Abstract: A communication system has an analog signal broadcasting station for transmitting an analog signal, a digital signal broadcasting station for transmitting a digital signal and a receiving unit for receiving the analog signal from the analog signal broadcasting station and the digital signal from the digital signal broadcasting station. The receiving unit has a recording and reproducing unit for selectively recording one of received analog and digital signals. The recording and reproducing unit has heads for analog signal each having a predetermined azimuth angle and operative to record an analog signal and heads for digital signal each having an azimuth angle larger than that of the analog signal head and operative to record a digital signal, and performs selective recording and reproduction of the analog signal and the digital signal on and from a recording medium.

Abstract: A digital information recording-reproducing apparatus is disclosed, in which a signal temporally compressed to 1/n and transmitted is encoded for recording by a recording encoder. The rotation speed of a rotary drum is set at R.sub.1, and the running speed of a magnetic tape at V.sub.1. The signal encoded is recorded on the magnetic tape by magnetic heads. At the time of reproduction, the rotary drum is driven at a speed m/n times faster than for recording, and the magnetic tape is run at a speed 1/n times faster than for recording. The signal reproduced by the magnetic heads is decoded and restored into the original digital information signal by a reproducing decoder. As a result, there is provided a recording-reproducing apparatus having the function of time-base expansion with a reduced recording time applied to a system for transmitting and recording the software information of video or the like through radio wave or cable.

Abstract: An input terminal (240) for assigning at least one information to be requested and a control circuit (100) for controlling a recording operation, a tape stopping operation and a detecting operation of a head of recorded information of a recording and reproducing apparatus (80) are provided on the side of a subscriber terminal (FIG. 1) having the recording and reproducing apparatus and, after all of information (A, B, C) assigned by the input terminal and received from an information transmitting station (FIG. 2) are recorded, a head of the first recorded information is detected.

Abstract: The present invention relates to an information providing system. More particularly, this invention relates to an information management apparatus capable of reliable management of distributed information and an information providing system employing the same information management apparatus. The information management apparatus comprises a main information reproducing means for reproducing main information recorded in a given recording medium; and a reproduction management means for managing the main information reproducing means for reproducing the main information. The present invention provides a receiving means provided with a means for recording distributed information and control information limiting the number of main information reproducing cycles on a recording medium, and a main information reproducing means provided with a reproduction disabling means for limiting the reproduction of main information.

Abstract: An object of the present invention is to increase the recording density of digital information signal in a recording medium without changing parameters of the recording medium and a RLL code. To accomplish the object, the present invention has a frequency response of the equalizer set so that an overall transmission frequency characteristic H(f) of the RLL coder, the recording medium, and the equalizer to an impulse becomes the one given by an equation below ##EQU1## where Fm denotes a cut-off frequency of the recording medium.

Abstract: In a digital information reproducing apparatus in which a clock signal can be recovered stably when reproduced digital information signals are detected by utilizing a partial response (PR) class 4 detection method, a digital information signal reproduced from a magnetic tape is equalized into a PR (1, -1) signal by means of an equalizer circuit, then equalized eventually into the PR class 4 signal by means of a (1+D) operation circuit and supplied to a ternary discriminator circuit to provide original digital information. A signal equalized into the PR (1, -1) signal and delivered out of the equalizer circuit is supplied to a clock component extractor circuit comprised of, for example, two squaring circuits, and a signal spectrum is generated in which a bright-line spectrum of high level develops at a bit frequency component of the reproduced digital information signal. The signal spectrum is supplied to a PLL circuit and a clock signal phase-locked to the bit frequency component can be obtained.

Abstract: A digital information signal transmitting/receiving method and system having a transmitter for transmitting an encrypted digital information signal and a plurality of receivers for receiving the encrypted digital information signal from the transmitter. The transmitter simultaneously distributes a plurality of identification codes associated with the receivers at a time ahead of the digital information signal. The receivers detect whether a particular identification code assigned to the receiver was included within a received plurality of identification codes. When the particular identification code has been detected as having been received the received encrypted digital information signal is decrypted into the original digital information. In order to request that a particular identification code be included so as to allow access to a program, either one of the receivers or the recorders each generate an information request signal.

Abstract: A rotary head type magnetic recording and reproducing apparatus for recording and reproducing an analog wide-band video signal, audio signal and compressed digital signal on the same recording medium. The modulated analog wide-band video signal or the narrow-band-converted compressed digital signal is recorded on two video tracks adjacent to each other on a magnetic tape by magnetic heads on a rotary drum.

Abstract: An information recording and reproduction apparatus for recording and reproducing the information supplied through the transmission line is capable of protecting the copyright by limiting the reproduction of the recorded information. A main information signal supplied through the transmission line and a deadline signal attached to the main information signal and representing the reproduction deadline of the main information signal are recorded and reproduced by a recording device and a reproduction device respectively. A temporal information signal representing the date and time is acquired. The deadline signal reproduced is compared with the temporal information signal acquired. The reproduction output of the main information signal is cut off in accordance with the comparison signal produced by the comparison. In the case where the temporal information has passed the deadline, the reproduction output of the main information signal is cut off.

Abstract: An object of the present invention is to increase the recording density of digital information signal in a recording medium without changing parameters of the recording medium and a RLL code. To accomplish the object, the present invention has a frequency response of the equalizer set so that an overall transmission frequency characteristic H(f) of the RLL coder, the recording medium, and the equalizer to an impulse becomes the one given by an equation below ##EQU1## where Fm denotes a cut-off frequency of the recording medium.

Abstract: An object of the present invention is to increase the recording density of digital information signal in a recording medium without changing parameters of the recording medium and a RLL code. To accomplish the object, the present invention has a frequency response of the equalizer set so that an overall transmission frequency characteristic H(f) of the RLL coder, the recording medium, and the equalizer to an impulse becomes the one given by an equation below ##EQU1## where Fm denotes a cut-off frequency of the recording medium.

Abstract: A digital magnetic recording method, recording apparatus, reproducing apparatus, and recording/reproducing apparatus for recording and/or reproducing a current digital video signal and a high-definition (HD) digital video signal in a common track format on a recording tape using rotary heads. In recording, the current digital video signal is compressed to a specified amount of data, the HD digital video signal is compressed to n (n is an integer of 2 or larger) times the amount of data of the compressed current digital video signal, and when recording the current digital video signal, digital audio signals of m (m is an integer of 2 or larger) channels are multiplexed with the current digital video signal in time division, and the multiplexed signal is azimuth-recorded with k (k is an integer of 2 or larger) magnetic heads on k tracks in every one revolution of the rotary drum, and when recording digital audio signals of n.times.

Abstract: A magnetic recording method and apparatus which performs a quadrature phase shift keying operation on a digital information signal, superimposes a high frequency bias signal on the performed signal, records the resulting signal into a deep portion of a magnetic layer of a magnetic tape with a first rotational head, and records a video signal in a surface portion of the magnetic layer above a track formed by the former recording, with a second rotational head which is different in azimuth angle from the first rotational head, the frequency of the high frequency bias signal being set to a value which is about four times as high as the carrier frequency of the quadrature phase shift keyed digital information signal, thereby eliminating a 5th-order distortion component due to cross modulation of the high frequency bias signal and the carrier frequency.

Abstract: A magnetic recording/reproducing apparatus is provided which includes a head structure compatible with a long-time play mode in handling either of two kinds of signals containing different amounts of information, such as a current digital picture signal and a high-definition (HD) digital picture signal in the rate of two to one at a constant number of revolutions of the drum by restricting an increase of the number of heads. In an aspect of the apparatus, four heads are arranged on the rotating drum equally 90.degree. spaced, a fifth head of an opposite azimuth is mounted close to any of those heads, the number of drum revolutions is increased to twice larger than the normal number, the current digital picture signal is recorded and reproduced for each channel by using two heads, that is, the fifth head and a head positioned 180.degree. opposite to the fifth head.

Abstract: A receiving circuit is designed for an MSK (Minimum Shift Keying) receiver and a QPSK (Quadrature Phase Shift Keying) receiver. The circuit provides a synchronous state determining device and a control voltage sweeping device for sweeping the output of a voltage oscillator. In the asynchronous state, a switch is turned off for interrupting a reproducing phase error signal so that the output of the voltage oscillator may be swept for causing the synchronous state. Then, the sweeping operation is stopped and the switch is turned on for controlling the voltage of the voltage controlled oscillator so that the low-frequency error component is removed from the phase error signal of the demodulating circuit. This results in implementing the simply-arranged demodulating circuit which keeps the proper demodulating performance against the shifted carrier frequency without any degrade and demodulates the input signal stably if the signal has a low C/N ratio.

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: In a recording and reproducing apparatus wherein a video signal and an audio signal are recorded on the same recording track, a signal subjected to a quadrature differential PSK modulation with PCM audio signal is generated as an audio recording signal. The audio recording signal is disposed between occupied bands of FM luminance signal and down converted chrominance signal in a video recording signal and also recorded on a track where the video recording signal is to be recorded.

Abstract: A phase locked loop circuit for use in a heterodyne receiver for stably demodulating a carrier-suppressed double-sideband signal such as a 2-phase or 4-phase PSK signal. The phase locked loop circuit comprises a reference oscillator oscillating at a frequency corresponding to an intermediate frequency, and the frequency difference between the reference frequency and the input frequency is detected by a Costas loop, a signal indicative of the frequency difference being fed back to a local oscillator through a loop filter thereby stabilizing the intermediate frequency.

Abstract: Method and apparatus for detecting and correcting code errors in processing a digital signal such as a digital audio signal are disclosed. An error word correcting parity word generated from a plurality of data words is added to the plurality of data words to form a first frame, and the data words and the parity word of a plurality of different first frames are distributed in a second frame and a plurality of additional parity words for detecting and correcting error words in the second frame are added to the second frame to form a Reed-Solomon code. The code errors are detected and corrected using this code. A code error rate counter is provided, and when an output of the code error counter exceeds a predetermined count, the code error correction is inhibited for a predetermined time period or until the code error rate reaches a second predetermined code error rate.