. I was ...
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46 views

Output of a band pass filter

Signal x(t) = | cos(2πft)|, f != 0 is the input of an ideal band-pass filter with bandwidth B = 3f/2. How can i Find the ...
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44 views

Claim: Given sampling time T, the hold operator is approximated at low frequency by a time delay of T/2

Can someone verify this statement? The hold operator is assumed to be a zero order hold Then the laplace transform of this hold operator has a well known form $(1-e^{-sT})/s$ Let w approach 0, we ...
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65 views

Signal Sampling

I am new in this field (junior year) and I have a question may a little lazy for the majority of the forum. I have a speech signal $ x(t)=0.4\cos(100πt)+0.3\cos(1800πt)+0.2\cos(980πt)$ and I know ...
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42 views

When sampling theory condition fails, what should I do?

I met with a problem: if I sample audio data at 11kHz (yes, that is slow!) for 10 seconds and apply a Fourier Transform to the data, at what frequency will a 15 kHz tone appear? So the original ...
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40 views

How does sampling a frequency result in a duplicated spectrum?

This is probably a simple question, but I have a hard time understanding how c. converts to d. in the following picture. Further reading as an answer is acceptable. After all, I am only asking this ...