MODULATION METHOD FOR DIGITAL OPTICAL COMMUNICATION SIGNAL, OPTICAL COMMUNICATION METHOD AND OPTICAL TRANSMITTER

摘要

PROBLEM TO BE SOLVED: To improve the communication efficiency that is drastically worsened when a sub lobe performs mutual interference with a main lobe of a remote control by making a direct current level of a baseband component constant when an optical signal is decomposed into a sub-carrier component and a baseband component. SOLUTION: An FSK bias IrBus modulator circuit 111 produces an IrTx electric signal 121 which is an IrBUS signal that is subjected to FSK bias by a logical circuit. Because a direct current level of a baseband component becomes constant due to the FSK bias, power spectrum sub lobe owing to a baseband component when the signal 121 is continuously outputted occurs only in OHz. A CMOS switch 103 is a switch that controls power supply and cutoff to a CR lowpass filter 102 and consists of a CMOS transistor and a damping resistance. A PowerCNT signal 123 that controls the switch 103 becomes L at the same time when the output of a redundant signal header is started.