The present invention has multiple AV/S terminals, an RF modulator, a S/AV
signal converter and multiple switches. The switches connect the AV/S
terminals with the RF outputs to allow the AV/S signal from the special
AV/S terminal input into the RF modulator to be converted to an RF-signal
input to the ANT terminal of the TV. Besides, the present invention
further has an ANT input with an electronic switch and a detecting unit
having a driver, which decides whether the electronic switch turns on. If
the detecting unit detects no AV-signal or S-signal input from the AV/S
terminals, the detecting unit first cuts off the power to the RF modulator
and then makes the electronic switch turn on. The RF-signal from the ANT
input is output to the RF output.
