Inventor
LEE DAVID Q
US7 patents
Patents
7 patentsUS4022981AMay 10, 1977
Conference circuit for pulse coded modulated telephony
GTE AUTOMATIC ELECTRIC LAB INC11 citations72
US3931474AJan 6, 1976
Tone injection circuit
GTE AUTOMATIC ELECTRIC LAB INC7 citations72
US4230912AOct 28, 1980
Dial pulse sensor and repeater circuit
GTE AUTOMATIC ELECTRIC LAB INC13 citations71
US4133982AJan 9, 1979
AC supervisory signal detector circuit
GTE AUTOMATIC ELECTRIC LAB INC9 citations71
US4190745AFeb 26, 1980
Call for service and continuity sensor circuit
GTE AUTOMATIC ELECTRIC LAB INC11 citations69
US3967070AJun 29, 1976
Memory operation for 3-way communications
GTE AUTOMATIC ELECTRIC LAB INC17 citations69
US4126765ANov 21, 1978
Detector circuit for sensing battery polarity and loop closure
GTE AUTOMATIC ELECTRIC LAB INC15 citations67