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Automatic frequency control

Automatic frequency control Automatic frequency control is a device or a method of automatic measuring and maintaining of the necessary frequency of electric vibrations of the oscillator. The picture shows the simplest scheme of receiving frequency control with the help of a variable capacitance diode. The method consists in automatic additional oscillator frequency control on the data from the feedback circuit on frequency disparity. Thus the negative frequency feedback is performed. The data can be produced by the discriminator on various parameters of the signal obtained in the wireless device using the actual oscillator frequency. Automatic frequency control is widely used in the front ends of domestic radio receivers, including the television ones. Its role usually consists in automatic measurement of heterodyne frequency change within a narrow range: from an out-of-rule frequency by other systems to the central frequency necessary for qualitative transformation and reproduction of the signal.