Abstract: In portable wireless communication systems wherein subscriber stations communicate with a plurality of base stations each covering a predetermined area, communication lines are provided for dedicating to the exchange of the use status and observation result of radio channels with the plurality of base stations in order that each base station can autonomically manage the determination of a base station with which a subscriber station communicates, the selection of a radio channel to be used, and the like.

Abstract: A power supply circuit, which steps down an input voltage, is provided in an optical repeater for an optical communications path. A DC current supplied from a regulated current supply through a conductor is increased by the power supply circuit before being provided to the amplifier circuit of the optical repeater, so that power consumption is reduced.

Abstract: A communications switch comprises a multi-layer switch configuration each layer comprising a synchronized packet switch with a pre-circulation stage 12, circulation re-entry stage 14, intermediate stage 16, re-circulation exit stage 17 and final exit stage 18. A re-circulation stage 15 allows re-circulation of data from one synchronized packet switch to another synchronized packet switch via paths 35. A number of switch input nodes 32 and output nodes 34 have accesss to each of the synchronized packet switches.

Abstract: In a superheterodyne receiver which employs a frequency synthesizer to generate local oscillator (LO) frequencies, there is provided apparatus which determines when an undesirable frequency relation exists, which may produce a condition known as a "tweet", and which adjusts the frequency of the LO signal so as to prevent, reduce or eliminate the tweet.

Abstract: A retiming circuit is provided which accurately converts half-width dual rail data with up to one unit interval of jitter with respect to the data clock, into full-width data. The circuit is comprised of D-flip-flops and associated logic elements which capture and hold a data pulse until the captured data pulse can be accurately transferred to the next circuit stage by a positive clock transition.

Abstract: The invention comprises a low power broadcast system that is applicable especially to the so-called "electronic shelf" for retail stores, wherein the shelf edge carries price displaying modules that can be addressed and controlled from a central computer operated station. The system also permits the modules to broadcast back to the central station to confirm safe receipt of data and to give information as to stock levels, etc. A broadcast system avoids the need for wiring so that location changes are facilitated.

Abstract: An optical signal regenerator includes an optical coupler having a first input for an optical information signal, a second input for optical clock pulses and an output for a combined signal. A resonant laser amplifier is located downstream of the output of the coupler and arranged to receive the combined signal and, in use, output a regenerated optical information signal. The bias current applied to the laser amplifier, in use, biases the amplifier to a level below its lasing threshold, and the power of the optical clock pulses is just below the bistable threshold of the amplilfier, so that, when an optical information signal is fed into the first input during the application of an optical clock pulse to the second input, the bistable threshold of the amplifier is exceeded causing a sudden jump in the power of the optical output of the amplifier to provide a regenerated optical information signal.

Abstract: A method for using an underground mine communication system to effect minewide communication and an intrinsically safe current limiter circuit for insuring that electrical equipment in the system will not cause incendiary conditions. The underground mine communication system comprises a plurality of repeaters and medium frequency radios, including, mobile, portable and personal-carried radios, inductively coupled to electrical conductors and natural waveguides existing in the earth by tuned loop antennas. Messages transmitted by the radios are carried to the repeaters by the conductors or coal seam waves. The repeaters amplify, replicate and retransmit the message at two different frequencies for transmission of the message to a surface base station and to other radios in the system. A paging system, which has a separate set of repeaters, is also coupled to the network of electrical conductors and natural waveguides by tuned loop antennas. The paging system alerts miners to contact the surface base station.

Abstract: An electric lamp assembly is disclosed which comprises a bulb unit including a filament, lead lines extending from the filament to the outside of the bulb unit and a hermetic seal portion, the lead lines extending through the hermetic seal portion; a bulb holder including a looped band portion which gripps the hermetic seal portion of the bulb unit having leading ends of the lead lines projected outward from the bulb holder, the bulb holder having foot portions each being formed with at least one opening; and a base assembly including a circular body part, a pair of conducting plate members having leading ends projected outward from respective slits formed in the body part and a plurality of supporting pins extending outward from the body part. The supporting pins are inserted into the openings of the foot portions of the bulb holder and welded to the foot portions to achieve a tight connection between the base assembly and the bulb holder.

Abstract: A bidirectional optical communications system is described using a multiple quantum well structure as both a photodetector and light modulator.

Abstract: A satellite communications system employs separate subsystems for broadcast and point-to-point two-way communications using the same assigned frequency band and employs an antenna system which uses a common reflector (12). The point-to-point subsystem achieves increased communication capacity through the reuse of the assigned frequency band over multiple, contiguous zones (32, 34, 36, 38) covering the area of the earth to be serviced. Small aperture terminals in the zones are serviced by a plurality of high-gain downlink fan beams (29) steered in the east-west direction by frequency address. A special beam-forming network (98) provides in conjunction with an array antenna (20) the multiple zone frequency address function. The satellite (10) employs a filter interconnection matrix (90) for connecting earth terminals in different zones to permit multiple reuse of the entire band of assigned frequencies.

Abstract: The device of the present invention provides a signal modulation system. The system has a first station communicatively connected to at least first and second optical fibers. The first station has a transmitter to produce an unmodulated light carrier signal through the first optical fiber and a receiver to convert a modulated light signal from the second optical fiber to a demodulated electrical signal for output. The system also has a second station communicatively connected to the first and the second optical fibers. The second station has an amplifier and power source which receive input carrier modulating signals, a modulation circuit, and an electro-optical modulator constructed and arranged to modulate transmission of the light carrier signal from the first optical fiber to the second optical fiber.

Abstract: Apparatus and method for detecting a sync signal in parallel data which has been reconstituted from serial data. The first occurrence of digital bits which corresponds to a predefined sync signal is recognized and causes the circuitry to shift to a mode of operation in which subsequent sync signals will be recognized if and only if they occur within a predetermined "window" around the expected position of the sync signal. The sync signal is used re-align the parallel data so that the bits are grouped into meaningful words.

Abstract: A circuit for decoding coded frequency modulated signals eliminates perturbing effects of noise pulse signals by coupling the signal to be detected through a filter having a transfer function that is related to the conjugated transfer function of the frequency modulation deemphasis filter, the spectrum of the noise pulse, the spectral power density of the signal to be demodulated, and the spectral power density of the noise. A comparison circuit provides the signal at the output of the filter when the output signal exceeds a threshold level. A decision circuit, which provides signals representative of the temporal position and polarity of the noise pulses to the correction circuit, is coupled between the comparison circuit and a circuit for generating noise correction pulses. The noise correction pulses are coupled to the decoder with the output signal of the detector to eliminate the effects of the noise pulse.

Abstract: A paging receiver to which various extra functions may be selectively added. A receiver body of the paging receiver has a miniature and thin configuration and is provided with only a sound type alerting function. Minimum necessary degrees of receiving function, antenna function, speaker function and power psupply function are furnished with in the receiver body. A holder adapted to hold the receiver body is provided with advanced functions a well as a vibrator function and other extra functions. Only when the holder is combined with the receiver body, it allows the receiver to exhibit the advanced functions or the extra functions as desired. In order that the receiver body and the holder may be fixed to each other when combined, a housing of the receiver body and the holder are individually provided with mating portions and electrical connecting terminals.

Abstract: A multichannel microwave relay station has first and second channels for respectively transmitting signals of different types of modulation, such as QAM and FM modulated signals. These different types of signal rely on a common standby transmission channel that is selectively capable of transmitting the different types of signals. The type of signal currently carried by the standby channel is automatically identified by a detector circuit, such as one that can automatically distinguish differences in the frequency spectrums of the different types of signals. A selecting circuit responds to the output of the detector circuit by selecting between first and second transmitting devices in the common channel, thereby dedicating it to the identified type of signal.

Abstract: A digital phase/frequency detector circuit in a phase locked loop comprises multiple bistable devices which are clocked up and down respectively by input and references digital signals to generate square waves. The duty ratio corresponds to the phase/frequency difference and sweeps repetitively between minimum and maximum values as the phase/frequency difference changes monotonically. The square waves are combined logically and additively in the output. The output is integrated to obtain an ever increasing output over many cycles of the phase/frequency difference until the maximum is reached depending on the number of bistable devices which are used. Added circuitry is used to avoid coincidence problems in the clocking input and reference digital signals, to minimize resultant irregularities, and hold the bistable devices at maximum or minimum, as appropriate, until the direction of phase/frequency difference reverses.

Abstract: A receiver comprising a multi-path detector which comprises a frequency noise peak detector, an AM-detector and a weighting circuit. When noise peaks and amplitude modulations occur in an antenna input signal selected by a diversity switch on account of a control signal of the weighting circuit one of a number of antennas is switched to. This switching is audible to an annoying degree. By inserting a threshold arrangement (31, 32) in the detector, by means of a low-pass filter and a rectifier circuit, an instantaneous threshold voltage is generated varying with the frequency swing of the modulating signal. With a large swing, corresponding with a large amplitude of the modulating signal, switching is audible to a less annoying degree. On the other hand, at moments when the modulating signal has a small amplitude, switching may take place more frequently and is less audible because of the small amplitude of the modulating signal.

Abstract: A clock regenerator generates a clock Co synchronized with an input data pattern and a data pattern generator generates a reference data pattern in synchronization with the clock Co. The reference data pattern and the input data pattern are compared by a data disagreement detector to detect disagreement therebetween. The disagreement detection signal thus obtained is frequency divided by a 1/m-frequency divider and its frequency-divided output is further frequency divided by a 1/-n frequency divider. The frequency-divided output of the 1/n-frequency divider is provided to a bistable flip-flop, placing it in one stable state. The logical sum of the output of the flip-flop in the one stable state and the 1/m-frequency divider is obtained, as an inhibit pulse, by an AND gate, and the inhibit pulse is applied to another AND gate to inhibit the passage therethrough of the clock Co to the data pattern generator, delaying the generation of the reference data pattern in the data pattern generator.

Abstract: An amplitude-adaptive vector quantization system intended for efficient signal coding and decoding. A mean value separation circuit (2) separates the mean value from an input signal which has been divided into blocks, and a tree-search vector quantizer (6) implements tree-search inner product vector quantization so that index information is truncated depending on the detected vector amplitude, thereby reducing the volume of information for transmission.