variable-frequency operation

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• Variable-frequency drive — A variable frequency drive (VFD) is a system for controlling the rotational speed of an alternating current (AC) electric motor by controlling the frequency of the electrical power supplied to the motor.cite book | first=Sylvester J. |… …   Wikipedia

• Variable frequency transformer — A variable frequency transformer is used to transmit electricity between two asynchronous alternating current domains. The VFT is a relatively recent development (first deployed in 2004). Most grid interties use high voltage direct current… …   Wikipedia

• Variable fractional delay filter — Introduction= One important advantage of the variable digital filter is that the frequency characteristics, including the magnitude response and the phase response are tunable without re implementation of the filter. Variable fractional delay… …   Wikipedia

• Frequency-hopping spread spectrum — (FHSS) is a method of transmitting radio signals by rapidly switching a carrier among many frequency channels, using a pseudorandom sequence known to both transmitter and receiver. A spread spectrum transmission offers three main advantages over… …   Wikipedia

• Variable capacitor — Rotary variable capacitor A variable capacitor (also known as a variable air condenser ) is a capacitor whose capacitance may be intentionally and repeatedly changed mechanically or electronically. Variable capacitors are often used in L/C… …   Wikipedia

• Variable Specific Impulse Magnetoplasma Rocket — Artist s impression of several VASIMR engines propelling a craft through space The Variable Specific Impulse Magnetoplasma Rocket (VASIMR) is an electro magnetic thruster for spacecraft propulsion. It uses radio waves to ionize and heat a… …   Wikipedia

• Frequency distribution — In statistics, a frequency distribution is an arrangement of the values that one or more variables take in a sample. Each entry in the table contains the frequency or count of the occurrences of values within a particular group or interval, and… …   Wikipedia

• Radio-frequency identification — (RFID) is a technology that uses radio waves to transfer data from an electronic tag, called RFID tag or label, attached to an object, through a reader for the purpose of identifying and tracking the object. Some RFID tags can be read from… …   Wikipedia

• Rotary variable differential transformer — A rotary variable differential transformer (RVDT) is a type of electrical transformer used for measuring angular displacement.More precisely, a Rotary Variable Differential Transformer (RVDT) is an electromechanical transducer that provides a… …   Wikipedia

• Superconducting Radio Frequency — (SRF) science and technology involves the application of electrical superconductors to radio frequency devices. The ultra low electrical loss of the superconductor yields RF resonators with extremely high quality factors, or Q . For example, it… …   Wikipedia

• Orthogonal frequency-division multiple access — Multiplex techniques Circuit mode (constant bandwidth) TDM · FDM · SDM Polarization multiplexing Spatial multiplexing (MIMO) …   Wikipedia