The Allan variance ( AVAR ), also known as two-sample variance, is a measure of frequency stability in clocks, oscillators and amplifiers.

The Allan deviation ( ADEV ) is the square root of Allan variance.

The Allan variance and Allan deviation describe frequency stability, i. e. the stability in frequency.

There are also different adaptations or alterations of Allan variance, notably the modified Allan variance MAVAR or MVAR, the total variance, and the Hadamard variance.

Allan variance and its variants have proven useful outside the scope of timekeeping and are a set of improved statistical tools to use whenever the noise processes are not unconditionally stable, thus a derivative exists.

The general M-sample variance remains important since it allows dead time in measurements and bias functions allows conversion into Allan variance values.

Nevertheless, for most applications the special case of 2-sample, or " Allan variance " with is of greatest interest.

To address these problems, David Allan introduced the M-sample variance and ( indirectly ) the two-sample variance.

Allan provided a method to convert between any M-sample variance to any N-sample variance via the common 2-sample variance, thus making all M-sample variances comparable.

Allan variance is defined as one half of the time average of the squares of the differences between successive readings of the frequency deviation sampled over the sampling period.

In addition, Mr. and Mrs. Allan Goodman are controllers, Mrs. Paul Stone is treasurer and Mrs. Albert Quell is in charge of admittance for the dancing at 9 P.m..

* 1857 – " The Spirits Book " by Allan Kardec is published, marking the birth of Spiritualism in France.

Bernard Allan Federko ( born May 12, 1956 ) is a retired professional ice hockey centre who played fourteen seasons in the National Hockey League from 1976 through 1990.

The name was inspired by Edgar Allan Poe's poem The Raven, as Poe lived for a time in Baltimore, died there in 1849, and is buried there.

The chosen name, " Ravens ," alludes to the famous poem The Raven by Edgar Allan Poe, who spent the early part of his career in Baltimore, and is also buried there .< ref >

Allan Huber " Bud " Selig (; born July 30, 1934 ) is the ninth and current Commissioner of Major League Baseball, having served in that capacity since 1992 as the acting commissioner, and as the official commissioner since 1998.

The mountain is a popular destination attracting an estimated 100, 000 ascents a year, " Ben Nevis " 80 /- organic ale is, by contrast, brewed in Bridge of Allan near Stirling.

University of Miami professor of architecture Allan Schulman said " Miami's brand is it's identity as a tropical city.

" Comic strip historian Allan Holtz described how strips were provided as mats ( the plastic or cardboard trays in which molten metal is poured to make plates ) or even plates ready to be put directly on the printing press.

A large state marina and boat launch is located at the southern end of the lake in Ithaca ( Allan H. Treman State Marine Park, the largest inland marina in New York ).

Actually the film draws its central character, Allan Gray, from Le Fanu's Dr. Hesselius ; and the scene in which Gray is buried alive is drawn from " The Room in the Dragon Volant ".

" Das Fräulein von Scuderi ", an 1819 short story by E. T. A. Hoffmann, in which Mlle de Scudery establishes the innocence of the police's favorite suspect in the murder of a jeweller, is sometimes cited as the first detective story and a direct influence on Edgar Allan Poe's " The Murders in the Rue Morgue ".

In the sonnet " To Science " by Edgar Allan Poe, science is said to have " dragged Diana from her car ".

The subject of this article should not be confused with a former newspaper correspondent, for who the Edgar Allan Poe Award is named

Edgar Allan Poe is buried in Baltimore, Maryland.

The piece began, " Edgar Allan Poe is dead.

The Edgar Allan Poe National Historic Site in Philadelphia is one of several preserved former residences of Poe

No childhood home of Poe is still standing, including the Allan family's Moldavia estate.

The oldest standing home in Richmond, the Old Stone House, is in use as the Edgar Allan Poe Museum, though Poe never lived there.

The earliest surviving home in which Poe lived is in Baltimore, preserved as the Edgar Allan Poe House and Museum.

It is open to the public and is also the home of the Edgar Allan Poe Society.

As Allan intended, Ravenscrag was both imposing and intimidating, with a three-hundred foot frontage and a gate guarded by a Gate Lodge on Pine Avenue.

* Edgar Allan Poe wrote a short story entitled " MS. Found in a Bottle ", possibly intended as a satire of sea tales.

In 2011, Chamberlain's Nutcracker ( 1958 ) from the Allan Stone Estate sold at auction for $ 4. 7 million, more than twice its high $ 1. 8 million estimate and a record price for the artist at auction.

Allan Cunningham, who forms only a humble estimate of his genius, remarks that his songs " have much softness and truth, an insinuating grace of manners, and a decorum of expression, with no small skill in the dramatic management of the stories.

This mechanics of the feedback oscillators was unknown when the work on oscillator stability started but was presented by Leeson at the same time as the statistical tools was made available by David W. Allan.

A low Allan variance is a characteristic of a clock with good stability over the measured period.

One may convert the Allan variance and other time-domain variances into frequency-domain measures of time ( phase ) and frequency stability.

The modified Allan variance measure is a frequency stability measure, just as the Allan variance.

The Allan variance and Allan deviation provides the frequency stability variance and deviation.

* Allan variance, a statistical measure of frequency stability