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Topic: Cutoff frequency

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Frequency

Filter design

Cutoff wavelength

Butterworth filter

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	Frequency - Wikipedia, the free encyclopedia
		Frequency is the measurement of the number of times that a repeated event occurs per unit time.
		Measuring the frequency of sound, electromagnetic waves (such as radio or light), electrical signals, or other waves, the frequency in hertz is the number of cycles of the repetitive waveform per second.
		The frequency of the standard pitch A above middle C is usually defined as 440 Hz, that is, 440 cycles per second (Listen [▶]) and known as concert pitch, to which an orchestra tunes.
	en.wikipedia.org /wiki/Frequency (485 words)

	Frequency - Encyclopedia.WorldSearch (Site not responding. Last check: 2007-11-07)
		The frequency of the standard pitch tone A above middle C is nowadays set at that is 440 cycles per second (or slightly higher) and known as concert pitch, after which an orchestra is tuned.
		In Europe the frequency of the alternating current is 50 Hz (close to the tone G), with 230 V of rated voltage.
		In North America the frequency of the alternating current is 60 Hz (close to the tone B flat), with 117 V of rated voltage.
	encyclopedia.worldsearch.com /frequency.htm (506 words)

	Cutoff frequency - Wikipedia, the free encyclopedia
		The frequency either above which or below which the power output of a circuit, such as a line, amplifier, or filter, is reduced to 1/2 of the passband power; the half-power point.
		A bandpass circuit has two cutoff frequencies and their geometric mean is the center frequency.
		The term cutoff frequency can also mean the frequency below which a radio wave fails to penetrate a layer of the ionosphere at the incidence angle required for transmission between two specified points by reflection from the layer.
	en.wikipedia.org /wiki/Cutoff_frequency (197 words)

	Hyperprism Filter Processes (Site not responding. Last check: 2007-11-07)
		In an ideally sharp filter, the cutoff frequency is a kind of brick wall: anything outside it is maximally attenuated, dividing the frequency response neatly into a pass band and a stop band.
		In actual filters, the slope of the filter leading up to the cutoff frequency is not linear (there is a slight ripple in the frequency response), and the area between the pass band and the stop band is called the transition band.
		The distance between the higher and lower cutoff frequencies in a band pass filter is called the bandwidth of the filter.
	arboretum.com /support/manuals/manual_hmmp/Files/hppc_proc_filters.html (1810 words)

	Frequency Response Notes (Site not responding. Last check: 2007-11-07)
		is the frequency corresponding to the sum of all of the pole frequencies.
		In the case of the lower cutoff frequency, this means that at the cutoff frequency one of the external capacitors is behaving like a capacitor but the operating frequency is sufficiently high that all of the other external capacitors are behaving like short circuits.
		Similarly, in the case of the upper cutoff frequency, this means that at the cutoff frequency one of the internal capacitors is behaving like a capacitor but the operating frequency is sufficiently low that all of the other capacitors are behaving like open circuits.
	web.uccs.edu /wbahn/ECE3220/frequencyresponse.htm (5463 words)

	Dispersion - Microwave Encyclopedia - MicroWaves101.com
		Frequency dispersion refers to the property of microwave transmission lines that have different group velocity versus frequency.
		For wideband signals, you may have to worry about the effects of dispersion distorting your signal, for example, when you are trying to put a one nanosecond pulse through a waveguide near the lower cutoff frequency, you could be in a heap of trouble.
		Note that the stripline provides a constant group delay of 1.54 nanoseconds across frequency, which is very close to the one nanosecond per foot rule, multiplied by the square-root of the dielectric constant.
	www.microwaves101.com /encyclopedia/dispersion.cfm (408 words)

	Low pass filter circuit device and method having selectable cutoff frequency - Patent 5296822
		Similarly, the low pass cutoff frequencies of clock driven filter stage succeeding the intermediate stage having the selectable cutoff frequency are adjusted to eliminate staircasing distortion in the output signal.
		Generally, these higher frequencies are eliminated utilizing a nonswitching operational-amplifier-based low pass filter at the input of the clock driven filter having a fixed cutoff frequency slightly greater than the highest predicted cutoff frequency at which the clock driven filter will be operated.
		The overall selectable low pass cutoff frequency of the device is eventually determined at an intermediate stage 35, which may be the middle stage where N is odd.
	www.freepatentsonline.com /5296822.html (2597 words)

	- - - IAEKM - - -
		If the cutoff is low, the sound will be "woofy" or "honky." With a higher cutoff, the sound will be more nasal, and with a high cutoff there will be a pronounced sizzle or a laser-like cutting edge.
		The cutoff frequency of the lowpass filter is set to, let's say, 600 Hz, so when you play the low C all of the overtones are below the cutoff frequency of the filter, and pass through the filter without being attenuated.
		If the cutoff is at 600 Hz when you play low C, it will be at 4,800 Hz when you play Middle C (because each octave doubles the frequency), and all of the overtones of our example wave will still be heard.
	www.iaekm.org /article39.htm (2061 words)

	Seventh Quarterly Progress Report
		Scores for the cutoff frequency of 12.5 Hz, for instance, appear to be lower than the scores for higher cutoff frequencies, at least for the male talker.
		Similarly, the maximum score for consonants in quiet is at the rate of 6900 pulses/s/channel and the cutoff frequency of 500 Hz, and the maximum score for consonants presented in noise at the +10 dB S/N is at that rate and the nearby cutoff frequency of 250 Hz.
		A further increase in cutoff frequency, from 1000 to 2000 Hz, produces a significant drop in averages for the +5 dB S/N. In particular, the average at the 125 Hz cutoff is significantly higher than the average at 2000 Hz.
	www.rti.org /reports/capr/qpr7a/qpr7a.html (9232 words)

	cutoff frequency at Filtronetics, Inc.
		The 3dB cutoff frequency of a lowpass filter is defined as the highest frequency where 3dB or less of attenuation occurs.
		Conversely, the 3dB cutoff frequency of a highpass filter is defined as the lowest frequency where 3dB or less of attenuation occurs.
		The term 3dB cutoff frequency is used in conjunction with lowpass and high pass filters when defining the passband of the filter.
	www.filtro.net /cutoff_frequency.html (640 words)

	Synthesizers.com --- Q107 State Variable Filter
		Both the cutoff frequency and the resonance (Q) of the filter can be controlled manually and/or controlled by another signal such as an envelope generator, oscillator, keyboard, etc. Control signals can be attenuated and inverted.
		The frequency at which attenuation starts (or close enough) is called the cutoff frequency.
		Resonance is the emphasis of frequencies near the cutoff frequency and has a great effect on the sound.
	www.synthesizers.com /q107.html (878 words)

	Re: cutoff frequency (Site not responding. Last check: 2007-11-07)
		For example, a 5 cm wide guide has lowest cutoff frequency for lambda = 10 cm or frequency = 3 GHz.
		A 50 cm guide has cutoff 300 MHz and a 5 metre guide has cutoff 30 MHz (eg a tunnel...like into London Heathrow airport).
		If the guide is filled with dielectric of relative permittivity epsilon, then the velocity to be used is c/sqrt(epsilon) so if epsilon = 4 then the guide dimensions are halved for the same cutoff frequency, or the cutoff frequency is halved for the same guide dimensions.
	www.antennex.com /storage/atheory/_atheory/0000007a.htm (140 words)

	Re: cutoff frequency (Site not responding. Last check: 2007-11-07)
		In electronic filter theory, the cutoff frequency of a filter is generally defined as the frquency at which the filter's response is down by 3dB.
		An antenna, using this defination, would have at least TWO "cutoff frequencies;" a low frequency and a high frequency.
		I said "at least" TWO frequencies because (unlike most filters) a resonant antenna can often be made to operate at frequencies other than the base frequency.
	www.antennex.com /storage/atheory/_atheory/00000074.htm (175 words)

	Olympus Microscopy Resource Center: Anatomy of the Microscope - Cutoff Frequency and Airy Disk Size - Interactive Java ...
		As the slider is moved to the right, cutoff frequency values decrease, producing a corresponding increase in Airy disk size and the intensity distribution of the point spread function.
		According to Abbe's theory of image formation, the objective rear aperture determines the highest spatial frequency passed by a microscope, which represents the cutoff frequency of the modulation transfer function.
		This relationship expresses, in terms of spatial frequency, the fact that resolution in the microscope increases with larger numerical apertures and shorter illumination wavelengths.
	www.olympusmicro.com /primer/java/mtf/airydisksize (730 words)

	report.html (Site not responding. Last check: 2007-11-07)
		Cutoff frequency : 5 Cutoff frequency : 15 Cutoff frequency : 30
		Cutoff frequency : 80 Cutoff frequency : 230
		Cutoff frequency : 15 Cutoff frequency : 30 Cutoff frequency : 80
	www.cse.iitd.ernet.in /~csd01415/dipass1.html (158 words)

	highpass (Site not responding. Last check: 2007-11-07)
		The cutoff frequency is also called the 0.707 frequency, the -3dB frequency or the corner frequency.
		The frequencies bellow the cutoff frequency are said to be in the stopband.
		The frequencies above the cutoff frequency are said to be in the passband.
	www.ee.surrey.ac.uk /Projects/CAL/op-amps/comparators/highpass.htm (126 words)

	Question (Site not responding. Last check: 2007-11-07)
		The picture shows an ECG with high frequency noise caused by, e.g., movement of the patient during the recording.
		A highpass filter with a cutoff frequency of ca.
		A bandstop filter with a lower cutoff frequency of ca.
	www.mihandbook.stanford.edu /qanda/us/toc_25/qst60usa1.htm (147 words)

	RIDGED CAVITY ANALYSIS
		The eigenvalue is actually the resonant frequency of the cavity, which, as we have demonstrated, is related to the cutoff wavelength and hence the cutoff frequency of the mn
		Fortunately we are interested in the cutoff frequency of the TE mode which is related to the resonant frequency of the TE cavity mode.
		The cutoff frequency of a ridged waveguide is a parameter, which in itself is dependent only upon the cross sectional dimensions of the guide.
	www.ecs.umass.edu /mie/labs/mda/fea/fealib/moser/anlysis3.htm (3080 words)

	[No title] (Site not responding. Last check: 2007-11-07)
		These frequencies correspond to the input fundamental frequency f and the next two harmonics of this frequency at 3f and 5f.
		The butterworth low-pass filter produces a relatively constant average amplitude for frequencies below the cutoff frequency and a gradually downward-sloping amplitude trend beyond the cutoff frequency.
		Also, there is only one frequency peak because the sine wave has only one fundamental frequency, whereas the square wave expansion has many terms producing many harmonics (with decreasing intensity).
	www.stanford.edu /~pdlytal/ME220/Paul7.doc (717 words)

	Filter Design Issues (Communications Toolbox)
		In many situations, a suitable cutoff frequency is half the carrier frequency.
		Because the carrier frequency must be higher than the bandwidth of the message signal, a cutoff frequency chosen in this way limits the bandwidth of the message signal.
		If the cutoff frequency is too low, then it might narrow the bandwidth of the message signal.
	www.weizmann.ac.il /matlab/toolbox/comm/tutor27.html (429 words)

	cheby1 (Signal Processing Toolbox) (Site not responding. Last check: 2007-11-07)
		Cutoff frequency is the frequency at which the magnitude response of the filter is equal to
		Cutoff frequency is the frequency at which the magnitude response of the filter is
		It transforms the lowpass filter into a bandpass, highpass, or bandstop filter with desired cutoff frequencies, using a state-space transformation.
	web.media.mit.edu /~bill/workspace/matlab/toolbox/signal/cheby1.html (422 words)

	lowpass (Site not responding. Last check: 2007-11-07)
		But as the frequency approaches and goes above that cutoff frequency, the output voltage is attenuated.
		The frequencies bellow the cutoff frequency are said to be in the passband.
		The frequencies above the cutoff frequency are said to be in the stopband.
	www.ee.surrey.ac.uk /Projects/CAL/op-amps/comparators/lowpass.htm (127 words)

	Filter Design Issues (Communications Blockset)
		Since the carrier frequency must be higher than the bandwidth of the message signal, a cutoff frequency chosen in this way limits the bandwidth of the message signal.
		If the cutoff frequency is too high, then the carrier frequency may not be filtered out.
		The lower cutoff frequency narrows the bandwidth of the demodulated signal.
	www.socsci.umn.edu /ssrf/doc/matlab/toolbox/commblks/tutor211.html (594 words)

	Optimal cutoff frequency for data smoothing (Site not responding. Last check: 2007-11-07)
		I have been smoothing the data using a Butterworth 4th Order digital filter with cutoff frequencies ranging from 1 to 60Hz and subsequently calculating the residual as the mean square difference between the filtered and raw data.
		Having plotted the residual against cutoff frequency I have been attempting to determine the optimal cutoff frequency by projecting the linear part of the resulting curve to the vertical axis and then back to the curve to determine the cutoff.
		The calculated optimal cutoff frequency is affected to a great extent by what range I define as the linear part of the curve.
	isb.ri.ccf.org /biomch-l/archives/biomch-l-1994-11/00142.html (236 words)

	Image Enhancement: Frequency-Domain Methods
		An ideal lowpass filter cuts off all frequencies greater than the cutoff frequency and passes perfectly all frequencies less than the cutoff frequency.
		The more lower the cutoff frequency, the more high frequencies are removed and the more smoothing is done.
		Notice that all we've done is to invert the ratio of the frequency to the cutoff frequency.
	rivit.cs.byu.edu /morse/550-F95/node18.html (748 words)

	Lecture Notes (Site not responding. Last check: 2007-11-07)
		It be should evident, that the resultant amplitude increases as the imposed frequency approaches the natural frequency and decreases as it moves away from the natural frequency.
		A band-reject filter pass energy at frequencies outside of some designated lower and higher cutoff frequencies (5d.).
		Notice that for all of these, the upper cutoff is some fraction (1/1, 1/2, 1/3, 1/10) higher than the lower cutoff frequency.
	courses.washington.edu /natsound/11_27.htm (954 words)

	BCIT ~ Mathematics - Examples (Site not responding. Last check: 2007-11-07)
		The voltage gain of a passive or active filter, as a function of frequency, is non-linear.
		A logarithmic scale is used to plot the frequency along the horizontal axis.
		For low frequencies, the gain of the circuit is equal to 1.
	www.math.bcit.ca /examples/biomed/logs_exponentials (270 words)

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