Abstract: A device for burying a submarine cable under the 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: The present invention aims at providing a method and a device therefor which can effectively as well as accurately bury a cable under marine beds not only when a cable is newly laid and buried but also when a cable has to be reburied. The method and the device according to the present invention are characterized in that a burying device is guided to approach the cable by using a travelling member provided on said burying device, a travelling control mechanism thereof being controlled by a receiving output from a transmitter which is mounted on the cable in advance by a receiver provided on the burying device, that the cable is caught and held by a cable engaging member of said burying device while the burying device is detecting the buried cable track and travelling therealong, and that at the same time an excavation member of said burying device digs and forms a groove while the burying device guides and buries the cable within the excavated groove.

Abstract: An input digital signal with M(=5) samples/second is converted to an output signal with N(=6) samples/second with n(=9) quantization bits. The device comprises parallel shift registers each having bit length P+n(P=11) for accepting an input signal with bit length n; an address converter for providing the continuous P bits in input signals from each of said parallel shift registers for every shift operation of said shift registers; N groups of ROMs (read only memory) storing the predetermined value in each address which is designated by output of said address converter; a shift register adder for accumulating output of said ROMs with shift operation; and an output gate coupled with output of said shift register adder for providing a converted output signal.

Abstract: In a speech analysis-synthesis system for the narrow band transmission of a speech signal, speech is separated into a plurality of spectrum information (K.sub.i), average (V.sub.0) of linear prediction error signal, pitch period (L), voiced/unvoiced decision signal (V/UV), a pseudo exciting signal (I) which is a part of a linear prediction error signal or an impulse response of the same, and a frame information which determines the interval and the duration of the spectrum analyzation, then, in a receive side, the product of said pseudo excitation signal (I) and said pitch period (L), a white noise is switched according to said voiced/unvoiced decision signal (V/UV), and the output of the switch is applied to a synthesis filter which attaches correlation components to an input signal according to spectrum information (K.sub.i) to provide synthesized speech.

Abstract: In a message communication system and process, a character string with a plurality of characters is encoded into a compact code, which is transmitted to a reception side. At the reception side, the compact code is decoded to an original character string. Thus, the amount of information to be transmitted is fairly reduced as compared with the transmission in which each character is encoded. Preferably, a combination of a word and a `space` code following the word is encoded to a single compact code. The compact code may also encode a combination of a plurality of words. Some particular control codes are defined for converting a small character to a capital character, or vice versa, and designating special code like period ".", quotation mark "?", etc.

Abstract: The present invention aims at providing a method and a device for guiding the cable burying device along the cable effectively as well as accurately even if the cable should be reburied after repairment. The present invention is mainly characterized in that an ultrasonic command signal transmitted from an ultrasonic transmitter/receiver mounted upon the cable burying device is received by an ultrasonic, transponder which has been mounted on the cable. An ultrasonic signal is transmitted in turn from said ultrasonic transponder to be received by said ultrasonic transmitter/receiver so that the position of said ultrasonic transponder on the cable is detected by processing such signals.

Abstract: A smear-desmear filter having the frequency depending group delay characteristics is implemented by a transversal filter having a plurality of delay elements each having the delay time 1/(2f.sub.2), where f.sub.2 is the highest frequency component of an input signal, tap weight coefficient means for providing the product of the output of the tap and the predetermined coefficient which is supplied from a digital memory, and an adder for summing up all the outputs of the tap weight coefficient means. A tap and/or a tap weight coefficient means is provided for every m number of delay elements, where m is an integer larger than 2, thus, the number of tap weight coefficient means is merely 1/m of the number of the delay elements. The tap weight stored in said the digital memory is determined by the position (n) of a tap, a delay time (.tau.) of each delay element, the required delay expansion width (a), and the value of said integer (m). The obtained delay characteristics is sinusoidal in the given frequency band.

Abstract: An improved Kalman equalizer for providing a tap weight of a transversal filter for equalizing a transmission line has been found. A complex number fast Kalman equalizer (FIG. 27), which is the improvement of the prior fast real number Kalman equalizer (see; "Fast calculation of gain matrices for recursive estimation schemes" by Lennart Ljung, et al, INT. J. Control, 1978, vol. 27, No. 1, 1-19), has a complex conjugate generator (C.sub.2) for processing a complex input signal so that an equalization can be performed on the bandwidth division concept, and a transmission line having a complex impulse response can be equalized. Then, a bandwidth division equalization in which a whole bandwidth is separated into a plurality of sub-bandwidth each being equalized by a related sub-equalizer becomes possible. Also, a QAM signal (Quadrature Amplitude Modulation) which has a complex impulse response can be equalized. A bandwidth division fast Kalman equalizer (FIG.

Abstract: An improved two or three error correcting system for BCH code (Bose, Chaudhuri, Hocquenghem code) has been found. In case of a two error correction system, a first syndrome A.sub.1 and a second syndrome A.sub.2 are obtained from a reception code C'=(a.sub.1 ', a.sub.2 ', . . . , a.sub.n '): ##EQU1## Then, S.sub.1 =A.sub.1 +.alpha..sup.n-t, and S.sub.2 =A.sub.2 +.alpha..sup.3(n-t) are obtained, for every value of t, where n is a code length, t is an integer equal to or less than n, and .alpha. is a primitive element of a Galois field. When A.sub.1 .noteq.0, a t'th bit a.sub.t ' is corrected by inverting the same on the condition that the t'th bit of S.sub.2 is equal to the t'th bit of S.sub.1.sup.3. When A.sub.1 =0, it is clear that no error exists, and no correction is performed. In case of a three error correction system, a third syndrome ##EQU2## and S.sub.3 =A.sub.3 +.alpha..sup.

Abstract: A maximum likelihood error correcting technique for a digital communication in which a transmit side provides coded data with some redundancy through a convolutional coding circuit, and a receive side corrects transmission errors automatically through a maximum likelihood error correcting circuit has been improved by deleting some symbols at a transmit side to increase a coding rate close to 1, and inserting dummy symbols at a receive side into each bit position where a symbol has been deleted at a transmit side. A likelihood value for that dummy symbol inserted at a receive side for the maximum likelihood decoding is a fixed predetermined value. Thus, both a coding circuit in a transmit side and a decoding circuit in a receiving circuit have only to handle original low rate code, while keeping a coding rate in a transmission line high.

Abstract: A cable buried under a sea bottom is located by causing to flow in the cable an AC current, and measuring the magnetic flux near the cable.

Abstract: Disclosed is a magneto-optic recording medium to which magnetic Kerr effect is applied and characterized by the tracking guide on an even surface free from disorder of linear polarization. Since the tracking guide may be any type if it has a different reflection characteristic from that of the memory area viewing from magneto-optic standpoint, the tracking guide can be produced by a thermal treatment for changing the magnetic property of a part of a thin film with its magnetization easy axis in the direction perpendicular to the film surface. As no difference exists between the memory area and the guide area other than their magnetic properties, they are on the same plane and have no unevenness between their surfaces. Where, the guide area is assumed to have such magnetic property as the magnetization easy axis is parallel to the film surface, or it is perpendicular to the film surface but has no rectangular hysterisis.

Abstract: An optical switch for switching laser beams, having a transparent glass plate with a reflection film on the surface of the same has been found. When the reflection film is at the first position, the first input beam is coupled with the output beam through the transparent glass plate, while the second input beam is prevented by said reflection film. When the reflection film is at the second position, the first input beam is prevented by said reflection film, and the second input beam is coupled with the output beam through the reflection by said reflection film. Thus, according to the displacement of the transparent glass plate together with the reflection film, the input beams are switched. Due to the above operational principle, the output optical level does not decrease even during the transient time, and then, the present optical switch is utilized in an optical repeater for digital communication.

Abstract: A speech path switching system in time-divisional electronic telephone switching system for the full availably switching between k number of incoming highways and k number of outgoing highways and each highway having n number of telephone channels comprises (a) k number of speech path memories for temporarily storing telephone signals, provided for each incoming highway, (b) k number of input counters provided for each speech path memory for designating the input address of said speech path memory, said input counter being circularly incremented synchronized with the frame phase of the corresponding incoming highway, (c) k number of holding memories provided for each outgoing highway for designating the read out address of said speech path memory to substantially connect an incoming channel to an outgoing channel, and (d) k number of output counters provided for each holding memory for designating the read out address of the holding memory.

Abstract: A new type of exchange system is disclosed which is suitable for the use in a facsimile communication system in which a large amount of information is transmitted in one direction, and the opposite direction has a small amount of information to be transmitted. According to the present invention, said large amount of information is transmitted using a circuit switching technique which assigns a fixed circuit to the forward direction to transmit said information, and a control signal or an acknowledgement signal in the backward direction from the receiving terminal, is handled through a packet switching technique in which a plurality of calls share a single transmission line or a time slot. Thus, a transmission line is used with the same efficiency as packet switching although information is transmitted mainly in one direction, and the switching load of the exchange is as small as in circuit switching.

Abstract: A feedthrough terminal for optical fiber cables (12), particularly for use in an underwater repeater, comprises a rod (22) received snugly in a tube (21) and having grooves (24), which are filled by a mass of solder (26) with the optical fiber cables placed in the respective grooves. The grooves may be formed along the tube inside surface or on opposing portion of the tube and the rod. The tube and/or the rod may be possessed of a recessed surface to provide a gap for the solder mass.

Abstract: The present invention has an object to provide an underwater cable burying device which can accurately be guided to align with the cables in the process of burying even if the cables have to be re-buried. The device according to the present invention is characterized in that a travelling device is provided on the body of the device which is further provided with a trenching device at the middle portion thereof, that a cable clamp member and a cable engaging member are provided at an arm projecting forward from the said device body and that said respective devices are controlled through a control cable on the mother ship.

Abstract: An antenna, such as Cassegrain or parabolic antenna, intended for use in the microwave or millimeter wavebands having improved wide angle radiation characteristics. At least one edge portion, in first embodiments, of a supporting post structure which supports a primary radiator or subreflector is modified to randomly scatter waves so that the field strength of scattered waves due to the presence of the supporting post is decreased.

Abstract: In an optical digital communication system having a plurality of optical repeaters inserted in an optical fiber cable, and a pair of terminal stations installed at the extreme ends of the optical fiber cable, the designation of the particular repeater from the terminal station is performed by the remote control signal which has the pulse pattern with the period designated to each repeater. Each repeater may have a plurality of switches for switching lasers for improving the operational reliability of the same by the redundant technique, and the control and/or the designation of the particular switch is also performed by said remote control signal by selecting the particular period and/or the repetition numbers of the period of the pulse pattern.

Abstract: A PCM signal calculator for non-linear encoded PCM signals in the A-law system or .mu.-law system having a sign bit and a plurality of absolute value bits with three bits of segment number and four bits of step numbers within segment comprises; (a) a pair of input terminals for receiving the input PCM signals; (b) a signal or plurality of calculation means for providing the addition, subtraction and/or multiplication between the absolute values of two input PCM signals; (c) means for providing sign bit of the calculated result from the sign bits of the input PCM signals and/or the output of said calculation means; (d) an output terminal for providing the sign bit of the result from said means (c) and the absolute value of the result from said means (d).