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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.
^"Frequency Drift". Time and Frequency from A to Z. Boulder, CO, USA: National Institute of Standards and Technology. Archived from the original on January 3, 2012. Retrieved December 8, 2011.
telecommunications, frequencydrift is an unintended and generally arbitrary offset of an oscillator from its nominal frequency. Causes may include component...
Genetic drift, also known as random genetic drift, allelic drift or the Wright effect, is the change in the frequency of an existing gene variant (allele)...
acceleration Incremental changes: Drift (linguistics), a type of language change Genetic drift, change in allele frequencyDrift (telecommunication), long-term...
a frequency modulated signal, and the nominal center or carrier frequency. The term is sometimes mistakenly used as synonymous with frequencydrift, which...
transmitter frequency, but the most common cause is drift of the center bandpass frequency of the receiver, due to thermal or mechanical drift in the values...
However, frequencydrift or a lack of selectivity may cause one station to be overtaken by another on an adjacent channel. Frequencydrift was a problem...
or imperfections such as frequencydrift or temperature effects. The Allan variance and Allan deviation describe frequency stability. See also the section...
drift, causing the receiver to drift off the station frequency. Automatic frequency control (AFC) solves some of the drift problem, but manual retuning...
decreases a given crystal's frequency but it can also increase a given crystal's frequency. Factors that can cause a small frequencydrift over time are stress...
produces a signal which is much more tolerant of receiver mis-tunings and frequencydrift than MFSK modulation. Additionally, IFK modulation is more resistant...
tuned circuits, which could easily drift off frequency by 3–4 kHz. Since broadcast stations were assigned frequencies only 10 kHz (Americas) or 9 kHz (elsewhere)...
same frequency range. While each individual Type I burst does not drift in frequency, a chain of Type I bursts in a noise storm may slowly drift from...
advanced laser systems that narrow the frequencydrift far below the difference frequency (intermediate frequency). This technique has been demonstrated...
convergence. The Hadamard variance can be used to counteract linear frequencydrift sensitivity. For categorical variables, it is less common to measure...
around a point called the guiding center and a relatively slow drift of this point. The drift speeds may differ for various species depending on their charge...
the input frequency. To reinforce the bunching, a klystron may contain additional "buncher" cavities. The beam then passes through a "drift" tube, in...
phase-locked loop which makes them run at exactly this frequency. This removes the jitter and frequencydrift in the clocks that is responsible for the offset...
coherent derived units (for example, hertz, the SI unit of measurement of frequency), but the rest merely reflect their derivation: for example, the square...
mutation combine to change allele frequencies across generations. Genetic drift causes changes in allele frequency from random sampling due to offspring...
deuterated solvent, as the field frequency is locked using the deuterium signal of the solvent to prevent frequencydrift. Commercial chloroform-d does,...
The heat generated in the gain medium leads to frequencydrift of the cavity, therefore the frequency can be actively stabilized by locking it to unpowered...
Hans Hollmann in Berlin. However, the German military considered the frequencydrift of Hollman's device to be undesirable, and based their radar systems...
control long-term drift in the radio frequency. In this way, the quantum-mechanical properties of the atomic transition frequency of the caesium can...
consistently indicated the presence of a small but anomalous Doppler frequencydrift. The drift can be interpreted as due to a constant acceleration of (8.74...
spectrum is compared to what it should be. FrequencydriftFrequency deviation Jitter Automatic frequency control Allan variance Rudolf Kingslake (2 December...
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