APPARATUS FOR ISOLATING THE VOICE FREQUENCY PATH FROM THE FLOATING BATTERY FEED DURING SIGNALLING

摘要

APPARATUS FOR ISOLATING THE VOICE FREQUENCY PATH FROM THE FLOATING BATTERY FEED DURING SIGNALLING by CONSTANTINE VICTOR SKIDANENKO and GREGOR DONALD McGIBBON In a floating battery feed circuit, the voice frequency is normally connected on the subscriber loop side of the blocking capacitor which is used to prevent the DC loop current from flowing in the winding of the associated voice frequency transformer. This capacitor adversely offsets the dial pulse signals. An optical isolator is responsive to the answer control signal from a dial pulse originating (DPO) channel unit and provides a control signal to a switching circult, which connects the voice frequency circuit to the loop during answer periods and disconnects the voice frequency circuit from the loop during dial pulse signaling.