Abstract: A redundant changeover apparatus causing no frame synchronization loss even upon occurrence of changeover between working system and protection system. In case of an in-apparatus synchronization system, when two input signals which are mutually asynchronous in phase are changed over by a changeover switch, a changeover switch, a clock extractor, a PLL circuit, and a clock changing portion transmit signals with clocks before the changeover being gradually changed to clocks after the changeover. Alternatively, in case of an in-apparatus synchronize system, data are separated from clocks so that the data are once changed to data with reference clocks, and then for the data, clocks before the changeover are gradually changed to clocks after the changeover.

Abstract: An apparatus having n-number of working cross-connects for cross-connecting an n-bit input signals arriving from a plurality of input paths on a per-bit basis; n-number of first logic circuits for calculating the exclusive-ORs of each said n-bit and applying outputs to a standby cross-connect for providing outputs; n-number of second logic circuits for calculating the exclusive-ORs of said output signals from each of said working cross-connects and from the single standby cross-connect; and third logic circuits for selecting output signals of said working cross-connects and outputs of the second logic circuits. The apparatus detects the occurrence of an abnormality in working cross-connects by monitoring the outputs of the second logic circuits, identifies the faulty cross-connect by successively turning off one of the n-inputs to the first and second logic circuits, and select outputs from the second logic circuits instead of from the faulty cross-connect by using the third logic circuits.

Abstract: An optical transmission device in which optical signal switching is performed to allow the device to be reduced in size and also which is capable of efficient recovery from fault, thereby improving system expansibility and communication quality. Overhead terminating section converts an optical signal to an electric signal and performs an overhead process including extraction of fault information and setting of status information. Optical switch section performs a process of switching the optical signal between active and standby lines, and switching control section provides a switching command to the optical switch section in accordance with the fault information.

Abstract: Disclosed is a cross-connect apparatus having n-number of working cross-connects for cross-connecting, on a per-bit basis, n-bit input signals that arrive from respective ones of a plurality of input paths; n-number of first logic circuits for calculating the exclusive-ORs of the n bits of each input signal and applying their outputs to a standby cross-connect; n-number of second logic circuits for calculating the exclusive-ORs of signals output from the n-number of working cross-connects and from the single standby cross-connect; and third logic circuits having a function for selecting output signals of the n-number of working cross-connects and outputs of the second logic circuits.

Abstract: The present invention provides a receiver apparatus for receiving digital data in which stuff data have been inserted by stuffing synchronization. The receiver apparatus has a memory unit having a plurality of memory cells. The digital data other than the stuff data are written in the memory unit in synchronization with a write clock signal, and read from the memory cell in synchronization with a read clock signal. The cycle of the read clock signal is adjusted on the basis of an interval from a reading address to an writing address of the memory cell.

Abstract: A communication apparatus for interfacing various types of signals with different bit-rates is provided. The communication apparatus includes a receiving part receiving input signals, generating frames of a predetermined common format containing control information of the input signals and determining whether the frames are valid and a control part receiving the frames from the receiving part and performing a predetermined internal process based on the result of the determination.

Abstract: A redundant changeover apparatus causing no frame synchronization loss even upon occurrence of changeover between working system and protection system. In case of an in-apparatus synchronization system, when two input signals which are mutually asynchronous in phase are changed over by a changeover switch, a changeover switch, a clock extractor, a PLL circuit, and a clock changing portion transmit signals with clocks before the changeover being gradually changed to clocks after the changeover. Alternatively, in case of an in-apparatus synchronize system, data are separated from clocks so that the data are once changed to data with reference clocks, and then for the data, clocks before the changeover are gradually changed to clocks after the changeover.

Abstract: An optical transmission unit and optical transmission system which have more efficient failure recovery functions to provide improved communication services, without increasing the size of network equipment. A control channel manager manages a control channel, as well as a control channel signal on that channel, for the purpose of failure recovery of optical signal transport. An optical switch fabric switches optical signal paths to perform protection switching between working facilities and protection facilities. A protection switching controller sends a switching command to the optical switch fabric, based on the information provided through the control channel.

Abstract: An optical transmission device in which optical signal switching is performed to allow the device to be reduced in size and also which is capable of efficient recovery from fault, thereby improving system expansibility and communication quality. Overhead terminating section converts an optical signal to an electric signal and performs an overhead process including extraction of fault information and setting of status information. Optical switch section performs a process of switching the optical signal between active and standby lines, and switching control section provides a switching command to the optical switch section in accordance with the fault information.

Abstract: A projection display device comprising three projection lenses arranged in a row in a side by side relationship and having respective optical axes extending toward a screen, and three liquid crystal display panels forming images of red, green and blue color lights, the liquid crystal display panels and the projection lenses being arranged to form sets individually. A mirror is arranged between the display element and the projection lens of at least one of the sets. Accordingly, one of the display elements is arranged so as to face in a first direction and the adjacent display element so as to face in a second direction. It is thus possible to reduce the distance between the adjacent projection lenses even if the size of the liquid crystal display panels is enlarged.