Atmospheric Noise


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atmospheric noise

[¦at·mə¦sfir·ik ′nȯiz]
(electronics)
Noise heard during radio reception due to atmospheric interference.

Noise, Atmospheric

 

electrical fluctuations in a receiving antenna caused by the heat radiation of the earth’s atmosphere in the radio spectrum (seeFLUCTUATIONS, ELECTRICAL).

Atmospheric noise worsens the quality of radio reception by engendering acoustical noise and false signals and decreasing measurement accuracy. A quantitative characterization of atmospheric noise is provided by noise temperature, which is equal to the product of the average physical temperature of the atmosphere (≈300°K) and the coefficient of absorption of the atmosphere. The latter depends on the state of the atmosphere (humidity, dust content, and the like), the shape of the antenna radiation pattern, the working length of the wave λ, and the orientation of the antenna in space. Ordinarily, when λ > 10 cm and altitudes of the main lobe of the radiation pattern are more than 20°, atmospheric noise is negligibly small.

References in periodicals archive ?
The ECRC software will serve a double mission: eliminate the atmospheric noise and make possible the simultaneous observation of multiple objects placed at different distances from the Earth.
This multiplicity reflects in Dreamcrusher's music, which follows in the tradition of frantic yet atmospheric noise music made by bands in the late ' 90s, when they were coming of age and finding their own musical tastes.
The procedures to generate TRNGs often measure a random physical occurrence, such as radioactive decay or atmospheric noise, although the use of dice or coin flipping is still used.
Typical EMI sources included natural atmospheric noise, motor commutators, fluorescent lights, automobile ignition systems, and overhead power lines.
Beck's alternation between still shots and movement, spoken utterances and atmospheric noise, contemporary conversation and forty-year-old text foregrounds communication itself--a communication in perpetual relay between subjects and contexts, past and present--as the film's main subject.
However, it has begun experimenting with long-range facial imagery under an Army contract with Securics, a company focused on eliminating the effects of atmospheric noise.
The rest of the package strikes all the right notes, with stunning visuals and perfect atmospheric noise.
At lower frequencies of short-wave band, the atmospheric noise predominates.
One of the first of these physical random-number generators, called Random.org, uses a radio to pull random numbers out of the atmospheric noise generated by weather systems.
With original music by Dusty Trails that included samba, atmospheric noise, and text with a slight delay, like a mirror reflection, the hour-long dance was utterly engaging.
At 1 GHz, the atmospheric noise temperature for clear air (7.5 g/[m.sup.3] of water vapor) increases from approximately 2 K for a narrow-beam antenna pointed at zenith to approximately 70 to 80 K at the horizon.
By 1967, radio astronomy had taken advantage of new masers - or microwave amplification by stimulated emission of radiation devices - that operated at cryogenic temperatures to obviate thermal and other atmospheric noise in deep-space radio detection.

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