| 摘要 |
PURPOSE:To prevent the 3rd party from viewing a television signal by transmitting and receiving the television signal while changing the carrier frequency at every prescribed unit time. CONSTITUTION:A numerical data DATA corresponding to each channel is given externally to a storage circuit 24 and stored in advance in a transmitter 20. The transmitting and receiving device changes the frequency of a carrier signal CAR at every frame and transmits the frequency information (numerical data) of the carrier signal CAR of the next frame while being superimposed on the vertical blanking period, then the television signal VID2 is transmitted and received by using the carrier signal having a frequency different from each frame. Then even when the transmission signal S from the transmitter 20 is received by other receiver of the standard television system, since the carrier frequency is changed at every frame, only 1 frame among plural frames each is received. Thus, the 3rd party cannot view the television signal VID2 and recognize the content. |
