Pre-Emphasis & De-Emphasis Networks
Aim:- To draw the frequency response of Pre-emphasis & De-emphasis networks. Introduction:- Educational trainer a useful kit for the demonstration of Pre-emphasis & De-emphasis at different time constants & plot the graph of the frequency response of Pre-emphasis and De-emphasis networks. The kit consists of 200 Hz-20 kHz audio oscillator 70µ sec & 50µ sec De-emphasis networks. Pre-Emphasis Circuit Diagram:- DE-Emphasis Circuit Diagram:- Theory:- Pre-emphasis refers to boosting the relative amplitudes of the modulating voltage for higher audio frequencies from 2 to approximately 15 kHz . De-emphasis means attenuating those frequencies by the amount by which they are boosted. However, Pre-emphasis is done at the transmitter and De-emphasis is done in the receiver. The purpose is to improve the signal-to-noise ratio for FM reception. A time constant of 75µ sec is specified in the RC or L/Z network for Pre-emphasis and De-emphasis. Tabular colu...