Drift differs from Doppler shift, which is a perceived difference in frequency due to motion of the source or receiver, even though the source is still producing the same wavelength. It also differs from frequency deviation, which is the inherent and necessary result of modulation in both FM and phase modulation.
frequency, drift, this, article, needs, additional, citations, verification, please, help, improve, this, article, adding, citations, reliable, sources, unsourced, material, challenged, removed, find, sources, news, newspapers, books, scholar, jstor, december,. This article needs additional citations for verification Please help improve this article by adding citations to reliable sources Unsourced material may be challenged and removed Find sources Frequency drift news newspapers books scholar JSTOR December 2011 Learn how and when to remove this template message In electrical engineering and particularly in telecommunications frequency drift is an unintended and generally arbitrary offset of an oscillator from its nominal frequency Causes may include component aging 1 changes in temperature that alter the piezoelectric effect in a crystal oscillator or problems with a voltage regulator which controls the bias voltage to the oscillator Frequency drift is traditionally measured in Hz s Frequency stability can be regarded as the absence or a very low level of frequency drift On a radio transmitter frequency drift can cause a radio station to drift into an adjacent channel causing illegal interference Because of this Frequency allocation regulations specify the allowed tolerance for such oscillators in a type accepted device A temperature compensated voltage controlled crystal oscillator TCVCXO is normally used for frequency modulation On the receiver side frequency drift was mainly a problem in early tuners particularly for analog dial tuning and especially on FM which exhibits a capture effect However the use of a phase locked loop PLL essentially eliminates the drift issue For transmitters a numerically controlled oscillator NCO also does not have problems with drift Drift differs from Doppler shift which is a perceived difference in frequency due to motion of the source or receiver even though the source is still producing the same wavelength It also differs from frequency deviation which is the inherent and necessary result of modulation in both FM and phase modulation See also editAllan variance Clock drift Phase noise Automatic frequency control AFC Phase locked loop PLL References edit Frequency Drift Time and Frequency from A to Z Boulder CO USA National Institute of Standards and Technology Retrieved December 8 2011 nbsp This electronics related article is a stub You can help Wikipedia by expanding it vte Retrieved from https en wikipedia org w index php title Frequency drift amp oldid 1120384089, wikipedia, wiki, book, books, library,