Abstract: The present invention relates to a device (10) for converting an AC voltage from the mains electricity supply into a DC voltage of predetermined level (and waveform), comprising:—a rectifier circuit (16, 17, 18, 19) for connecting to the mains electricity supply;—a switching circuit connected to the rectifier circuit;—a main transformer (26) connected to the switching circuit; and—an auxiliary transformer (28) which is connected to the switching circuit and the secondary winding of which is coupled to the secondary winding of the main transformer such that the current through the switching circuit and the main transformer is limited to a predetermined value.

Abstract: A battery charger having a detachable plug has a charger body and a changeable plug provided with a first plate and second plate. The second plate has at least two conductor blades extending out therefrom. The plug is detachably connected to the charger body by the first retaining device on the first plate and the second retaining device on the second plates. Therefore, the battery charger is securely and electrically insertable in an outlet of a power supply.

Abstract: An apparatus for displaying a waveform of an input signal on a display includes a synchronization detecting circuit, a sweep generating circuit, a horizontal axis drive circuit, a switching circuit, a variable gain amplifier, a vertical axis drive circuit, and a vertical location arrangement circuit. The horizontal axis drive circuit drives the horizontal axis of the display on the basis of a sweep signal generated at the sweep generating circuit synchronously with a sweep trigger signal obtained by dividing synchronization detecting pulses from the synchronization detecting circuit by N (N-1, 2, . . . ). The switching circuit alternately transfers the input signal and a cursor signal at a high rate to provide a multiplexed input/cursor signal to the vertical axis drive circuit through the variable gain amplifier.

Abstract: A system for measuring electric field strength of radio waves transmitted from cell station and arriving at an arbitrary measuring location is provided that includes a tuner unit, cell station ID (CS-ID) demodulator unit, signal level (or electric field strength) detector (RSSI detector), memory unit, display unit, and controller (CPU). CS-ID codes included in radio waves from cell stations and transmitted to an arbitrary measuring location are detected by the demodulator unit, and electric field strength (RSSI) data of the received radio waves are detected by the RSSI detector. All sets of the CS-ID and RSSI data are stored at addresses in the memory unit corresponding to each of the measuring locations, and the stored sets of the CS-ID data and RSSI data are read from the memory unit and displayed on the display unit in association with information indicative of the measuring location.

Abstract: A signal waveform display system for displaying waveforms of one or two input signals on a display screen is provided which comprises first-third input switching circuits, first and second trigger generators, first and second horizontal sweep generators, and a composite horizontal sweet generator. The trigger generators respectively generates first and second trigger pulses synchronously with the input signals provided thereto through the first and second input switching circuits. The sweep generators are triggered by the trigger pulses and generate first and second sweep signals having variable time periods, respectively. The composite sweep generator generates a composite sweep signal including lower portions of the first sweep signal which are smaller than a reference voltage, and upper portions of the second sweep signal which are higher than the reference voltage.

Abstract: A compensating method and apparatus is provided which collectively compensates for variations in a variety of characteristics in respective circuit portions of a signal processing circuit. A correction data generator is provided for generating correction value data for correction to be made for an output signal of the signal processing circuit, in order to compensate for variations in the characteristics of the at least one circuit portion. Also, a compensator is connected to receive an output signal from the signal processing circuit as well as to receive the correction value data from the correction data generating means, for correcting the output signal in accordance with the respective correction value data corresponding to the at least one circuit portion to generate a compensated output signal.

Abstract: A battery holder incorporated in an electrical device is provided which includes a housing for holding a battery which supplies a voltage to electrical circuits of the device. The battery holder contains positive and negative side contacts fixed to the housing for connecting positive and negative electrodes of the battery to supply a voltage to electrical loads. The positive side contact includes a back plate fixed to the housing, a conductive contact plate for contacting the positive electrode of the battery, the contact plate forming a U-shaped or V-shaped spring together with the back plate, and at least two protective plates of an insulation material arranged along the outer periphery of the contact plate and protruding from it. The distance between the protective plate is defined to be larger than the diameter of the positive electrode of the battery and smaller than the diameter of the battery itself.

Abstract: An evaluator for evaluating a digital transmission system is provided which comprises a signal power decrease detector and a system margin evaluator. The signal power decrease detector receives a digital signal which has been transmitted through the transmission medium of a transmission system so as to generate a signal power decrease signal. The system margin evaluator evaluates the system margin of the transmission system in response to the signal power decrease signal. The system margin of the digital transmission system can be evaluated in a simple and convenient manner.

Abstract: An apparatus for displaying a waveform of an input signal on a display includes a synchronization detecting circuit, a sweep generating circuit, a horizontal axis drive circuit, a switching circuit, a variable gain amplifier, a vertical axis drive circuit, and a vertical location arrangement circuit. The horizontal axis drive circuit drives the horizontal axis of the display on the basis of a sweep signal generated at the sweep generating circuit synchronously with a sweep trigger signal obtained by dividing synchronization detecting pulses from the synchronization detecting circuit by N (N-1, 2, . . . ). The switching circuit alternately transfers the input signal and a cursor signal at a high rate to provide a multiplexed input/cursor signal to the vertical axis drive circuit through the variable gain amplifier.

Abstract: A jitter measuring method and apparatus is provided which is capable of measuring jitters in serial digital signals transmitted at a high bit rate. The method and apparatus detects from a serial digital signal frequency deviations of a predetermined frequency corresponding to a predetermined period. The detected frequency deviations are converted to period deviations of the predetermined period.

Abstract: The apparatus for displaying a clamp point on a screen includes an input amplifier; a clamp circuit which includes a sync separation circuit and a one shot; and a blanking circuit. The video signal is applied to the clamp circuit via the input amplifier and the output signal therefrom is applied to the blanking circuit to be modulated with respect to its brightness. Thus, the brightness-modulated clamp point is readily located on a screen of, for example, an oscilloscope.

Abstract: A flow display type indicator is provided which indicates the variation or the velocity of variation of the value of a physical quantity or a parameter in a readily identifiable form. The indicator includes a flow image forming unit to indicate the value of the predetermined physical quantity in a flow representation by enabling a flow representing image to be formed at one of a plurality of positions including first to n-th positions which are orderly disposed and offset from each other along a predetermined line. A flow image selector selects one from flow representing images at the first to the n-th positions in one of first and second directions depending on the polarity of an input signal at a speed in accordance with the magnitude of the input signal to allow the flow representing image forming unit to form a selected flow representing image.

Abstract: A sound image display apparatus displays a sound image waveform representing a sound image produced by a multi-channel surround audio signal in a readily visible form. The sound image display apparatus includes a scaling section which has a variable gain calculator. The calculator determines the variable gain commonly applied to the X-axis and Y-axis components for displaying a sound image on a limited space of the screen of a display.

Abstract: A signal processing circuit for a vector scope adapted to display and measure characteristics of a color video signal on a screen which comprises a variable gain circuit 3, a demodulation circuit 6, timing signal generator 7, amplitude detection circuits 8,9, memory 12 storing a reference amplitude and CPU11. An input signal V.sub.in through the variable gain circuit is supplied to demodulation circuiting from where chrominance components R-Y, B-Y are provided to the amplitude detection circuits. When the timing signal is provided to the amplitude detection circuits, the circuits detect their amplitudes. The CPU computes an amplitude of a burst signal in accordance with the detected amplitudes and the difference between the computed amplitude and the reference amplitude stored in the memory. If the difference is not zero, the CPU controls the variable gain circuit so that it become zero.

Abstract: An apparatus and method for generating a linearly filtered composite signal, wherein the original signal of said composite signal can be divided into a plurality of sequentially arranged original sub-signals. The apparatus having a plurality of memory (1.sub.1, 1.sub.2) which have stored filtered sub-signals y.sub.1 (n), y.sub.2 (n) obtained by linearly filtering the original sub-signals, respectively; an adder (5) for adding data of the sub-signals y.sub.1 (n), y.sub.2 (n) read out from the memory to provide the resultant data y.sub.1 (n)+y.sub.2 (n) to an output terminal of the apparatus; and a controller for controlling timings of providing the data of the sub-signals stored in the memory to the adder.

Abstract: An apparatus capable of quickly capturing a channel to be measured of a cordless telephone in a shorter period of time than the time required by a conventional apparatus. After the waves received within all channels are converted in respect of their frequencies by a frequency converter, those out of the band are eliminated by an all-channel band pass filter. The waves outputted from the filter are amplified by an intermediate frequency amplifier and then inputted to a counter circuit. Since magnitude of the amplitude of the signal in the received channel to be measured is two or three times as large as that of interference waves, the counter circuit outputs a value within (the frequency of the channel to the measured).+-.

Abstract: An apparatus for displaying line and frame waveforms having different time-scales of a video signal on a display screen is described which comprises complex sweep signal generating means including a line sweep signal generating circuit 2, a frame sweep signal generating circuit 3 and a switching circuit 4, and horizontal axis drive circuit including a horizontal location arrangement circuit 5 and a horizontal axis drive circuit 6. The line and frame sweep signal generating circuits 2 and 3 generate line and frame sweep signals S.sub.2 and S.sub.3 synchronously with line and frame synchronization signals of the video signal, respectively, and the switching circuit 4 alternatively transfers the line and frame sweep signals S.sub.2 and S.sub.3, synchronously with the frame synchronization signal to generate a complex sweep signal S.sub.4.

Abstract: A digital phase shifter is provided which uses a direct digital synthesizer. The digital phase shifter is provided with a digital phase-shifted waveform signal generator in which a plurality of digital phase-shifted waveform signals having different phase shifts are stored. The generator outputs a digital phase-shifted waveform signal corresponding to a specified phase shift from a phase shift specifying section in synchronism with an oscillation signal from a PLL circuit. The output is converted to an analog form by a D/A convertor to generate a phase-shifted waveform.

Abstract: A phase shifting device for a vectorscope is provided which enables a vector-displayed waveform to be instantaneously and accurately rotated to an arbitrary or variable predetermined target phase position, with an arbitrary or variable predetermined portion of the vector-displayed waveform being selected as a reference for phase shifting. The phase shifting device includes first and second phase shift input generators. The first generator produces a first phase shift input signal representative of an arbitrary amount of phase shifting. The second generator produces a second phase shift input signal representative of a predetermined amount of phase shifting for the instantaneous and accurate rotation of the vector-displayed waveform.

Abstract: A measuring apparatus is provided which is capable of measuring CN ratio. The measuring apparatus has a measuring band specifying unit for specifying a band under measurement; a display for displaying the spectrum of levels measured in the specified band; first and second noise measuring frequency specifying units; a transmission channel selector; and a CN ratio calculating unit for estimating a noise level at a carrier of a selected transmission channel and for calculating the CN ratio using the estimated level.