Abstract: The present invention provides a low-cost optical transmission system using a plurality of subscriber lines which is capable of efficiently utilizing an optical transmission path. A communication status observing section 116 in a transmitting device 1 classifies subscribers into a plurality of groups based on a communication status at each subscriber end, and outputs constellation level information and level information which are different for each group. For each constant cycle, a modulation control section 117 and a gain control section 118 respectively set a QAM constellation level and a signal level which are different for each group and used in a basic modulating section 103.

Abstract: A light emitting section outputs an optical signal having an intensity corresponding to a transmission timing signal, the optical signal modulated based on a radio transmission signal. A received photocurrent detection section detects an intensity of an optical signal received by a light receiving section. In accordance with the detected intensity, a high frequency amplification section amplifies the output signal of the light receiving section, and a transmission timing signal reconstruction section reconstructs the transmission timing signal.

Abstract: Modulators respectively modulate baseband signals into IF signals having different frequencies. A multiplexer multiplexes the IF signals. An electrical-optical converter intensity modulates the multiplexed IF signals into optical signals. A local oscillation signal source outputs a predetermined local oscillation signal. An external modulator intensity-modulates the optical signal using the local oscillation signal. An optical branching portion branches the intensity-modulated optical signal and respectively outputs branched optical signals to radio base stations. An optical-electrical converter converts the optical signal into an electric signal, to obtain an RF signal by frequency-converting the IF signal. An antenna only transmits a component having a desired radio frequency extracted in a band filter from the RF signal to a subscriber terminal.

Abstract: In order to improve a transmission speed of multilevel light transmission, increasing a number of light emitting elements is effective. However, in a method in which light outputs from a plurality of light emitting elements are added, because common mode noise contained in the light outputs is added, deterioration in transmission quality caused by the common mode noise prominently arises. Therefore, a difference between two light outputs is previously assigned to data to be transmitted. Specifically, an optical transmitter 102 converts data Dt to multilevel optical signals OSm1 and OSm2 and transmits the converted multilevel optical signals to an optical receiver 103. The optical receiver 103 restores the data Dt which is previously assigned to a difference between electrical signals ESr1 and ESr2 converted from the multilevel optical signals OSm1 and OSm2.

Abstract: A space optical transmission apparatus is provided which achieves high-speed simultaneous space optical transmission with respect to a plurality of terminals. In the space optical transmission apparatus, a light receiving section receives an optical signal from a terminal. A control section estimates how much optical axes of a master station and the terminal are deviated from each other, based on the received optical signal. The control section selects one of a plurality of light sources which requires a smallest amount of shift of an optical axis thereof, based on the estimated optical axis deviation amount, so as to communicate with the terminal.

Abstract: A new, more efficient memory translation algorithm facilitating the acquisition of a most appropriate translation in a target language from among those of nearly narrowed-down candidates of translation by separately applying the so-called dimension reducing functions of a template automaton and the LSI (latent semantic index) technique. Both the template automaton and the LSI principle play an important role in implementing an efficient process of narrowing down an efficient solution space from among the many example sentences of the databases in a target language by exploiting their respective unique search space reduction function. Once developed into a fully operational system, an expert editor rather than an expert translator can tune up the translation memory system, markedly widening the range of available experts who can utilize the system.

Abstract: A dynamic traffic control method is disclosed that controls traffic in a radio network system where a radio network controller causes plural radio base stations to change radio outputs. The method comprises a step of measuring a channel utilization rate of each of cells of the radio base stations every predetermined period, a step of predicting whether the rate of a first cell of the cells reaches an implementation level, at which radio output control over the first cell is required, in a next period based on a movement of the rate in the past if the channel utilization rate of the first cell is at a warning level, and a step of reducing the radio output of the first cell and increasing the radio output of a second cell adjacent to the first cell if the rate of the first cell is predicted to reach the implementation level.

Abstract: A computerized method for automatic document classification based on a combined use of the projection and the distance of the differential document vectors to the differential latent semantics index (DLSI) spaces. The method includes the setting up of a DLSI space-based classifier to be stored in computer storage and the use of such classifier by a computer to evaluate the possibility of a document belonging to a given cluster using a posteriori probability function and to classify the document in the cluster. The classifier is effective in operating on very large numbers of documents such as with document retrieval systems over a distributed computer network.

Abstract: An accurate grammar analyzer based on a so-called POST (part-of-speech tagged) parser and a learners' model for use in automated language learning applications such as the template-based ICALL (intelligent computer assisted language learning) system.

Abstract: To provide an optical transmission system which cancels out noise components and whose construction cost is lower than that of the conventional system, the present invention is an optical transmission system for transmitting an optical signal from an optical transmitter to an optical receiver and outputting an output electrical signal after a noise canceling process is performed. The optical receiver and transmitter are connected by one optical fiber, through which an optical signal is transmitted before being intensity-modulated.

Abstract: A SW (70) receives an Ethernet® signal from an outside of areas E and F. The SW (70) selects and outputs the obtained Ethernet® signal to any one of APs (91a to 91e) in accordance with a network structure managed by the SW (70). The AP (91a to 91e) converts the Ethernet® signal to an electrical signal type wireless LAN signal, which is in turn output to a main station (10). The main station (10) frequency-multiplexes the signal output from each of the APs (91a to 91e), and converts the signal to an optical signal, which is in turn output to sub-stations (20a and 20b) The sub-station (20a and 20b) transmits the signal transmitted from the main station (10) to a terminal in the form of a wireless radio wave. Thereby, when a plurality of communication areas are present, the accommodation capacity of an AP can be effectively utilized in each communication area.

Abstract: An arrangement is made such that the magnitude of cure shrinkage obtained by multiplying the thickness of a resin layer 2 between a master mold 1 and a negative mold substrate 3 by the cure shrinkage ratio of the resin and the magnitude of cure shrinkage obtained by multiplying the thickness of a resin layer 4 between the negative mold 23 and the surface of the spherical or flat substrate 5 by the cure shrinkage ratio of the resin can be compensated for by each other. In accordance with this method, an aspherical optical element having a higher precision than ever can be formed at reduced cost by a replica method involving the addition of a resin layer to the surface of a spherical or flat substrate.

Abstract: An accurate grammar analyzer that works effectively even with error-ridden sentences input by learners, based on a context-free probabilistic statistical POST (part-of-speech tagged) parser, for a template-automation-based computer-assisted language learning system. For any keyed-in sentence, the parser finds a closest correct sentence to the keyed-in sentence from among the embedded template paths exploiting a highest similarity value, and generates a grammar tree for the correct sentence where some ambiguous words are preassigned by expert language teachers. The system marks the errors under the leaves of the grammar tree by identifying the differences between the keyed-in sentence and the grammar tree of the correct sentence as errors committed by learners. By identifying most frequently recurring grammatical errors of each student, the system sets up a learner's model, providing a unique level of contingent remediation most appropriate to each learner involved.

Abstract: The present invention aims to provide a radio frequency optical transmission system having a simple structure while allowing a signal to be prevented from being lost due to the influence of chromatic dispersion without requiring considerably high adjustment accuracy. An optical intensity modulation section (14) of a control station (10) modulates an intensity of an optical signal generated by a light source (12) with a radio frequency signal, and divides the optical signal having its intensity modulated into two optical signals. The optical intensity modulation section (14) outputs one of the two optical signals without processing it, and the other optical signal is inverted (i.e. 180 out of phase) and outputted. The two optical signals are transmitted through two separate optical fibers (31 and 32) to base stations (21 through 2n). Each of the base stations (21 through 2n) receives one of the two optical signals transmitted via the two optical fibers (31 and 32).

Abstract: The present invention is directed to a wireless communication system capable of keeping a level of a wireless signal received by a relay apparatus (20) within a predetermined dynamic range. In a control apparatus (10), a transmitting section (102) converts a downstream electric signal into a downstream optical signal and transmits the downstream optical signal to the relay apparatus (20) via an optical transmission path (40). The relay apparatus (20) converts the received downstream optical signal into a downstream electric signal and transmits the downstream electric signal as a wireless signal to a wireless communication terminal (30) from a transmitting/receiving antenna section (204). In the relay apparatus (20), a level adjustment section (207) adjusts the level of the wireless signal transmitted by the relay apparatus (20) such that the receiving level of the wireless signal received by the relay apparatus is kept within a predetermined range.

Abstract: A wireless access system and method are provided by which the wireless communications area covered by a single access point is increased while maintaining the maintainability of the access point, minimizing an increase in system cost, and avoiding the hidden terminal problem. An access point (12) and terminals (16a to 16c) are connected via a master station (13), an optical multiplexing/demultiplexing section (14), and slave stations (15a to 15c). A downstream signal to the terminals (16a to 16c) from the access point (12) is transmitted such that the master station (13) outputs the downstream signal to each of the slave stations (15a to 15c) in a distributed manner through the optical multiplexing/demultiplexing section (14).

Abstract: A CATV station apparatus 100 subjects received optical signals to processes of optical-electrical conversion, signal separation, coupling, and demodulation for obtaining an uplink signal. A received photocurrent monitoring section 170 compares a received photocurrent at a optical receiving section 110 with a predetermined reference current. If the received photocurrent is equal to or higher than the reference current, an amplifying section 130 amplifies a signal output from a signal separating section 120 at a predetermined level. If the received photocurrent is lower than the reference current, on the other hand, it is determined that a non-linear phenomenon, such as stimulated Brillouin scattering, has occurred in an optical fiber 200. The amplifying section 130 then outputs a signal at a level which does not affect, even after being coupled with other signals, communications performed by other optical transmission systems.

Abstract: Frequency converting sections 104a to 104n convert the frequency of modulated transmission signals to signals of an intermediate frequency by multiplying the transmission signals by a local signal; filter sections 105a to 105n attenuate the transmission signals after frequency conversion in the frequency regions outside the frequency band of the desired signals; and E/O sections 106a to 106n convert the transmission signals from electric signals to optical signals and output them to the O/E sections 151a to 151n of the base station apparatus 150.

Abstract: To retrieve an optimum template pattern in response to an input sentence, a set of templates is arranged in a plurality of template blocks containing an arbitrary number of sentence components, including grammatically correct and/or incorrect components. A score is assigned to every word in the set of templates according to its importance. The candidate template patterns and the input sentence are retrieved, the scores of the matched words are calculated, and the total of the scores of the entire paths are calculated. Optimum level comparison values are then calculated using the score of the matching words as the numerator and the total score as the denominator. The candidate template pattern having the largest optimum level comparison value among optimum level comparison values that provide the largest numerator, is selected as the optimum template pattern. The input sentence is then corrected using this optimum template pattern.

Abstract: The present invention provides a low-cost optical transmission system using a plurality of subscriber lines which is capable of efficiently utilizing an optical transmission path. A communication status observing section 116 in a transmitting device 1 classifies subscribers into a plurality of groups based on a communication status at each subscriber end, and outputs constellation level information and level information which are different for each group. For each constant cycle, a modulation control section 117 and a gain control section 118 respectively set a QAM constellation level and a signal level which are different for each group and used in a basic modulating section 103.