Abstract: A method and apparatus for recovering the time base of signals which change at periodic intervals is disclosed. The apparatus comprises gated voltage controlled oscillators (GVCO) that are alternated or exchanged, to reduce phase and frequency deviations in the recovered time base signal, such as the deviations induced by inherent GVCO differences. Each GVCO is stabilized by a respective phase locked loop. The respective GVCOs are gated only in response to a chosen polarity transition in the input signal, to make the circuit more tolerant of waveform distortions. More than two GVCOs may be used to provide improved frequency drift resistance. The circuit uses resynchronization control signals, such as the time slot signal in synchronous switching systems, to indicate resynchronization or reassignment of the GVCOs in gaps in the data transmission.

Abstract: A hybrid optical switching-fabric architecture, for implementation via Y-branch switching elements, comprises an 8.times.8 array (100) of eighty Y-branch switching elements (110) configured as a Benes outer layer (105) consisting of two columns (105a, 105b) of four 2.times.2 networks (103) and an active-splitter/active-combiner inner layer (106) consisting of one column of two 4.times.4 active-splitter/active-combiner networks (104).

Abstract: An apparatus and method are disclosed for implementing a polarization-independent optical switch wherein switchable communication signals are retained in the optical mode while being switched between optical links in an optical communication network. The polarization-independent optical switch comprises polarization-dependent components which are advantageously arranged to switch arbitrary polarized light waves. The polarization-independent optical switch is achieved by splitting incoming arbitrary polarized light waves into two paths, a light wave with a TE radiation component and a light wave with a TM radiation component. The light wave with the TE radiation component is converted to a light wave with a TM radiation component. Both light waves having the TM radiation component are then switched in a polarization-dependent photonic switch device.

Abstract: A multipurpose bus connects subsets of intercommunicating modular circuit packs in a complex electrical system. An individual one of the subsets may use the bus leads to transport signals differently from the other subsets. Each of the subsets of the circuit packs is selected to use the bus in particular time intervals. The subset, thus selected, uses the bus leads the way its own protocol governs during those particular time intervals and otherwise ignores the bus.