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Topic: Beat frequency

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	Beat Frequencies
		When two sound waves of different frequency approach your ear, the alternating constructive and destructive interference causes the sound to be alternatively soft and loud - a phenomenon which is called "beating" or producing beats.
		The beat frequency is equal to the absolute value of the difference in frequency of the two waves.
		Beats are caused by the interference of two waves at the same point in space.
	hyperphysics.phy-astr.gsu.edu /hbase/sound/beat.html (126 words)

	United States Patent Application: 0040091062
		The beat frequency is likely to be relatively low, in the range of the audio frequencies that are to be received, and thus in effect modulated on to the base-band audio.
		Beat frequency canceller 12 operates to cancel out the beat frequency between the signals from filters 10 and 11 to generate a receiver output signal at 13.
		Beat frequency canceller (BFC) 12 implements an algorithm to remove the beat frequency by evaluating a trigonometrical relationship between the beat frequency of the Q and I channels.
	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="20040091062".PGNR.&OS=DN/20040091062&RS=DN/20040091062 (4273 words)

	Binaural beats - Wikipedia, the free encyclopedia
		Binaural beats or binaural tones is a technology of controversial uses, where sine waves of slightly different frequencies are played separately to each ear through binaural headphones.
		When the perceived beat frequency corresponds to the delta, theta, alpha, beta or gamma range of brainwave frequencies, this causes the brainwaves to entrain to or move towards the beat frequency.
		In addition to lower the brain frequency to relax the listener (or to raise it to help focusing), there are other controversial, alleged uses for binaural beats.
	en.wikipedia.org /wiki/Binaural_tones (548 words)

	The Acousto-Optic Modulator and Optical Heterodyning
		Beat notes are also familiar at radio frequencies, especially in the AM broadcast band (540-1600 kHz) during the late evening hours when broadcast stations from around the country, and from South America, can be heard because of improved propagation of low frequency electromagnetic waves by the nighttime ionosphere.
		The two frequency shifted laser beams are then recombined at beamsplitter BS2 and the combined beams pass on to a lens L that expands the beams for viewing on the laboratory wall and to a photodiode detector PD that detects electronically the beating of the two light beams.
		The interaction of two waves of different frequency in a nonlinear detector (here the photodetector) to produce a beat frequency is technically known as heterodyning, a term that you might have encountered in connection with superheterodyne radio receivers, such as FM stereo or short wave receivers.
	cat.middlebury.edu /~PHManual/acousto.html (4169 words)

	high frequency oscillator ventilator (high fequency oscillator ventilator) information. (Site not responding. Last check: 2007-10-14)
		The Beat Frequency Oscillator (BFO) is an audio oscillator made by AWA (Amalgamated Wireless Australia) in 1943.
		Beat frequency oscillator A beat frequency oscillator or BFO in radio telegraphy, is a dedicated oscillator used to create an audio frequency signal.
		4 is a schematic diagram of a beat frequency oscillator and Fig.
	www.tag-generator.com /h/high_frequency_oscillator_ventilator.html (137 words)

	Hemi-Sync - EEG and Subjective Correlates of Alpha-Frequency Binaural-Beat Stimulation Combined with Alpha Biofeedback (Site not responding. Last check: 2007-10-14)
		Delta frequency waves are generally associated with deep sleep, theta waves with light sleep or dreaming, alpha waves with relaxed consciousness, and beta and gamma waves with active consciousness.
		For example, if a pure tone with a frequency of 400 Hz is presented to one ear and a second tone of 410 Hz is presented to the other ear, a third binaural beat with a frequency of 10 Hz will also be heard as a result of the interaction of the two frequencies.
		Two subjects associated the beats with sensations in the sinuses; one reported that the beat caused a pressure build-up while another reported that the beat seemed to cause her sinus drainage to stop.
	hemisyncforyou.com /research/10 (12041 words)

	Beat Frequencies in Sound - Succeed in Physical Science (Site not responding. Last check: 2007-10-14)
		A beat frequency or beat wave is a sound of fluctuating volume caused when you add two sound waves of slightly different frequencies.
		If the piano is slightly out of tune, he will be able to hear the beat frequency and then adjust the piano wire until it is at the same frequency as the tuning fork.
		A beat frequency is the combination of two frequencies that are very close to each other.
	www.school-for-champions.com /science/soundbeat.htm (1162 words)

	The Science Of Binaural Beat Brainwave Entrainment Technology - for meditation relaxation stress management
		The binaural beat is perceived as a fluctuating rhythm at the frequency of the difference between the two auditory inputs.
		Binaural beats in the delta (1 to 4 Hz) and theta (4 to 8 Hz) ranges have been associated with reports of relaxed, meditative, and creative states (Hiew, 1995), and used as an aid to falling asleep.
		Binaural beats in the alpha frequencies (8 to 12 Hz) have increased alpha brain waves (Foster, 1990) and binaural beats in the beta frequencies (typically 16 to 24 Hz) have been associated with reports of increased concentration or alertness (Monroe, 1985) and improved memory (Kennerly, 1994).
	www.brain.web-us.com /thescience.htm (2307 words)

	Patent 4744653: Distance measurement by laser light
		However, the frequency of 30 MHz is usually the range of ultrasonic waves, and accordingly it is difficult to catch the reflected signal from the object which is disposed at a position of 10 m-100 m from the detector.
		For instance, the frequency change may be made by changing the geometric length of the resonator of the changeable oscillator, or changing its optical refraction index by changing CO.sub.2 gas pressure or the discharge current, to resultantly change the optical resonator length.
		In this case, when.omega..sub.1 and.omega..sub.2 are selected as frequencies in the of ultrasonic range the number of nodal points of the light beam are several, and therefore a distance measurement in the range of 10-100 m can be made at high speed and with high accuracy.
	www.freepatentsonline.com /4744653.html (4631 words)

	Beat Frequency Oscillator - Top Beat Frequency Oscillator Sites, Reviews and Information (Site not responding. Last check: 2007-10-14)
		beat frequency oscillator: Information From Answers.com beat frequency oscillator A beat a oscillator or BFO in analysis radio telegraphy, is frequency dedicated oscillator used phase to create an audio frequency signal.
		BEAT R7077 OSCILLATOR FREQUENCY The Beat Frequency Oscillator (BFO) is an audio oscillator function made by AWA (Amalgamated Wireless Australia) in 1943.
		Early Electric Bliley Patents: 2240452 4 is a schematic diagram of a beat frequency frequency oscillator and Fig.
	www.justoscillators.com /listings11.html (629 words)

	The Effect of Aging on Nasal Mucociliary Clearance, Beat Frequency, and Ultrastructure of Respiratory Cilia -- HO et ...
		beat frequency, and ultrastructure of respiratory cilia in a cohort
		beat frequency (Hz) by an MPV-COMBI photomultiplier (Leitz) and
		and of the increasing frequency of ciliary ultrastructural anomalies,
	ajrccm.atsjournals.org /cgi/content/full/163/4/983 (3389 words)

	Beat-Frequency Oscillator
		you must heterodyne (beat) any cw signal with an rf signal of the proper frequency.
		the difference frequency of 1 kilohertz is heard in the output.
		When you vary the bfo control, you are varying the output frequency of the bfo
	www.tpub.com /content/neets/14189/css/14189_57.htm (360 words)

	FlashWebHost.com - Ham Radio BFO (Beat Frequency Oscillator).
		We have many modes of HF (high frequency) communications like CW (continuous waves) where the signals are transmitted in the form of morse telegraphy.
		It would be advisable to use a broadcast receiver with three or more bands because it permits better tuning on the small spectrum of ham frequencies.
		A simple free running oscillator oscillating at the receiver's IF (intermediate frequency) beats with the incoming signals in either CW or SSB and the resultant audio frequency goes to the AF amplifier.
	www.flashwebhost.com /circuit/ham_radio_bfo.php (1211 words)

	Binaural Beat Stimulation Combined with Alpha Biofeedback
		Eyes-open baselines: Eyes-open baselines are defined as the ratio of the 10.5 Hz band of the EEG to the entire measured EEG spectrum during the two minute period of time after orientation and before the procedure while the subject is mentally and physically relaxed in dim ambient light with eyes open and gaze fixed.
		The normal human EEG has a frequency range from 0.5 Hertz (Hz) to 30 Hz which is usually subdivided into four or five bands: delta (0.5-3.5 Hz), theta (4-7 Hz), alpha (8-12 Hz), beta (13-28 Hz), and gamma (28+ Hz).
		The tendency for the electrical rhythms of the brain to become entrained to frequencies of sensory stimuli in the environment is called the frequency-following response (Moushegian, Rupert, and Stillman, 1978; Sohmer, Pratt, and Kinarti, 1977; Stillman, Crow, and Moushegian, 1978).
	brain.web-us.com /foster.htm (11717 words)

	Time and Frequency from A to Z
		The national frequency standards developed by NIST derive their resonance frequency from the cesium atom, and use cesium beam or cesium fountain technology.
		Audible beat frequencies, often called beat notes, are used for simple frequency calibrations.
		Usually, headphones are used to listen for zero beat, since the receiver’s speaker might not be able to produce the low frequency beat note signals.
	tf.nist.gov /general/enc-am.htm (905 words)

	Analysis of ciliary beat pattern and beat frequency using digital high speed imaging: comparison with the ...
		Cilia were found to beat with a forward power stroke and a backward recovery stroke within the same plane.
		Respiratory cilia beat in a coordinated manner with a specific frequency and pattern, clearing mucus and debris from the airways.
		The beat angle is formed by the point of maximum deviation of the cilium during the recovery stroke from the path the cilium travels during the power stroke.
	thorax.bmjjournals.com /cgi/content/full/55/4/314 (2305 words)

	Functional analysis of cilia and ciliated epithelial ultrastructure in healthy children and young adults -- Chilvers et ...
		the beat cycle and measurement of the ciliary beat frequency.
		Figure 3 (A) Mean ciliary beat frequency (CBF) plotted against age showing a negative correlation between increasing age and a reduction in ciliary beat frequency (correlation coefficient r=–0.30).
		The effect of aging on nasal mucociliary clearance, beat frequency, and ultrastructure of respiratory cilia.
	thorax.bmjjournals.com /cgi/content/full/58/4/333 (3154 words)

	FlashWebHost.com - Ceramic Filter Beat Frequency Oscillator.
		Because the ceramic filter operates at fixed frequency, no turning is required to demodulate the single side band (SSB) signals and no regulated power supply is necessary.
		To resolve stronger stations connect a wire not bigger than 10 cm to the out put of the beat frequency oscillator.
		For best result the receiver IF amplifier frequency and the beat frequency oscillator frequency should be the same.
	www.flashwebhost.com /circuit/ceramic_filter_bfo.php (229 words)

	Beat Frequency
		This is called the beat frequency, which is caused by the interference of the two sounds.
		There is a simple way to predict the beat frequency if you know the two source frequencies.
		This may seem simple, but just subtract the two source frequencies, and that will be the beat frequency.
	physics.pingry.org /Explorations/Acoustics/Beats (327 words)

	Demonstrations Catalog; Beat Frequency (Site not responding. Last check: 2007-10-14)
		irst, the frequency of the weighted fork of the matched/weighted pair can be adjusted to produce beats.
		This method has a wide range of beat frequencies.
		The gong has a defect that causes it to vibrate with two modes of slightly different frequency producing a long beat.
	www.physics.uc.edu /~rlharris/beatfreq.htm (116 words)

	Fastest Wing Beat
		Appropriately the fastest recorded wing beat was achieved by a small, lightweight ceratopogonid midge.
		In asynchronous muscle systems (Hymenoptera, Diptera, Coleoptera, and Hemiptera), the impulses in the motor nerves and the mechanical activity of the muscles do not occur at the same frequency (Pringle 1976.) The arrangement of muscles in the asynchronous system is antagonistic which causes cyclic deformations of the thorax (Smyth 1985).
		One advantage for rapid wing beat is the ability of the insect to remain relatively stationary in air (hover).
	ufbir.ifas.ufl.edu /chap09.htm (644 words)

	8010G beat frequency metal detector (Site not responding. Last check: 2007-10-14)
		The unit consists of an oscillator/ amplifier assembly, flat search probe, probe extension cable, special 2,000 ohm headset and carrying case.
		The 8010G operates on the "beat-frequency" principle where an internal oscillator is tuned to, or near, the frequency of an external oscillator whose frequency is determined by the coil and circuitry in the probe.
		When the two oscillators are tuned to exactly the same frequency they are said to be in "zero-beat." Any difference in frequency between the internal and external oscillators is amplified and applied to the headset.
	www.martykaiser.com /8010g~1.htm (531 words)

	1304-B Beat Frequency Audio Generator (Site not responding. Last check: 2007-10-14)
		The 1304-B was often paired with the 1521-B Graphic Level Recorder to make frequency response measurements.
		The two were coupled with sprockets and a chain, allowing the frequency sweep to synchronize with the chart paper.
		There were also motorized dial drives that would automatically sweep the 1304-B in similar applications.
	www2.rpa.net /~choffman/GR1304B.htm (715 words)

	TMI Research: Alpha-Frequency Binaural-Beat Stimulation (Site not responding. Last check: 2007-10-14)
		H(1) Alpha frequency binaural-beat stimulation will increase alpha brain wave production above eyes- open baseline levels.
		Research clearly indicates the possibility of entraining specific frequencies of brain waves by presenting subjects with frequency-specific flickering lights (Arinibar and Pfurtscheller, 1978; Nogawa, Katayama, Tabata, Ohshio, and Kawahara, 1976; Regan, 1966; Williams and West, 1975; Yaguchi and Iwahara, 1976).
		Hypothesis 2, that visual eyes-open alpha- frequency biofeedback training would increase alpha production above eyes-open baseline levels, was not rejected.
	www.monroeinstitute.org /research/alpha-binaural-beat.html (11902 words)

	Beat Frequency (Site not responding. Last check: 2007-10-14)
		As two tones become more similar, the "beat frequency" becomes lower.
		As two tones become more different, the "beat frequency" becomes higher.
		Eventually the beat frequency becomes so high that it sounds like a third tone.
	www.sciencejoywagon.com /explrsci/media/tonebeat.htm (47 words)

	Publications about 'Multilook Beat Frequency'
		Keywords: SAR Processing, Doppler Centroid, Doppler Centroid Estimation, Multilook Cross Correlation, MLCC, Multilook Beat Frequency, MLBF, Clutterlock, Doppler Ambiguity Solver.
		Keywords: SAR Processing, Doppler Centroid, Doppler Centroid Estimation, Multilook Cross Correlation, MLCC, Multilook Beat Frequency, MLBF, Clutterlock, Doppler Ambiguity Solver, Satellite SAR.
		Please note that access to full text PDF versions of papers is restricted to the Institute of Geography of the University of Zürich.
	www.geo.unizh.ch /~ofrey/SARbibliography/Keyword/MULTILOOK-BEAT-FREQUENCY.html (187 words)

	frequency oscillator information. (Site not responding. Last check: 2007-10-14)
		Oscillator Noise And Frequency Drift In Transceivers by Haroon...
		Introduction to Quartz Frequency Standards - Oscillator Comparison...
		IBIG standard for pulse repetition frequencies and reference...
	www.tag-generator.com /f/frequency_oscillator.html (244 words)

	Beat Frequency - Eduseek (Site not responding. Last check: 2007-10-14)
		Subjects > Science > Science - 16+ > Physics - Physical Processes > Oscillations and Waves > Vibrations > Beat Frequency
		Beats - Information about ''beats'' concept of waves
		Link to us : Add Eduseek to your site : Newsletter
	www.eduseek.com /navigate.php?ID=2467 (62 words)

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