| 摘要 |
PURPOSE:To simplify the circuit constitution and to attain low cost, by obtaining LSB or USB waves in frequency-shifting sound and adding a synchronizing signal to a sound scramble signal obtained with the product between FSK waves and the LSB or USB waves. CONSTITUTION:When a sound signal is inputted to an input terminal 1, signals of the LSB or USB waves are picked up at the output of a band pass filter 9, at least two carrier signals f1, f2 are changed over with a switching circuit 13, and the FSK wave signal is picked up. The sound scramble signal S0 is obtained with the product between the FSK waves and the LSB waves or the USB waves, the synchronizing signal S is added to the signal S0 from a synchronizing signal generator 22 to pick up a scrambled sound signal S'0 from a terminal 23. |
