| 摘要 |
PURPOSE:To prevent interception by obtaining a data signal required to operate a converter of a terminal device from a signal applied to two cables. CONSTITUTION:A data signal is separated from a signal inputted from a cable (a) at a terminal side and inputted to a converter 17 via an RF switch 16 and also applied to a mixer 23. On the other hand, an auxiliary signal is applied to the mixer 23 with multiplication from a signal inputted from a cable (b), mixed with a data signal and converted into an IF frequency, demodulated and a TV receiving is attained in the range of channel selection permitted. Thus, the interception is disabled even if an input from one cable with distribution to the input terminal of the terminal device or inverse connection is executed. |
