Abstract: A digital signal multiplexing apparatus comprising variable multiplexers each of which can alter a multiplexed channel format every call in compliance with a subscriber's request, a fixed multiplexer which has a multiplexing capacity integral times as large as the total multiplexing capacity of the variable multiplexers and the multiplexed channel format of which is fixed, and fixed multiplexed signal demultiplexers each of which fixedly demultiplexes signals in a capacity integral times as large as that of each of the variable multiplexers into signals in a capacity equal to the total capacity of the variable multiplexers, wherein the outputs of the fixed multiplexed signal demultiplexers are distributed to the variable multiplexers through a distributing switch network, and the outputs of the variable multiplexers are multiplexed by the fixed multiplexer.

Abstract: A high speed digital signal multiplexing method and apparatus are provided wherein a plurality of first higher bit rate transmission frames are provided, each first higher bit rate transmission frame being multiplexed therein with lower bit rate signals in an n-byte (n is an integer) interleave manner, and the lower bit rate signals are selectively derived from the plurality of first higher bit rate transmission frames and multiplexed into a second higher bit rate transmission frame. When a phase conflict is detected among the derived lower bit rate signals, all the data columns of at least one of the derived lower bit rate signals are given a predetermined delay by means of a shift register, and the derived signals are multiplexed into the second higher bit rate transmission frame. When a first higher bit rate transmission frame asynchronous with the system frame is detected, a pointer is derived which pointer represents a predetermined information unit within the derived lower bit rate signal.

Abstract: A switch operation indicator is disclosed which comprises a frame fitted with a push-type switch having a drive member which is locked into a pressed-in position by a first pressing action and unlocked to return to an original position by the next pressing action; a push button fitted in the panel of the frame so that the button can be pressed in; a coupling bar which couples the button and the drive member to each other and has an operating notched portion; an indication opening provided in the panel adjacently to the button and an indication member attached to the frame so as to be swung, along with the movement of the bar, to be engaged with or disengaged from the notched portion and is provided with an indicating portion which alternatively faces or does not face the opening as the indication member is swung back and forth by the repeated pressing actions. Alternatives include an optical guiding version and a vibration-clamping version.

Abstract: A two-way optical transmission system in which a plurality of light signals of wavelengths differing one from another are transmitted through a single optical fiber from one end thereof to the other end and from the other end to the one end. One or more assemblies each including an electrooptic transmitter, a dielectric thin-film filter and a rod lens and one or more assemblies each including a rod lens, a dielectric thin-film filter and an opto-electric receiver are connected to the single optical fiber at both ends thereof, respectively.

Abstract: An FSK signal demodulator for demodulating digital data from a frequency shift keying signal. A timing clock for the digital data is extracted from the FSK signal, and a sampling circuit samples the FSK signal by means of a clock having a frequency which is almost equal to one frequency of the FSK signal or which is almost equal to an integral multiple of that fequency.

Abstract: A demodulator for demodulating a phase shift keying signal to regenerate a data signal. The demodulator comprises a clock generator for generating three-phase clock signals which are of substantially the same frequency as a carrier frequency of the phase shift keying signal and 120.degree. out of phase from each other, phase difference detectors for detecting phase differences of the phase shift keying signal relative to respective three-phase clock signals, a timing extractor for producing a data clock signal by fetching the three-phase clock signals and detected phase differences, and a phase difference change detector for producing the data signal by detecting the presence or absence of a change of phase difference between portions of the phase shift keying signal corresponding to preceding and succeeding bits of the data clock signal.