Abstract: In an information recording/reproducing apparatus for recording/reproducing a digital audio signal on/from a magnetic medium, a modulator/demodulator for modulating/demodulating the digital signal by offset quadrature phrase shift keying (O-QPSK). This technique is particularly applicable to the multi-layer recording of video and audio signals in a video tape recording/reproducing system and has the advantage of avoiding interference between the recorded digital audio and video signals at the time of reproduction.

Abstract: A PCM audio signal recording and reproducing apparatus samples an audio signal with a sampling frequency having an asynchronous relation to a field frequency of a video signal; converts it to a PCM signal, adds error detection/correction data to a predetermined number of PCM data, forms a data frame by those signals, modulates it in accordance with a predetermined modulation system, and records the audio signal together with the video signal or just the audio signal on a record medium by using a rotary head type scanner which is controlled so as to have a synchronous relation to the field frequency of the video signal. A digital signal processing circuit having a memory of a predetermined capacity is provided, and the number of digital data to be recorded in one data frame is varied in accordance with a difference between the number of input data of the digital audio signal to the digital signal processing circuit and the number of output data supplied to the record medium for recording.

Abstract: A method of producing a tracking control signal in a rotary head type magnetic recording and reproducing apparatus and a rotary head type magnetic recording and reproducing apparatus capable of a proper tracking by the use of the tracking control signal.

Abstract: Disclosed is a VTR of the helical scan type having a plurality of rotary magnetic heads. This VTR can select one of a first and a second signal recording forms which are different from each other, and record signals on a magnetic tape. In the first recording form, a frequency-modulated video signal including a luminance signal and a color signal and a frequency-modulated sound signal are recorded on the same track so as to be superimposed one on the other. In the second signal recording form, a frequency-modulated luminance signal and a frequency-modulated color signal are recorded separately on tracks adjacent to each other. This VTR has compatibility with respect to the recording/reproducing of two different signals.

Abstract: The recording area of the magnetic tape is divided into a first area for recording a PCM converted audio signal and a second area for recording a PCM converted video information. In recording the audio signal and the video information which have been separately PCM converted, the magnetic tape is wrapped around the rotary heads so that a wrap angle of each of said first and second areas is less than 90.degree. with respect to the rotary heads of a predetermined diameter.

Abstract: In receiving a narrow band video signal transmitted through a narrow band transmission line such as a telephone line, a sound tape recorder or the like, the narrow band video signal is first stored in memories and is then read out therefrom at a higher reading-out speed than the writing-in speed so that the band allocated to the read-out signal is broadened to facilitate the display of the video signal. When reading out the video signal from the memories, the timing of reading out even lines constituting a display image of the video signal is shifted from the timing of reading out odd lines constituting the same display image by a time substantially equal to half the reciprocal of the frequency in terms of the bandwidth of the read-out video signal, the reciprocal corresponding to the resolution limit for the received video signal.

Abstract: A method for transmitting a color video signal on a narrow-band transmission line such as a telephone line or an audio tape recorder is disclosed. The carrier frequency is so reduced that no clock signal of high frequency is used. The carrier chrominance signal and the brightness or luminance signal are transmitted separately in time-division multiplication thereby to eliminate color distortion. The write clock signal frequency for the carrier chrominance signal is rendered inversely proportional to the product of a given number determined by the number of samples required for faithful transmission of the carrier chrominance signal and a multiple enabling the carrier frequency to be minimized. The read clock signal frequency for the carrier chrominance signal is reduced to one over an integer of the luminance signal, so that the carrier chrominance signal is read at intervals of the integer in order of storage in a memory.

Abstract: A horizontal synchronizing signal contained in a composite video signal undergoing a phase fluctuation is phase modulated and substituted for the original horizontal synchronizing signal. The phase modulation of the horizontal synchronizing signal of the input signal is effected at a phase modulation circuit and then the phase modulated signal is applied to an AFC circuit unit which has the same transfer characteristic as that of a horizontal AFC circuit of an ordinary television receiver set. The phase modulation circuit is controlled by a signal in response to a phase difference between the output of the AFC circuit unit and the original horizontal synchronizing signal. A composite video signal containing the horizontal synchronizing signal subjected to the phase modulation in this manner is applied to the television receiver set, thereby displaying a picture image free from the fluctuation.

Abstract: A signal multiplexing method and system for transmitting a television signal by a narrow-band transmission medium incapable of transmitting d.c. components. In this method, a two-polarity pulse train signal consisting of pulses of alternately inverted polarities is subject to pulse modulation by the video information only of the television signal. The horizontal and vertical synchronizing signals indicative of the beginning of a line, field or the like are coded in such a form that some of the successive pulses in the pulse train signal have the same polarity.

Abstract: There is provided a receiving system for receiving the video signal for each one frame. The video signal is divided into line signals each corresponding to the horizontal scanning period and transmitted sequentially in such a manner that each line signal is inserted in a television signal during each vertical blanking period.The line signals inserted in the transmitted television signal are separated therefrom and the separated line signals are selectively recorded on the odd and even field tracks of a rotary recording medium.Switches for selectively recording the line signals on the even field and odd field tracks are controlled by the output of an odd/even field selection signal generating circuit.

Abstract: A system for converting a broad-band picture signal into a narrow-band signal or converting a narrow-band picture signal into a broad-band signal comprising a first memory means which has a capacity of storing a picture signal corresponding to one frame and can record and reproduce a broad-band picture signal at the same speed as the transmitted speed, and a second memory means which has a capacity of storing a picture signal corresponding to one scanning line and is such that writing speed and reading speed can be freely varied.