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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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Show that $S[n]= \frac1M \sum e^{\frac{2\pi l n}M}$ for $l = 0$ to $M - 1$

I am learning about image processing. Currently, I am reading about upsampling and down sampling. Here is some background what I am reading: I was wondering if someone show me a proof of how ...
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92 views

How to filter a signal sampled at different frequencies

I have a signal which was sampled using different frequencies. The 3 regions are: 0-10 ms: 10000 Hz 10-50 ms: 1000 Hz 50-200 ms: 100 Hz The signal is very noisy, so I thought about smoothing it with ...
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33 views

Conditions for representing (perfectly) an analog signal as a digital signal

Consider the following cases: Sampling with a frequency of the "signal's central frequency" Sampling a BP signal with twice the frequency of the signal BW. Sampling an LP signal with the highest ...
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44 views

Changing a filter as a function of different sampling rate or gain?

Dear fellow signal processors, my problem is the following, I have a butterworth filter (Matlab) applied to EEG data with which I already published and it is essential that only the most necessary ...
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243 views

Does speaker recognition system need the same sample rate audio?

I'm a new man in speaker recognition project. I've train a model with some .wav files, its sample rate is 16000. I want to test this model with my record, but my record's sample rate is 8000 Doed it ...
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15 views

Design a filter to signals VHT

I have 4 signals: vht_20MHz, vht_40MHz, vht_80MHz and vht_160MHz. I sample the three first signals to have a 160MHz of sampling frecuency, and then I filter vht20MHz and vht40MHz and use a comparator ...
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277 views

How does it go about implementing pitch shifting without affecting the duration or speed on matlab? [closed]

I am creating a project that will record a sound sample from the world, for example, a bird's chirping. And then through pitch scaling, I could create different notes. I first tried to change the ...
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11 views

Getting amplitude / phase information for a smaller subset of a large amount of spectrum

I have captured a few seconds of samples from an SDR, at 2Msps. I'd like to examine characteristics of the I/Q data at subsets of this 2MHz spectrum (for example, every 10kHz). Is this possible, or ...
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69 views

Determining the features of the DSP

I need to sample a signal of 40MHz with a sampling frequency of 120MHz at least with a 8/12 bits ADC and send them through the USB serial port of a PC. That means the serial communication bandwith ...
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2answers
45 views

Determine minimum sample rate for continuous sinusoid

Consider a signal $$ x(t) = \cos(175\pi t) $$ which is sampled to produce discrete time signal $$ x[n] = x(nT_s) $$ The fundamental period of $x[n]$ is $$ N_0 = 7 $$ Given this, what is the smallest ...
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644 views

What is the difference between the sampling frequency of signal and sampling frequency of filter

I believe that there is no connection between the sampling frequency used for converting an analogue filter to digital filter and the one used to sample a signal that the filter will be used on. But I ...
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117 views

Where does this star came from? [EDIT - Detailed Question]

First of all, it's a rare topic in google, so I can't find intuitive explanation about step-invariant, so I don't understand actually what it is, except to solve zero order hold transfer function. In ...
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413 views

Use of the Dirac delta as a sampling operator

As we are all taught in signal processing classes, the Dirac delta is not a normal function but a generalized function. It is sometimes defined as either the limit of some normal function whose ...
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62 views

Time-variance and causality of $y(t)=\sum_{k=-\infty}^{+\infty}x(t)\delta(t-kT)$

Is the following system time invariant and/or causal? $$y(t)=\sum_{k=-\infty}^{+\infty}x(t)\delta(t-kT)$$ I think that it isn't time invariant and it is causal, and my thought is based on the ...
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60 views

Basic sampling excercise - unsure of rationale informing np.arange parameters for time array

I'm extremely new to DSP, so I apologise if it's a very basic question. I'm having issues understanding the following exercise: "Create an array of 201 samples containing a sin wave with a frequency ...
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40 views

Hardware selection for acquiring signal in digital form

I want to it clear that I am a mechanical engineer and so my knowledge on electronics and signal processing is limited. I am working in a hydrophone system. My job is to find the position of an ...
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2answers
183 views

compensation for irregular timestep for FFT

I want to run a clustering algorithm (svm, knn) on the ferquency spectrum data of a temperature sensor that published at irregular times. Here is the temperature data to take the FFT: I got the ...
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50 views

Minimum time delay that can be estimated between two sensors

Consider a 1-dimensional toy problem. I have two sensors at different points along the $x$-axis. Somewhere away from the sensors, a disturbance is created which travels towards the sensors, first ...
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30 views

Signal view from two different receivers (of the same model)

I have two SDRs hooked up to two different computers, both radios tuned to the same frequency. They sample at 2Msps. What I would like to do is start up both (at 'about the same time'), and, after ...
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1answer
105 views

Does the Nyquist Sampling Theorem hold for a triangular wave?

Does the Nyquist Sampling theorem hold for a triangular wave produced by a function generator? For example, a triangular wave with a frequency of 15 Hz sampled at 60 Hz, 180 Hz and 15000 Hz.
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45 views

Analog Integrator Sampling Rate

What would be the effective sampling rate of an op amp analog integrator (such as the one described here ) taking in a rapidly varying signal be? Ie what time resolution would such an integrator have? ...
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116 views

Estimate sampling frequency given an array of values

Given an array x of size 2000, is there any way to calculate (or estimate) the sampling frequency using Matlab? The values are the only information I have about the signal. I know the signal has been ...
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77 views

How to best separate my signal into frequency regions?

I have a signal with frequencies betwwen [0.5,500] Hz and i want to create a filter to best separate the signal in the following regions: [0.5-3]Hz [3-8]Hz [8-13]Hz [13-30]Hz [30-500]Hz My ...
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57 views

Temporal Orthogonality

I'm studying Digital Communication and I couldn't understand the relationship between temporal orthogonality and sampling theorem. Definition of the Temporal Orthogonality is as follows: $$\mathrm{...
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219 views

why total energy of a finite duration continuous signal becomes infinite after sampling

If I have a continuous-time energy signal and multiply it with an impulse train, the frequency domain representation has infinite replicas. The total energy if we sum them up becomes infinite. What ...
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235 views

Convolution effects width of the signal?

Let's say there are two signal with different frequency: \begin{align} X_1(\omega) &= 0\quad\text{for}\quad \lvert \omega\rvert > 1000\pi\\ X_2(\omega) &= 0\quad\text{for}\quad\lvert \omega\...
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68 views

Does Forward Error Correction (FEC) affect upsampling factor?

Is the redundant data introduced during forward error correction (FEC) counted as upsampling? I'm taking a binary data stream, doing convolutional encoding of rate 1/2 on it, then making it NRZ ...
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166 views

Reconstruction of a signal using an ideal DAC

I think I was able to do part (a) correctly, but now am stuck on part (b). I don't know how to approach this part or what is the theory behind it. My MATLAB code is shown below. Please let me know if ...
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1answer
130 views

Smallest sampling frequency to fully reconstruct a signal

Given the spectrum of analog signal $x_a(t)$ which is imaginary and band-limited, find the lowest sampling frequency to be able to reconstruct $x_a(t)$ from samples $x[n]$. My attempt: Bandwidth of ...
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1answer
441 views

Typical number of samples per symbol

Assuming a pulse shaping of a source of symbols (like $s=\{3,-i,2+5i\}$), and a SRRC waveform (or any other waveform). I know that it depends on many factors like modulation scheme, but, in practice, ...
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3answers
139 views

I have a graph where I need to find a particular point based on sampling

I currently have a graph which looks something like this: Now I have discrete data that represents the Number of Clusters(the x values), giving us the Average Cluster Distance (the y values). There ...
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56 views

Explaining a statement regarding aliasing in a document

I am reading this document and in the section "Aliasing and Anti-Aliasing", the author make the following statement: Consider a signal with two frequency components: $f_1 = 10\,\text{Hz}$ which is ...
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119 views

Plotting the discrete time signal

Consider the following analog signal $$x(t) = 2 \sin(100\pi t)$$ The signal $x(t)$ is sampled with a sampling rate $F_s=50\textrm{Hz}$. Determine the discrete time signal. Plot the discrete time ...
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66 views

Custom ringtone sounds good on computer, can't be heard on phone [closed]

I did a ringtone using Audacity and then used this website to convert to mp3. I sent this mp3 file to a friend who said he couldn't hear it well. I have an iPhone so I converted it to m4r. Both the ...
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167 views

Understanding the mathematical proof for the alias frequencies in a sampled sine wave

I'm struggling to get my head round the mathematical proof for the alias frequencies in a sampled sine wave. I understand that sampling a sine wave of frequency $f_0$ every $t_s$ seconds gives you: $...
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721 views

Suitable sampling rate for triangle wave

I know this is a fairly simple question but I can't convince myself of the right answer. For a 5KHz triangle wave, being sample at Fs sampl/second, what's a suitable choice for Fs such that an ...
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38 views

From where this Laplace transform for tracking error came?

System for estimating the tracking error in an A-D converter. Let $e_i(t)$ be ramp function with slope $e_i'$ and assume that the sampling switch is closed at $t = 0$, at which time $e_i = e_0$...
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2answers
250 views

sampling a sinusoidal signal at the Nyquist rate

To sample a sinusoidal signal at the Nyquist rate, we have to take two samples per cycle. Is there any condition on the position of the two samples? is it necessary to take them at the peaks?
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133 views

Lock-In Amplifier Sampling Rate

For a digital lock-in amplifier (synchronous demodulator) I have a sinusoidal reference signal in the range of 10-15kHz, the amplitude and phase I want to observe changes very slowly <10Hz. My ...
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60 views

Sub nyquist sampling, required number of samples for time sparse grouped signals

Question: Does it make sense to perform compressed sampling if the non zero samples are grouped in time? If so, what is the minimal length of the vector x that should be acquired to allow full signal ...
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148 views

Phantom harmonics when using cosine windows why do they appear and how to avoid them?

Given an L order cosine window, it is possible to show that the width of the main lobe is given by: $$\omega_w = \frac{2 \pi L}{(2N+1)}$$ Where $L$ is the order of the window, $N$ is the maximum ...
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If a person at rest has an average heart rate between 60 and 100 beats per minute, how manysamples should you plot to obtain 5 beats in the signal?

If a person at rest has an average heart rate between 60 and 100 beats per minute, how many samples should you plot to obtain 5 beats in the signal?
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5k views

Find the minimum sampling rate

As the signal $m(t)$ is Baseband signal after modulation it wil be bandpaas signal will look like this So I need to use the Baseband sampling Here $f_L=15kHz,f_H=25kHz,B=5kHz,$Now Undersampling ...
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3answers
1k views

Waveform samples and I/Q components

I'm quite new to DSP and I guess my problem it's quite silly but I can't find a clear answer. Basically I'm writing some python code for a test. The test requires me to write a memory with the I/Q ...
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662 views

Upsampling before performing pulse shaping

I know what an upsampler does. We insert L-1 zeros between the samples. As a result, it creates spectral repetitions. What if we have a symbol impulse stream and then we apply a Root Raised Cosine ...
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520 views

Compressive sensing vs. Sparse coding

There apparently are different terminologies used to refer to the same field called "compressive sensing" such as (see this wiki page): compressed sensing, compressive sampling, or sparse sampling. I ...
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114 views

What will be the filtered output?

I tried to solve this question from basic Here is my work Image 1 Image 2 But the correct answer is Option $(B)$.What is the mistake i am doing?
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What is differences between Zero-order hold, First-order hold and Polygonal hold? [duplicate]

I learned that the purpose of the hold operation is to fill the spaces between sampling periods and roughly reconstruct the original analog input signal. Also, I learned Zero-order hold, First-order ...
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457 views

Find the nyquist sampling rate?

I have a signal $x(t)$ for which I want to find the Nyquist frequency : $$ x(t) = \frac{\sin{\pi t/2}}{\pi t/2} \ast \sum^\infty_{n=-\infty}\delta(t-10n)$$ I am trying to solve this in the time ...
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144 views

Bandwidth confusion

Let's imagine that I took a Fourier analysis of a random voice signal that I want to sample and plotted it's frequency components in frequency domain (frequency vs amplitude). Now I want to sample it. ...