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Topic: Highpass filter

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	Analog Filter Design Demystified - Maxim/Dallas
		To ensure conformance with the generic filter described by equation 4, and to ensure that the last term equals unity, the first two quadratics have been multiplied by a constant.
		Equation 9 is the transfer function of the highpass filter block.
		Once the highpass pole locations are obtained, we ensure the correct frequency response by interposing the capacitors and resistors.
	www.maxim-ic.com /appnotes.cfm/appnote_number/1795 (2272 words)

	iirlp2lp (Filter Design Toolbox)
		This example transforms an IIR filter from lowpass to high pass by moving the magnitude response at one frequency in the source filter to a new location in the transformed filter.
		Moving the edge of the passband from 0.0175 to 0.2 results in a new lowpass filter whose peak response inband is the same as the original filter: same ripple, same absolute magnitude.
		Notice that the rolloff is slightly less steep and the stopband profiles are the same for both filters; the new filter stopband is a "stretched" version of the original, as is the passband of the new filter.
	www.cs.berkeley.edu /titan/sww/software/matlab/toolbox/filterdesign/iirlp2lp.html (481 words)

	Filter Design (Signal Processing Toolbox) (Site not responding. Last check: 2007-10-12)
		The filters are optimal in the sense that they minimize the maximum error between the desired frequency response and the actual frequency response; they are sometimes called minimax filters.
		filter's maximum error over the passband and stopband is smaller and, in fact, it is the smallest possible for this band edge configuration and filter length.
		Another possibility is a filter that has as a transition region the line connecting the passband with the stopband; this can help control "runaway" magnitude response in wide transition regions.
	caligari.dartmouth.edu /doc/matlab6.1/toolbox/signal/filterd9.html (985 words)

	Dyadic Analysis Filter Bank (DSP Blockset)
		At the transmitting end, the output of the dyadic analysis filter bank is fed to a lossy compression scheme, which typically assigns the number of bits for each filter bank output in proportion to the relative energy in that frequency band.
		The filter coefficients of the complementary analysis and synthesis stages are designed to cancel aliasing introduced by the filtering and resampling.
		The highpass filter should be a half-band filter that passes the frequency band stopped by the filter specified in the Lowpass FIR filter coefficients parameter.
	www.weizmann.ac.il /matlab/toolbox/dspblks/dyadicanalysisfilterbank.html (1960 words)

	Active Filters
		The two outputs from the LR2 crossover filter are 180 degrees out of phase at all frequencies, which requires to use one of the drivers with reversed polarity, so that the two acoustic outputs add in phase.
		The acoustic frequency and polar response is controlled by the electrical filters and the response of the mounted drivers.
		The steep filter slopes make the combined acoustic response less sensitive to magnitude errors in the driver responses, but phase shift errors usually have to be corrected with an additional allpass network.
	www.linkwitzlab.com /filters.htm (2352 words)

	Digital Filters - Frequency Filters
		All frequency filters can also be implemented in the spatial domain and, if there exists a simple kernel for the desired filter effect, it is computationally less expensive to perform the filtering in the spatial domain.
		We obtain the filter function of a bandpass by multiplying the filter functions of a lowpass and of a highpass in the frequency domain, where the cut-off frequency of the lowpass is higher than that of the highpass.
		To perform the frequency filtering we transform both the image of the house and the mask into the Fourier domain where we multiply the two images with the effect that the frequencies occurring in the mask remain in the output while the others are set to zero.
	homepages.inf.ed.ac.uk /rbf/HIPR2/freqfilt.htm (2854 words)

	highpass filter at Filtronetics, Inc.
		The highpass filter prevents the transmission of frequencies below a determined cutoff point and appears electrically transparent to frequencies above this point.
		Microwave highpass filters are typically in the range of 500 MHz to 20 GHz.
		It is important to note that in practice, a highpass filter’s upper pass band does not extend to infinity due to stray capacitance, inductive effects, and multimode phenomena.
	www.filtro.net /highpass_filter.html (600 words)

	Lowpass & Highpass Filters
		The 6211LP/HP series of lowpass and highpass filter networks consist of channel deletion filters and a custom-designed lowpass or highpass filter.
		This combination results in a "brickwall" filter which eliminates a block of channels while preserving the adjacent channel and beyond.
		3378 highpass filters pass frequencies above the cut-off frequency, and suppress lower frequencies.
	www.microwavefilter.com /lowhighpass.htm (195 words)

	[No title]
		This part of the program allows you to enter some basic information about your filter requirements- regarding the type of filter (lowpass, bandpass, highpass, notch) as well as your specifications describing which frequencies are to be passed by the filter and which must be filtered out (and to what degree).
		The filter steepness at these transition frequencies is usually very important, because it determines how fast attenuation can be achieved just outside of the passband- how close we can get to the ideal "brick wall" filter with infinite attenuation at frequencies outside the passband.
		Each filter "box" on the screen represents one second-order filter section (each defined by one Fo/Q combination); the sections are cascaded (connected in series) to yield the overall desired response of your filter design.
	www.chem.duke.edu /~boris/datasheets/MAX274/TMP/FILTER.HLP (4834 words)

	fir1 (Signal Processing Toolbox)
		By default, the filter is scaled so that the center of the first passband has magnitude exactly 1 after windowing.
		For highpass and bandstop filters, N must be even.
		Filter data with a recursive (IIR) or nonrecursive (FIR) filter.
	www.tau.ac.il /cc/pages/docs/matlab/help/toolbox/signal/fir1.html (339 words)

	High Pass Filter
		If there is a preceding upgrade message, or this paragraph has huge text (much bigger than the other paragraphs), or this paragraph has a red background, or this paragraph has a yellow dashed or solid border, or any combination thereof (including all), then your browser has failed.
		A filter with a transmission band starting at a lower cutoff frequency and extending to (theoretically) infinite frequency.
		This is accomplished by linking to a "filter" style sheet which uses a parsing bug in older browsers to trick them into failing to recognize the imported style sheet contained therein.
	tantek.com /CSS/Examples/highpass.html (575 words)

	Filter Theoretical (Site not responding. Last check: 2007-10-12)
		The passive low-pass filter is discussed here as high-pass filters can be obtained by performing low-pass to high-pass transformation, which will be explained in the later part section.
		Understanding the response characteristic of the filters is required as it enables one to decide on the design (choosing the filter orders) that will meet the specification (attenuation band) requirements and optimize the filter performances.
		Filter is to pass signals having a certain frequency range and to stop signals having a different frequency range.
	www.eng.newcastle.edu.au /~c3004525/filter_theory.htm (284 words)

	Highpass & Notch Filters & Band Reject Filters
		The second table shows various filters many of which may also be customized according to your specifications.
		50 KHz highpass, >55 dB at 25 KHz
		250 KHz highpass, >65 dB at 25 KHz
	www.krfilters.com /highpass.htm (78 words)

	All-Pole IIR Filters
		Basically the filter function (also called the transfer function) is a ratio with a constant in the numerator and a polynomial in the denominator.
		We'd find that the filter coefficients may have magnitudes different by several orders (say, one coefficient might be 0.013 and another might be 128.2), which will result in instability due to the finite precision of the computer.
		After all this, the 4-pole filter is then realized by feeding the input data into the first stage, and feeding that output into the second stage.
	unicorn.us.com /alex/buttercrit.html (1777 words)

	highpass
		The filter works by subtracting the result of the lowpass operator from the original image.
		The cutoff frequency is determined by the size of the filter kernel.
		An odd integer between 1 and 2Overscan+1 specifying the width of the filter* kernel which determines the horizontal cutoff frequency.
	www.imagewarp.com /reference/_highpass.htm (240 words)

	VBF 44 Versatile 4 channel Laboratory Electronic Filter (Site not responding. Last check: 2007-10-12)
		The VBF 44 is our top of the range 4 channel laboratory filter, with versatile channel tracking and grouping modes, gain, and 5 built in filter responses.
		Each filter channel can be used independently to produce a 4 channel programmable filter/amplifier, or in pairs to produce 2 channels of bandpass, bandstop and other composite filters of many kinds.
		The filter can also be bypassed and the unit used as a programmable amplifier.
	www.kemo.com /kemohtml/vbf44.html (542 words)

	EDN Access--04.10.97 Notch filter uses only lowpass filters
		This scheme ensures that the frequency responses of the highpass and lowpass filters are mirror-symmetric.
		When the phase of the lowpass filter is not zero, you must compensate for the phase shift that this filter introduces into the datapath.
		The resulting notch filter has infinite attenuation at the center frequency, and you can meet all other filter specifications, such as ripple in the passband and bandwidth by designing the lowpass filter accordingly.
	www.edn.com /archives/1997/041097/08di_03.htm (440 words)

	[No title]
		By filter design we can create filters that pass signals with frequency components in some bands, and attenuates signals with content in other frequency bands.
		It is cumstomary to classify filters according to their frequency domain charachteristics.
		One of them is in recording systems, where the notch filter serve to remove the power-line frequency 50 Hz and its harmonics(100 Hz, 150 Hz,...).
	cnx.org /content/m11868/1.3/source (194 words)

	[No title]
		All filters share the same cutoff frequency, and this cutoff frequency is preserved when cascading multiple filters of the same type.
		The recognized filter types are: "butter_lowpass" = Butterworth lowpass "butter_highpass" = Butterworth highpass "critical_lowpass" = Critically-damped lowpass "critical_highpass" = Critically-damped highpass "bessel_lowpass" = Bessel lowpass "bessel_highpass" = Bessel highpass passes: The passes parameter sets the number of filters to cascade to get the final result.
		IIR filters like these are extremely fast to calculate, so cascading multiple filters shouldn't adversely affect execution time.
	unicorn.us.com /trading/src/_buttercrit.txt (460 words)

	Priism Help: 3D Butterworth Filter (Site not responding. Last check: 2007-10-12)
		That is the filter lets low frequency components pass and block high frequency components.
		Since the FT expansion assumes that the image is periodic we pad the image with nxpad, nypad, and nzpad pixels, in such a way that it becomes periodic in x, y, and z.
		If the entire image is filtered, the default for nxpad, nypad, and nzpad is the smallest value that brings the size of the image to the next power of two.
	www.msg.ucsf.edu /IVE/IVE3.3_HTML/ButterFilter3D.html (442 words)

	Inline High Pass Filter
		A high pass filter which is used inline, rather than in an external file.
		This is the same mechanism which is used in the high pass filter to selectively @import a style sheet only into CSS1 parsing compliant browsers.
		Just as with the high pass filter, only you can decide when you are comfortable letting non-compliant browsers eat unstyled markup.
	tantek.com /CSS/Examples/inlinehpf.html (586 words)

	Spatial Filters - Unsharp Filter
		It can be implemented using an appropriately defined lowpass filter to produce the smoothed version of an image, which is then pixel subtracted from the original image in order to produce a description of image edges, i.e.
		Adaptive filtering using these kernels can be performed by filtering the image with each kernel, in turn, and then summing those outputs that exceed a threshold.
		This use of a threshold makes the filter adaptive in the sense that it overcomes the directionality of any single kernel by combining the results of filtering with a selection of kernels --- each of which is tuned to an edge direction inherent in the image.
	homepages.inf.ed.ac.uk /rbf/HIPR2/unsharp.htm (1116 words)

	2-03tec.htm
		The filter is synthesized with a filter synthesis program [1], by extracting elements from a network impedance or admittance function.
		Four transmission zeros are located at the stopband and one zero is placed at DC to make an elliptic highpass filter.
		However, the highpsss filter response is maintained from low frequencies up to 4 times cut-off frequency with the stepped impedance lines.
	www.rsmicro.com /2-03tec.htm (467 words)

	Digital Filters - Frequency Filters (Site not responding. Last check: 2007-10-12)
		All frequency filters can also be implemented in the spatial domain and, if there exists a simple mask for the desired filter effect, it is computationally less expensive to perform the filtering in the real domain.
		A highpass filter, on the other hand, yields edge enhancement or edge detection in the real domain, because edges contain many high frequencies.
		The drawback of this filter function is a ringing effect which occurs along the edges of the filtered real domain image.
	www.cee.hw.ac.uk /hipr/html/freqfilt.html (2880 words)

	RF FILTER at Filtronetics, Inc.
		A RF filter or radio frequency filter passes certain bands of frequency while rejecting others.
		A bandpass filter can be thought of as a highpass plus a lowpass with the cut-off frequency of the highpass filter less than the lowpass filter.
		Finally, a bandstop filter (or band reject filter) is the compliment of a bandpass.
	www.filtro.net /rf_filter.html (339 words)

	CSE/EE 485: Project 3 (Site not responding. Last check: 2007-10-12)
		The tasks are completed in the order, first beginning with a fourier transform, then a lowpass and highpass filter design, and then finally ending with a two dimenional filter design based on three algorithms: fsamp2, fwind1, and fwind2.
		In this project, we were able to observe the effects of bandpass, lowpass, and highpass filters performed in the frequency domain.
		While, it's difficult for us to say at this time when sample filtering should be used and when window filtering should be used to be most effective, it is clear that they all have a definitive purpose that should be thought through before choosing the best one.
	www.cse.psu.edu /~mchenry/proj3.html (1281 words)

	Passive Crossovers: Lowpass, Highpass And Bandpass
		A filter is called lowpass when it lets pass unchanged the inferior portion of a signal, rejecting the superior one — the terms inferior and superior are intended in the domain of frequency.
		A filter is called highpass when it lets pass unchanged the superior portion of a signal, rejecting the inferior one.
		A filter is called bandpass when it lets pass unchanged the middle portion of a signal, rejecting the contiguous ones.
	www.passivecrossovers.com /section05.htm (576 words)

	fir1
		Design a 34th order FIR highpass filter with a cutoff frequency of 0.48, using a Chebyshev window with 30 dB of ripple:
		Constrained least square FIR filter design for multiband filters.
		Constrained least square filter design for lowpass and highpass linear phase FIR filters.
	grove.ufl.edu /matlab_help/toolbox/signal/fir1.html (279 words)

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