Noise (physics) - Noise (physics) In science, and especially in physics and telecommunication, noise is random fluctuations and the addition of external factors to the stream of target information (signal) being received at a detector. More specifically, in physics, the term noise has the following meanings: 1. An undesired disturbance within the frequency band of interest; the summation of unwanted or disturbing energy introduced into a communications system from man-made and natural sources. 2. A disturbance that affects a signal and that may distort the information carried by the signal. 3. Random variations of one or more characteristics of any entity such as voltage, current, or data. 4. A random signal of known statistical properties of amplitude, distribution, and spectral density. 5. Loosely, any disturbance tending to interfere with.
Shot noise - Shot noise Shot noise refers to the random fluctuations of the electric current in an electrical conductor, which are caused by the fact that the current is carried by discrete charges (electrons). The strength of this noise increases for growing magnitude of the average current flowing through the conductor. Shot noise is to be distinguished from current fluctuations in equilibrium, which happen without any applied voltage and without any average current flowing. These equilibrium current fluctuations are known as Johnson-Nyquist noise. Shot noise is important in electronics, telecommunication, and for fundamental physics. The strength of the current fluctuations can be expressed by giving the variance of the current, <(I-)>2, where is the average ("macroscopic") current. However, the value measured in this way depends on the frequency.
Noise - Noise In general usage, noise can be considered sound without meaning; that is, sound that is not being used to transmit information, but is simply produced as a by-product of other activities. Most often it is defined as meaningless sound of greater than usual volume. Thus, a loud activity may be referred to as noisy. However, conversations of other people may be called noise for people not involved in any of them. See: Noise (environmental) noise music Noise (Goidelic mythology) noise (physics) This is a disambiguation page; that is, one that just points to other pages that might otherwise have the same name. If you followed a link here, you might want to go back and fix the link, so that it points to the appropriate.
List of physics topics F-L - List of physics topics F-L A B C D E F G H I J K L M N O P Q R S T U V W X Y Z F Famous physicists; see list of physicists Faraday cage Faraday constant Faraday's law Faraday, Michael Fahrenheit Fahrenheit, Daniel Gabriel Fast Fourier transform Faster-than-light Fermat's principle Fermi energy Fermi gas Fermi liquid theory Fermi paradox Fermi-Dirac statistics Fermi, Enrico Fermi-Thomas screening wave vector Fermion Ferroelectric effect Ferromagnetism Feynman diagram Feynman, Richard Ficks law of diffusion Field Fifth force Fincke, Thomas Finite difference Finite element method Fitch, Val Logsdon FitzGerald, George Francis FitzGerald-Lorentz Contraction Fizeau, Armand Hippolyte Louis Fizeau-Foucault apparatus Float-Zone process Fluid dynamics Fluid mechanics Fokker-Planck equation Forbidden line Force (physics) Force carrier Force spectroscopy Foucault, Jean.
Jet engine - to a very large cross section for the engine, as well as having the air flowing the wrong way after compression - it has to be collected up and "bent" to flow to the rear of the engine where the turbine is located. Anselm Franz of Junkers' engine division (Jumo for Junkers Motoren) addressed this problem with the introduction of the axial-flow compressor. Essentially this is a turbine in reverse. Air coming in the front of the engine is blown to the rear of the engine by a fan, where it is crushed against a set of non-rotating blades called stators. The process is nowhere near as powerful as the centrifugal compressor, so a number of these pairs of fans and stators are placed in series to get the needed compression..
Invisibility - tales and role playing games. The concept of invisibility has also been explored in several movies, many of them comedies. Some mystical creatures can make themselves invisible at will, such as Chinese dragons in some tales, which can shrink so small that humans cannot see. According to physics a truly invisible man would be blind. The eye works by absorbing photons, however transparency would dictate that no photon would be absorbed. Examples of invisibility devices in fiction: The ring of Gyges, described in a story in Plato's Republic. A peasant finds a ring in the tomb of a dead king which allows him to become invisible at will. Plato has him enter the palace, seduce the queen, and plot to kill the king, arguing that power, such as this, corrupts absolutely..
Intellectual history of time - can look at the Grand Canyon and "see" how it evolved over millions of years from the river flowing through it eating away at the rocks, or one can be God and see how what really happened was a gigantic flood that made the canyon in weeks, and left a little river at the bottom. It's the ultimate contradiction of history that catastrophes aren't subject to science, and hence the biggest history-makers are unrepeatable in a laboratory. So, too, along with natural history, the history of ideas, including the way that we experience (socially) and measure time has evolved. By way of the changing tempo and structure of our lives through the passing generations, contorted by inventions, ideas, art, and altogether changing paradigms and philosophies, we have consistently found new ways.
Harry Nyquist - Sweden. He emigrated to the USA in 1907 and entered the University of North Dakota in 1912. He received a Ph.D. in physics at Yale University in 1917. He worked at AT&T from 1917 to 1934, then moved to Bell Telephone Laboratories. As an engineer at Bell Laboratories, he did important work on thermal noise ("Johnson-Nyquist noise") and the stability of feedback amplifiers. His early theoretical work on determining the bandwidth requirements for transmitting information, as published in "Certain factors affecting telegraph speed" (Bell System Technical Journal, 3, 324-346, 1924), laid the foundations for later advances by Claude Shannon, which led to the development of information theory. In 1927 Nyquist determined that an analog signal should be sampled at twice the frequency of its highest-frequency component in order to be converted.
Hypercomputation - the observer is being dropped into a black hole). A Turing machine which increases its speed exponentially over time. In a Newtonian universe, such a gadget might operate by manufacturing a clone of itself which was only half the size and operated at twice the speed. A non-deterministic Turing machine which has a preference ordering over its final states. A "real computer" (a sort of idealized analog computer) might be able to perform hypercomputation if physics admits general real variables (not just computable reals), and these are in some way "harnessable" for computation. This might require quite outlandish laws of physics (for example, a measurable physical constant with an oracular value, such as Ω), and would at minimum require the ability to measure a real-valued physical value to arbitrary precision despite.
Guglielmo Marconi - signal on December 12 1901 in St. John's, Newfoundland (now in Canada) using a 400-foot kite-supported antenna for reception. The transmitting station in Poldhu, Cornwall used a spark-gap transmitter to produce a signal with a frequency of approximately 500kHz and a power of 100 times more than any radio signal previously produced. The message received was three dots, the Morse code for the letter S. To reach Newfoundland the signal would have to bounce off the ionosphere twice. Dr. Jack Belrose has recently contested this, however, based on theoretical work as well as an actual reenactment of the experiment; he believes that Marconi heard only random atmospheric noise and mistook it for the signal. On March 16, 1905 he married Beatrice O'Brien, daughter of Edward Dunnough (O'Brien), 14th Baron Inchiquin. They.
Electronics - electrically charged particles in devices such as thermionic valves and semiconductors. The pure study of such devices is considered as a branch of physics, while the design and construction of electronic circuits to solve practical problems is called electronic engineering. The main uses of electronic circuits are the controlling, processing and distribution of information, and the conversion and distribution of electromagnetic power. Both of these uses involve the creation or detection of electromagnetic fields and electric currents. While electricity had been used for some time to transmit data over telegraphs and telephones, the development of electronics truly began in earnest with the advent of radio. Today, electronic devices perform a much wider variety of tasks. One way of looking at an electronic system is to divide it into the following parts:.
Electronic amplifier - this by taking power from a power supply and shaping the output to match the input signal. This process invariably introduces some noise and distortion into the signal, and the process cannot be 100% efficient - amplifiers will always produce some waste heat. An idealised amplifer can be said to be "a piece of wire with gain", the output is an exact replica of the input, only larger. Different designs of amplifier are used for different types of applications and signals. We can broadly divide amplifiers into three categories - small signal amplifiers, low frequency power amplifiers and RF power amplifiers. Each of these calls for a slightly different design approach, mainly because of the physical limitations of the components used to implement the amplifier, and the efficiencies that can be.
1956 - Song Contest - May 24 1956 in sports 1956 in television April - WNBQ Chicago becomes the first TV station to broadcast all its local programming in color. April Ampex demonstrates a videotape recorder at the NAB Convention in Chicago. The three networks place orders for the recorders. August 8 - Final telecast of the DuMont network October 1 - Ernie Kovacs becomes the host for NBC's Tonight Show on Mondays and Tuesdays. October 29 - First use of videotape in network television programming; CBS uses its Ampex VTR to record the evening news, anchored by Douglas Edwards. The tape is then fed to West Coast stations three hours later October 29 - Chet Huntley and David Brinkley take over anchor duties of the NBC evening newscast, which is renamed The.
Arno Allan Penzias - American physicist. He won the 1978 Nobel Prize in physics, together with Robert Woodrow Wilson, for their 1964 accidental discovery of the cosmic microwave background radiation (CMB): while working on a new type of antenna at Bell Labs in Holmdel, New Jersey, they found a source of noise in the atmosphere that they could not explain. After clearing the antenna of pigeon droppings, the noise was finally identified as CMB, the single most striking proof of the Big Bang. External Links Arno Allan Penzias.
Corona discharge - the tip of a needle, or a narrow wire) and one of low curvature (such as a plate, or the ground). The high curvature ensures a high potential gradient around one electrode, for the generation of a plasma. Coronas may be positive, or negative. This is determined by the polarity of the voltage on the highly-curved electrode. If the curved electrode is positive with respect to the flat electrode we say we have a positive corona, if negative we say we have a negative corona. The physics of positive and negative coronas are strikingly different. This asymmetry is a result of the great difference in mass between electrons and positively charged ions, and so only the electron having the ability to undergo a significant degree of ionising inelastic collision at common.
Scott Base - of the base will not be unduly brief. Its usefulness was measurably increased during the 1962-63 season by extending some huts and erecting a new garage and a second seismic hut. By the end of the 1960-61 season, HMZS Endeavour was considered unfit for further Antarctic service. Her successor is a small tanker loaned by the United States to the New Zealand Navy, also named Endeavour. She currently resupplies Scott Base, transports fuel for the United States “Deep Freeze” operations and carries out oceanography and associated studies. Planning and Operation. The Ross Dependency Research Committee formulates the New Zealand Antarctic Research Programme. The committee comprises representatives of divisions of the Departments of Scientific and Industrial Research, the Lands and Survey, the Dominion Museum, the Royal Society of New Zealand, New Zealand.
Signal - operating system). A means of controlling road vehicles, pedestrians or trains. See Traffic signal, Pedestrian crossing or Railway signal. See also Signal processing, noise (physics). This is a disambiguation page; that is, one that just points to other pages that might otherwise have the same name. If you followed a link here, you might want to go back and fix the link, so that it points to the appropriate page..
Signal theory - the strength of a resonance), time constant (of a filter), great-signal and small-signal bandwidth, maximum output swing, noise floor. Low-level perceptions include the whole spectrum of mathematics, for example integrals and differentials. If you incidentally are in statistical physics or op-amp electronics you are common with this stuff..
Solar neutrino problem - was a major discrepancy between observation and the theory of nuclear physics, lasting from the mid-1960s to about 2002. The discrepancy has since been resolved by new understanding of neutrino physics, requiring a modification of the Standard Model of particle physics. The sun is a natural nuclear fusion reactor, fusing hydrogen to helium. Our current understanding of physics is quite clear about what happens, four hydrogen nuclei (protons), with and without the help of catalysts are transformed into helium, neutrinos and energy. The energy is released as gamma rays and as kinetic energy of the particles, including the neutrinos. Neutrinos were originally theorized to make up the energy and angular momentum difference when a neutron decays into a proton and an electron. Neutrinos were later demonstrated to exist, but accomplishing this.
Static - for static electricity. In the context of consumer electronics, static is a synonym for white noise. An entirely different meaning of static, used in literature, etc., is to mean "not changing"; as in the term "static character", or, a character who does not significantly change over the course of the work. Inaddition to these meanings, in mechanics, static implies a system that does not possess a deterministic processes or changing variable values, but is a well-defined sytem which only involves the current values. This type of system is the opposite of dynamic systems. In computer science/computer engineering, the word static has many unrelated definitions, which may be confusing for novices. Some of the more common uses of the word are: In object-oriented programming, static refers to a property of an object.
