Abstract
In digital terrestrial TV broadcasting, many TV relay stations are needed for broadcasting services at mountainous areas that requires high construction cost. In order to reduce the cost, we theoretically discussed a system that can retransmit UHF band terrestrial digital TV signals (OFDM <Orthogonal Frequency Division Multiplexing> signals: 9 channels) sent via long distance (340km) optical fiber networks and verified the performance through experiments. In this system, an LD direct modulation optical modulator is used to reduce the construction cost and high equivalent C/N of about 40dB and very low distortion, which are traditionally considered to be very difficult to realize with direct modulation method, are obtained by adopting optimum design for obtaining a high C/N and wavelength dispersion compensation method at OFDM signal transmission.
