Abstract: An illegal recording prevention apparatus used for preventing an illegal recording with a video camera in a movie theater, comprises a unit for emitting infrared light which has a center wavelength in a wavelength of 800-980 nm wavelength, so that an automatic-focusing regulating function or automatic exposure regulating function of the video camera is deteriorated.

Abstract: An optical radio system includes a host device, an end device, and a repeater. The host device and the end device communicate with each other via the repeater by use of optical radio. The repeater includes a section for receiving a first light signal from one of the host device and the end device, a section for converting the received first light signal into a first electric signal, a section for frequency-converting the first electric signal into a second electric signal, and a section for generating a second light signal in response to the second electric signal and transmitting the generated second light signal. The repeater also includes a section for demodulating one of the first electric signal and the second electric signal into a baseband signal, a section for detecting a quality of the baseband signal, and a section for enabling transmission of the second light signal only when the detected quality of the baseband signal is equal to or greater than a predetermined quality.

Abstract: A spread spectrum communication system has, in a transmission part, a first circuit for extracting a first carrier signal from a predetermined broadcase wave and generating a first clock signal by using the first carrier signal, a second circuit for generating a first pseudo-noise signal by using the first clock signal from the first circuit, and a third circuit for modulating an information signal and broadening a frequency band of the modulated information signal by using the first pseudo-noise signal from the second circuit. A reception part of the spread spectrum communication system uses a second clock signal, a frequency of which is identical to that of the first clock signal. Thereby the second clock signal becomes identical to the first clock signal in frequency.

Abstract: An antenna device for a system which includes cordless apparatuses, e.g. home automation system. Conductive patterns or conductive wires are provided on a conduit, which may comprise a round or a flat composite cable, for radiating signals to and receiving signals.

Abstract: A data producing device in a signal reproducing apparatus, comprises a shift register supplied with synchronizing signals and codes which are time-sequentially reproduced from a recording medium, synchronizing signal detectors supplied with the synchronizing signals from the shift register, data transfer circuits provided in parallel with respect to each other and in series with the synchronizing signal detectors, and a control circuit for controlling the data transfer circuits so that a data is selectively read out and produced from a desired data transfer circuit among the plurality of data transfer circuits. The reproduced synchronizing signals and codes are transferred to the shift register and are read out from the shift register in response to a clock pulse having a predetermined frequency. The number of the synchronizing signal detectors is equal to the number of kinds of the synchronizing signals, and the synchronizing signal detectors are provided in parallel with respect to each other.

Abstract: A synchronizing signal detecting circuit is used in a digital signal transmitting system which transmits a digital signal in which signals are time-sequentially multiplexed in terms of blocks, where each of the blocks are made up of digital data which are information signals subjected to a digital modulation, a synchronizing signal having a fixed pattern, and an error checking code arranged at a location separated from a location of the synchronizing signal by a predetermined number of bits. The synchronizing signal detecting circuit comprises a counter which is reset when a synchronizing signal detection output which has been discriminated as being correct by use of the error checking code is continuously obtained for N times, where N is a natural number greater than or equal to two.

Abstract: A memory circuit write-in system comprises a first circuit for supplying a digital signal including a time base fluctuation component, where one frame of the digital signal is constituted by at least a synchronizing signal and information data and the digital signal has a first repetition frequency with a period of one frame of the digital signal, a memory circuit for writing therein and reading out therefrom the digital signal supplied from the first circuit, and a second circuit for applying a write-in control signal to the memory circuit. The write-in control signal includes no time base fluctuation component and has a second repetition frequency substantially equal to the first repetition frequency, and the memory circuit is controlled by the write-in control signal so that write-in of the digital signal is carried out with a write-in period in a range of two times within the one frame period.

Abstract: A digital information recording system comprises a randomized digital signal forming circuit for forming a randomized digital signal by carrying out modulo-2 addition of at least digital information signals of a plurality of channels in a digital signal and a random code sequence which is generated independently, a detector for successively detecting values of each of a predetermined number of words from each of the digital information signals of a plurality of channels in the randomized digital signal, in terms of one word, and generating a detection signal only when values of bits in the one word are all "1" or all "0", a timing circuit for generating a timing signal for every period corresponding to a transmission period of a least significant bit in one word from each of the digital information signals of a plurality of channels, a polarity inverting circuit for passing the randomized digital signal unchanged during a period in which the detection signal is not generated from the detector, and inverting t

Abstract: In a circuit arrangement for a disk player of the type arranged to reproduce information prerecorded in the form of pits, a variable gain circuit for changing the frequency characteristic of the reproduced signal is provided. The level of the reproduced signal is detected at high and low frequencies so as to produce a control signal the voltage of which varies in accordance with the difference between the level of the high frequency signal component and the level of the low frequency component. The control signal is then applied to the variable gain circuit receiving the reproduced signal so that the frequency characteristic of the reproduced signal will be controlled. Thus, the level of the reproduced signal is boosted at its high frequency range.

Abstract: An apparatus for reproducing information signals recorded on a recording medium comprising a pickup transducer for picking up a recorded signal from an information signal recording medium in which an analog information signal is successively recorded in units of a plurality of data blocks, the data block having a train of digital signals obtained by digitally modulating the analog information signal, error correcting words, and an error detection word, a frequency characteristic regulation circuit for regulating the frequency characteristic of the signal picked up from the information signal recording medium by the pickup transducer, an error detection circuit for detecting whether an error exists in the data block of a signal which has passed through the frequency characteristic regulation circuit, by use of the error detection word, and a control circuit for controlling the frequency characteristic regulation circuit to vary the frequency characteristic according to an output of the error detection circuit.

Abstract: A multichannel record disc reproducing apparatus comprises a first phase locked loop circuit including a phase comparator and a voltage controlled oscillator for demodulating an angle-modulated wave signal. The modulated signal is separated from a composite signal picked up from a multichannel record disc on which a multiplexed direct wave signal and an angle-modulated wave signal are recorded. The output of the first phase locked loop is a demodulated signal. A second phase locked loop circuit includes a phase comparator and a voltage controlled oscillator, supplied with the separated angle-modulated wave signal and having a lock range of a width which covers and is wider than the maximum lock range width of the first phase locked loop circuit. A synchronous detector compares the phases of the angle-modulated wave signal and the output signal of voltage controlled oscillator of the second phase locked loop.

Abstract: An angle modulated wave demodulation system demodulates an input angle modulated wave by means of a phase locked loop system which comprises a phase comparator, which is operated responsive to an input angle modulated wave. A voltage controlled oscillator is supplied with a part of the output of the phase comparator which controls its oscillation frequency. The oscillator supplies its oscillation frequency to the phase comparator. The phase locked loop system has a lock frequency range which decreases its width when the level of the input angle modulated wave is below a predetermined level. The portion of this lock range in which the width of the lock range decreases is positively utilized. The voltage controlled oscillator oscillates at a frequency equal to the center frequency of the carrier of the input angle modulated wave, when the phase locked loop becomes unlocked.

Abstract: A multichannel record disc recording system comprises: a circuit for shaping sum and difference signals from multichannel signals, angle modulating the difference signal, multiplexing the sum signal and the angle-modulated difference signal, and recording the resulting signal on a record disc. A first level control circuit, in the transmission system for the sum signal, operates to attenuate the high-frequency band of components of the sum signal when its level is at a high level. A second level control circuit, in the transmission system of the difference signal, operates to attenuate the middle-high frequency band of components of the difference signal when its level is at a high level. The first level control circuit attenuates the level of the sum signal to prevent an admixing of the higher harmonics of the high frequency component of the sum signal into the band of the angle-modulated difference signal.

Abstract: An angle modulated wave demodulation system demodulates an input angle modulated wave by means of a phase locked loop system which comprises a phase comparator, which is operated responsive to an input angle modulated wave. A voltage controlled oscillator is supplied with a part of the output of the phase comparator which controls its oscillation frequency. The oscillator supplies its oscillation frequency to the phase comparator. The phase locked loop system has a lock frequency range which decreases its width when the level of the input angle modulated wave is below a predetermined level. The portion of this lock range in which the width of the lock range decreases is positively utilized. The voltage controlled oscillator oscillates at a frequency equal to the center frequency of the carrier of the input angle modulated wave, when the phase locked loop becomes unlocked.

Abstract: A system for demodulating angle modulated waves comprises a phase locked loop including a phase comparator and a voltage controlled oscillator. An attenuation means is inserted into the phase locked loop. This attenuation means does not affect the DC component of an input angle modulated wave, but does cause an attenuation with respect to an AC component, to cause a decrease in the loop gain. The phase locked loop has a DC lock range exhibiting a relatively wide lock range width even when the input level is relatively low and an AC lock range produced by the attenuation circuit and exhibiting a relatively narrow lock range width when the input level is relatively low. The attenuation means detects an abnormality in the angle modulated wave, the harmonics component of the direct wave, and the like. A variable attenuation circuit controlled by the output of the detecting means is varied in its attenuation quantity.