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 information signal recording system comprises a circuit for generating pilot signals for tracking control, a circuit for generating a rectangular waveform signal of a specific frequency existing in an artificial synchronizing signal duration in every specific period and having almost no frequency component equal to and in the vicinity of the frequencies of the pilot signals, a circuit for pulse code modulating or difference modulating an information signal, further digital modulating the information signal, and obtaining a digital information signal existing in a time interval other than the artificial synchronizing signal duration. The digital information signal is recorded along a main track on a recording medium and the pilot signals are recorded along pilot signal tracks contiguous to the main track.

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: 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.