A television telephone system utilizes a tone signal of a predetermined duration. The tone signal has a plurality of frequencies and is positioned at the starting portion of a transmission signal. The tone signal reduces the possibility of mis-detection of signals during reception and allows video signals to be transmitted more satisfactorily.
申请公布号
US4881253(A)
申请公布日期
1989.11.14
申请号
US19880203927
申请日期
1988.06.08
申请人
NIPPON TELEGRAPH AND TELEPHONE CORPORATION;SONY CORPORATION