TELEVISION WAVE-RECEIVING SYSTEM USING OPTICAL MODULATOR

A signal transmission system for a television (TV) relay station was d eveloped and tested by using an optical intensity modulator (without a power supply), in which the intensity of the transmitted optical wave varies in response to a weak RF signal. If this system is used, an op tical fiber can be used as a transmission line; the receiving station does not require a power supply. Because the transmitting and receivin g stations can be fully isolated electrically, significant benefit is gained by protecting the system from lightning. As the receiving stati on can be constructed with solely passive components, reliability, and maintainability can be improved and cost can be lowered. In the prese nt system, the sensitivity of the optical modulator was improved by th e use of a reflection-type design. Voltage amplification by resonance was realized. Even at a low electric field of 60 dB mu V/m, a C/N of m ore than 50 dB was obtained. The differential gain (DG) was 1.8 percen t and differential phase (DP) was 1.2 degrees.