Abstract: In a packet switching system of the present invention, a packet handler is facilitated for each incoming circuit to the switching system. The packet handler analyzes the header of each incoming packet from the correspondent circuit and decides the outgoing route of the packet. The packet is then sent out to an outgoing circuit of the decided route, the rest of it including the data field not being stored in the switching system, through a conventional cross-point switch for circuit-switching. Thus, elimination of storing the whole packet raises the efficiency of packet processing and shortens the processing delay. The use of a cross-point switch enables the functional sharing of the system by circuit-switched calls and packet-switched calls.

Abstract: A motion vector V.sub.x of a picture block X between a current input picture and a preceding frame picture is corrected to V.sub.p, when said motion vector V.sub.x differs from a motion vector V.sub.r of adjacent blocks of said current input block, and (S.sub.v.sbsb.x <T.sub.hl, and S.sub.v.sbsb.p .gtoreq.T.sub.h2) is not satisfied, where S.sub.v.sbsb.x is a block difference of the block X between the current frame F.sub.0 and the preceding frame f.sub.2 for said motion vector V.sub.x, V.sub.p is one of motion vectors V.sub.r giving the minimum value of S.sub.v.sbsb.r, and S.sub.v.sbsb.p is a block difference for said v.sub.p. The present invention provides correct motion vector of a moving object on a screen irrespective of noise in a picture signal and sudden intensity change. The present invention is applicable to a frame interpolation in a television standard system conversion system, and an efficient coding of a television signal.

Abstract: A device for burying a submarine cable under water by easily and accurately detecting the cable position and a method for guiding the same by utilizing the characteristics unique to submarine cables, by supplying an AC only to the portion of the cable between two arbitrary repeaters through a so-called transformer-coupling system to generate an AC magnetic field, and by detecting the magnetic field with a magnetic field detector.

Abstract: In a fluoride glass optical fiber with extremely small transmission loss for infrared light having a core layer and a clad layer each consisting mainly of ZrF.sub.4 - BaF.sub.2 - LaF.sub.3 - AlF.sub.3, NaF and H.sub.f F.sub.4 are used as additives to obtain a desired refractive index difference between the core layer and the clad layer. The mixing ratio of the NaF to the H.sub.f F.sub.4 satisfies the realtions;.vertline.0.25 .DELTA.H.sub.f F.sub.4 -3.DELTA.NaF.vertline..ltoreq.5,where .DELTA.NaF is the difference between the amount (mol %) of the N.sub.a F to be added to the core layer and that to be added to the clad layer, and .DELTA.H.sub.f F.sub.4 to be added to the core layer and that to be added to the clad layer.

Abstract: A frame rate conversion, for instance between NTSC and PAL, or SECAM, has been improved by interpolation system in which an interpolation is performed from picture elements of two consecutive frames of an original picture signal whose positions are shifted from the position of a picture element to be interpolated by amounts related to the move length of a picture block between the two consecutive frames period, instead of using picture elements of two consecutive frames of the original signal that have the same position coordinates as those of the picture element to be interpolated. Picture quality of the converted signal is improved in particular when a picture moves.

Abstract: The DPCM (differential pulse code modulation) for color television signal transmission has been improved both in picture quality and information compression, by a vector signal quantization called embedding quantization. According to the present invention, vector signal comprising a plurality of elements is quantized while the quantized output signal is obtained after a plurality of quantization and prediction operations. Number of repetition times of the quantization and prediction is for instance equal to the number of elements composing vector signal. A vector is for instance composed of three elements relating to red, green, and blue primary signals of a color television signal.

Abstract: This invention aims to provide an optical fiber which is capable of sufficiently dissipating the leaky mode in the cladding thereof characterizing in those particulate substances such as minute hollow glass beads having different refractive indices are sealed in the primary buffer layer or on the boundary between the primary buffer layer and the cladding, or between the primary and secondary buffer layers of the optical fiber, whereby nucleous elements for scattering or absorption can be formed uniformly.

Abstract: In order to prevent tap coefficient values from drifting toward excessively large values or divergence, an adaptive echo canceller is provided with a correction signal controller which (a) reduces the tap coefficient values upon the polarities of the tap coefficient signal and the tap coefficient correction signal coinciding and (b) increases the tap coefficient values upon the polarities differing.

Abstract: A feed forward microwave power amplifier having a divider for dividing an input signal into two parts, a first main amplifier for amplifying one of the divided signals, means for providing a part of the output of the first amplifier as a signal S.sub.1, means for providing a signal S.sub.2 by another output of the divider, a subtractor for providing the difference between S.sub.2 and S.sub.1, a second amplifier having the same gain as that of the first amplifier for amplifying this difference, a 3 dB coupler for coupling an output S.sub.4 of the first amplifier and an output S.sub.4 e, where e is a constant, of the second amplifier to provide coupled power which is free from distortion, and adjusting means for adjusting the level of signals S.sub.1 and S.sub.2 so that S.sub.2 is higher than S.sub.1, and the value e is in the range between 0.2 and 0.5.

Abstract: A device for burying a submarine cable under water by easily and accurately directing the cable position and a method for guiding the same by utilizing the characteristics unique to submarine cables, by supplying an AC only to the portion of the cable between two arbitrary repeaters through a so-called transformer-coupling system to generate an AC magnetic field, and by detecting the magnetic field with a magnetic field detector.

Abstract: Amorphous thin film with easy magnetization axis perpendicular to film surface for magneto-optical recording with low recording power and high S/N in reading signal is set forth. The medium is an alloy of heavy rare earth element and iron with substitution of some heavy rare earth elements by light rare earth element, and the preferable chemical formula of the thin film is (R.sub.z A.sub.1-z).sub.x Fe.sub.1-x, or [(R.sub.z A.sub.1-z).sub.y B.sub.1-y ].sub.x Fe.sub.1-x where R is a light rare earth element, A and B are heavy rare earth elements, and the atom ratios satisfy 0.15.ltoreq.x.ltoreq.0.35, 0.00<y<1.00, 0.00<z<1.00. Recording is effected by using Curie point, or magnetic compensation temperature, and reading of information is effected by using the Kerr effect.

Abstract: A phase synchronization circuit of a phase lock loop having a phase comparator, a loop filter or a low-pass filter and a voltage controlled oscillator controlled by output of said loop filter has been improved by a phase comparator having the hysterisis characteristics in which one of a pair of output levels is provided for each input phase difference according to phase error direction, except in the vicinity of a stable point of phase.

Abstract: In a speech transmission or storage system using LPC parameters and a Baseband Signal derived from the prediction error signal, the synthesis excitation signal is formed from the baseband plus high-frequency regeneration, which is then spectrum-flattened for proper synthesis.

Abstract: A mechanical translation system is provided to obtain a sentence of target language from the tree expression of source language. The processing progresses as follows: First, a pattern which coincides with partial structure, including the highest node, of the tree fragment chosen, is selected among patterns previously contained in the pattern dictionary. The pattern has a production rule attached to the pattern.

Abstract: A fluoride glass for infrared optical transmission fiber is purified for dehydration and deoxidation to reduce transmission loss by reacting melted fluoride glass with NF.sub.3 gas at temperature between 500.degree. C. and 800.degree. C. No scattering loss is increased by the present purification as decomposed product in the reaction does not precipitate.

Abstract: Elongation distortion at any location of an optical fiber cable is measured by using the principle of the stimulated Raman effect in which a stokes beam with a little frequency difference from that of a pumping beam is generated when a pumping beam and a seed beam with the same frequency as that of the stokes beam meet in a Raman material like an optical fiber cable. Due to the fact that the group refractive index of an optical fiber cable for a pumping beam is different from that for a stokes beam, elongation of a cable is measured by observing time difference of the arrival of pumping beam and stokes beam. The location that the pumping beam meets with the stokes beam can be adjusted merely by shifting the pumping pulse, then, elongation distortion at any location can be measured. According to the invention, the pumping pulse is applied to the cable to be tested from both the ends of the cable with one of the pumping pulse delayed according to the desired location for meeting of two pulses.

Abstract: The error rate of a signal is monitored by sampling an input signal with a first clock and also with second and third clocks phase delayed in equal but opposite directions with respect to the first clock, and then logically combining the first through third sampled outputs in order to obtain an error signal.

Abstract: An optical de-polarizer is implemented by using an optical fiber, and/or a beam splitter coupled with output of said optical fiber. An optical fiber is longer than a predetermined length so that equation .vertline.t.sub.1 -t.sub.2 .vertline.>t.sub.c is satified where t.sub.1 is polarization mode dispersion in a first optical fiber, t.sub.2 is a polarization mode dispersion in a second optical fiber which is coupled with output of the first optical fiber, and t.sub.c is coherence time of a beam defined by an optical source. According to the present invention, one of the conditions (1) an angle between polarization axis of the first optical fiber and polarization axis of the second optical fiber is 45.degree., and (2) an angle between polarization axis of the optical fiber and polarization axis of the beam splitter is 45.degree., is satisfied.

Abstract: A bit error rate of M-phase digital phase-modulated waves is measured by the steps comprising multiplying a received wave by M, phase-detecting the M-multiplied signal either directly or after frequency conversion, detecting errors by comparing the output level of the phase detection with a threshold, and counting the number of such errors. By employing above mentioned system, a bit error rate can be measured easily and accurately by a simple circuit structure.

Abstract: A connector for connecting together in a water-tight housing various optical instruments of an underwater or submarine arrangement having optical fiber cables. The connector is constructed in a manner such that a plug containing the terminals of optical fiber cables is connected in an easily attachable/detachable fashion to a receptacle which is mounted on the water-tight housing. Sealing material is interposed between the water-tight housing and the receptacle and between the receptacle and the plug for preventing the infiltration of water or sea water into the water-tight housing.