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Topic: Phase difference

	Encyclopedia: Phase (waves)
		The phase may be measured as a time, distance, a fraction of the wavelength, or as an angle.
		The phase difference of the waves is thus zero, or, the waves are said to be in phase.
		In this case, the two waves are said to be out of phase or in antiphase, or the phase difference of the two waves is π radians, or half the wavelength (λ/2).
	www.nationmaster.com /encyclopedia/phase-(waves) (626 words)

	Phase-locked loop - Wikipedia, the free encyclopedia
		This generates a low-frequency signal whose amplitude is related to the phase difference, or phase error, between the oscillator and the reference, and an unwanted high-frequency signal that is filtered out.
		Phase noise is another type of jitter observed in PLLs, and is mostly caused by the amplifier elements used in the circuit.
		Another desirable property of all PLLs is that the phase and frequency of the generated clock be unaffected by rapid changes in the voltages of the power and ground supply lines, as well as the voltage of the substrate on which the PLL circuits are fabricated.
	en.wikipedia.org /wiki/Phase-locked_loop (2786 words)

	Nikon MicroscopyU: Apodized Phase Contrast (Site not responding. Last check: 2007-09-18)
		Differences in light absorption are often negligible between the various intracellular components and plasma membranes in living cells, rendering them barely visible when observed through the microscope utilizing the classical technique of brightfield illumination.
		For specimens that have a spherical geometry, the phase difference between the specimen and the surrounding medium increases as the specimen thickness grows larger, resulting in a smaller diffraction angle for light deviated by the specimen.
		The transmittance of the phase shift ring in the classical phase plate is approximately 25 percent, while the pair of adjacent rings surrounding the phase shift ring in the apodized plate have a neutral density with 50 percent transmittance.
	www.microscopyu.com /articles/phasecontrast/apodized.html (2264 words)

	Nikon MicroscopyU: Phase Contrast Microscopy - Introduction (Site not responding. Last check: 2007-09-18)
		Phase relationships between the surround, diffracted, and particle (S, D, and P) waves in the region of the specimen at the image plane for brightfield microscopy (in the absence of phase contrast optical accessories) are presented in Figure 3.
		The slight phase shift of 1/20th wavelength exhibited by the resultant particle wave (which arises from interference between the diffracted and surround waves) is typically observed for minute details in a cell, and is related to the optical path length difference.
		The mechanism for generating relative phase retardation is a two-step process, with the diffracted waves being retarded in phase by a quarter wavelength at the specimen, while the surround waves are advanced (or retarded) in phase by a phase plate positioned in or very near the objective rear focal plane.
	www.microscopyu.com /articles/phasecontrast/phasemicroscopy.html (7881 words)

	Acoustical behavior of brass player's lips
		A system for measuring the phase difference between the acoustic pressure in a mouthpiece and the vibrational displacement of the upper lip is sketched in Fig.
		We have to determine the relation between the strain and displacement of the upper lip because the calibrated phase difference between the mouthpiece pressure and the lip displacement is required.
		The phase difference between the mouthpiece pressure and the lip displacement was derived from the pressure-strain phase difference and was calibrated from the near-field pressure of a vibrating convex diaphragm on which a strain gauge was secured.
	la.trompette.free.fr /Yoshikawa/lips.htm (7978 words)

	Phase difference -- Facts, Info, and Encyclopedia article (Site not responding. Last check: 2007-09-18)
		Consider a (A drawing illustrating the relations between certain quantities plotted with reference to a set of axes) graph of a (Click link for more info and facts about sinusoidal) sinusoidal waveform with amplitude on the y or vertical axis and time on the horizontal or x axis.
		Phase difference is expressed in degrees from 0 to 360, or in (The unit of plane angle adopted under the Systeme International d'Unites; equal to the angle at the center of a circle subtended by an arc equal in length to the radius (approximately 57.295 degrees)) radians.
		If the phase difference is 90 degrees then the signals are said to be in (The construction of a square having the same area as some other figure) quadrature.
	www.absoluteastronomy.com /encyclopedia/p/ph/phase_difference.htm (262 words)

	Phase (waves)
		The phase may be measured as a time, distance, a fraction of the wavelength, or as an angle in radians.
		The phase difference of the waves is thus zero, or, the waves are said to be in-phase.
		In this case, the two waves are said to be out-of-phase, or the phase difference of the two waves is π radians, or half the wavelength (λ/2).
	www.fact-index.com /p/ph/phase__waves_.html (622 words)

	Phase-Locked Loop Tutorial, PLL
		The phase detector is a device that compares two input frequencies, generating an output that is a measure of their phase difference (if, for example, they differ in frequency, it gives a periodic output at the difference frequency).
		At that point the filtered output of the phase detector is a dc signal, and the control input to the VCO is a measure of the input frequency, with obvious applications to tone decoding (used in digital transmission over telephone lines) and FM detection.
		With low-pass filtering, the graph of the output voltage versus phase difference is as shown, for input square-waves of 50% duty-cycle.
	www.uoguelph.ca /~antoon/gadgets/pll/pll.html (3380 words)

	Synchronization of asynchronous data signals - Patent 4811340
		The phase difference is, or the threshold values are, cyclically changed in a manner to produce additional stuffing, not necessitated by the asynchronous frequency difference, whereby the frequency of jitter, due to stuffing, in the synchronized data signal is increased.
		As the phase difference is compared with the threshold value to produce the stuff request signal, it is a matter of convenience as to whether a signal representing the phase difference or the threshold value is changed.
		The analog phase detector 54 is responsive to phase differences between the clock signals supplied to the write and read address generators 20 and 24 to generate an output signal 62 whose amplitude is proportional to the phase difference between the two clock signals.
	www.freepatentsonline.com /4811340.html (5531 words)

	Stereo Phase Shifter
		A phase difference of 10 degrees between both stereo channels will lead to a recognizable deterioration of the signal quality (signal smearing).
		Because the ear interprets a sound on the basis of the transients and recognizes a relevant phase difference between input and output by the different movement of the phase of the separate harmonious changes to each other, the composition of the signal in the transients and with it the sound impression.
		A phase displacement between both stereo channels has an effect directly on the stereo basis and on the spatial impression of the stereoscopic picture.
	www.adt-audio.com /UsProducts/V700/VFrame/VFU790.html (453 words)

	United States Patent Application: 0040091026
		A portable communication apparatus, according to claim 25, wherein: said phase difference measuring unit measures said phase difference from said phase variation component that is obtained from said pilot symbol that is included in a given individual channel of a downlink from the base station.
		Since these phase difference information are measured by using the channel estimated value using the pilot symbol of the downlink DPCH that is used for the current user communication, it can be said that these phase difference information are in line with the current conditions.
		Thus, the phase difference measuring unit 10 may obtain the phase difference information of the channel estimated value that is obtained from each pilot symbol group between the slots.
	appft1.uspto.gov /netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PG01&p=1&u=/netahtml/PTO/srchnum.html&r=1&f=G&l=50&s1="20040091026".PGNR.&OS=DN/20040091026&RS=DN/20040091026 (7587 words)

	Magnus Encyclopeadia: The P page
		The phase is an relative measurement to tell where in the cycle an event is. Phase is measured as an angle due to its strong relationship with sine and cosine functions.
		The waveform from an phase accumulator is an sawtooth waveform.
		Phase modulation is a modulation method in which the phase of the signal is altered instead of the frequency or amplitude.
	home.swipnet.se /cfmd/encyclopeadia/p.html (1049 words)

	World Intellectual Property Organization (Site not responding. Last check: 2007-09-18)
		Thus, it is R550 difficult to fabricate a phase difference film adaptable for the wavelength dispersion characteristic of liquid crystal of the VA-LCD by using the conventional negative C plate having the limited phase difference wavelength dispersion ratio value.
		Thus, when two phase difference films are stacked on each other, the phase difference values in the thickness direction of the complex positive C plate as a function of the wavelengths represent difference values between the absolute phase difference values of the positive C plate and the negative C plate at each wavelength (see, FIG.
		has a phase difference value of 350nm in the thickness direction thereof at the wavelength of 550nm, and a phase difference value of 400nm in the thickness direction thereof at the wavelength of 450nm, the dispersion ratio value of the positive C plate C2 is represented as (R450)c2 = 400nm = 1.14.
	www.wipo.int /ipdl/IPDL-CIMAGES/view/pct/getbykey5?KEY=05/17613.050224&ELEMENT_SET=DECL (6795 words)

	phase - a Whatis.com definition (Site not responding. Last check: 2007-09-18)
		Phase can also be an expression of relative displacement between or among waves having the same frequency.
		Phase difference, also called phase angle, in degrees is conventionally defined as a number greater than -180, and less than or equal to +180.
		One radian of phase corresponds to approximately 57.3 degrees.
	whatis.techtarget.com /definition/0,,sid9_gci213803,00.html (304 words)

	Investigations on the appearance of material faults in holographic interferograms
		Different approaches for the automated recognition of fault indicating partial patterns by means of digital image processing and other modern techniques as neural nets and knowledge based systems are known [3,4].
		The points where the gradient of the phase difference is zero correspond to the critical points of system (6).
		For the considered case of a disappearing gradient of the phase difference we can conclude that only centres may be caused by material faults.
	www.ndt.net /article/v07n04/mieth/mieth.htm (3443 words)

	Phase difference (Site not responding. Last check: 2007-09-18)
		The phase difference between two signals of the same frequency can be thought of as a or advance in the zero crossing of signal with respect to another.
		Phase difference is expressed in degrees from to 360 or in radians.
		If phase difference is 90 degrees then the are said to be in quadrature.
	www.freeglossary.com /Phase_difference (485 words)

	Method and apparatus for flow velocity determination - Patent 4334543
		Computer unit 14 generates a signal corresponding to the phase of the average phase difference vector for each point of the velocity profile to be measured, and the signal is used to obtain the output signal 59, whose wave-form corresponds to the velocity profile, i.e.
		In accordance with the averaging time, the phase of the mean phase difference vector is more finely defined than at the output of the phase difference detector and there is thus a corresponding reduction in the region around.pi.
		This is shown by a reduction in the averaged "phase difference vector" and in a statistical fluctuation in its phase.
	www.freepatentsonline.com /4334543.html (6011 words)

	Beats (Site not responding. Last check: 2007-09-18)
		Except in case when the frequency difference is zero, you would see the phase differnece between the oscillations varying with time.
		Since the resultant amplitude depends on the phase difference between the two oscillations you see maximum amplitude when they are in phase and minimum when they are out of phase.
		You would see that the waves have the same phase difference at all times giving rise to resultant oscillations of constant amplitude- either zero or twice the amplitude of one of the waves depending on whether phase difference is PI or zero.
	www.mta.ca /faculty/science/physics/suren/Beats/Beats.html (231 words)

	Phase modulation (Site not responding. Last check: 2007-09-18)
		Phase modulation (PM) is the encoding of information a carrier wave by variation of its phase in accordance with an input signal.
		Note that phase modulation can be regarded a special case of frequency modulation where the carrier frequency modulation is time derivative of the PM modulating signal.
		Phase modulation can also be regarded as special case of quadrature amplitude modulation.
	www.freeglossary.com /Phase_modulation (379 words)

	Reduction of Phase Ambiguity in an Offset-QPSK Receiver
		Resolution of the phase ambiguity is necessary in order to synchronize, with the received carrier signal, the signal generated by a local oscillator in a carrier-tracking loop in the receiver.
		Without resolution of the fourfold phase ambiguity, the loop could lock to any of four possible phase points, only one of which has the proper phase relationship with the carrier.
		A carriertracking loop of a different design optimized for the reception of offset QPSK could reduce the phase ambiguity from fourfold to twofold, but would be more complex.
	www.nasatech.com /Briefs/May04/NPO30384.html (503 words)

	Application Note: Phase Detectors & Phase Shifters (Site not responding. Last check: 2007-09-18)
		The phase detector performance curve displays the variation of DC output at the IF port with phase difference between the RF inputs at the Reference and RF ports.
		The performance curve is sinusoidal for a double-balanced mixer, DBM, used as a phase detector.
		If the user requires a positive DC output, he would merely reverse the connections at the reference port; for positive DC output, pin 8 is grounded with the reference input applied to pin 7.
	www.minicircuits.com /appnote/phase12-3.2.htm (127 words)

	Bamberg Engineering Sound Lab (Site not responding. Last check: 2007-09-18)
		When the woofer and tweeter acoustic phase are in close agreement with each other, the two drivers vibrate in "lock step", and the sound improves.
		The same effect is seen by a clockwise rotation of the phase vs. frequency curve.
		Always expect to see a phase difference of less than 5 degrees at the cross frequency, 10 degrees within an octave on either side of crossover, and typically less than 35 degrees over a four-octave span centered at the crossover.
	www.bamberglab.com /phase_comp_def.shtml (280 words)

	Psychoacoustics Article, Psychoacoustics Information (Site not responding. Last check: 2007-09-18)
		The human hearing is basically a spectral analyzer, that is, the ear resolves the spectral content of the pressure wavewithout respect to the phase of the signal.
		between ears) phase difference is a notable exception by providing asignificant part of the directional sensation of sound.
		A tonal (sinuisodal) masker exhibits slightly different frequency-dependent masking properties from a non-tonal (noise-like) masker.
	www.anoca.org /sound/sounds/psychoacoustics.html (937 words)

	Phase detector for huge jitter ??
		If the PLL has a loop bandwidth of = 1.5 * 18kHz, the phase detector inside the PLL will never see a phase difference of more than 2 UI p-p, which means that a standard phase detector can be used without going outside its linear range.
		With the normal Phase detector with a working range of one period (T), you have a 16 T working range on the desired frequency.
		Classic phase detectors fail on NRZ, but there are a variety of methods to extract a clock from such messes.
	www.ee-one.com /new-5867430-4295.html (1507 words)

	Phase_Difference (Site not responding. Last check: 2007-09-18)
		Constant phase differences are not normally detected by the ear, but this is not true for time-dependent spectra, (i.e.
		Although they look different, their perceived sound will be the same.
		Four waveforms composed of a fundamental and second harmonic where the phase difference between these components is as listed at right.
	www.sfu.ca /sonic-studio/handbook/Phase_Difference.html (176 words)

	Phase Difference (Site not responding. Last check: 2007-09-18)
		Two SHM's along the x-axis of differing amplitudes and frequencies are being added.
		The motion of the cyan particle and the yellow particle represent the individual oscillations.
		How the phase difference between the two affects the resultanat oscillation is shown visually.
	surendranath.tripod.com /Applets/Oscillations/Phase/PhaseDiffApplet.html (98 words)

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