An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



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Number of Results: 25 Search : noise
atmospheric noise
  نوفه‌ی ِ جوی   
nufe-ye javvi

Fr.: bruit atmosphérique   

Noise in radio wavelengths caused by natural atmospheric processes, mainly lightening discharges in thunderstorms. They can affect radio observations.

atmospheric; → noise.

background noise
  نوفه‌ی ِ پس-زمینه، ~ زمینه   
nufe-ye paszaminé, ~ zaminé

Fr.: bruit du fond   

An unwanted signal in a system which is producing or recording a signal. For instance, a randomly fluctuating signal superimposed on the signal from a cosmic radio source.

background; → noise.

cosmic radio noise
  نوفه‌یِ رادیوییِ کیهانی   
nufe-ye râdioyi-ye keyhâni

Fr.: bruit radio cosmique   

Radio waves emanating from extraterrestrial sources.

cosmic; → radio; → noise.

dark current noise
  نوفه‌ی ِ جریان ِ تاریکی   
nufe-ye jarayân-e târiki

Fr.: bruit du courant d'obscurité   

In a → CCD detector, statistical fluctuation of the → dark current, equal to the square root of the dark current. CCDs can be cooled either with thermoelectric coolers or liquid nitrogen to reduce this effect. Ideally, the dark current noise should be reduced to a point where its contribution is negligible over a typical exposure time.

dark; → current; → noise.

Galactic radio noise
  نوفه‌ی ِ رادیویی ِ کهکشان   
nufe-ye râdioi-ye kahkešân

Fr.: bruit radio de la Galaxie   

A diffuse radio signal that originates outside the solar system. It is strongest in the direction of the Galactic plane.

galactic; → radio; → noise.

Johnson-Nyquist noise
  نوفه‌ی ِ جانسون-نیکوییست   
nufe-ye Johnson-Nyquist (#)

Fr.: bruit de Johnson-Nyquist   

The random fluctuation of voltage across a resistor caused by the thermal excitation of electrons within it, and the dissipation of power associated with these fluctuations. More generally, an intrinsic noise generated by thermal agitation of electrons by all bodies whose temperature is above 0 K. Also called → thermal noise, Johnson noise, or Nyquist noise.

Named after John Bertrand Johnson (1887-1970) and Harry Nyquist (1889-1976) Swedish-born American engineers and physicists, who did important work on thermal noise and information theory. → noise.

nufé (#)

Fr.: bruit   

1) The → random → fluctuations that are always associated with a measurement that is repeated many times over. Any unwanted disturbance, random or → systematic, which contaminates the → signal from an object under study. More specifically:
2) Electronics: An undesired signal within the useful frequency band.
3) Acoustics: Any extraneous sound tending to interfere with the perception of wanted sound.
See also:
atmospheric noise, → background noise, → cosmic radio noise, → dark current noise, → Galactic radio noise, → Johnson-Nyquist noise, → noise source, → noise temperature, → noise voltage, → noise-equivalent power, → photon noise, → quantum noise, → radio noise, → random noise, → readout noise, → receiver noise, → Schottky noise, → shot noise, → signal-to-noise ratio, → speckle noise, → stationary noise, → system noise, → thermal noise, → white noise.

Noise, of obscure origin; it has been related to O.Fr. noise "uproar, brawl," apparently from L. nausea "disgust, annoyance," literally "seasickness." Alternatively the O.Fr. word is traced to L. noxia "hurting, injury, damage."

Nufé "noise," related to Mod.Pers. noyidan "to cry loud, lament," navidan, nâvidan "to lament," noyé, nôyah "plaint, mown," navâ "sound, song," (with prefix *uz-) zenudan, zenav-, zonudan "to wail," Ossetic niwyn/newun "to howl," O.Khotanese nuva- "to make a noise," Yaqnâvi nuyok "crying, howling," novva "sound," Shahmirzâdi nâv- "to cry; cf. Skt. nav- "to sound loudly, roar," náva- "show of joy or triumph;" L. nuntius "messenger," adnuntiare "to annoince;" Tocharian AB nu- "to roar, PIE *neu- "to shout".

noise source
  خن ِ نوفه   
xan-e nufé

Fr.: source de bruit   

An electronic device designed to generate known amounts of radio noise in order to test and calibrate the receivers of radio telescopes.

noise; → source.

noise temperature
  دمای ِ نوفه   
damâ-ye nufé

Fr.: température de bruit   

A means for specifying the noise generated as unwanted → electromagnetic radiation in a receiver system or one of its components. It is usually measured in terms of the equivalent temperature in a → Rayleigh-Jeans spectrum. Noise temperature is used mainly in radio astronomy.

noise; → temperature.

noise voltage
  ولتاژ ِ نوفه   
voltâž-e nufé

Fr.: voltage de bruit   

Fluctuations of electric potential in a physical system due to spontaneous disturbances in the system.

noise; → voltage.

noise-equivalent power
  توان ِ هم‌ارز ِ نوفه   
tavân-e ham-arz-e nufé

Fr.: puissance équivalente de bruit   

A measure of the sensitivity of an electronic detector, defined as the power input to the detector that will create a signal to noise ratio of one for an integration time of half a second.

noise; → equivalent; → power.

photon noise
  نوفه‌ی ِ فوتون   
nufe-ye foton

Fr.: bruit de photons   

An intrinsic noise caused by the quantum nature of light. Same as → quantum noise.

photon; → noise.

quantum noise
  نوفه‌ی ِ کو‌آنتومی   
nufe-ye kuântomi

Fr.: bruit quantique   

A random variation of signal due to fluctuations in the average rate of incidence of quanta on a detector. Quantum noise is described by the → Poisson distribution. Same as → photon noise and → shot effect.

quantum; → noise.

radio noise
  نوفه‌ی ِ رادیویی   
nufe-ye râdioyi (#)

Fr.: bruit radio   

The electromagnetic noise at radio wavelengths.

radio + → noise.

random noise
  نوفه‌ی ِ کاتوره   
nufe-ye kâture

Fr.: bruit aléatoire   

Unpredictable noise comprising large numbers of frequent, transient impulses occurring at statistically random time intervals. Thermal noise is a form of random noise.

random; → noise.

readout noise
  نوفه‌ی ِ خوانش   
nufe-ye xâneš

Fr.: bruit de lecture   

The noise added in the process of reading a detector such as a CCD.

reading rate; → noise.

receiver noise
  نوفه‌ی ِ گیرنده   
nufe-ye girandé

Fr.: bruit de récepteur   

The unwanted signal affecting a receiver.

receiver; → noise.

Schottky noise
  نوفه‌ی ِ شوتکی   
nufe-ye Schottky

Fr.: bruit de Schottky   

Excess voltage generated by random fluctuations in the emission of electrons from a hot cathode, causing a hissing or sputtering sound (shot noise) in an audio amplifier and causing snow on a television screen. Same as → shot effect, → shot noise.

Named after Walter Hans Schottky (1886-1976), German physicist; → noise.

shot noise
  نوفه‌ی ِ شاتکی   
nufe-ye Schottky

Fr.: bruit de grenaille   

Same as → Schottky noise and → shot effect.

shot effect.

Schottky noise.

signal-to-noise ratio
  وابَر ِ نشال-به-نوفه   
vâbar-e nešâl-bé-nufé

Fr.: rapport signal sur bruit   

Concept used to quantify the effects of noise. It is the ratio of a signal to the standard deviation of the signal.

signal; → noise; → ratio.

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