Questions tagged [sinc]

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2 votes
1 answer
31 views

Applying Kaiser Window to sinc interpolation

I am trying to apply the kaiser window during sinc interpolation. The following is my sinc interpolation code: ...
  • 21
5 votes
2 answers
477 views

Odd artifacts after sinc interpolation

I am trying to upsample a signal using sinc interpolation. I have written a way to do this in python. ...
1 vote
2 answers
217 views

Why use sinc function to downsample an image in fourier domain?

I'm very confused about downsampling in image processing and the use of sinc function to do it. I read this post [1]: 2D Fourier downsampling some time ago that talked about my own doubt, that is to ...
-1 votes
2 answers
92 views

Convolution of squares / boxcars

$$ \Pi(t/A) \star \Pi(t/B) $$ where $$ \Pi(t) = \begin{cases} 1,\ -1/2 \leq t \leq 1/2 \\ 0,\ \text{otherwise} \end{cases} $$ How to compute? Derivation/steps optional but welcome. Note: I'm aware of ...
2 votes
0 answers
54 views

Convolve sinc trains

$$ \begin{align} & \mathrm{sinc}(As + .5)\sum_{n=-\infty}^{\infty} \delta (s - n/A)\ \star \\ & \mathrm{sinc}(Bs + .5)\sum_{n=-\infty}^{\infty} \delta (s - n/B) \end{align} $$ How to compute? ...
2 votes
1 answer
117 views

Fractional Frequency Shifting a Discrete Signal in the Frequency Domain

In our current hardware-based signal processing pipeline, we have a time-domain signal $x[n]$ that we want to frequency shift by $f_0$. To do this, we multiply the signal by a complex exponential in ...
  • 55
2 votes
1 answer
241 views

Impulse response of IIR low-pass filter

(Disclaimer. I have started doing some DSP. The last time I worked with this was in the eigthies. And I wasn't much of a specialist then, either.) Is the impulse response different for IIR and FIR ...
2 votes
1 answer
52 views

Is the ideal reconstruction process BIBO stable?

It is well known that ideal lowpass filter, i.e. the lowpass filter whose impulse response is $h(t) = \text{sinc}(t)$, is not BIBO-stable because $h(t)$ is not absolutely integrable. However, think ...
2 votes
1 answer
142 views

Downsampling an image using sinc interpolation?

I have a discrete image of size $2^N \times 2^N$ which I would like to iteratively downsample to produce a pyramid with image sizes $2^k\times 2^k, \, k=0,\ldots,N$. That is, each subsequent image ...
1 vote
1 answer
84 views

How do I confirm that range cell migration correction was done correctly? Is there a way to check this graphically without looking at the signal data?

I am implementing the Range Doppler Algorithm for a Synthetic Aperture Radar project and I am at the step where I must perform Range Cell Migration Correction. This step involves creating a sinc ...
1 vote
2 answers
263 views

Differences in transforming a sinc FIR filter from lowpass to highpass using spectral inversion and spectral reversal

I have designed a lowpass sinc 1023 tap FIR filter with a Blackman window and this works fine. I understand there are then two ways to transform this lowpass filter to a highpass one. One is spectral ...
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1 vote
0 answers
126 views

Triangular dither - What does it mean to say that an input signal is uncorrelated with the dither

In the oft-cited ADC dithering appnote: Oversampling Techniques using the TMS320C24x Family http://www.ti.com/lit/pdf/spra461, it notes under triangular dither: However, this approach requires that ...
0 votes
2 answers
262 views

Inconsistency Between Analysis and Simulation Results of Fourier Transform of a Sinc Function

First of all, hello. This question is about a problem that I’ve faced during an attempt to obtain both time and frequency responses of a sinc function in MATLAB. The problem is an inconsistency ...
0 votes
1 answer
78 views

Output of a linear time-invariant(LTI) system

I am very confused about one of the questions I received during an exam. How do I solve this question?
1 vote
2 answers
224 views

How do I sort out my window sinc low pass filter

I started writing a windowed sinc low pass filter, but I cannot seam to get the code figured out right. I followed these two links http://doctord.webhop.net/Courses/textbooks/Smith_DSP/dsp_book_Ch16....
1 vote
0 answers
465 views

Sinc3 Filter in FPGA

I working on FPGA block which requires an Sinc3 Filter for Sigma-Delta ADC coming in. I read about it and Sinc filter, is filter with frequency response of sinc, that means its just a moving average ...
1 vote
1 answer
2k views

How to correctly use sinc interpolation in Matlab?

What is the right way to use sinc interpolation for a given discrete signal $x[n]$? Following is the sinc interpolation formula: $$x(t) = \sum_{n=-\infty}^\infty x[n] \mathrm{sinc}\left(\frac{t-nT}{T}\...
0 votes
0 answers
77 views

Fourier transform and energy of a convolution

Hi guys i have to find the fourier transform of the convolution: $$ sinc(t/2T)*\sum\limits_{n-\infty}^{+\infty} (-1)^{n}\delta(t - nT) $$ i was thinking of express the summatory as : $$\sum\limits_{n-\...
0 votes
1 answer
43 views

how sinc pulses can be used to distinguish different symbols

Let's say we want to transmit a sequence of numbers Using PAM, this sequence is transmitted with the signal $s(t)$ The pulses in $s(t)$ are transmitted at a rate $R_p=\frac{1}{T_p}$. This is called ...
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0 votes
0 answers
120 views

Rectangular Pulse Train and Sinc Function

I wanted to ask that in frequency domain the rectangular pulse is a sinc function, so is this sinc function periodic or aperiodic? Also if signals that are continuous in time domain then they are ...
1 vote
0 answers
203 views

Convolution of Heaviside function with a sinc low pass, is it band limited?

Is the result of convolution of a heaviside function with a sinc low pass with cut off at fc, say 25khz, band limited ((sin(2 x Pi x fc x i))/(Pi x i))? I've been working it out in frequency domain (...
0 votes
0 answers
64 views

Sinc Low pass and transients

Assume, I am trying to use a 50khz sampling rate for some signal. I don't know what the spectrum of input signal is, so I will have to low pass manually with sinc (theoretical best low pass) to band ...
1 vote
1 answer
129 views

How to prove a train of sinc pulses in digital communicaton system are orthogonal to each other?

Consider a train of sinc pulses: $$\phi_n(t)= \frac{\sin(\omega_M(t-nT_s))}{\omega_M(t-nT_s)}\quad; n=0,\pm1,\pm2,\dots$$ $\quad$where,$\quad T_s=\frac{\pi}{\omega_M}$ Now ,in order to show sinc ...
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2 votes
1 answer
647 views

How to implement sinc interpolation

I'm trying to write my own high quality audio sample rate converter. I barely know anything about signal processing though so I need help. From what I understand I need to sum together normalized sinc ...
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3 votes
1 answer
956 views

Getting the power of a signal from its Fourier transform?

I have a non-periodic signal that contains the sinc function in the time domain and so it is a bit difficult to calculate its power (because of the integral) through: $$ {P_x} = \lim_{T \to \infty} \...
1 vote
1 answer
105 views

DTFT and a Downsampled Sinc Function

I found the answers to this question and this question to be extremely helpful in understanding the derivation of the downsampling or decimation property of the DTFT. Thank you! I am now struggling ...
2 votes
3 answers
604 views

aliasing in image processing

I know that aliasing occurs when a signal is subsampled. If the sampling rate is lower than twice the max frequency in a signal, aliasing occurs. How is it in pictures? as far as I know, a sinc-filter ...
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1 vote
2 answers
556 views

Why notches in sinc filter response

Below response shows sinc1,sinc2 and sinc3 filter response. I understand that notches in the frequency response happens at the output data rate of the sigma-delta ADC. But I am not able to figure out ...
1 vote
1 answer
57 views

How $\Delta f=\frac{1}{2T}$ satifies the orthogonality condition?

Let $$s_{ml}(t)=\sqrt{\frac{2E}{T}}\exp(j2\pi\Delta fmt)$$ where $T$ is the time-period of signal $\Delta f$ is the frequency spacing The text says that two signals $s_{ml}(t)$ and $s_{nl}(t)$ are ...
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1 vote
1 answer
327 views

Discrete-time Fourier transform of $\frac{\cos(\frac{n\pi} 6)}{(n+3)\pi}$

Find the Discrete-time Fourier transform of $\frac{\cos(\frac{n\pi} 6)}{(n+3)\pi}$ I thought of making it to be a sinc, but at the bottom there is $n+3$ and if I replace $n+3$ then I don’t know how ...
0 votes
1 answer
126 views

Sinc Interpolation Artifacts

I have written a program that uses sinc interpolation to resample some data. The general algorithm is a that I compute the previous N values and the next N values to get a new sample at a non-integer ...
0 votes
4 answers
70 views

How do I prove that delta - sinc function is the same as an (-1)^n times the sinc

$$\delta(n) - \frac{1}{2} \mbox{sinc} \left(\frac{n}{2}\right) = (-1)^n \frac{1}{2} \mbox{sinc} \left( \frac{n}{2} \right)$$ The picture shows what I've tried
0 votes
2 answers
81 views

ZOH non ideal sampling loss formula

Hello i am trying to calculate the amplitude loss of non ideal sampling. My signals amplitude is 10 at 70 frequency. When we sample it at Fs=400 we have al 0.511 loss as shown in plot bellow. How can ...
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0 votes
1 answer
209 views

Reconstruction using sinc

The signal that I produce above. What is the reason for it to slide to the right? In oversampling at Nyquist rate can I make like below picture ? do you think the signal i produced at nyquist rate is ...
1 vote
1 answer
724 views

Convolution Integral of Harmonic Signal (Cosine) with the Sinc Function

I was asked to show that this convolution integral results in the answers also given in the image. Not quite sure how to approach this integral, everything seems to be coupled together. Does anyone ...
-1 votes
1 answer
31 views

Impulse coefficient when it does not match the bin index

Assume that I have a N=10 samples with Fs=10. assume in the time domain an unit impulse event happens which should be placed at 3.425 index in time domain. Assume that I could not change Fs or ...
1 vote
1 answer
1k views

windowed sinc filter in matlab

Hello i'm designing a low pass filter windowed sinc in matlab ...
0 votes
1 answer
65 views

Purely theoretical question about idelal filters and infinite oscillations

I am asking perhaps a naive question, but still, it would be nice to have this formally stated one time: in theory, if we could do it (of course, we cannot, but imagine we could), if we could ...