Abstract: Music piece data of so-called managed music pieces, each of which requires allowance of performance for each karaoke apparatus are stored in a hard disk in the same manner as music piece data of other karaoke music pieces. A ROM (20), which has stored therein key data for allowing performance of a managed music piece, is produced for each of the managed music pieces and for each of karaoke apparatuses. Performance of a managed music piece is allowed by setting a corresponding ROM (20) into a karaoke apparatus. Accordingly, a karaoke apparatus is not required to have a medium such as a CD-ROM for each of managed music pieces, and the copyright holder of a managed music piece can physically manage the number of allowed performances by way of the ROM (20).

Abstract: Even music piece data of so-called managed music pieces each of which requires allowance of performance for each karaoke apparatus are stored in a hard disk in the same manner as music piece data of other karaoke music pieces. A ROM (20), which has stored therein key data for allowing performance of a managed music piece, is produced for each or the managed music pieces and for each of karaoke apparatuses. Performance of a managed music piece is allowed by setting a corresponding ROM (20) into a karaoke apparatus. Accordingly, a karaoke apparatus is not required to have a medium such as a CD-ROM for each of managed music pieces, and the copyright holder of a managed music piece can physically manage the number of allowed performances by way of the ROM (20).

Abstract: A dropout detection device for use in a device for playing back an optical disc such as a video disc and a Compact Disc comprises a four-split photodetector receiving laser beam through a disc on which information is recorded, a sum signal generation circuit for generating sum signals of output signals of two detectors positioned on diagonals of the four-split photodetector, and a dropout detection circuit for detecting difference in the waveform between two output sum signals of the sum signal generation circuit. A dropout in a reproduced signal is detected directly on the basis of result of detection by the dropout detection circuit without subjecting the reproduced signal to other signal processings so that a simplified circuit design can be realized.

Abstract: A circuit for compensating change in delay time of a delay circuit due to variation in temperature employs, as a phase shifter of a pulse FM detection circuit, a delay circuit whose delay time is subject to change due to variation in temperature and can be controlled in response to a control signal. A dc component in an output of this pulse FM detection circuit is compared with a preset reference value and a resulting comparison output is used for controlling the delay time of the delay circuit and thereby compensating the temperature characteristic of the delay time. In a device using plural delay circuits, these delay circuits can be disposed on the same substrate and the delay times of these delay circuits can be controlled by the same comparison output. Since a signal which is handled by a delay circuit is utilized for the temperature compensation, an accurate temperature compensation can be realized with a simple circuit construction.

Abstract: A circuit for eliminating a beat signal resulting from interference between a broadcast signal of a received station and a broadcast signal of an adjacent station during the reception of an AM broadcast. A cancel signal generating circuit for forming a cancel signal synchronized to the beat signal contained in an AM detected output signal is connected to the output of an AM detector. The cancel signal is combined with the AM detected output signal in a mixing circuit connected to the AM detector, to eliminate the beat signal. Such a beat signal cancelling circuit may be served by a pilot signal cancelling circuit in an FM receiver.

Abstract: A station-signal frequency indicating system for a radio receiver, in which the content in a counter counting an output of a local oscillator in the receiver is temporarily retained by a latching circuit and in turn is displayed by an indicator, and in which a control circuit inhibits the retained content in the latching circuit from being changed, immediately after the receiver is tuned exactly to a station signal until the receiver is detuned from this station signal.