New Fiber Optic Analog Baseband Transmission Plan for Color TV Signals

A new fiber optic baseband analog transmission plan is proposed. It arranges the original signal into a pulse train for driving the laser diode to generate baseband components at the transmitter. The receiver can be just the same as those used in conventional direct linear intensity modulation systems using light emitting diodes (LED). Advantages of this new plan are (i) potentially cheap fibers can be used, since the plan requires neither an extra wide bandwidth nor special light acceptance conditions, (ii) long repeater spacings can be attained, since abundant light can be coupled into fibers using laser diodes and also the simple structures required for fibers are suitable for realizing low transmission losses, and (iii) the transmitter and receiver can be quite simple. Some candidate pulse arranging plans for generating baseband components are investigated. A pulse frequency arranging plan and pulse width arranging plan seem to be promising for efficient picture transmissions. An experiment using pulse frequency arrangement proves the theory developed here to attain a color TV transmission using a 10 km long step index low-loss fiber for a signal to noise ratio of 44 dB. Future improvements are expected by redesigning the transmitter and receiver and also by improving the mode stability of laser diodes.