Abstract: An optical submarine branching unit employing an optical circuit structure which is small in the number of optical components used, permits reduction of optical insertion loss and is well compatible with the ADD/DROP function suitable for use in wavelength multiplex transmission. An optical fiber pair provided in an optical submarine cable connecting between first and second points is branched toward a third point, an optical circulator capable of reversing the direction of rotation of an optical input/output is provided as optical switching means by which, in the event of a failure in the branch transmission system having the branched optical fiber pair, the optical fiber pair is connected between the first and second points directly without being branched to the third point.

Abstract: The object of this invention is to provide a facsimile communication supplementary service device that allows facsimile communication users to receive accurate service information from telephone switching facilities without performing any operations whatsoever. When a call is received, the facsimile signal analysis and decision part determines whether said call is a facsimile signal, and if it is, monitors the communication until it is completed. When the communication is completed, the charging system calculates the communication charge and the facsimile response part prepares the facsimile information. Then, if the originating party requested for the automatic immediate charge notification service, then the system calls back the originating terminal and sends said facsimile information. As a result, the originating terminal, if it is a facsimile terminal, can receive information on communication charge as a facsimile message. Consulting information may also be added to said charge information.

Abstract: An object of the present invention is to provide an optical add-drop multiplexer capable of giving improved characteristics with a simple, inexpensive arrangement which needs not a corresponding number of optical bandpass filters to the wavelength components of a light signal to be carried. The wavelength components .lambda.1 to .lambda.n of an input n-wave signal is received by an input optical fiber and transmitted through an optical circulator and an optical fiber to an optical bandpass filter which allows a specific wavelength .lambda.1 to pass but rejects the other wavelengths .lambda.2 to .lambda.n. While the rejected wavelengths .lambda.2 to .lambda.n are returned back to the optical fiber, the specific wavelength .lambda.1 runs through another optical fiber and another optical circulator and then is dropped from an output optical fiber. Meanwhile, another signal component of the wavelength .lambda.

Abstract: An optically amplifying transmission system available for wider signal bands includes an optical transmission line 42 divided into two sections 42a and 42b, optically amplifying repeaters 48a having 7 m-long erbium-doped optical fibers to repeat transmission optical fibers 46a in the section 42a, and optically amplifying repeaters 48b having 10.8 m-long erbium-doped optical fibers to repeat transmission optical fibers 46b in the section 42b. The transmission optical fibers 46a an 46b are optical fibers absolutely identical in construction and length.

Abstract: There is disclosed a reshaping device for optical short pulses to effectively perform reshaping of and eliminate noise from an optical short pulse of a pulse width of pico second order less than a carrier life time. Input optical short pulses are applied to a saturable absorption element, while an assist light of a wavelength longer than that of the input optical signal pulses is also applied to the saturable absorption element to accelerate, by stimulated emission, recombination of excited electrons and holes produced in the saturable absorption element in response to the input optical signal pulses, so that the input optical signal pulses reshaped are derived from the saturable absorption element.

Abstract: The short optical pulse generator is provided with a semiconductor laser which oscillates continuously at a single wavelength, a semiconductor electro-absorption type optical modulator which performs the intensity modulation of the output light from the laser, and a sinusoidal voltage generator and a DC voltage generator for driving the electro-absorption type optical modulator. A DC voltage is applied to the electro-absorption type optical modulator so that the output light from the laser is sufficiently extinguished. By applying a sinusoidal voltage to the optical modulator, short optical pulses are generated.

Abstract: An optical communication system in which the degradation of the signal-to-noise-ratio during transmission is alleviated. An optical signal from an optical transmitter is propagated over a transmission line comprising optical fibers and optical amplifiers, and received by an optical receiver. The signal-to-noise ratio is improved by inserting an injection-locked laser device at a specified point on the optical transmission line, improving the transmission characteristics of the optical communication system.

Abstract: A wavelength division multiplexed (WDM) optical communication method and apparatus uses a pre-emphasis technique to adjust the attenuation or amplification of a particular optical channel at a transmitter terminal to produce identical signal-to-noise ratios for all of the optical channels at a receiver terminal. The pre-emphasis adjustments to the transmitted signals are made on the basis of signal-to-noise ratio measurements performed at the receiver terminal. The signal-to-noise ratio values for each channel are transmitted through a facing line that is also used to transmit data along optical communication lines from the receiver terminal back to the transmitter terminal. The present invention also provides a method and apparatus for monitoring optical transmission paths for the deterioration of optical amplifier repeaters or an optical fiber. The optical signals are then adjusted to account for the location of the particular amplifier or fiber that has deteriorated.

Abstract: An optical communication system of a construction wherein the average wavelength dispersion value of the transmission optical fiber used, the optical output intensity of each optical amplifier repeater inserted in the transmission optical fiber and the widths of return-to-zero optical pulses transmitted over the transmission line are determined so as to compensate for the pulse compression effect by the nonlinear optical effect produced on the optical pulses by the pulse spreading effect by the wavelength dispersion effect. An optical multiplexer in the optical transmitting device time-division multiplexes the return-to-zero optical pulses, and the optical multiplexed signal is provided as an alternating-amplitude optical signal with the amplitudes of the return-to-zero optical pulses alternated.

Abstract: A laser light generator includes an adder 12 which adds an optical frequency modulation signal Sm onto a d.c. voltage for driving a laser diode 10 for continuous laser oscillation, and applies the sum signal to the laser diode 10 to drive it. An light output from the laser diode 10 is introduced to an optical intensity controller 14 that is controlled by a control signal prepared by adjusting the optical frequency modulation signal Sm both in phase and in amplitude by a phase adjusting circuit 16 and an amplitude adjusting circuit 18. The optical intensity controller 14 may be an electroabsorption modulator that changes its transmissivity in response to an output voltage of the circuit 18. Quantities of adjustment by the circuits 16 and 18 are determined so that fluctuation in transmissivity of the optical intensity controller 14 suppresses intensity fluctuation of the light output of the laser diode 10.

Abstract: A remotely operated submersible robot 10 is provided with two differential triaxial orthogonal dc magnetic sensing units, 1 and 2, each comprising two triaxial orthogonal dc magnetic sensors spaced at a predetermined distance apart and with their corresponding axes set in parallel; each triaxial orthogonal dc magnetic sensor incorporating three dc magnetic sensing elements sensitive only to a magnetic field in a specific axial direction and disposed such that the axial directions of respective dc magnetic sensing elements cross each other at right angles. Analog signals sent out from the differential triaxial orthogonal dc magnetic sensing units 1 and 2 are converted into digital signals by an analog-to-digital converter, and transmitted to a mother ship 20 via a tether cable 6.

Abstract: To provide a fast video browsing system in which a fast playback suitable for keeping track of the contents can be performed by adaptively determining the number of skipped pictures according to the motion vector of picture, and displaying the picture after the skipped pictures. In step S1, pictures to be fast viewed are sequentially inputted, and in step S2, n pictures are skipped. In step S3, the picture after the n skipped pictures is displayed. In step S4, using the picture before or after the displayed picture with respect to time, a motion vector at one frame interval is detected, and in step S5, the number n of skipped pictures is determined from the motion vector. As a result, the number of skipped pictures can be adaptively determined by the motion vector of a picture.

Abstract: It is the object of the present invention to provide a fixed earth station in which many antennas can be placed in a site area limited to one-several tenth of the conventional one.On a rotatable base 2, a plurality of antennas 1a to 1e are mounted. A control unit 4 controls the rotation angle of a drive unit for driving the base by the previously known orbital parameters of communication satellites. Further, the azimuth angle and the elevation angle of the respective antennas are controlled by antenna control units 5a to 5e, and the antennas catch and track communication satellites having appeared in the sky. As a result, the rotation angle of the base 2 can be set so that a beam accessing a satellite of a low elevation angle is not intercepted by other antennas. In addition, the area in which the antennas are placed can be reduced to about 1/50 of the conventional one.

Abstract: An optical transmitter which reverses the ON-OFF state of the optical intensity of a bright soliton lightwave and generates a dark soliton lightwave having an optical phase shift, an optical receiver for the dark soliton lightwave, and a superfast, high-capacity optical transmission system which is capable of increasing the soliton pulse array density while suppressing timing jitter. The optical transmission system is provided with the optical transmitter which transmits a dark soliton lightwave having digital information, the optical receiver which receives the dark soliton lightwave as a return-to-zero pulse and a transmission optical fiber interconnecting the transmitter and the receiver.

Abstract: A device for modulating optical short pulses, while preventing a pulse compression optical fiber from degradation of the transmission characteristics even if the length of the pulse compression optical fiber varies, utilizes an optical short pulse generator 1, a pulse compression optical fiber 2, an optical divider 3, a photodetector 6, an amplifier 7, a band pass filter 8, a phase comparator 9, a loop filter 11, and a driving signal generator 12. The loop which comprises loop filter 11 and driving signal generator 12 controls an oscillation frequency in a VCO 12-1 so that the phase of a compressed optical pulse fed to an optical intensity modulator 4 is identical to the phase of a data signal that is synchronized with a reference clock and used to modulate the compressed optical pulse. In this manner, the extinction ratio of the modulation output is not degraded even if the length of the pulse compression optical fiber 2 varies due to ambient temperature variations.

Abstract: An input image and a reference image which are input to a contracted image processing unit, are converted into contracted image, which are constituted by average values of blocks of the input and reference frames. With respect to the contracted image, an inter-frame difference unit determines the inter-frame difference D.sub.n between the input and reference images and the temporal change .DELTA.D.sub.n in the inter-frame difference. A first judging unit judges, according to the above data, the input frame to be a non-cut frame, a cut frame or a cut frame candidate. When the input frame is judged to be a cut frame, an output unit effects a cut frame output, and then the next input frame processing is performed. With respect to a cut frame candidate, a chrominance histogram correlation unit calculates the correlation .rho. of the color distribution of the chrominance histogram by using contracted image of chrominance signal. A second judging unit makes an overall judgment on the inter-frame difference D.sub.

Abstract: A high power laser transmitting fluoride glass fiber of an enhanced 2.94- .mu.m laser damage threshold value is disclosed, in which either of the core with a high refractive index and the cladding with a low refractive index is formed of fluoride glass which contains fluorine (F) as a component but has it substituted with 0 to 4.1 mol % of bromine (Br), chlorine (Cl), or bromine and chlorine. The optical fiber of the present invention may have its core formed of fluoride glass and its cladding formed of fluorine-contained resin, and the core glass has a composition that 70 to 80% of fluorine (F) is substituted with 0 to 4.1 mol % of bromine (Br), or chlorine (Cl), or bromine and chlorine.

Abstract: Registered on the voice dial card, which is not shown in the drawings, are a number for accessing the dial-less calling service and a user identification number. Public telephone 1 is equipped with reader 1a that reads the card. When the card is inserted in direction p, the aforementioned access number and user identification number are read by the reader. These numbers are automatically originated from public telephone 1, and switch 3 connects the line to controller 5 according to the access number. Controller 5 judges whether the customer is eligible to receive the dial-less calling service according to the user identification number, and if it judges that the customer is eligible to receive the service, it requests the caller to speak the destination name. In the following steps, the well known voice dialing is performed. According to this invention, a user can access voice dialing service from public telephones as well as non-public telephones.

Abstract: It is sought to provide a motion vector post-processor, which can improve motion vectors of blocks containing boundaries of objects in different movements to provide as visually satisfactory interpolated field quality as possible. Motion vectors generated in a motion estimator are stored in a memory, and their magnitudes are calculated in a magnitude calculator. Magnitude data is fed to an order statistics filter. The filter detects the serial number of a motion vector (for instance third motion vector) less than a magnitude at the center among a plurality of (for instance nine) input motion vectors and outputs corresponding serial number data to the memory. The memory outputs the vector corresponding to the input serial number data to a field interpolator. According to the invention, it is possible to provide a motion vector of an area containing small movement as motion vector of a block containing mixed movements.

Abstract: It is sought to provide a coding apparatus which permits high efficiency coding of bi-level images with black-and-white pixels halftoned with error diffusion algorithm. An image input/pixel selection unit selects, from an input image as a bi-level image with black-and-white pixels halftoned with error diffusion algorithm, first selected pixels with respect to a pixel "?" to be coded and second selected pixels as peripheral pixels with respect to the first selected pixels. The first selected pixels are fed to a pixel pattern binary scale translator for translation into a binary number. The second selected pixels, on the other hand, is fed to a pixel value adder for counting of black pixels. The count is fed to a binary scale translator for translation into a binary number. The binary number outputs of the pixel pattern binary scale translator and the binary scale translator are combined to be input to an address input terminal of a ROM having a coding information table.