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

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Envelop detection with low sample rate?

I have a signal up to 3Mhz. The ADC that sample it has a rate of 1.5us . So a full T of the signal is 0.3us, and I can only sample each 1.5us. It sounds not enough, but i don't need to reconstruct ...
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33 views

Flat top sampling to a step shape signal

Flat Top Sampling During transmission, noise is introduced at top of the transmission pulse which can be easily removed if the pulse is in the form of flat top. Here, the top of the samples are flat ...
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Plotting band-pass filtered signal of an audio in MATLAB [on hold]

I am new in MATLAB and try to plot some form of an audio file and I have managed to open and plot in time domain and FFT using the following code: Step I: Opening the Wave File ...
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1answer
34 views

Should the order of a filter be proportional to the sampling rate?

I have designed a fir filter with my desired frequency response at a specific sampling rate and filter order. If I were to redesign my filter for a new higher sampling rate, should I change the filter ...
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42 views

Output a sine wave from samples-limits?

Using a micro-processor of 48MHz, I am trying to output a sine wave from the DAC (digital to analog ), and I am not sure if my ...
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33 views

Generating very short signals

So I need to program (using Java) some things that include generated sounds. I am struggling to understand how to make it work because I require a rather short signal while still using a sampling rate ...
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31 views

Sampling frequency of audio

Based on what we choose sampling frequency when sampling some song? Do we use Nyquist–Shannon sampling theorem, or maximum sampling frequencies are pre-defined, so it will never come to aliasing ...
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30 views

Sampling a sinusoidal signal

Consider the signal $g(t) = \cos(2\pi\lambda t + \phi)$ that is sampled with a frequency $\tau$. Let $g_k$ denote the values of $g$ at the times $t_k =\frac{k}{\tau}$, $k \in \mathbb{N}$. (a) Show ...
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60 views

Random sampling vs uniform sampling

In this paper of Lustig, he speaks about a something which appears unintuitive: sampling at random may exhibit better performance than sampling uniformly. I tried to understand this starting from page ...
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19 views

Simple sample and reconstruction code - MATLAB

I am trying to go from theory to code. I take x (let say 16KHz is continuous time) then I sample it in 2Khz So I do ...
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1answer
19 views

EEG signal processing with sampling frequency

What is the relation between sampling frequency and the frequency of the signal after sampling? For example sampling frequency is 100 Hz, that is the signal contain maximum frequency of 50 Hz. Then ...
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1answer
27 views

how to sample and modulate a gps gold code

I am trying to simulate the data transmission of a GPS satellite. Telecommunications is not my field so I am struggling a bit with some concepts. I managed to generate the Gold code of the GPS ...
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47 views

Sampling Rate and SNR

Assume I have a signal that oscillates between 10KHz and 9Khz every 500msec (Change happens linearly, so at t=0, it is 10KHz and it goes to 9.5Kz at t=250msec and 9KHz at t=500msec and frequency start ...
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42 views

How to do the highest resolution FFT?

I wish to do the FFT of streaming audio data coming into a computer. I am just interested in frequencies from 80 Hz up to 1000 Hz but with a frequency resolution of 3 to 4 Hz and no more. Basically ...
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2answers
54 views

Why is $e^{i2\pi Nf_snT}=1$?

Why is $e^{i2\pi Nf_snT}=1$ in snippet from book?
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3answers
61 views

Performing DFT of streaming audio problem. Is there a limit?

I am trying to write software that will perform the discrete fourier transform of real time data coming from the microphone into the sound card on a computer. I am using Java with the javax.sound ...
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2answers
39 views

Aquila DSP C++ Library - Wave file FFT analog frequency off by factor of 4?

I'm working with the Aquila C++ DSP library. I'm computing the FFT of a wave file (16 bit depth, single channel, 44100 sample rate). I am using a window size of 16384 to calculate the FFT spectrum. ...
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3answers
65 views

What is the underlying concept behind Bandpass sampling?

Can you suggest me some books/webpages on Bandpass sampling? I undestand that if the signal is restricted between $f_L$ and $f_H$, then the minimum bandwidth required is $2(f_H - f_L)$. But say the ...
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38 views

Closed-form expression for Whittaker-Shannon interpolation for non-bandlimited signals

For a bandlimited signal $x(t)$ that is reconstructed after Nyquist-sampling at intervals $T$, $$x(t) = \sum_{k=-\infty}^{\infty} {x[k]\textrm{sinc}\left(\frac{t-kT}{T}\right)}$$ where $x[k]$ = ...
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31 views

How do we actually obtain samples to form discrete time samples? [closed]

I'm in my second week of an online DSP class and I'm still kinda lost on some of the concepts of what we are actually doing. I'm hoping you guys can help clear up my understanding. Please forgive me ...
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22 views

Approximation of Step Response from Data with delay

How can I approximate a Step Response curve from a measured data of a single input and a single output using Matlab while the delay between the input and the output is 30 minutes?
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1answer
68 views

Calculating a signals frequency when given the number of samples

This place has been great in helping me to understand my online image and signals class! I've moved on to another question and wanted to see if I'm correctly grasping the subject. The next question ...
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42 views

Capturing the sampling rate from a basketball being dribbled

I'm taking an online image and signals class and the structure is absolutely horrible. I'm wondering if you can provide me hints, or tips to solving the below question. I'm not looking for an ...
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15 views

Reduction of Sample Size of a Gaussian Pulse

I need to sample a gaussian wave of pulse width of 1 us which is being modulated by a cosine wave of GHz frequency. The different cases that I am interested in are 1) The initial phase of the cosine ...
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112 views

Zero, First, Second … nth-order Hold

The rectangular function is defined as: $$\mathrm{rect}(t) = \begin{cases} 0 & \mbox{if } |t| > \frac{1}{2} \\ \frac{1}{2} & \mbox{if } |t| = \frac{1}{2} \\ 1 & \mbox{if } |t| < ...
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113 views

Relation between the DTFT and the spectrum of a sampled signal

In the $\rm DTFT$ (Discrete Time Fourier Transform) the spectrum is periodic with period of $2\pi$ . A continuous signal when sampled has a spectrum which is a repeated version of its original ...
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58 views

Sampling and zero crossing

I am sampling a sine wave of 50Hz(stepped down from 230V) at the rate of 500KHz. For identifying disturbances in the wave, i was thinking of comparing a cycle of incoming sine values with reference ...
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40 views

Zero-order-hold for two dimensional signal $x(t_1,t_2)$

From Wikipedia: A zero-order hold reconstructs the following continuous-time waveform from a sample sequence $x[n]$, assuming one sample per time interval $T$: $$x_{\mathrm{ZOH}}(t)\,= ...
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52 views

Number of samples needed to convert a analog->digital, frequency bound, signal with decent quality to the Fourier domain

Similiar question(s) have been asked before, but I didn't fully get the answer I was looking for, so I figured I'd ask again. My excuses if there's something really basic in signal processing I've ...
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28 views

What are the implications of resampling the derivative of a signal with a higher frequency than the original signal?

Suppose I have a digital signal measured with sampling time, $T_s=1$ sec. If I take it's derivative, it will, naturally have $T_s=1$ sec. But what are the implications if I re-sample this derivative ...
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40 views

How can I duplicate this type of image?

I'm very new to the idea of signal processing, could someone point me in the direction of of a program to toy with images, below is a link to 2 taken a split second apart that showed up on my Amazon ...
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34 views

IDFT of H(z) sampled in N values

If a have a causal IIR filter described by $H(z)$ and I sample it in $N$ equispaced values around the unit circle, I get a DFT of $N$ points. That DFT corresponds to $h[n]$ truncated in $n=N-1$ or to ...
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51 views

Zero-order interpolation problem

Let $x_c(t)=\cos(\omega_0t)$. This signal is sampled with $\omega_s$, which is greater than the Nyquist rate. It is then interpolated with a zero-order interpolator. The signal obtained is ...
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170 views

Sampling Theorem: How to know the value between two samples of a Signal

According to Sampling theorem, in order to reconstruct a signal we need to sample it at the rate => twice the highest frequency component of that signal. (provided signal is band limited). Let's say, ...
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Why is it better to sample white noise in frequency domain here?

We have a channel $c(t)$ that we want to sample. It can be expressed as $ c(t)= g\ast x(t)$ where $x(t)$ is white complex Gaussian noise and $g(t)$ is a function that we know the PSD of, let's call it ...
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76 views

Downsampling and Then Upsampling

Given this system: I need to show the $\mathcal Z$-transform of $y[n]$ as a function of the $\mathcal Z$-transform of $x[n]$. Now I know that for downsampling alone: $$Y(z) = ...
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24 views

A reference request for zero-order hold (ZOH)

From Wikipedia: A zero-order hold reconstructs the following continuous-time waveform from a sample sequence $x[n]$, assuming one sample per time interval $T$: $$x_{\mathrm{ZOH}}(t)\,= ...
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2answers
55 views

Sampling H(z) to get DFT

Suppose that I have a $H(z)$ and I sample it to get a DFT of 15 values. Let's call this DFT $H_{1}[k]$. Then, suppose I antitransform $H(z)$ and grab the first 10 values of the sequence, and then I ...
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48 views

Does the hold part in sample and hold turns the signal from discrete to continuous?

I am trying to link sample and hold to discrete and continuous time domain. Could someone please confirm: When sampling but not holding for "an extended" period of time, you have discrete samples. ...
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26 views

How to calculate output from non-uniformly sampled transfer function data?

I have non-uniformly sampled transfer function data (magnitude only) in the range of 100kHz and 200MHz. Using this transfer function, I would like to calculate output from specific input. Question : ...
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65 views

Sampling frequency lower than half of sampled signal frequency?

In GNURADIO when RTL-SDR Source block is placed there is a parameter Sample Rate (sps) and ...
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20 views

Sampling a Signal with maximum frequency content of 600Hz

I am looking to sample a signal with a maximum frequency content of 600Hz. From Nyquist, 2x fmax= 1200Hz, therefore would a sampling frequency of 2kHz be suitable?
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81 views

fmcw radar sampling requirements

I have been reading about "all-digital" or "software-defined radars". Lately, I was trying to simulate an FMCW short range radar in Matlab. One thing that struck me during the simulation is that to ...
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34 views

Cut-off frequencies for fractional sample rate adjustment

We have a signal sampled att 22 kHz that we want to interpolate to 40 kHz. So we can do this by upsampling by a factor 20, then downsampling by a factor 11. My question regards the choice of cut-off ...
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107 views

Minimum Sampling Rate of Bandpass signal

Consider a DSBSC signal s(t) = m(t).cos(2.pi.20k.t) where say m(t) is multi-tone signal with frequencies less than 5 kHz. The ...
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191 views

Why is a square wave aliased?

I understand an ideal analog square wave contains sine-wave-components above Nyquist frequency (and towards infinity) and is thus subject to aliasing. So obviously we need an anti-aliasing-filter. Or ...
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57 views

Understanding “voltage” and “power” in SNR of a sampled signal

I'm facing a gap in my understanding of when a signal is a "voltage" signal and when it is a "power" signal that I've always managed to avoid resolving until now... First what I think I understand, ...
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1answer
56 views

Oversampled polyphase filter banks

i would a confirm of this: with polyphase structure is possible only design a filter bank with a INTEGER oversampling ratio? For non-integer i've seen the weighted overlap-add metod, is right? thanks ...
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84 views

DFT Filter Banks

i have a doubt about DFT filter banks. For example I have $M=4$ channels and a filter with cut-off frequency of $0.25$ right. The prototype filter $H_0$ is a low-pass centered around $0$ ok. The ...
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39 views

Undersampling with Simulink

i'm modeling an ADC with Fs = 40 MHz with a signal sine at Fc=130MHz, sampled at 520 MHz. I'm expected to see this at 10 MHz after to be sampled, thanks to undersampling. The problem is the sample ...