Glossary of Aviation Terminology


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UHF/VHF Automatic Direction Finding (U/V ADF): An Automatic Direction Finder that determines relative bearing to a transmitter to which it is tuned, in either the UHF band or VHF band;

Unit functions: A collection of functions used as standard test cases in control systems engineering; The primary unit functions of interest in avionics are the unit impulse, the unit step, and the unit ramp. Symbols: u sub k ( t );

Unit impulse: A function used as a standard test case in control systems engineering; a spike of ``area'' one at time t = 0; Synonyms: impulse; See Also: unit functions; Symbols: u sub <0> ( t ), delta ( t );

Unit ramp: A function used as a standard test case in control systems engineering; a line of slope 1 starting at zero at time t = 0; Synonyms: ramp; See Also: unit functions; Symbols: u sub < -2> ( t );

Unit step: A function used as a standard test case in control systems engineering; a step from zero to one at time t = 0; Synonyms: step; See Also: unit functions; Symbols: u sub< -1>( t ), u( t );

Unitless: No units, such as ratios; a quantity with standard units of 1; a quantity with primary units of 1; Synonyms: dimensionless;

Units: A standard quantity, such as ft or mi; Synonyms: dimension;

Universal Transverse Mercator (UTM): A system of fixed earth coordinates, sometimes used instead of latitude and longitude, accurate relative to others close by, such as ground troops;

Update: A process by which position is reset with a known better position; updates occur at the data source level or at the physical device level, depending upon specific implementation of the device and the data source (choice of implementation is transparent above the data source); all updates are operator initiated, but the new position may be derived from other sources such as FLIR, MMR, or radio navigation; a basic control to a data source from controls and displays for updating a device Compare: aiding;

UTM: Universal Transverse Mercator

U/V ADF: UHF/VHF Automatic Direction Finding


A , B , C , D , E , F , G , H , I , J - K , L , M , N , O , P , Q - R , S , T , U , V, W, X - Z