Abstract: A device for objectively evaluating the quality of a digitally transmitted picture. This device compresses encoded pictures x1 and x2 transmitted on two links that are decoded by a first decoder and a second decoder. A variance value &sgr;2(x1) of the decoded picture decoded by the first decoder is measured by a variance measuring unit. A variance value &sgr;2(x1−x2) of a signal indicative of a difference between the decoded pictures decoded by the first and the second decoders is measured. These two variance values are used to determine image quality.

Abstract: A measuring system of transmission characteristics comprises a reference signal light generator for generating reference signal light of a reference wavelength optically intensity-modulated at a reference frequency, a measuring signal light generator for generating measuring signal light of a measuring wavelength optically intensity-modulated at a measuring frequency synchronizing with the reference frequency, a multiplexer for multiplexing the reference signal light and measuring signal light respectively generated by the reference signal light generator and measuring signal light generator and outputting them onto a to-be-measured optical line, a photodetector for converting the lights propagated on the to-be-measured line into electric signals, a reference frequency extractor for extracting the component of the reference frequency from the output of the photodetector, and a phase detector for detecting a phase of a frequency component corresponding to the measuring frequency contained in the output of the

Abstract: A dispersion compensating optical transmission line comprises a plurality of optical transmission fibers for transmitting signal light, at least one first dispersion compensator disposed at a first dispersion compensating cycle for compensating an accumulated chromatic dispersion of the signal light so that an average chromatic dispersion is equal to a first desired value, and a plurality of second dispersion compensators disposed at a second dispersion compensating cycle shorter than the first dispersion compensating cycle for compensating the accumulated chromatic dispersion of the signal light so that an average chromatic dispersion is equal to a second desired value which absolute value is larger than that of the first desired value.

Abstract: The apparatus 10 is set on the line between the first and second computers 1,2 which respectively communicates by a protocol, such as TCP, having a flow control. The delay between the first computer 1 and a position, at which the apparatus 10 is set, is less than the delay between the position and the second computer 2. The apparatus 10 sends and receives a packet to/from the computers 1,2. The apparatus 10 transfers to the second computer 2, a data packet sent from the first computer 1 and being larger than a maximum data amount notified by the second computer 2. The apparatus 10 transfers, to the first computer 1, a data packet sent from the second computer 2, but does not transfer, to the first computer 1, an ACK packet sent from the second computer 2. The apparatus 10 generates, instead of the second computer 2, an ACK packet for a data packet sent from the first computer 1 and then sends the ACK packet to the first computer 1.

Abstract: An optical repeater monitoring system, according to the invention, comprises an oscillating source, a reference signal transmitter for transmitting a reference signal of a predetermined frequency generated from an output of the oscillating source to a first optical fiber, and an optical repeater. The optical repeater has a first photodetector for converting light from the first optical fiber into an electrical signal, a reference signal extractor for extracting a component of the reference signal from an output of the first photodetector, a carrier generator for generating a carrier from an output of the reference signal extractor, a monitor signal modulator for modulating the carrier generated by the carrier generator with a monitor signal showing a operating state of the optical repeater, a transmitter for transmitting an output of the monitor signal modulator to a second optical fiber.

Abstract: The soliton pulse compression optical fiber comprises a core and a clad that surrounds the core for compressing the injected light pulse in width. The maximum relative index difference between the core and the clad is between about 1.2% and 2.5%. The core diameter of the soliton pulse compression optical fiber varies along the length of the soliton pulse compression optical fiber and the core has a step-like refractive index distribution. The optical fiber perform of the soliton pulse compression optical fiber comprises a core preform, which is to be a core of the soliton pulse compression optical fiber, and a clad preform that surrounds the core preform. The maximum relative index difference between the core perform and the clad preform is also between about 1.2% and 2.5%.

Abstract: An input video signal is distributed to two links. The distributed video signals are coded by encoders in a spacewise or timewise shifted manner, and then, are transmitted over the transmission links. On a receiving side, the video signals are decoded by decoders, respectively. An averaging processor determines an average of the video signals per pixel, and then, outputs it. A data selector selects an output from the averaging processor when the plural links are operated normally; to the contrary, it selects a decoded output on the normal link in the case where an accident occurs in any one of the plural links. Specific methods for shifting the video signals spacewise or timewise include: a method for shifting a timing of intra-frame coding; a method for shifting the video signals on the links by several pixels or lines at least one of upward, downward, rightward and leftward; a method for disposing a sampling conversion filter in at least one of the links; and the like.

Abstract: A TCP gateway terminates TCP flow control and retransmission control of TCP packets which are input from a transmitter side terminal, in place of a receiver side terminal. Also, the TCP gateway transfers the packet to the TCP gateway which is located on the opposite side, by using selective retransmission procedures in a data link layer using SSCOP and by using peculiar flow control procedures. In addition, the TCP gateway provides the process of transferring the packet to the receiver side terminal in accordance with the TCP process procedures in place of the transmitter side terminal, to a plurality of TCP connections simultaneously.

Abstract: An optical digital regenerator for digitally regenerating an input signal in an intact optical state. A first operating unit has a first probe light generator for generating a first probe light and a first optical operator for converting a waveform of the first probe light output from a first probe light generator according to an optical intensity waveform of the input signal light. A clock extractor extracts a clock component of the input signal light from a photocurrent generated by the first optical operator. A second optical operating unit has a second probe light generator for generating a second probe light pulsed in accordance with the clock output from the clock extractor and a second optical operator for sampling the second probe pulse light output from the second probe light generator.

Abstract: A control method of transmitting power in a cellular system includes a step of measuring a signal to interference power ratio of a received signal at said receiving side, a step of detecting frame errors of the received signal at the receiving side, a step of counting the number of the detected frame errors n(k) (k and n(k) are positive integers and 1≦k≦K) for every M(k) (M(k) is a positive integer) frames, or for last N(k) (N(k) is a positive integer) frames just before the frame error is detected, a step of adjusting a value of a target SIR depending on one or set of the counted numbers of frame error n(1) to n(K), a step of comparing the measured SIR with the adjusted target SIR to provide a compared result, and a step of controlling at the transmitting side the transmitting power depending on the compared result.

Abstract: A network interworking device for executing conversion between IP packets and ATM cells, the network interworking device being to be connected between an IP network in which information are transmitted in a form of the IP packets and an ATM network in which information are transmitted in a form of the ATM cells, the IP network having a hierarchy structure with an IP layer, the ATM network having a hierarchy structure with an AAL layer, the network interworking device comprising means for assembling a plurality of ATM cells in the ALL layer of the ATM network into an IP packet when the plurality of the ATM cells are to be transmitted to the same address in the IP communication network, the assembled IP packet being transmitted to the IP layer, and means for disassembling an IP packet in the IP layer of the IP network into a plurality of ATM cells, the disassembled ATM cells being transmitted to the AAL layer.

Abstract: To increase the number of multiplexed wavelengths and to improve transmission characteristics in a wavelength-division-multiplexed transmission, a bandwidth compressor for bandwidth-compressing the wavelength-division-multiplexed signal light is disposed at a front part of respective optical amplifiers and a bandwidth expander for bandwidth-expanding the wavelength-division-multiplexed signal light output from said optical amplifiers is disposed at a rear part of said optical amplifiers.

Abstract: There are provided an optical transfer characteristic measuring method and apparatus capable of measuring an optical transfer characteristic of an optical device on optical frequency axis in wide optical frequency bandwidth with high resolution. There are provided a variable wavelength sweep type light source capable of switching the wavelength of an optical signal generated therefrom stepwise and sweeping the optical frequency of the optical signal in a predetermined frequency range, and a variable wavelength reference light source capable of switching the wavelength of an optical signal generated therefrom stepwise and not capable of sweeping the optical frequency of the optical signal.

Abstract: A coding parameter extracting unit extracts predictive-coded mode information, motion vectors, and coded transformed coefficients from video-signal-demultiplexed information. An abrupt scene change judging unit uses a characteristic that scenes change greatly before and after an abrupt scene change, to classify blocks on the basis of the predictive-coded mode information among the compressed moving picture data, so that an abrupt scene change is detected. A special effect judging unit detects dissolve from motion characteristic values calculated from the values of motion vectors, predictive-coded picture characteristic values derived from coefficients on frequency domains in blocks, and the number of blocks each having a motion vector that is larger than a threshold; and detects wipe by motion characteristic values calculated from the values of motion vectors, and predictive-coded picture characteristic values derived from coefficients on frequency domains in blocks.

Abstract: A laser diode continuously laser-oscillates and its output light is applied to an optical modulator. A pulse driver drives the optical modulator according to a data to be transmitted. A phase modulator is driven by a phase modulator driver and phase-modulates the output from the optical modulator. The polarization direction of the incident light of the phase modulator is set so that the modulation efficiency of the phase modulator becomes the maximum. The output light of the phase modulator inputs a birefringent medium and applies to an optical transmission line after transmitting the birefringent medium. The principal axis of the birefringent medium is disposed so as to be at an angle of 45° to the polarization direction of the output light from the phase modulator.

Abstract: A method of transferring file of the present invention by the two simultaneous data transmissions comprises the steps of transmitting data in a forward direction starting from a first specified position to a bottom in the file, and transmitting data in a backward direction starting from a second specified position to a top in the file. And a method of transferring file in FTP of the present invention comprises the steps of establishing a control connection, establishing multiple data connection, dividing a file into segments from each arbitrary point in the file, transferring segments through each of the multiple data connections, respectively, and synthesizing file from the segments transferred through the multiple data connections.

Abstract: A variance between sequential video pictures is extracted, and then, a GOP boundary position is decided based on inter-frame variance information. Furthermore, simple motion estimation is carried out with respect to video pictures inside one GOP. If a motion variation between the video pictures is large, a small predictive frame interval is taken; to the contrary, if the motion variation is small, a large predictive frame interval is taken. The simple motion estimation is carried out between two downscaled feature planes at a timewise fixed interval with respect to a video picture which is discriminated to be an interlaced video picture, wherein a motion compensatory prediction error at that time is output as image variance information. If the image variance is small, coding is conducted by a frame structure; to the contrary, if the image variance is large, the coding is conducted by a field structure.

Abstract: An optical switching system is implemented by providing a transmitting section with a preparatory transmitted optical signal selector and a working transmitted optical signal splitter, which are each implemented by a 1×2 optical space switch, and by providing a receiving section with a receiving optical switch which is implemented by a 2×2 optical space switch, and with a preparatory receiving optical gate which is implemented by a 1×2 optical space switch. This makes it possible to switch between the working system and preparatory system without employing any 4×4 optical space switch, thereby implementing a practical optical switching system without causing such problems as communication interruption during maintenance or impairment of transmission path working efficiency.

Abstract: A corresponding MB2 for the left sequence is determined from the parallax vector of a coding-object MB1 of the frame Bi for the right sequence. The motion vector {circle around (2)} of the corresponding MB2 is used as an origin of the search area for finding the motion vector of the coding-object MB1. As an alternative, the motion vector {circle around (3)} of MB3 adjacent to the coding-object MB1 is used as an origin of the search area for finding a motion vector of the coding-object MB1. As another alternative, the motion vector {circle around (2)} or {circle around (3)}, whichever is higher in utility evaluation, is used as an origin. As a result, both the search area and the circuit size for detecting a motion vector can be reduced. This configuration provides a stereo video data motion vector coding apparatus small in circuit size and capable of detecting a motion vector with high accuracy.

Abstract: An optical beam diameter reducer for reducing a beam diameter of an optical beam comprises a three-layer structure composed of a central core, a refractive index inclined layer formed outside the core which refractive index gradually decreases toward the outside in the radial direction and a cladding layer formed outside the refractive index inclined layer.