| 摘要 |
PROBLEM TO BE SOLVED: To attain frame synchronization between a sending end and a receiving end at the time of superimposing another signal upon a data signal point. SOLUTION: A sending part 30 allocates a data signal to a data signal point of two-dimensional coordinate space, superimposes an analog sound signal on a data signal point and transmits it to a transmission line, while a receiving end 32 decides the data signal point of the two-dimensional coordinate space from a receiving signal of the transmission line, reproduces a data signal and reproduces an analog sound signal from an error determined between the signal points before and after determination. The part 30 multiplies a signal of the data signal point upon which the analog sound signal is superimposed by a frame synchronizing signal and sends it to the transmission line, while the part 32 demodulates the frame synchronizing signal from a received signal of the transmission line and attains frame synchronization of the receiving end. |
