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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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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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209 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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83 views

Representing a positive 0-limiting continuous time domain function, in terms of spectral samples, outside of a window

Bit of an odd question Assume you have a known function $x(t)$ which is continuous, but approaches but is not equal to, 0, on the interval $[-\infty,\infty]$ . You know also that it approaches 0 ...
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601 views

frequency domain zero padding in OFDM

I have a matlab code for OFDM system, in this code the auther added a zero padded subcarriers before the IFFT stage, in the middle of the raws, and added zero padded guard interval after IFFT, my ...
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546 views

Sampling rate versus number of sample of I and Q

I am acquiring data of an O-QPSK signal (chip rate : 2Mchip/s) with a SDR. I am undersampling the signal at 20 Mhz (carrier is at 2.8 GHz) so I respect the Shannon-Nyquist criterion that you need to ...
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108 views

Artifacts in sub-sample delay

There are at least two ways of achieving sub-sample delay. One is to simply over-sample the signal and then delay it by the wanted sub-sample amount. The over-sampling is equivalent to creating new ...
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59 views

Why is an audio compressed in FLAC(Free Lossless Audio Codec) changing its bit rate?

I just recognized that the bit rate of an audio file compressed in FLAC is changing during play. On the other hand, MP3 file has a fixed bit rate such as 128, 192, 320kbsp etc. But why FLAC is not? ...
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39 views

Received waveform frequency is way too low than it was sent

I am using Quartus 12.1 sp1, vhdl and Altera Nios II programmed in C code for DE0-Nano Development. Basically, what I have is, data is sent from fpga vhdl block to NIos II system, Nios II system sends ...
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573 views

Sampling rate: camera resolution when taking a photo of an LCD

Consider a digital camera that faces an LCD and that is perfectly focused on the LCD. The LCD shows an image of $n \times n$ pixels. What resolution does the camera have to have to perfectly capture ...
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183 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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342 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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27 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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54 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} A\sin(\...
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837 views

What are the frequency components of a sampled signal after low-pass filtering?

A continuous signal $x_a(t)$ is a linear combination of sinusoids of frequency 250 Hz, 450 Hz, 1 kHz, 2.75 kHz and 4.05 kHz. The signal $x_a(t)$ is sampled at $f_s=$1.5 kHz, and the resulting digital ...
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355 views

Recording square waves at sample frequency

For a project I am working on, I need to incorporate GPS data into an audio file. As things currently are, the easiest way for me is to record the audio in a multi-channel .wav file, and add the GPS ...
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37 views

Matlab:Sampling Curve into Frames and Plotting

I have a Output Curve of following characteristics http://i.imgur.com/hABfsiC.jpg Following is the data which represents the output curve cited above ...
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338 views

Sampling Clock Offset estimation

I want to estimate sampling clock offset. I am currently referring this paper " CRAMER-RAO BOUNDS FOR DATA-AIDED SAMPLING CLOCK OFFSET AND CHANNEL ESTIMATION ". Is there any other method to estimate? ...
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184 views

Can somebody help me solve this signal accumulation problem?

Investigation of the method of suppression of random noise by coherent signal accumulation Purpose - to identify opportunities for the coherent accumulation for cases of stationary and quasi-...
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272 views

Direct IQ sampling symbol transition problem

In a direct sampling RF front-end, we can get real samples. But when we sample the signal with two ADC with a sampling delay $ \frac{4n+1}{4fc}$ where $n$ can be $0,1,2 \dots$ Then we have In phase(I) ...
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78 views

Trying to understand whether digital signals help in better bandwidth utilisation or not

Suppose x(t) is a continuous-time signal and x(n) is a discrete time signal obtained by sampling the signal x(t) at a Nyquest sampling frequency Fs. The signal x(t) requires a bandwidth of B1 Hz for ...
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22 views

What happens when the frequencies of the signal does not lie within the reconstruction filter passband?

Assume we have an analog signal that has frequency components between 40Hz and 50Hz and 0 otherwise. If we sampled this signal with 100Hz sampling frequency then passed to DAC with the same sampling ...
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630 views

how to sample sine wave to 4 points dft output

sinusoid x(t)=1+sin(2*pi *500) sampling rate :1000 samples/s Can I have 4 points DFT output with the above data.