| 摘要 |
PURPOSE:To obtain an RF modulator not requiring the changeover of sound carrier, by corresponding the sound carrier to plural TV broadcast systems having different carrier frequencies and providing functions of simultaneous output. CONSTITUTION:Plural sound carriers are generated as RF modulation signals at the same time. To mix two sound carriers with different frequencies outputted from the 1st FM modulator 6 and the 2nd FM modulator 7 respectively at the 2nd mixer 13, the two sound carriers exist in the RF modulation signals, allowing to receive the sound signals without switching, even if a receiver of any broadcast system corresponding to the two sound carriers is connected to an RF signal output terminal 12. Since the switch of the RF modulator is not required for switching for the receiver connected to the RF modulation signal output, malfunction and trouble of switching are avoided. Since the switch is replaced into a simple mixer, the RF modulator is manufactured inexpensively. |
