Noise (electronics)

About: Noise (electronics) is a research topic. Over the lifetime, 42029 publications have been published within this topic receiving 622342 citations. The topic is also known as: measurement noise.

Anthropogenic and natural sources of ambient noise in the ocean

Abstract: Ocean ambient noise results from both anthropogenic and natural sources. Different noise sources are dominant in each of 3 frequency bands: low (10 to 500 Hz), medium (500 Hz to 25 kHz) and high (>25 kHz). The low-frequency band is dominated by anthropogenic sources: pri- marily, commercial shipping and, secondarily, seismic exploration. Shipping and seismic sources con- tribute to ambient noise across ocean basins, since low-frequency sound experiences little attenua- tion, allowing for long-range propagation. Over the past few decades the shipping contribution to ambient noise has increased by as much as 12 dB, coincident with a significant increase in the num- ber and size of vessels comprising the world's commercial shipping fleet. During this time, oil explo- ration and construction activities along continental margins have moved into deeper water, and the long-range propagation of seismic signals has increased. Medium frequency sound cannot propagate over long ranges, owing to greater attenuation, and only local or regional (10s of km distant) sound sources contribute to the ambient noise field. Ambient noise in the mid-frequency band is primarily due to sea-surface agitation: breaking waves, spray, bubble formation and collapse, and rainfall. Var- ious sonars (e.g. military and mapping), as well as small vessels, contribute anthropogenic noise at mid-frequencies. At high frequencies, acoustic attenuation becomes extreme so that all noise sources are confined to an area close to the receiver. Thermal noise, the result of Brownian motion of water molecules near the hydrophone, is the dominant noise source above about 60 kHz.

Mechanical-thermal noise in micromachined acoustic and vibration sensors

Abstract: The small moving parts in acoustic and vibration microsensors are especially susceptible to mechanical noise resulting from molecular agitation. For sensors designed for small-signal applications, this mechanical-thermal noise is often one of the limiting noise components. Several techniques for calculating the mechanical-thermal noise in acoustic and vibration sensors in general, and in micromachined sensors in particular, are reviewed. >

Thermal noise in mechanical experiments

Abstract: The fluctuation-dissipation theorem is applied to the case of low-dissipation mechanical oscillators, whose losses are dominated by processes occurring inside the material of which the oscillators are made. In the common case of losses described by a complex spring constant with a constant imaginary part, the thermal noise displacement power spectrum is steeper by one power of $\ensuremath{\omega}$ than is predicted by a velocity-damping model. I construct models for the thermal noise spectra of systems with more than one mode of vibration, and evaluate a model of a specific design of pendulum suspension for the test masses in a gravitational-wave interferometer.

Electron counting statistics and coherent states of electric current

Abstract: A theory of electron counting statistics in quantum transport is presented It involves an idealized scheme of current measurement using a spin 1/2 coupled to the current so that it precesses at the rate proportional to the current Within such an approach, counting charge without breaking the circuit is possible As an application, we derive the counting statistics in a single channel conductor at finite temperature and bias For a perfectly transmitting channel the counting distribution is Gaussian, both for zero‐point fluctuations and at finite temperature At constant bias and low temperature the distribution is binomial, ie, it arises from Bernoulli statistics Another application considered is the noise due to short current pulses that involve few electrons We find the time‐dependence of the driving potential that produces coherent noise‐minimizing current pulses, and display analogies of such current states with quantum‐mechanical coherent states

Wide-band CMOS low-noise amplifier exploiting thermal noise canceling

Abstract: Known elementary wide-band amplifiers suffer from a fundamental tradeoff between noise figure (NF) and source impedance matching, which limits the NF to values typically above 3 dB. Global negative feedback can be used to break this tradeoff, however, at the price of potential instability. In contrast, this paper presents a feedforward noise-canceling technique, which allows for simultaneous noise and impedance matching, while canceling the noise and distortion contributions of the matching device. This allows for designing wide-band impedance-matching amplifiers with NF well below 3 dB, without suffering from instability issues. An amplifier realized in 0.25-/spl mu/m standard CMOS shows NF values below 2.4 dB over more than one decade of bandwidth (i.e., 150-2000 MHz) and below 2 dB over more than two octaves (i.e., 250-1100 MHz). Furthermore, the total voltage gain is 13.7 dB, the -3-dB bandwidth is from 2 MHz to 1.6 GHz, the IIP2 is +12 dBm, and the IIP3 is 0 dBm. The LNA drains 14 mA from a 2.5-V supply and the die area is 0.3/spl times/0.25 mm/sup 2/.