Abstract: A diversity system utilizing a plurality of branches has been found for an angle modulated digital signal transmission. The received signal on each branch is modulated with a local signal which has the same period as the digital signal, and satisfies the orthogonal relationship with each other. The modulated signals are combined by simply summing them, and the combined signal is differentially detected. In the case of two branches, said orthogonal local signals are .sqroot.2/T.multidot. sin (2.pi./T)t, and .sqroot.2/T.multidot. cos (2.pi./T)t, where T is the bit duration of the digital signal, and said local modulation is the amplitude modulation. The present invention can provide the same diversity effect as the prior maximal ratio combining system, although the present invention does not utilize a complicated cophasing means between each branches.

Abstract: The semiconductor device is provided with semiconductor elements having the complementary characteristics and high breakdown strength. These semiconductor elements are formed in N and P islands respectively each having an inverted frustum shape.Surfaces of the frustum are inclined by an angle determined by semiconductor crystal structure. Side and bottom surfaces of the islands are formed adjacent to an insulating layer and both islands are supported part from the polycrystalline semiconductor layer. All side and bottom surfaces of the islands adjacent the insulating layer are made of high impurity substance of the same type as respective islands.

Abstract: The spectral envelope of speech signals are characterized by LSP (line spectral pair) parameters, termed w.sub.i and .theta..sub.i. In a speech synthesizer the control parameters for the filter may be a.sub.i =-2 cos w.sub.i and b.sub.i =-2 cos .theta..sub.i. The synthesizer filter is essentially an all pole filter consisting of two feedback paths each of which has a transfer function having zeroes on a unit circle in the complex plane.

Abstract: A system for testing subscriber lines and terminals by leading the subscriber line to the testing system through an associated semiconductor switch of a type driven by a constant current. The system includes a circuit for varying a current fed through the switch from the subscriber line to be tested, a circuit for measuring current values corresponding to the circuit states of the circuit, and a circuit for determining on the basis of the measured values derived from the measuring circuit a current value from which the constant current component for driving the switch is eliminated.

Abstract: An electronic key telephone set in an electronic key telephone system which is connected to the office line during the power failure by a power failure detecting relay in the key service unit having a common selection signal sender is provided with a circuit for detecting power failure to the key telephone system, additional contacts to respective keys of the key dial and a selection signal generator coupled with the additional contacts. The selection signal generator is connected to the voice signal pair line by a transistor which is turned on by a signal from the power failure detecting circuit during the power failure, and receives a D.C. power on the office line to be operable, so that a call may be generated from the key telephone set even during the power failure to the key telephone system. The signal from the power failure detecting circuit is fed to the transistor through a photo-coupler element.

Abstract: An apparatus for producing a multi-component glass fiber preform includes a multi-conduit burner 31 having five concentric conduits 31a-31e, the center three conduits (a), (b) and (c) being flush with each other at their ends, the fourth conduit d, interposed between the third (c) and outermost conduit (e) extends axially beyond the first three. The burner has a flange 33 to direct the flame onto a substrate.In operation glass raw material is fed through the inner-most conduit (a) by a carrier gas. The material emitted from conduits (a -d) is mixed in a mixing area 32. Glass raw material and a nebulized dopant salt solution are emitted and burned with hydrogen gas depositing particulate glass material or soot on an adjacent substrate to produce a multi-component glass fiber preform.

Abstract: A process for producing an optical fiber is described, wherein a fiber that has been drawn from a glass preform is coaed with a resin composition curable with heat, ultraviolet rays, or electron beams, and then cured, wherein before the drawn fiber contacts another solid object, the fiber is cooled by being passed through a cooling means filled with a non-reactive liquid material which is the same as said resin composition except that it is free from any compound that catalyzes curing of the resin, selected from among a curing agent, a cross-linking agent, curing catalyst, curing accelerator, sensitizing agent and a reactive diluent, and then the fiber is coated and with said resin composition and cured.

Abstract: A surface acoustic wave (SAW) resonator in which a pair of surface acoustic wave reflectors are spaced apart on a piezoelectric substrate from each other by a suitable distance and each consists of a grating electrode construction and a periodic array of grooves and a surface acoustic wave transducer which consists of an interdigital electrode structure and a periodic array of grooves is interposed between the reflectors and spaced apart therefrom by a suitable distance. The electrode period L.sub.T of the transducer and the electrode period L.sub.R of the reflectors are so selected as to satisfy the following equation: ##EQU1## where C.sub.1T : the acoustic mismatching term at the boundary between the electroded portion and the non-electroded portion of the transducer and is given byC.sub.1T =.vertline.1-Z.sub.2 /Z.sub.1 .vertline./.pi.whereZ.sub.2 : the acoustic impedance of the electroded portion, andZ.sub.1 : the acoustic impedance of the non-electroded portion;C.sub.

Abstract: This invention relates to a current supplying circuit for supplying a current to a terminal apparatus through a ring line and a tip line which are connected through resistance elements to a potential source and ground, respectively. This current supplying circuit includes respective detectors for generating first and second detection signals of amplitudes proportional to the currents flowing in the ring and tip lines, respectively, a circuit for generating a reference signal, and a comparator for comparing the signal difference between the first and second detection signals and the reference signal so as to produce a signal in accordance with the compared result, thus a shorted-to-ground fault on the ring line or tip line being detected by monitoring the signal produced in accordance with the compared result. After the shorted-to-ground fault is detected, the current supplying circuit is protected from breakdown.

Abstract: A method for fusion-splicing aligned optical fibers using heat generated by gas discharge produced between electrodes which are energized by an AC voltage. At first, a high trigger voltage is applied across the electrodes to generate the discharge, after which an AC voltage lower than the trigger voltage is applied across the electrodes to produce steady-state discharge. The AC voltage is selected to satisfy the relation, 10t.sub.O .gtoreq.(t.sub.f +t.sub.d +t.sub.r), where t.sub.O is the time necessary for ions created by the discharge to flow from one of the electrodes to the other and t.sub.f, t.sub.d and t.sub.r are the fall time, the quiescent time and the rise time of the AC voltage. Alternatively, a sine-wave AC voltage is used having a frequency higher than 500 Hz.

Abstract: In a sealed system, a polymerization initiator and a chain transfer agent are added to a methyl methacrylate monomer distilled under reduced pressure condition via a distillation step of the former both ingredients, the methyl methacrylate monomer is successively polymerized to prepare a core polymer while maintaining the reduced pressure condition, then the resulting core polymer is subjected to melt spinning to form a core fiber while maintaining the sealed system, and a clad of a macromolecular compound having a refractive index lower than that of the aforesaid core fiber is adhered around the periphery thereof, whereby a low-loss plastic optical fiber with excellent optical transmission characteristics having a core-cladding structure is fabricated. Plastic optical fibers so made exhibit light attenuation as low as 60 dB/km or lower.

Abstract: An infrared ray-transmitting glass composition for optical fibers consisting essentially of 28 mol % to 38 mol % of BaF.sub.2, 2 mol % to 7 mol % of GdF.sub.3 and 58 mol % to 69 mol % of ZrF.sub.4, and optical fibers comprising said glass composition.

Abstract: A signalling system for multi-address calling and a signal control equipment therefor in which a control signal starts with a synchronize signal, followed by a function determination field indicating that the control signal is any one of a selection signal, a call accepting state indication signal and a data receiving state indication signal, the function determination field being followed by a terminal appointing field in which the signal, set in the function determination field is provided bit by bit in a predetermined order for each destination terminal. Circuit arrangements for transmitting and receiving such a control signal are provided as signal control equipments both on the side of an originating terminal and on the side of an exchange.

Abstract: An optical printing device includes a photosensitive means having a photosensitive surface and an optical print head. The optical print head has a plurality of arrays of a plurality of light emitting devices selectively energized and an optical means to form light images from the light emitting devices on the photosensitive surface.A plurality of the light emitting device arrays are arranged in a plurality of rows, with the light emitting devices aligned in a common direction with the arrays.The optical means comprises a plurality of graded index optical fiber arrays causing light images from the light emitting devices to be formed in a single line on the photosensitive surface.

Abstract: A recording medium suitable for a laser thermal recording is characterized in that a plasma polymerized film of carbon disulfide or an organic monomer containing a metal is used as the recording medium.A method for manufacturing a laser beam-recording medium of this type is characterized by producing an electric discharge in a CS.sub.2 or an organic monomer gas while evaporating a metal such as Te so as to form a plasma polymerized film containing the evaporated metal on a predetermined substrate.

Abstract: In a single mode optical fiber of the type comprising a core, a cladding surrounding the core and an intermediate layer, the refractive indices n1, n2 and n3 respectively of the core, the cladding and the intermediate layer are selected such that the following relations are satisfied0.5<.DELTA.1<1.5-0.3>.DELTA.2>-1.

Abstract: A high operational speed print head for mosaic printing is provided which has a plurality of print needles positioned on a straight line, each being selectively driven toward a piece of paper through an ink ribbon. The printer head comprises a cylindrical permanent magnet ring magnetized in the axial direction; a circular bottom plate covering the bottom of the permanent magnet; and a plurality of electromagnets each having a center core and a coil wound around the core positioned on a circle on said bottom plate so as to be surrounded by the permanent ring magnet. A yoke provides a closed magnetic path with the permanent ring magnet, the bottom plate and each of the electromagnets. A plurality of moving bodies equal in number to the number of electromagnets are provided, each having at least an elongated armature overlying the core of the related electromagnet and composing a part of said closed magnetic path.

Abstract: An input picture signal is converted, for each picture element, into a K-bit, first time-serial signal having "ls" corresponding in number to the gradation level of the picture element, and the first time-serial signal are written in a random access memory, sequentially updating its column addresses upon every writing of K bits in its column direction. The random access memory is read out, updating its row addresses upon every reading out of M bits in the row direction. A second time-serial signal thus read out from the random access memory is subjected to a serial-parallel conversion by steps of M bits and parallel outputs of the M bits are supplied to recording elements respectively corresponding thereto.

Abstract: A push-button dial circuit having a low DC resistance and a high output impedance. An oscillator for generating a multi-tone dial signal is connected through a buffer transistor to terminals for coupling the multi-tone dial signal to a subscriber's line. The terminals also supply a DC power source current to the dial circuit. A constant voltage circuit is connected to the oscillator to stabilize the DC current supplied to the oscillator, and a reactance transistor circuit is connected between the terminals and the oscillator for defining a DC supply path from the terminals through the reactance transistor circuit to the oscillator. The reactance transistor circuit includes a transistor having a capacitor and a resistor respectfully connected across the base-emitter path and across the base-collector path of the transistor.

Abstract: A method of fabricating an optical fiber preform wherein a synthesizing torch is inclined between 10.degree. and 60.degree. with respect to the rotation axis of a seed rod. Moving the rod while rotating it, a glass raw material gas and a flame forming gas are blown out individually from the torch to synthesize glass particles which are deposited onto one end of the rod, so that a cylindrical porous preform is grown in the direction of the rotation axis of the rod. Then the porous preform is heated at a high temperature to vitrify the porous preform into a transparent optical fiber preform. At least one exhaust port is disposed at a distance of 1 mm to 50 mm from the periphery of the porous preform and in the vicinity of the growing surface of the porous preform. In fabricating the porous preform the outer diameter fluctuations are small, and the preform is formed stably without formation of cracking on the periphery of the preform.