Degree of modulation equalization circuit

摘要

PURPOSE:To set automatically the degree of modulaiton of an audio signal corresponding to the presence or absence of designation of a tone frequency. CONSTITUTION:When a channel is designated by a channel switch 3, a microcomputer 2 reads data representing the presence of designation of a tone frequency corresponding to a channel stored in an EEPROM 1 and a tone frequency. When the tone frequency is designated, a tone encoder 4 generates a tone frequency. An audio signal 6 is given to a variable resistor 8 and an analog switch 9 via a pre-emphasis circuit 7 in which the modulation is adjusted. When the tone frequency is not designated, the analog switch 9 sets the audio signal to a level corresponding to the maximum allowable modulation at a changeover contact 9a. When the tone frequency is designated, a level is set to a level lower than the corresponding to the maximum allowable modulation at a changeover contact 9b.