Telephone station circuit using digital tone generation

摘要: A telephone instrument station circuit using a digital tone generator for generating dual multifrequency (DTMF) signals. The employs both series and shunt muting of the receiver during intervals occurring depressive release movements key or button keyblock. is doubly muted these to prevent inductively derived spikes from causing audible clicks in receiver. During period generation on full depression button, released allow generated be sent line, remaining effect.