Questions tagged [sinc]
The sinc tag has no usage guidance.
46
questions
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4
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Why is the time domain low-pass filter the "sinc" shape?
Consider:
I'm looking at low-pass filters, and I see that the time domain representation of an "ideal" filter resembles the shape above whereas the frequency domain is a box. I also get the ...
- 133
0
votes
1
answer
59
views
Filtering in time domain vs filtering in frequency domain
The signal is an impulse repsonse. I am filtering the signal using a windowed sinc filter in both frequency and time domain. I am interested in knowing the differences between the two methods and ...
1
vote
0
answers
94
views
How can the DCT be used for bandlimited interpolation?
I know the discrete cosine transform (DCT) is used for compression, but can anyone give an example of how to use it for bandlimited interpolation?
One way might be zero-padding in the DCT domain and ...
- 1,664
3
votes
1
answer
315
views
java resampling implementation using sinc function
To be as succinct as possible, I've written a Java method that implements resampling of a signal using the sinc function interpolation formula. When I test this code with a simple sinusoid, I'm able ...
- 81
0
votes
1
answer
66
views
Intuition for how much ringing a particular filter will induce
I've seen figures in various books about the the tradeoff between aliasing and blurring when using a gaussian-like filter: the narrower it is, the more it cuts off low frequencies and thus blurs it, ...
4
votes
1
answer
397
views
Fourier Transform of impulse train proof in Julius O Smith's textbook
$\DeclareMathOperator{\sinc}{sinc}\DeclareMathOperator{\asinc}{asinc}$I'm trying to follow the proof of the Fourier Transform for an Impulse train given in Julius Smith's textbook. I come across the ...
- 225
0
votes
2
answers
411
views
Designing a digital band pass filter with Sinc filter in time domain
I want to design a sinc filter in the time domain (a bandpass filter in the frequency domain).
I wrote test code in python to investigate, and would appreciate help understanding it and answer my ...
- 31
2
votes
0
answers
62
views
Synthesizing a pure tone in Frequency Domain: can it be done more efficiently?
I came to the conclusion that synthesizing pure tones in Frequency Domain is much less efficient than synthesizing cosines in Time Domain and then computing the FFT. But I suspect this is the case ...
- 331
2
votes
1
answer
291
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:
...
- 93
5
votes
2
answers
779
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.
...
- 153
2
votes
2
answers
608
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 ...
- 21
0
votes
3
answers
358
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Convolution of squares / boxcars in functional form
$$
\Pi(t/A) * \Pi(t/B)
$$
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 ...
- 8,815
2
votes
0
answers
93
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?
...
- 8,815
2
votes
1
answer
483
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
3
votes
1
answer
1k
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 ...
- 79
2
votes
1
answer
75
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 ...
- 21
3
votes
1
answer
401
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 ...
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1
vote
1
answer
156
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 ...
- 37
2
votes
2
answers
503
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 ...
- 123
1
vote
0
answers
290
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 ...
- 11
0
votes
2
answers
532
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 ...
- 573
0
votes
1
answer
105
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
347
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
875
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 ...
- 155
1
vote
1
answer
4k
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:
$$x(t) = \sum_{n=-\infty}^\infty x[n] \mathrm{sinc}\left(\frac{t-nT}{T}\...
- 37
0
votes
0
answers
90
views
Fourier transform and energy of a convolution
Hi guys i have to find the fourier transform of the convolution:
$$ 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
82
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 ...
- 349
0
votes
0
answers
201
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
277
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
83
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
276
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 ...
- 275
2
votes
1
answer
1k
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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 ...
- 23
3
votes
1
answer
2k
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:
$$ {P_x} = \lim_{T \to \infty} \...
- 33
1
vote
1
answer
180
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DTFT and a Downsampled Sinc Function
I found the answers to this question and this question to be extremely helpful in understanding the derivation of the downsampling or decimation property of the DTFT. Thank you! I am now struggling ...
- 63
2
votes
3
answers
702
views
aliasing in image processing
I know that aliasing occurs when a signal is subsampled. If the sampling rate is lower than twice the max frequency in a signal, aliasing occurs.
How is it in pictures? as far as I know, a sinc-filter ...
- 141
1
vote
2
answers
981
views
Why notches in sinc filter response
Below response shows sinc1,sinc2 and sinc3 filter response.
I understand that notches in the frequency response happens at the output data rate of the sigma-delta ADC.
But I am not able to figure out ...
1
vote
1
answer
72
views
How $\Delta f=\frac{1}{2T}$ satifies the orthogonality condition?
Let
$$s_{ml}(t)=\sqrt{\frac{2E}{T}}\exp(j2\pi\Delta fmt)$$
where $T$ is the time-period of signal
$\Delta f$ is the frequency spacing
The text says that two signals $s_{ml}(t)$ and $s_{nl}(t)$ are ...
- 181
1
vote
1
answer
675
views
Discrete-time Fourier transform of $\frac{\cos(\frac{n\pi} 6)}{(n+3)\pi}$
Find the Discrete-time Fourier transform of $\frac{\cos(\frac{n\pi} 6)}{(n+3)\pi}$
I thought of making it to be a sinc, but at the bottom there is $n+3$ and if I replace $n+3$ then I don’t know how ...
- 174
0
votes
1
answer
175
views
Sinc Interpolation Artifacts
I have written a program that uses sinc interpolation to resample some data. The general algorithm is a that I compute the previous N values and the next N values to get a new sample at a non-integer ...
0
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4
answers
82
views
How do I prove that delta - sinc function is the same as an (-1)^n times the sinc
$$\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
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0
votes
2
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119
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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 ...
- 171
0
votes
1
answer
411
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
1k
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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 ...
- 11
-1
votes
1
answer
33
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 ...
2
votes
1
answer
2k
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0
votes
1
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70
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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 ...
- 683