JPS63175271A - Method for reproducing digital voice - Google Patents

Abstract

PURPOSE:To improve the matching accuracy for processing timing and the error detecting accuracy of the digital sound signals, by detecting and correcting the errors of the digital sound signals recorded with multiplication of frequencies in a reproduction process based on the horizontal and vertical synchronizing signals, a drop-out detecting signal, etc. CONSTITUTION:The errors of the digital data are detected by an error detecting circuit 7 for the digital sound signals subjected to the FM demodulation through an FM demodulation circuit 6. Then the digital data errors are corrected by an error correcting circuit 8 and these corrected data are outputted through a voice terminal 12. If a DT (drop-out) signal is detected by an HD (horizontal synchronization)/VD (vertical synchronization)/DT detecting circuit 9, the detection of an error is decided in preference. Thus this error data is sent to the circuit 7. In such a way, the error detecting accuracy even though the misdetection of errors is caused by the DT signal. In addition, the HD and VD signals inputted to the circuit 8 can be used as the signals showing the position of the digital data on a disk since both signals are synchronous with the revolution of the disk.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention provides a VHD (Video High-Density) system in which video signals and audio signals are FM-modulated and recorded.
The present invention relates to a digital audio reproduction method for reproducing a disc 5ystea) type recording medium.

(Prior art) A VHD recording medium (hereinafter simply referred to as a disk) is used by a digital audio playback device (hereinafter simply referred to as a player).
When reproducing a disc, the signal read from the disc is FM demodulated and inputted to a video signal processing circuit and an audio signal processing circuit to obtain desired video and audio signals. At this time, a horizontal synchronization signal (HD signal), a vertical synchronization signal (VD signal), a dropout detection signal (DT signal), etc. are obtained from the video signal processing circuit. On the other hand, when an audio signal is digitized, converted into a PCM code, FM modulated, frequency-multiplexed with the above-mentioned video signal and audio signal, and recorded on a disc, when playing back this frequency-multiplexed digital audio, First, it is necessary to perform FM demodulation and return it to digital data, and then perform processing such as error detection and error correction in a digital circuit.

(Problem to be solved by the invention) In order to perform this error detection and error correction, a synchronization bit,
It is necessary to detect CRC and the like, but conventionally there has been a problem that this detection circuit is complicated.

In the process of error detection, error correction, etc., the present invention refers to the HD signal, VD signal, and DT signal obtained from the video signal processing circuit, thereby adjusting the timing of digital audio processing and detecting errors. It is an object of the present invention to provide a digital audio playback method that makes it possible to increase the accuracy of digital audio, simplify the conventional digital audio processing circuit, and improve the functionality.

(Means for Solving the Problems) The digital audio reproduction method of the present invention records a video signal and an audio signal with FM modulation, and also digitizes another new audio signal and converts it into a PCM code. A method for reproducing an information recording disc recorded by modulating and frequency multiplexing the respective signals, the method comprising: a horizontal synchronization signal, a vertical synchronization signal, and a dropout obtained in a signal processing process when reproducing the video signal; Based on signals such as detection signals,
It performs processing such as error detection and error correction in the reproduction process of the digital audio signal recorded by frequency multiplexing.

(Function) Error detection in the reproduction process of digital audio signals recorded by frequency multiplexing based on the horizontal synchronization signal, vertical synchronization signal, dropout detection signal, etc. obtained in the signal processing process when reproducing video signals. , performs processing such as error correction. This makes it possible to match the timing of digital audio signal processing and improve error detection accuracy.

(Example) Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

The drawings schematically show the configuration of a playback device for realizing the digital audio playback method of the present invention.

In the figure, 1 is a turntable on which a disk (not shown) is placed, 2 is a pickup circuit, 3 is a preamplifier section, 4 is a tracking servo section, 5 is a time base servo section, 6 is an FM demodulation circuit, and 7 is a Error detection circuit, 8 error correction circuit, 9 HD, VD-DT detection circuit, 10 video signal processing circuit, 12 audio terminal, 13 video terminal, 1
4 is a player control section, 15 is a motor servo circuit, 16 is an operation input section, and 18 is a power supply circuit that supplies power to each of the above circuits. The disc contains FM-modulated video and audio signals as well as digitized and PC-readable signals.
Another new audio signal that has been converted to M code and then FM modulated is frequency multiplexed and recorded.

Next, the operation of the above-described playback device will be explained.

Disc placed on turntable 1 (not shown)
The signal read by the pick amplifier circuit 2 from
The signal is input to the preamplifier section 3, where it is amplified and separated into a video signal component and a shifter component. The video signal component is output to a tracking servo section 4, a time base servo section 5, and an FM demodulation circuit 6. Further, the jitter component is output to the time base servo section 5.

The tracking servo section 4 separates a tracking signal necessary for tracking control from the video signal input from the preamplifier section 3, detects the deviation of the stylus (not shown) from the track center based on this signal, and detects the deviation of the stylus (not shown) from the track center. The pickup circuit 2 is controlled to trace the center of the trunk.

The time base servo section 5 corrects jitter based on the video signal input from the preamplifier section 3 and the jitter component input as an error signal, and controls the pickup circuit 2.

The rotation of the turntable 1 is controlled by a motor servo circuit 15.
5 is further controlled by a player control section 14. Further, a signal indicating the rotational state of a motor (not shown) is output from the motor servo circuit 15 to the player control section 14.

The player control section 14 controls the operations of the pickup circuit 2, tracking servo section 4, and time base servo section 5 in addition to controlling the operation of the motor servo circuit 15. This player control section 14 is connected to an operation input section 16.

The video signal input to the FM demodulation circuit 6 is FM demodulated here and then output to an error detection circuit 7 and a video signal processing circuit 10. Then, the video signal processing circuit 10 converts it into a standard color television signal and outputs it from the video terminal 13.) ID-VD-DT detection circuit 9
Here, the video signal is input to the HD signal, VD signal,
and DT times signal is detected. On the other hand, the FM demodulation circuit 6
The M-demodulated digital audio signal is sent to the error detection circuit 7.
After an error in the digital data is detected and the data is actually corrected by the error correction circuit 8, the audio terminal 12
is output from. At this time, it is shown that the DT double signal detected by the HD/VD-DT detection circuit 9 and the signal read from the disc are partially missing, and therefore the digital data that should become digital audio is also missing in that part. So it's missing. Therefore, when this DT multiplied signal is detected, it is regarded as an error detection with priority, and the data is outputted to the error detection circuit 7. The accuracy of error detection can be improved by using this DT multiplied signal even if error detection is omitted. Furthermore, since the HD signal and VD signal input to the error correction circuit 8 are signals that are synchronized with the rotation of the disk, they can be used as signals indicating the position of digital data on the disk.

(Effects of the Invention) As explained above, according to the digital audio reproduction method of the present invention, by processing digital audio using a signal detected when processing a video signal, the circuit can be simplified and , it is possible to improve detection accuracy.

[Brief explanation of the drawing]

The drawing shows a schematic block diagram of a playback device for realizing the digital audio playback method of the present invention. 1...Turntable 2...Pickup circuit 3...Preamplifier section 4...Tracking servo section 5...Time base servo section 6...FM demodulation circuit 7...Error detection circuit 8.
...Error correction circuit 9...HD-VD/D detection circuit 10...Video signal processing circuit 12...Audio terminal 13...Video terminal 14...
...Player control section 15...Motor servo circuit

Claims (1)

[Claims] 1) Video signals and audio signals are FM-modulated and recorded, and another new audio signal is digitized and converted into a PCM code, then FM-modulated, and frequency-multiplexed with each of the above-mentioned signals. A method for reproducing a recorded information recording disk, the method comprising frequency multiplexing based on signals such as a horizontal synchronization signal, a vertical synchronization signal, and a dropout detection signal obtained in the signal processing process when reproducing the video signal. A digital audio playback method, characterized in that processing such as error detection and error correction is performed in the playback processing process of the digital audio signal recorded in the digital audio signal.