Abstract: A method and associated system for providing multi-channel transmission of digital and broadband video information in optical fiber communication for local area networks through frequency-division-multiplexing, comprising the steps of generating a plurality of closely spaced optical carrier wave pairs with the optical carrier waves within each optical carrier wave pair having a predetermined separation frequency between one another, assigning each of the plurality of optical carrier wave pairs to a predetermined frequency slot and optically combining the plurality of optical carrier wave pairs to provide a multiplexed optical output wave. Advantageously, in addition to direct detection the plurality of optical carrier wave pairs may be detected by opto-electronic heterodyne detection and/or incoherent optical-heterodyne detection to electronically recover the optical carrier wave pairs.

Abstract: There is disclosed a technique for interfacing various subscriber groups having different security levels which subscribers are associated with the same telephone system. According to this invention, every terminal element or subscriber has a programmable frame delay for the out and in registers associated with the switching network. In this manner, each subscriber of the same priority will receive the same delay on the transmit and receive paths. This delay is accommodated by means of an up or down counter which is inserted in the frame sync signal to the appropriate input and output registers. The input and output registers are controlled according to the priority of the subscriber, such that there is a complementary delay in the receive path and the transmit path so that the total delay for the same priority subscriber is equivalent to one complete frame. In this manner, only subscribers of the same priority can communicate with each other.

Abstract: A liquid crystal polarization reorientation cell includes Helmholtz coils disposed on either side of the cell to provide a magnetic field that is substantially perpendicular to the transparent members. The energizing of the magnetic field is utilized to selectively reorient the polarization of at least one frequency of an incident light beam.

Abstract: A digital data and orderwire combiner employs a first and a second inverting gate amplifiers. The first amplifier receives the orderwire signal which is a low rate digital signal, while the second amplifier receives the data signal which is of a higher rate. The amplifiers have a common ground return where current through the amplifiers is directed through a resistive impedance network. The amplifiers as coupled together providing a 3-level amplitude modulated signal indicative of the combined data and orderwire signal. In order to reduce jitter, a portion of one of the signals is directed from one amplifier to the other. The configuration assure low jitter operation while producing reliable voltage levels indicative of 3-level amplitude modulation.