Abstract: In a controller for a semiconductor laser light source, a portion of light emitted from the source is fed back to regulate the spectral line width of the source and to regulate the oscillation frequency of the source in terms of the phase of the portion or the driving current for the source, the very small portion of the light is allowed to pass through an external resonator so as to be subjected to optical frequency discrimination by an optical frequency discriminator, the portion does not need to be divided from a communication signal light. Therefore, the communication signal light can be undergo a loss.

Abstract: In an image coding system having a plurality of coding characteristics, such as quantization characteristics, information of a digital image signal sequence is monitored in each of a number of predetermined intervals by forming a histogram of a sequence of coefficients which is calculated from the digital image signal sequence in accordance with each of the coding characteristics. The amount of information is calculated by summing up the coefficients in relation to every one of the coding characteristics. An optimum one of the coding characteristics is indicated by the coding control circuit to code the coefficient sequence into a sequence of coded signals in accordance with the optimum coding characteristic. The coefficient sequence in each frame may be divided into a sequence of blocks each of which is judged to be either valid or invalid in relation to each coding characteristic. Results of judgement may be included in the amount of information.

Abstract: A PSK signal which is subject to frequency fluctuation and noise is demodulated by using a regenerated carrier signal and a regenerated clock signal which are derived from the output of bandpass filters (19, 24) for increasing the carrier to noise ratio C/N. The center frequency of bandpass filter is determined by converting the received time domain signal to a frequency domain signal by using a FFT (fast Fourier transform) circuit, and estimating the center frequency on the frequency spectrum based on the fact that the modulated signal component exists only on a portion which has a high level on the frequency spectrum.

Abstract: Four channels of group 3 facsimile signal are transmitted through a digital transmission line of Bearer rate 64 Kbits/s for a speech signal. A facsimile signal is separated into a tone signal, a binary control signal, and a picture signal, each converted to digital form. Then, a block having 160 bits is assembled including 96 data bits and some control bits, and a justification bit. A justification bit matches clock rate of the present system with clock rate of an external digital transmission line by deleting or inserting one bit in a block. Thus, a conventional group 3 facsimile device is coupled with 16 Kbits/s digital transmission line with no design change for the facsimile device itself.

Abstract: In a communication system which handles both a demand call, and a reservation call which appoints the start time and the end time of the communication, the reservation call must be connected at the desired time even if the circuits are full of the demand calls. The service process node which has a data base storing the information of the reservation calls, tries to connect the reservation call repetitively until the scheduled end time of the reservation call in every predetermined pause, if the circuits are full of the demand calls. Also, when it is anticipated that the circuits would be full at the desired time, the service process node suggests to the subscriber the alternative time for reservation.

Abstract: An up-link power from an earth station in a satellite communication system is controlled to compensate rain attenuation caused in an up-link so that the transmission power of the earth station is adjusted according to the difference between the level of a received reference signal, which is sent from a reference earth station to the satellite, and the level of its own received signal which is transmitted to the satellite from itself and is received at its own station after being relayed by the satellite. A transmission power of the reference earth station is adjusted so that the level of the received reference signal at the satellite is constant.

Abstract: In an encoding system responsive to a sequence of coefficient signals which results from a predetermined linear transform and which is divided into a sequence of blocks, anterior processing is carried out prior to quantization about the coefficient signals in each block to determine a significant area of the coefficient signals by comparing each level of the coefficient signals with a threshold level. Only the coefficient signals within the significant area are judged to be valid and produced as a sequence of significant coefficient signals from a classifying circuit (20) to be quantized by a quantizer (15) into a sequence of quantized signals. The quantized signal sequence is subjected to posterior processing to produce a sequence of encoded signals. The significant area may be decided by the use of a selected one of zone detection, zigzag scanning, and adaptive scanning.

Abstract: A speech synthesis system comprises an input terminal for accepting text code, accent code, and phrase code.

Abstract: A speech synthesizer that synthesizes speech by actuating a voice source and a filter which processes output of the voice source according to speech parameters in each successive short interval of time according to feature vectors which include formant frequencies, formant bandwidth, speech rate and so on. Each feature vector, or speech parameter is defined by two target points (r.sub.1, r.sub.2), and a value at each target point together with a connection curve between target points. A speech rate is defined by a speech rate curve which defines elongation or shortening of the speech rate, by start point (d.sub.1) of elongation (or shorteninng), end point (d.sub.2), and elongation ratio between d.sub.1 and d.sub.2. The ratios between the relative time of each speech parameter and absolute time are preliminarily calculated according to the speech rate table in each predetermined short interval.

Abstract: An interference cancellation system has a combiner which removes an undesired component from a main signal including both a desired signal and an undesired signal received by a main antenna. A power sensor measures output power of a main signal. A weight control circuit is coupled with an output of the power sensor. An auxiliary antenna receives an undesired signal. A variable complex weight control circuit adjusts an undesired signal from the auxiliary antenna according to the output of the weight control circuit to provide an input signal to the combiner. The variable complex weight control circuit operates so that the output power becomes a minimum.

Abstract: A monitoring control system for a digital transmission line including above one repeater provided between two end stations uses a monitoring control signal of an alternating code with the polarity thereof inverted at a frequency or out-of-serice of a digital transmission line. The alternating code is transmitted, with the polarity thereof inverted at a frequency determined by monitoring control information, from an information transmission side between the repeater and one of the end stations for the transfer of control information. On an information reception side therebetween an exclusive OR of a received signal and an alternating code obtained through frequency division of a clock signal extracted from the received signal is obtained. The frequency component is reproduced from the exclusive OR. And the monitoring control information transmitted from the information transmission side is identified in a step of generation of the reproduced frequency component.

Abstract: A system of coding moving image signals produces a predictive error signal by a predictive coding based on inter-frame correlation and quantizing the predictive error signal for each block of a picture frame constituted by N lines of M pixels. The system includes a block coding/non-coding decision unit for calculating a first evaluation value Sm of the predictive error signal for each block of the picture frame. This unit decides that block non-coding is applicable when the first evaluation value Sm is less than a first threshold value T.sub.1 and that block coding is applicable when the first evaluation value Sm is greater than the first threshold value T.sub.1. The predictive error signal is not transmitted when the result of the decision is for block non-coding, and the predictive error signal is quantized and transmitted when the result of the decision is for block coding.

Abstract: Moving picture signal transmission system, wherein the data-compression is effected for the moving picture by the intraframe-encoding and the interframe-encoding, the signal is divided into the fixed frame-length transmission frame, the transmission frame has the header (A, B, C) which identifies whether it is the first transmission frame, the middle transmission frame or the last transmission frame in one picture frame signal, and then the transmission frame is transmitted, a receiver informs a transmitter of the validity of the received sequence and the result of the error check, when a transmitter receives the error message from a receiver, the picture frame immediately after the message is encoded by only the intraframe-encoding, the succeeding frames are encoded through interframe-encoding, so that the influence of the error is removed within a short time.

Abstract: A speech signal coding system comprises a prediction filter coupled with an output of a quantizer for prediction of a signal. A subtractor provides the difference between an input signal and an output of the prediction filter. A quantizer quantizes the residual signal, which is the difference provided by the subtractor. The quantizer is improved by adaptively adjusting step size for quantization. Thus, the coded outputs, according to the present invention, are the parameter information of the prediction filter, quantized output of the residual signal, and step information for quantization. The quantization step is determined according to the fundamental step size which provides the statistical variance, equal to one, to the quantized signal, and/or the power of the residual signal. Because of an efficient encoding with an adaptive control of the quantization step, the bandwidth for transmission of the coded signal in a communication system or transmission rate of coded speech signal is minimized.

Abstract: A high power pump light source for optical direct amplifier using the stimulated Raman effect is obtained by using a plurality of semiconductor lasers each of which provides low output power. More than two beams of the same wavelength generated by semiconductor lasers are combined (polarization multiplex) by using a polarization prism block, which provides sufficient high power pump light for the stimulated Raman effect amplifier. The output of said polarization prism block is wavelength division multiplexed with signal light to be amplified by using an interference filter block, the output of which is applied to a transmission optical fiber in which amplification of said signal light is effected.

Abstract: An anchor for hooking and cutting a submarine cable comprises an anchor body part, a cable-hooking part and a connecting part, these parts being connected together into a form like a fishing hook. A cable-sensing device is provided on the inner side of the connecting part and spring-biased in the floating-up direction. A cutting device is provided for cutting and holding the submarine cable by being advanced from the anchor body part by hydraulic pressure making use of a force such as sea water pressure or a tugging force for raising the submarine cable externally applied to the anchor body part when the cable-sensing device is caused to sink against the biasing force in the floating-up direction by receiving the tension in the cable hooked on the inner side of the connecting part.

Abstract: For decoding by the use of a decoder buffer memory an encoded video signal into which an encoder input signal is encoded with data compression on a basis of frames, a decoding device comprises a control signal producing unit for delivering a decoder control signal to a decoder when the frame of data written into the buffer memory coincides with the frame of data read out of the buffer memory. Responsive to the control signal, the decoder produces a supply control signal to the buffer memory to stop delivery of the read-out data to the decoder. Preferably, the decoding device should comprise a processing unit for producing frame pulses at heads of the respective frames of the encoded video signal. A counter counts the frame head pulses to make the write-in data and the read-out data indicate frame numbers for use in the signal producing unit. Alternatively, the decoding device may receive an encoded video signal in which frame number data are included for use in the signal producing unit.

Abstract: A motion compensation difference interframe or intra-frame coding system includes a block data redundancy compression and coding unit, a PIXEL data coding unit and a prediction data generator unit. The block data redundancy compression and coding unit codes a motion compensated (MC) difference between an input image in a block and a motion predicted image from the prediction data generator unit, and transmits coded data to a receiver. The PIXEL data coding unit receives an error between the MC difference and a decoded MC difference from the block data redundancy compression and coding unit, rearranges the error in PIXEL data and codes the PIXEL error, when the error is greater than a predetermined value. The PIXEL coded data is also transmitted to the receiver. The prediction data generator unit generates predicted block data of the motion of the image. The redundancy compression and coding unit may include a filter circuit rejecting pulse components contained in the MC difference.

Abstract: A transmission line between terminals of a three-terminal station is branched by a branching unit and power is transmitted between the terminals of the three-terminal station and a power feed system in the transmission line including: a switch for switching a power feed line feeding power to a repeater between a both-end power feed mode and a single-end power feed mode; and connection holding means for holding a power feed connection state without change upon an occurrence of a failure.

Abstract: An audio frequency signal identification apparatus of the present invention has a correlator for obtaining the full band power component and autocorrelation coefficients of a digital audio frequency signal to be identified for each analysis time, a plurality of band pass filters for dividing and filtering the audio frequency signal into a plurality of bands, a plurality of integrators for full wave rectifying and integrating the outputs from the plurality of band pass filters for each analysis time so as to obtain individual power components for the respective bands, a first identification parameter calculator for calculating a maximum power component, a minimum power component, a frequency band yielding the maximum power component, a bandwidth, and a difference between the individual band power components in the respective analysis times, from the individual band power components as the outputs from the plurality of integrators, a second identification parameter calculator for calculating a difference betwee