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Topic: Sinc filter

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	Understanding the Effects of Clock Tolerances on 50/60Hz Noise Rejection in High Performance Sigma Delta ADCs - ...
		Common implementations of the digital filter in sigma-delta ADCs are a lowpass filter with a SINC (Sin(x)/x) impulse response.
		Filter order and decimation ratios are typically defined by the design of the sigma-delta ADC and shown in the ADC data sheet.
		filter response with a 60Hz notch frequency, 19.2kHz modulator frequency, and a decimation ratio of 320.
	www.maxim-ic.com /appnotes.cfm?an_pk=3418 (763 words)

	Anti-aliasing - Wikipedia, the free encyclopedia
		Figure 1-c shows another anti-aliasing algorithm, based on the sinc filter, which is considered better than the algorithm used in 1-b.
		Since this requires that the primitives be in some order, and hence interacts poorly with an application programming interface such as OpenGL, the latest attempts simply have two or more full sub-pixels per pixel, including full color information for each sub-pixel.
		However, in many instances, the filtering should not be uniform in each direction (it should be anisotropic, as opposed to isotropic), and a compromise resolution is used.
	en.wikipedia.org /wiki/Anti-aliasing (1742 words)

	[No title] (Site not responding. Last check: 2007-11-03)
		The filtering stage is realized by a classical sinc-filter cascaded with two other filters obtained from the first one by rotating its zeros by two opposite angles.
		Since the designed filter eliminates the most part of the quantization noise, the following filtering stages may be designed with relaxed specifications adopting classical filter design methods.
		Since the decimation function is a sampling process in the discrete-time domain, it requires, as a first step, an anti-aliasing low-pass filter with bandwidth W
	web.tiscali.it /laddomada/articolipubblicati/SincTaiwan.html (1396 words)

	CS 248: Midterm Solutions (Site not responding. Last check: 2007-11-03)
		Since in general the signal to be sampled may contain high frequencies, it should be filtered before sampling to remove frequencies above the Nyquist frequency.
		Drawn in the frequency domain, the ideal low-pass filter is a box filter centered at the origin and extending to the Nyquist frequency (1/2 the sampling frequency).
		Thus, to perfectly low-pass filter the signal requires a convolution with a sinc function, and by the reasons described in 4A, this is impractical.
	graphics.stanford.edu /courses/cs248-98-fall/Midterm/q4.html (578 words)

	Articles - Aliasing (Site not responding. Last check: 2007-11-03)
		The filtered version corresponds to applying a sinc filter to the rational function f.
		Therefore, the assumptions used to justify the optimality of the sinc filter are false in this case.
		This is an example where fl-box filtering with a sinc filter is not able to recover the desired data.
	www.digital-voicerecorders.net /articles/Aliasing (2144 words)

	Talk:Nyquist–Shannon sampling theorem - Wikipedia, the free encyclopedia (Site not responding. Last check: 2007-11-03)
		The filter is supposed to be fed directly with the sample impulses and generates the original analog signal.
		Applying a sinc filter of the correct frequency to a bandlimited signal won't change it at all, since it's already bandlimited.
		Since this paragraph actually deals with an extended topic which is related but not part of the article topic I am going to remove the paragraph.
	en.wikipedia.org /wiki/Talk:Nyquist-Shannon_sampling_theorem (5282 words)

	FIR Filters by Nuhertz Technologies
		Filter Solutions offers 1st, 2nd, and 3rd order compensations that maintain the FIR characteristic of the filter and approximate X/Sin(X) that are valid for frequencies up to half the sample rate.
		This is a sinc pattern for the 29 tap low pass filter depicted in the subsequent table.
		The purpose of the Matched Filter is to maximize the signal to noise ratio and to minimize the probability of undetected errors received from a signal.
	www.filter-solutions.com /FIR.html (1604 words)

	ECEn 444: Notes on Raised-Cosine Filters (Site not responding. Last check: 2007-11-03)
		This is desirable since it reduces the interference the modulated signal creates for uses in adjacent channel bands.
		In theory, the impulse response of the raised cosine filter or the square-root raised cosine filter is infinitely long.
		Since we will not be using a such a system, set this parameter to 0.
	www.ee.byu.edu /class/ee444/simulink/usdc/rcnotes.html (302 words)

	TechOnLine - Designing Digital Filters (Site not responding. Last check: 2007-11-03)
		Since you already have all of the past data values stored from the initial filter calculation, you simply run the filter using later values instead of prior values.
		When the filter has overshoot, it becomes impossible to determine whether the signal is being distorted by the system that generates it, or by the filter.
		The width of this transition band is the filter's roll-off, which is one of the important parameters of a frequency domain filter.
	www.techonline.com /community/tech_group/26649 (2410 words)

	Arecibo Radar Interface
		The 20 MHz filter was chosen because it is a substantial fraction of the transmitter bandwidth (26 MHz at -1 dB), and because there are cellular allocations in the 2390-2417 MHz band (but possibly not in Puerto Rico).
		This filtered 260 MHz signal is then down-converted to 20 (or 30) MHz by a Doppler-correcting high-side mixer with an LO at 280 (or 290) MHz, then analog low-pass filtered for sideband rejection.
		Because the half-band filters decimate the frequency (unlike the sinc filters), the output will have a messy frequency response, but an analog filter will be provided to smooth it (is some interpolation necessary anyway?).
	www.naic.edu /~nolan/radar/ri.html (2731 words)

	how to implement Sinc filter for sigma delta AD downsampling
		The filter is multi-stage and the first stage is a Sinc filter.
		The implementation of the Sinc filter as a cascade of integators and differentiators, the integators operate at high clock rate, the differentiators operate at low clock rate.
		Sinc filter can be inplemented without considering overflow, if you have reserved addition bit width for word length growth.
	www.edaboard.com /ftopic98285.html (605 words)

	TechOnline \| Designing Digital Filters
		Since you already have all of the past data values stored from the initial filter calculation, you simply run the filter using later values instead of prior values.
		When the filter has overshoot, it becomes impossible to determine whether the signal is being distorted by the system that generates it, or by the filter.
		The width of this transition band is the filter's roll-off, which is one of the important parameters of a frequency domain filter.
	www.dspdesignline.com /showArticle.jhtml?articleID=192200504 (2524 words)

	Ron Nicholson's Digital Signal Processing Page
		Using a windowed sinc is one method of designing a FIR filter, starting with an arbitrary rectangle in the frequency domain, and then creating an approximation of that rectangle's Fourier transform in the time domain by cutting a sinc's width using a finite width window.
		A sinc is then the Fourier transform of that frequency domain rectangle into the time domain (or the impulse response).
		The sinc is the Fourier transform of a rectangle.
	www.nicholson.com /rhn/dsp.html (1633 words)

	Reconstruction in practice
		One solution to the first problem is to sample the sinc filter with a certain rate and reconstruct it (as cheap as possible) to reconstruct the function.
		Since the sinc filter is the ideal reconstruction filter it fulfills both conditions, because it is one below some certain frequency and zero above (i.e., a box in frequency domain).
		This error is due to the use of a reconstruction filter different from the sinc filter.
	www.cg.tuwien.ac.at /~theussl/DA/node30.html (392 words)

	Semidigital FIR filter design
		Since the continuous time low-pass filter may not influence the characteristic at the audio-band, its cutoff frequency is set to 140 kHz.
		The coefficients of the filter are subject for mismatch, rounding and quantization to the incremental grid span of the process.
		In contrast to a digital filter, where the only important error is caused by truncation or rounding due to the finite word length, in the time discrete filter the mismatch of the coefficients will impair the frequency characteristic.
	www10.pcbcafe.com /book/phdThesis/Chapter-7.5.php (1885 words)

	TechOnLine - Collective Filter Evaluation of an FSD Filter-Based Resampling Algorithm (Site not responding. Last check: 2007-11-03)
		Since then, he has been with the Faculty of Electronics, Telecommunications and Informatics at the Technical University of Gdansk engaged in DSP algorithm research and development.
		As the zero-insertion causes spectrum replication, the interpolation filter with normalized cutoff frequency at 0.5/L is needed to remove replicas.
		The maximally flat filters are the best for narrow-band signals, and the truncated sinc filter has the smallest transition bandwidth but with generally poor stop-band attenuation.
	developonline.com /community/related_content/14917 (1394 words)

	Project 3: Antialiasing, Subsampling, Supersampling and the Frequency Domain
		Since we're modeling sampling as multiplication by a sequence of pulses, the effects of aliasing in the frequency domain are a sequence of convolutions of the image frequencies, displaced by an amount dependendent on the sampling rate: the higher the sampling rate is, the farther apart the pulses are in the frequency domain.
		Since it seems that an exponentially decreasing power spectrum is at least somewhat appropriate for real-life images, this could give optimal filters for a certain subsampling.
		On the frequency domain, this is equivalent to multiplying with a sinc filter of period 1/2.
	www.sci.utah.edu /~cscheid/spr05/imageprocessing/project3 (3361 words)

	Arecibo Radar Interface
		The 20 MHz filter was chosen because it is a substantial fraction of the transmitter bandwidth (26 MHz at -1 dB), and because there are cellular allocations in the 2390-2417 MHz band (but possibly not in Puerto Rico).
		This filtered 260 MHz signal is then down-converted to 20 MHz by a Doppler-correcting high-side mixer with an LO at 280 MHz, then analog low-pass filtered for sideband rejection.
		Because the half-band filters decimate the frequency (unlike the sinc filters), the output will have a messy frequency response, but an analog filter will be provided to smooth it (is some interpolation necessary anyway?).
	alumnus.caltech.edu /~nolan/radar/ri.html (2670 words)

	Windowed sinc filter sample program in Visual Basic - DSP
		The Inverse transform of the ideal low - pass response is the sinc function (sinx/x).
		The inverse fourier transform of the required frequency response is taken and used as kernel a normal filter.
		But the problem is that the sinc function is infinite in length.
	www.logix4u.net /winsinc.htm (355 words)

	[No title]
		The second picture shows a filter that is twice as wide as tall in the frequency domain, which would be twice as tall as wide in the space domain.
		For this filter the image is clearer in the horizontal direction because the image has more higher frequency waves in that direction.
		Since only detail is represented in this image, you only see the correct color of the image near high contrast areas.
	www.cs.unc.edu /~reb/classes/comp235/assignment5/solution.html (713 words)

	Filtering and Sampling assignment - comp238
		A window sinc filter differs from the Lanczos sinc in that it uses a hamming window in place of the lanczos window.
		The gaussian reconstruction filter seems to be avoiding the artifacts by blurring out several details near the horizon.
		Due to the artifacts near the horizon, I felt that the sinc filters didnt perform real well, whereas the halton sampler in conjunction with the mitchell filter performed relatively better.
	www.cs.unc.edu /~rohit/courses/comp238/1 (366 words)

	VTK: vtkWindowedSincPolyDataFilter Class Reference
		The transfer functions of the low-pass filters are approximated by Chebyshev polynomials.
		This decoupling of the filter into an iteratively applied polynomial is possible since the Chebyshev polynomials are orthogonal, i.e.
		For those interested, the filter is adjusted by searching for a value sigma such that the actual pass band is k_pb + sigma and such that the filter transfer function evaluates to unity at k_pb, i.e.
	noodle.med.yale.edu /vtk/classvtkWindowedSincPolyDataFilter.html (1221 words)

	Graphics: MIP Maps
		Filtering a signal means convoluting it with the filter.
		The result of filtering is a new signal that has the low-frequency component intact, but with the high-frequency component gone.
		The goal of low pass filtering is getting rid of high frequencies (or fine detail, in the case of pictures).
	www.relisoft.com /Science/Graphics/filter.html (991 words)

	3DELIGHT User's Manual: 3.3 Using the Texture Optimizer - tdlmake
		' filters (which are infinite in width) to achieve a softer cut at the filter's support boundaries.
		Filter's width is the diameter of the filter and not the radius.
		All internal filtering algorithms are executed in floating point to preserve as much accuracy as possible.
	www.3delight.com /ZDoc/3delight_12.html (1049 words)

	pamscale
		Since the filter functions are built into the program, the integrals of them could be too.
		So instead, there are filter functions that approximate sinc but are nonzero only within a manage- able range.
		For some filter functions, you can tell just by looking at the convolu- tion how they vary the resampling process from the perfect one based on sinc: The impulse filter assumes that the original continuous image is in fact a step function -- the very one we computed as the first step in the resampling.
	linuxcommand.org /man_pages/pamscale1.html (3322 words)

	Sinc filter -- Facts, Info, and Encyclopedia article (Site not responding. Last check: 2007-11-03)
		In (Click link for more info and facts about signal processing) signal processing, the sinc filter strips high-frequency data from a (Any communication that encodes a message) signal.
		One method of minimizing such defects is to (Device that removes something from whatever passes through it) filter the sounds and images, to remove obvious noises and scratches.
		If the signal is (Click link for more info and facts about convolved) convolved with the sinc filter then the original signal can be restored.
	www.absoluteastronomy.com /encyclopedia/s/si/sinc_filter.htm (487 words)

	Choice of Table Size
		It is desirable that the stored filter impulse response be sampled sufficiently densely so that interpolating linearly between samples does not introduce error greater than the quantization error.
		The maximum curvature is determined primarily by the bandwidth of the filter since, generalizing equations Eq.
		A lowpass-filter design will move the cut-off frequency slightly below that of the ideal lowpass filter in order to provide a ``transition band'' which allows the filter response to give sufficient rejection at the ideal cut-off frequency which is where aliasing begins.
	ccrma-www.stanford.edu /~jos/pasp/Choice_Table_Size.html (436 words)

	Buie - IDL - sincfltr.pro (Site not responding. Last check: 2007-11-03)
		For large values it is much faster to do the filtering in multiple steps (provided you sub-sample the output vector).
		The filter is a damped sinc function and requires 21*smofac points in the convolution kernel.
		Since the filter reduces the band-limit of the data, you can sub-sample the output array with no loss of information.
	www.lowell.edu /users/buie/idl/pro/sincfltr.html (412 words)

	Antialiasing
		Although we cannot use the ideal sinc filter to eliminate aliasing, we can obtain very good results using a Gaussian truncated at 2 pixels (i.e., a filter with a 2-pixel radius).
		Since this blending equation is non-commutative, artifacts may result unless the lines are drawn in back-to-front order (the same is true for transparent polygons).
		Since this cannot currently be done using the z-buffer in conjunction with alpha blending, an approximate sort can be performed in object-space (or equivalently, world-space or eye-space).
	people.csail.mit.edu /ericchan/articles/prefilter (2186 words)

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