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Abstract

A sub-center type switched-star CATV system network in which a number of transmission signals are transmitted from a central source to a number of sub-centers over a number of sets of optical fibers. In view of the long distances involved, the transmission signals are transmitted in pulse frequency modulation form, one pulse frequency modulation signal being applied to each optical fiber. At each sub-center, each pulse frequency modulation signal is converted into a frequency modulation signal by first frequency dividing the pulse frequency modulation signal and then passing the divided signal through a band-pass filter which eliminates all signal components except the fundamental frequency. The pulse frequency modulated signals may pass through a switch to select the number of transmission signals which ultimately reach the subscribers. The frequency modulated signals are then frequency multiplexed to produce a multiplexed signal and the multiplexed signal is sent to a number of subscribers. A single optical fiber connects a sub-center with each associated subscriber, respectively. At each subscriber, the multiplexed signal is converted back into the selected number of transmission signals.

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First Claim