PURPOSE: To inexpensively but successfully deal with the fading of frequency selectivity by providing a converting means which converts digital signals to be transmitted into base-band signals of a double-current RZ system and a modulation circuit which modulates the phase of carriers with the base-band signals.
CONSTITUTION: This digital signal modulator is constituted of a converting means 1 which converts digital signals to be transmitted into base-band signals of a double-current RZ system and a modulation circuit 6 which modulates the phase of carriers with the base-band signals. Therefore, the expensive ring modulator can be omitted by one circuit by converting the digital signals into the base-band signals of the double-current RZ system with a relatively inexpensive gate circuit. The fading of frequency selectivity caused by delayed multiplex waves can be successfully coped with at a low manufacturing cost.
YOSHIDA SUSUMU
TAKEUCHI TSUTOMU
YOSHIDA SUSUMU
TAKEUCHI TSUTOMU
| JPH0396138A | 1991-04-22 | |||
| JPS6323449A | 1988-01-30 |