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Topic: Reference noise

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Noise level

DBrn

Decibel

M8 motorway

Kingston Bridge, Glasgow

Al Capone

	AllRefer.com - noise pollution, Environment (Environmental Studies) - Encyclopedia
		Transportation vehicles are the worst offenders, with aircraft, railroad stock, trucks, buses, automobiles, and motorcycles all producing excessive noise.
		One burst of noise, as from a passing truck, is known to alter endocrine, neurological, and cardiovascular functions in many individuals; prolonged or frequent exposure to such noise tends to make the physiological disturbances chronic.
		Noise is recognized as a controllable pollutant that can yield to abatement technology.
	reference.allrefer.com /encyclopedia/N/noisepol.html (517 words)

	WaveWarp Component Library-- Noise Reduction-- Broadband De-Noiser 3
		Broad-band noise removal based on non-linear spectral subtraction of the measured noise spectrum (derived from a reference noise input via a separate channel).
		The simplest form of spectral subtraction is to, literally, subtract the averaged noise spectrum from the noisy signal spectrum, on a point-by-point basis in the frequency domain.
		The noise spectrum is estimated from the average of the left and right channels of the second input.
	www.soundslogical.com /support/wavewarp/documentation/english/documentparts/Broadband_De_Noiser_3.html (1299 words)

	World Intellectual Property Organization (Site not responding. Last check: 2007-09-17)
		The feedback reference pulses in beam 40 and return pulses in beam 14 appear in a waveform that is incident on detector 26.
		This enable the reference pulses and return pulses to experience the same propagation delay when passing through preamplifier 24 and comparator 22-allowing corresponding points on the reference and return pulses to be easily matched when assessing time of flight.
		These components are noise that is related to the operation of source 50 when driving a pulse signal and noise that is not related to source 50 driving a pulse signal.
	www.wipo.int /ipdl/IPDL-CIMAGES/view/pct/getbykey5?KEY=03/89949.031030&ELEMENT_SET=DECL (12557 words)

	Elec 301 Project
		The reference signal is a tapped version of the noise in the primary signal, i.e.
		The reference signal may come from another microphone that is placed away from the speaker and closer to the car engine, so the reference noise will be similar to the noise in primary but perhaps with a different phase and with some additional white noise added to it.
		The one important condition on the use of adative filters for noise cancellation is that the noise can't be similar to the desired voice signal.
	www.owlnet.rice.edu /~elec301/Projects00/site/design.html (968 words)

	Channel noise level - Wikipedia, the free encyclopedia
		The ratio of the channel noise at any point in a transmission system to an arbitrary level chosen as a reference.
		Note 1: The channel noise level may be expressed in (a) dB above reference noise (dBrn), (b) dB above reference noise with C-message weighting (dBrnC), or (c) adjusted dB (dBa).
		Note 2: Each unit used to measure channel noise level reflects a circuit noise reading of a specialized instrument designed to account for different interference effects that occur under specified conditions.
	en.wikipedia.org /wiki/Channel_noise_level (156 words)

	Suppression of Powerline Noise with Isolation Transformers - Bruce C. Gabrielson and Mark J. Reimold - EMC EXPO87 - San ...
		The mechanism through which this electrical coupling of noise occurs is the capacitance between the coils of the primary and secondary windings of the transformer, which does not include a Faraday shield.
		Bonding the transformer shield to either the primary or secondary ground establishes current paths for high frequency noise in the reference conductor of the circuit to be isolated.
		Since this noise is referenced to the power system ground, the most obvious method of eliminating this noise is by grounding the transformer center tap to the system ground via the lowest impedance path possible.
	molasar.blackmagic.com /ses/bruceg/EMC/isolatrans.html (1976 words)

	Frequency Synthesizers
		Inside the loop the oscillator noise is improved by the reference, yet outside the loop it is not degraded by the reference.
		If the reference is divided to a smaller step size its phase noise decreases by the same 20 log N factor.
		To maintain good noise performance with small step size it is possible to down-convert the oscillator thereby keeping N low and avoiding the noise floor.
	www.emfsystems.com /400.htm (1330 words)

	Reference Voltage for Multiple ADCs - Maxim/Dallas (Site not responding. Last check: 2007-09-17)
		A single external reference voltage applied to all reference inputs of the ADC array: Such a configuration lets you engineer an external reference voltage of arbitrary accuracy, but incurs error due to small variations among the resistor ladders (one ladder internal to each ADC).
		Additive noise is easily filtered by local bypass capacitors on the individual ADCs, which in most designs are already present to optimize the ADC's dynamic performance.
		The use of a common, high precision, low noise reference driving all the ADCs is a valuable approach for achieving high accuracy matching.
	www.maxim-ic.com /appnotes.cfm?an_pk=994 (1441 words)

	Noise-reference (Site not responding. Last check: 2007-09-17)
		This uses a cold-load to measure the basic system noise on each of the 450 and 850 micron bolometers.
		However, there are frequently a handful of bolometers which show much higher noise than the rest (G9,I2 and I9 are the usual suspects on the 850 micron array).
		There are sometimes occasions throughout a shift where the bolometer noise across both arrays appears to to drift up considerably, typically to the 100-150nV level (the suspicion is that there's a floating ground somewhere in the system).
	www.roe.ac.uk /ifa/shades/cookbook/cookbook/node9.html (154 words)

	Minutes - 18 July 2002
		Typically this involves using an additional antenna to collect a copy of the RFI, (known as a reference signal), which is altered to be a close match to the RFI in the contaminated astronomy signal stream.
		A modified version of the adaptive filter was discussed which uses a second reference (with system noise uncorrelated to that of the first) in the weight generation process.
		The major advantage of the modified (dual reference) filter over the conventional (single reference) filter is that it achieves superior RFI excision, particularly when the interference to noise ratio in the reference antennae is low.
	www.atnf.csiro.au /intmit/minutes/minutes2002-07-18.html (1277 words)

	SR510 - Lock In Amplifier
		The reference frequency range is 0.5 Hz to 100 kHz, and detection at both the fundamental and second harmonic of the reference is allowed.
		The reference can be phase shifted with 0.025° resolution from the front panel, or shifted in 90° increments for easy measurement of quadrature signals.
		Noise is defined as the rms deviation of the signal from its mean.
	www.thinksrs.com /products/SR510530.htm (1228 words)

	FreeHearingTest.com - Gunfire Noise Levels
		According to Dr. William Clark, Ph.D. senior research scientist in charge of the NOISE LABORATORY at the Central Institute for the Deaf in St. Louis, the damage caused by one shot from a.357 magnum pistol, which can expose a shooter to 165 dB for 2msec, is equivalent to over 40 hours in a noisy workplace.
		It should be noticed that this figure of 164.5 dB approaches the practical limit of impulse noise measurement capability inherent in most modern sound level meters.
		Imagine what the noise levels must be when we incorporate muzzle brakes or porting into firearms, or have a gun explode near the ear due to malfunction.
	www.freehearingtest.com /hia_gunfirenoise.shtml (371 words)

	VCO Phase Noise Optimization for the MAX2309 - Maxim/Dallas (Site not responding. Last check: 2007-09-17)
		PLL bandwidth, reference noise, and VCO components are changed to allow ~-90dBc/Hz phase noise at a 10kHz offset.
		After measuring phase noise with the modified VCO and loop filter, a second loop filter was evaluated.
		The phase noise was measured and the results are shown in Figure 3 and Figure 4.
	www.maxim-ic.com /appnotes.cfm/appnote_number/1744 (463 words)

	PNIntro1
		Notice that the amplitude noise does not affect the zero crossings and that the phase noise does not affect the amplitude of the signal peaks.
		Levels of phase noise that are far too small to detect on an oscilloscope can cause changes to the spectrum of a signal that can be very important in radio applications.
		Such minute amounts of phase noise on a transmitter signal can result in the transmitter causing significant interference to other services, whereas minute amounts of phase noise on a receiver local oscillator can severely reduce the receiver selectivity or cause other undesirable effects.
	www.radiolab.com.au /DesignFile/PNRef/intro1.htm (422 words)

	EPA: Federal Register: Noise Certification Regulations for Helicopters
		Noise certification data collected to date demonstrate that EPNL values corrected using atmospheric data measured at 33 feet (10 meters) are acoustically identical to the previous correction standard.
		Noise certification data voluntarily collected by industry to date have demonstrated that EPNL values corrected using atmospheric data measured at 33 feet (10 meters) are acoustically identical to those corrected using averaged temperature and relative humidity.
		are the measured and reference takeoff distances from the noise measuring station A to the measured and the reference takeoff paths, respectively.
	www.epa.gov /fedrgstr/EPA-IMPACT/2004/June/Day-02/i12069.htm (12066 words)

	WaveWarp Component Library-- Noise Reduction-- Broadband De-Noiser 1
		Under such circumstances, the noise spectrum can be accurately estimated by averaging across successive spectral snapshots.
		A further improvement can often be realised by performing some averaging of the noisy signal spectrum before carrying out the subtraction (in order to reduce the distortion due to variations in the noisy contribution to the mixed spectrum that are absent from the averaged noise spectrum and therefore are not removed by the subtraction).
		Adjusts the overall magnitude of the noise spectrum estimate, before performing the spectral subtraction.
	www.soundslogical.com /support/wavewarp/documentation/english/documentparts/Broadband_De_Noiser_1.html (1474 words)

	IAC - Noise Control Reference Handbook (Site not responding. Last check: 2007-09-17)
		Ambient noise is usually a composite of sounds from near and far sources none of which are particularly dominant.
		Noise -- Unwanted sound which may be hazardous to health, interferes with communications or is disturbing.
		White Noise -- A noise whose spectrum (level) density is substantially independent of frequency over a specified range and has equal power for any range of frequencies of constant band width.
	www.industrialacoustics.com /us/blue_book/acoustics_1.htm (884 words)

	Scantek Inc. TYRE/ROAD NOISE REFERENCE BOOK
		Several major policy documents from international organisations or expert groups have identified tyre/road noise as the component of road transportation noise which is the most urgently in need of being reduced.
		Road traffic noise from a fleet of modern vehicles is generally dominated by noise from tyre/road interaction.
		In 2001, the EU introduced noise emission limits for tyres and preparations are currently being made within the UN/ECE to introduce a tyre noise emission regulation.
	www.scantekinc.com /datasheets/tyre.htm (322 words)

	EDN: Filter your voltage reference for low-no=se performance.(analog angle)@ HighBeam Research (Site not responding. Last check: 2007-09-17)
		Reference-voltage noise occurs in two frequency ranges: 0.1 to 10 Hz for short-term, peak-to-peak drift, and 10 Hz to 1 kHz for wideband noise.
		Expressing noise in parts per million is popular because the noise voltage is usually proportional to the reference voltage, thereby keeping the parts-per-million value relatively constant.
		Bandgap-voltage references have noise voltages ranging from 3 to 16 ppm, but buried-zener voltage references are quieter, with noise voltages ranging from 0.1 to 0.5 ppm.
	www.highbeam.com /library/doc0.asp?DOCID=1G1:125955764&refid=holomed_1 (182 words)

	dnoise (Site not responding. Last check: 2007-09-17)
		This is a noise reduction scheme using frequency-domain noise-gating.
		The -i flag is used for a reference noise file (normally created from a short section of the denoised file, where only noise is audible).
		The algorithm is that suggested by Moorer & Berger in "Linear-Phase Bandsplitting: Theory and Applications" presented at the 76th Convention 1984 October 8-11 New York of the Audio Engineering Society (preprint #2132) except that it uses the Weighted Overlap-Add formulation for short-time Fourier analysis-synthesis in place of the recursive formulation suggested by Moorer & Berger.
	www.kevindumpscore.com /docs/csound-manual/dnoise.html (379 words)

	Symmetric Adaptive Decorrelation: Stability, Convergence, Uniqueness (Site not responding. Last check: 2007-09-17)
		The symmetric adaptive noise canceler is derived from the interpretation of the adaptive noise canceler as a decorrelator between signal estimate and noise reference.
		The new algorithm performs the decorrelation between the signal estimate and a "signal free" noise estimate, obtained by adding a symmetric filter to the classical structure.
		Experiments for speech enhancement have shown that SAD is indeed very useful for the case of signal leakage into the noise reference.
	www.esat.kuleuven.ac.be /~spch/yearreports/1992/node6.html (303 words)

	DriverHeaven.net - I made a noise canceller filter (get it here)
		It works best the if the noise in the primary and in the reference are recorded at the same time.
		If the noise is highly periodic, it can be sent delayed to reference and of different amplitude and it will still be removed effectively.
		I noticed that I cannot run two noise canclers at once (if I wanted to cancel stereo noise) one "clicks off" and stops outputing (testable by hooking into the removed noise from both plugins, one removes noise, one wont.) I dont know if this is a bug or not.
	www.driverheaven.net /printthread.php?t=69790 (2198 words)

	[No title]
		ÔThe FRA high-speed rail initial noise evaluation procedures are indispensable for their discussion of the more subtle elements of the noise assessment, and for interpreting the noise assessment results.
		The user is referred to Chapter 4 of the FRA "High-Speed Ground Transportation Noise and Vibration Impact Assessment" for a detailed discussion of these issues.
		For each of three types of high-speed rail sources (electric, fossil fueled, and maglev), reference noise levels and equations are given along with appropriate adjustments for factors such as attenuation of noise as a function of distance and geometry, and shielding from intervening rows of buildings.
	www.fra.dot.gov /downloads/RRDev/hsrnoise.xls (474 words)

	5.7 From diffusive noise to escape noise
		(5.114) is then a function of the noise-free reference trajectory only.
		, where the reference trajectory has a discontinuity, the distribution of the membrane potential is shifted instantaneously across the threshold.
		With this new escape rate the typical error E in the super-threshold regime is as small as that in the subthreshold regime.
	diwww.epfl.ch /~gerstner/SPNM/node39.html (679 words)

	Books on acoustics (Site not responding. Last check: 2007-09-17)
		This comprehensive reference is one of the few books of its kind to include richly detailed case studies that demonstrate real-world applications of acoustic principles, materials, and methods.
		Carefully organized and cross-referenced to cover an enormous field, 166 articles address linear and nonlinear acoustics and cavitation, aeroacoustics and atmospheric sound propagation, underwater acoustics, ultrasonics, mechanical vibrations and shock, statistical methods, noise control, architectural acoustics, signal processing, physiological acoustics, psychological acoustics, speech communications, musical acoustics, bioacoustics, animal bioacoustics, measurements and instrumentation, and transducer design.
		It covers engineering aspects (aerodynamics and jet noise, interaction of fluid motion and sound, infrasound, ultrasonics, quantum acoustics, etc.) and scientific aspects (auditory function, acoustical properties of the outer and inner ear, psychological speech perception, music and musical acoustics, hearing and sound perception among vertebrate/invertebrate animals).
	tlpsound.com /acoustics-books.htm (627 words)

	RANATEC Waveguide Components (Noise Injection Units)
		Noise Injection Unit model 150 provides an accurate noise reference source for use with the RF Performance Monitor Series 9000.
		Noise Injection Unit model 150 is designed for injecting a reference noise signal into a radar receiver without disruption to normal operation.
		When Solid State Noise Sources are operated in systems with high peak and average power, an isolator is required to protect the noise source.
	www.ranatec.se /niu.htm (202 words)

	► » A/D Reference Levels (Site not responding. Last check: 2007-09-17)
		noise performance, rather than the reference noise performance.
		converters it is probably the reference noise that dominates.
		wasted sampling noise and interference outside of the band of the signal.
	www.comp-one.net /AD-Reference-Levels-7680761.html (2673 words)

	Demo Beamforming (Site not responding. Last check: 2007-09-17)
		As a consequence background noise is picked up by the microphones, typically resulting in a low signal-to-noise ratio at the microphone outputs.
		A noise source was placed at an angle of 55 deg w.r.t.
		The signal-to-noise ratio corresponding to this reference signal is -9.9 dB.
	www.esat.kuleuven.ac.be /~eneman/demo_beam/demo_beam.html (291 words)

	Soundlabs Group - LC Audio LClock XO3 Technical (Site not responding. Last check: 2007-09-17)
		The reference voltages are kept clean to accommodate this performance, using high grade regulators and big capacitors.
		The 200 mV signal is amplified in a gate with around 5 mV p-p resident noise, it is a gate, not an analog amplifier.
		Airborne noise from inside the CD player (and there is a lot!) will have free access to the input of the Pierce oscillator, only stopped by the 200 k impedance of the crystal in parallel mode.
	www.soundlabsgroup.com.au /lcaudio/lc_audio_lclock_xo_technical.htm (1752 words)

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