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	notch filter at Filtronetics, Inc.
		The most common is LC notch filters, or lumped element, which is comprised of inductors and capacitors.
		Crystal filters with low insertion loss in the passband are achievable for stopband widths from 0.005% to 0.1% of the center frequency.
		Our notch filter have been utilized in systems that are in space, military, undersea, airborne, testing, and commercial applications.
	www.filtro.net /content/notch_filter.html (545 words)

	Two-pole notch filter - US Patent 6842086 (Site not responding. Last check: 2007-10-08)
		Tuned notch filters are used to remove the scrambling signal from the television channel signal to thereby allow reception of the television channel signal (i.e., positive trapping).
		Filters employed for this purpose are commonly known as notch filters.
		It is a further object of the present invention to provide a notch filter having two tunable poles, which may be quickly and economically constructed and precisely tuned to a desired notch center frequency, while stably maintaining tuning to that desired frequency regardless of environmental factors.
	www.patentstorm.us /patents/6842086.html (4773 words)

	Adaptive notch filter using acousto-optics and photorefraction - Patent 5050967
		The notch filter of claim 3, wherein said predetermined time delay is selected so that portions of said first and second light beams modulated by said narrowband components remain mutually coherent and portions of said first and second light beams modulated by said broadband components become mutually incoherent.
		The adaptive notch filter of claim 5, wherein said predetermined time delay is selected so that portions of said first and second diffracted light beams modulated by said narrowband component remain mutually coherent and portions of said first and second diffracted light beams modulated by said broadband components become mutually incoherent.
		The output of summing junction 60 is processed by a filter 62 to cancel the echo portions of the signal caused by the time delay T. The final output at terminal 64 of adaptive notch filter 10 is proportional to the original broadband RF signal with the narrowband noise n(t) effectively removed.
	www.freepatentsonline.com /5050967.html (2647 words)

	notch filters at Filtronetics, Inc.
		Other names for a notch filters are band elimination filter, band reject filter, band suppression filter, and notch filters.
		Our notch filters have been utilized in systems that are in space, military, undersea, airborne, testing, and commercial applications.
		Notch filters are available in Surface mount (SMD), Through-hole, and connectorized (BNC, TNC, SMA, or N filter) packages.
	www.filtro.net /content/notch_filters.html (545 words)

	LCD with notch filter - Patent 5737045
		Notch filter 57 is designed for the purpose of substantially eliminating either or both of peaks 37 and 39 shown in FIG.
		When notch filter 57 is designed to block red-green peak 39 (instead of or in addition to blue-green peak 37), the filter substantially blocks transmission at about 585-590 nm, preferably from about 570-595 nm, and may or may not be designed to not affect transmission outside of this range.
		Notch filter 57 is preferably disposed between the source and the color filters but may be located elsewhere in the stack or panel provided that the targeted spectrum is filtered out before the image reaches viewer 3.
	www.freepatentsonline.com /5737045.html (4015 words)

	Helical Filter
		I have been experimenting with a compact Helical Resonator Notch Filter since discovering by accident that when a transmission line was brought near to a high-Q resonator, a notch was introduced at the resonant frequency.
		It is important that the resonators be mechanically stable as the filter should have a stable notch frequency.
		I have not measured the temperature sensitivity of the filter.
	www.david-taylor.pwp.blueyonder.co.uk /wxsat/filters/HelicalNotch.htm (1021 words)

	ipedia.com: Electronic filter Article (Site not responding. Last check: 2007-10-08)
		Filters can also be implemented using a combination of passive components and amplifiers to create active filters.
		The filter's output becomes a signal by passing it through a digital to analog converter.
		Another method of filtering, at frequencies from 800 megahertz to about 5 gigahertz, is to use a synthetic single-crystal garnet sphere made of a chemical combination of titanium, iron and nitrogen.
	www.ipedia.com /electronic_filter.html (956 words)

	Series Notch Filter Help (Site not responding. Last check: 2007-10-08)
		A Series Notch Filter is simply a capacitor (C), inductor (L) and resistor (Rc) all in series, in parallel with the driver.
		Sometimes, a series notch filter is called a LCR filter, because of the L, C, and R components.
		Outside of these bandpass frequencies, the resistance of the series notch filter and the driver is simply the resistance of the driver.
	www.lalena.com /audio/calculator/seriesNotch/help.shtml (470 words)

	[No title]
		Building the digital filter The purpose of this section is to design a 60 Hz digital Notch filter and to compare the properties of the digital filter to that of a similar analog Notch filter.
		The filter was then run on an EKG sample of sampling rate of 400 s-1 and the effects of the digital filter on the output were recorded and compared using the Fast Fourier Transform (FFT) of the filtered and unfiltered signals.
		Performance of 60Hz digital notch filter on EKG signal The FFT signals in figure 6 show that there were other peaks at 100Hz and 180Hz, which could be responsible for the remaining noise in the filtered signal output.
	www.seas.upenn.edu /courses/belab/LabProjects/2004/be309f04r4.doc (3339 words)

	Notch Filter Descramblers
		Though Notch Filters are considered an old, archaic technology (and probably aren't used on any new systems), notch filters are still in use at many places around the country as the transition to modern gear hasn't been complete.
		The difference in the two types of notch filters is in the exact positioning of the poles - that is, the tuning of the frequency (or frequencies) that the filter attenuates.
		Details for building a filter for channel 23 is not included in the DF-222 assembly instructions, but if you extrapolate the capacitor and inductor values in the part selection table, you can easily choose parts that will work for channel 23.
	www.dewtronics.com /tutorials/descramblers/notchfilter/notch.html (1031 words)

	A Notch Filter (Site not responding. Last check: 2007-10-08)
		The circuit diagram of a notch filter and output stage appears in Fig.
		The notch filter is based on IC11 and IC12, which are used in a conventional state variable filter.
		The resistor R52 enables the Q of the filter to be varied.
	www.qsl.net /vu2upx/Projects/notch.htm (340 words)

	Filters (Site not responding. Last check: 2007-10-08)
		Filters are used internally by Apache to perform functions such as chunking and byte-range request...
		Active band pass filters are simply filters constructed by using operational amplifiers as active devices configured to simulate inductors or what are known...
		Heliopan filters are "dyed in the mass" and ground, polished and coated to the...
	www.theflowerinfo.com /filters.html (905 words)

	Audio Filters -- Theory and Practice
		One type of filter is the high-pass (or low-cut) shown schematically in Figure 1, along with the resultant frequency response.
		The low-pass filter, shown in Figure 2, is constructed by transposing the resistor and capacitor.
		Notch filters used for eliminating hum might need a Q as high as 100 if adjacent frequencies are to be left untouched.
	www.ethanwiner.com /filters.html (2678 words)

	Notch filter -- Facts, Info, and Encyclopedia article (Site not responding. Last check: 2007-10-08)
		Other names for the notch filter include 'T-notch filter', 'notched filter', 'band-elimination filter', and 'band-rejection filter'.
		Typically, the width of the stopband is less than 1 to 2 decades (that is, the highest frequency attenuated is less than 10 to 20 times the lowest frequency attenuated).
		In the (The sound elements of television) audio band, a notch filter uses high and low frequencies that may be only (The musical interval between adjacent keys on a keyboard instrument) semitones apart.
	www.absoluteastronomy.com /encyclopedia/n/no/notch_filter.htm (160 words)

	Switched-Capacitor IC Forms Notch Filter - Maxim/Dallas
		Universal filters (either SCF or continuous-time types) allow any combination of low-pass, high-pass, bandpass, or band-reject response, but they cost $3 to $10 each (1k pcs) and come in 14- to 16-pin DIPs or large surface-mount packages.
		To obtain a notch response, the input signal in Figure 1 is applied to OS as well as the input, so these two signals are summed together at the output.
		Applying a 47.5kHz clock frequency to the circuit of Figure 1 produces a 400Hz notch filter with (a) notch depth of 50dB and (b) Q of 1.7.
	www.maxim-ic.com /appnotes.cfm?appnote_number=431 (454 words)

	Radio-Electronics.Com :: RC Twin T Notch Filter
		This notch filter can be useful in rejecting unwanted signals that are on a particular frequency.
		In theory, at the notch frequency the level of attenuation provided by the twin T notch filter is infinite.
		The response of the notch circuit falls away slowly and affects a wide band of frequencies either side of the cut-off frequency.
	www.radio-electronics.com /info/circuits/rc_notch_filter/twin_t_notch_filter.php (407 words)

	Series Notch Filter - Speaker Impedance Correction at Fs (Resonant Frequency)
		A series notch filter can be used to control the impedance peak present at the resonant frequency (Fs) of a speaker.
		The upward curve at higher frequencies is caused by the voice-coil inductance and is corrected using a Zobel or parallel notch filter.
		The crossover filter goes in the circuit before the notch filter (closer to the source).
	www.carstereo.com /help/Articles.cfm?id=23 (402 words)

	NOTCH FILTER AND POLE ON PEDESTAL
		In the all-pass filter the pole and zero have an equal (logarithmic) relative distance from the unit circle.
		As the zero is moved farther away from the circle, the notch becomes less deep until finally the zero is farther from the circle than the pole and the notch has become a hump.
		Design a single-pole, single-zero notch filter to reject 59 to 61 Hz on data which are sampled at 500 points per second.
	sepwww.stanford.edu /sep/prof/toc_html/toc_html/fgdp/c2/paper_html/node8.html (604 words)

	Notch Filter (Site not responding. Last check: 2007-10-08)
		A variable notch filter with both high and low pass filters.
		At first glance this circuit looks fairly complex, but when broken down,can be divided into high pass and low pass filter sections followed by a summing amplifier with a gain of around 20 times.
		The controls may also be adjusted for use as a band stop (notch) filter or band pass filter.
	www.mitedu.freeserve.co.uk /Circuits/Audio/notch.htm (63 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)

	Rainbow TV Notch Filter Kit DF-222
		If all poles of the filter are set to the same resonant frequency the overall depth will be 45 to 55 dB and the notch width will be approximately 0.5 MHz.
		One filter would be adjusted to remove the video information and you would use the other filter to remove the audio and color information.
		Typically you will adjust 3 poles of a 4 pole filter or 2 poles of a 3 pole filter for a frequency about 100 KHz above the video frequency of the desired channel and the remaining pole would be adjusted to a frequency approximately 400 KHz higher than the video frequency.
	www.dewtronics.com /tutorials/descramblers/notchfilter/df222.html (645 words)

	Coronagraphic Notch Filter for Raman Spectroscopy
		Corona-graphic notch filters could offer alternatives to both (1) the large and expensive double or triple monochromators in older Raman spectrometers and (2) holographic notch filters, which are less expensive but are subject to environmental degradation as well as to limitations of geometry and spectral range.
		A notch filter can be used to suppress the pump-beam spectral peak while passing the nearby faint Raman spectral lines.
		One characteristic of a classical coronagraph essential to the proposed notch filter is that within the narrow typical Raman spectral range associated with a given pump laser line, the size of the PSF changes little with wavelength.
	www.nasatech.com /Briefs/Aug04/NPO30504.html (756 words)

	Notch Filter Is DC-Accurate - Maxim/Dallas
		Most active filters exhibit noise, distortion, gain error, and DC offset, but a filter topology that separates the DC and AC paths can eliminate the last two of these unwanted behaviors completely (Figure 1a).
		The result is an active circuit that emulates the passive filter of Figure 1b.
		The filter, consisting of the source/load connection shunted by the series network of C1 and the synthetic inductor, was tested on a network analyzer that includes the 50
	www.maxim-ic.com /appnotes.cfm?an_pk=2115 (590 words)

	Electronic Filters Circuit - Active Filters - Notch Filter
		Build an adjustable high frequency notch filter: 02/06/03 EDN-Design Ideas / Although you can obtain universal, resistor-programmable switched-capacitor filters that are configurable as notch filters, most cannot operate at bandwidths higher than 100 kHz.
		RC Notch Filter Twin T: The twin T notch filter can be used block an unwanted frequency or if placed around an op-amp as a bandpass filter.
		The notch frequency occurs where the capacitive reactance equals the resistance Xc=R and if the values are close, the attenuation can be very high and the notch frequency virtually eliminated.
	www.hobbyprojects.com /N/Active.html (259 words)

	Notch Filter (Site not responding. Last check: 2007-10-08)
		An audio notch filter can be created based on the following example: to remove a signal of 1Khz, you delay the signal by 1/2 cycle and add back to the original.
		Note that unfiltered signals far from the notch are doubled, essentially added to itself, while the notch is down to zero.
		It turns out that the above notch filter is actually a comb filter with 16 notches between 0 and the sample rate.
	webpages.charter.net /cswiger/notch_filter.html (328 words)

	EDN Access -- 03.02.95 Notch filter is dc accurate (Site not responding. Last check: 2007-10-08)
		However, a filter topology that separates the dc and ac paths can eliminate the last two of these unwanted behaviors (Fig 1a).
		The result is an active circuit that emulates the passive filter of Fig 1b.
		The overall filter determines the peak voltage across the synthesized inductor at pin 13 of IC Therefore, you adjust the peak value at IC 's pin 13 to match that of IC by varying the gms.
	www.edn.com /archives/1995/030295/05di1.htm (428 words)

	Digital AC Notch Filter
		The Digital AC Notch (DAN) Filter is used for removing AC noise “hum” from an audio signal.
		The digital filter algorithm is the key to the operation of this device.
		The filter algorithm is On+1 = (Vn – On) /128 + On, where Vn is the input signal, On is the past answer, On+1 is the current answer.
	image.gsfc.nasa.gov /poetry/inspire/DAN/index.html (1731 words)

	Parallel Notch Filter Circuit for Speaker Design
		C is the capacitor value required for your filter.
		L is the required inductor value for your filter.
		R is the desired resistor value for this filter.
	www.carstereo.com /help2/Articles.cfm?id=19 (271 words)

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