JPS6010464A - Digital audio reproducing device - Google Patents

Abstract

PURPOSE:To reproduce sounds faithful to original sound at a recording time by setting a phase rotation quantity, which can cancel the phase rotation applied to a recorded audio signal in a sound recording system, to a digital filter. CONSTITUTION:In a digital filter 2, the phase rotation quantity is switched to three kinds of preliminarily determined state by an external switches 3a-3c; and for example, when a switch 3a (3b) is closed, the phase rotation quantity which cancels the phase rotation quantity due to a low-pass filter provided in the sound recording system in a company X (Y) is set; and when a switch 3c is closed, the phase rotation quantity which cancels the phase rotation quantity due to a low- pass filter 6 is set. The phase rotation quantity which cancels the phase rotation quantity applied in the sound recording system in the company X is given forcibly to the digital filter 2 where the switch 3a is selected. The processing for fetching and averaging of a stabilized part in an operture circuit 5 is executed, and then is outputted as a reproduced audio signal B through the high-band noise eliminating low-pass filter 6.

Description

[Detailed Description of the Invention] Technical Field The present invention relates to a digital audio playback device, and in particular to a method for correcting, on the playback side, phase rotation that is added to a recording signal by a low-noise filter provided on the recording side. The present invention relates to a digital audio playback device that improves the playback fidelity of original sound.

Background Art In recent years, with the rapid development of electronic technology, there has been a trend toward digital recording of audio signals.
Digital audio devices that play back recorded media include digital audio disc playback devices (OD) and digital audio tape playback devices (DAT).
etc. have been developed.

A digital audio disc playback device rotates a disc as a recording medium at a constant linear velocity, optically reads digital audio signals optically recorded on the surface of the disc, and converts the digital audio signals into electrical signals. It's something to bring out. After this extracted electrical signal is subjected to signal processing such as error correction and decoding, it is changed to an analog signal in a digital-to-analog converter, and then stabilized in an aperture circuit. The device is configured to obtain a reproduced audio signal by extracting the signal through a filter after being averaged and averaged.In an apparatus configured in this way, the digital data is recorded on a disk as a recording medium. Because it reads and plays audio signals that are recorded as signals,
It has the feature of faithful reproduction.

However, in a recording system that writes digital audio signals onto a disk as a recording medium, a low-pass filter is installed to remove high-frequency noise, so the recorded audio signal is subject to phase rotation due to this low-pass filter. The audio signal that is digitally recorded on the disk has been subjected to phase rotation by a low-speed filter installed in the recording system.

As a result, no matter how faithfully the reproduction system reads and reproduces the signals recorded on the disc, the phase rotation received in the recording system will be reflected in the reproduced audio signal. This has a negative effect on the mid-to-high range.

Accordingly, an object of the present invention is to provide a digital audio reproducing apparatus that can reproduce sound faithful to the original sound during recording.

In order to achieve such an object, the present invention provides a digital filter on the input side of a digital-to-analog converter that converts a digital signal read from a recording medium into an analog signal, and calculates the amount of phase rotation of this digital filter. This value is set to a value that can cancel out the phase rotation that the recording signal receives in the recording system.

Therefore, in a device configured in this way, the phase rotation of the digital recording signal received by the low-noise filter in the recording system can be corrected in the playback system, so that the original sound during recording can be corrected. It has an excellent effect of being able to reproduce faithful sound.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram showing an embodiment of a digital recorder according to the present invention.

In the same figure, l receives a read signal supplied from a big amplifier (not shown) that reads a digital audio signal optically recorded on the surface of a digital audio disk as a recording medium, for example, and performs error correction and correction. A signal processing circuit that performs various signal processing such as decoding.

Reference numeral 2 denotes a digital filter which receives the output signal of the signal processing circuit 1 as an input, and this digital filter 2 has a phase rotation amount that can be switched between three predetermined types by externally connected switches 38 to 3C. 11. 4 is a digital-to-analog converter that converts the output signal of the digital filter 2 into an analog signal.5 is an analogue circuit that converts the output signal of the digital to analog converter 4 into an analog signal. The stable portion is captured and an averaged signal is output. Reference numeral 6 denotes a low-pass filter, which removes noise contained in the output signal of the aperture circuit 5 and sends out the reproduced audio signal B.

In the digital audio playback device configured in this manner, when a readout signal A of a digital audio signal being written on a digital audio disk is generated from a pickup (not shown) and supplied to the signal processing circuit l, this signal is generated. The signal processing circuit l supplies the signal to the digital filter 2 after performing various signal processing such as correction and decoding. Here, the digital filter 2 is a filter whose cutoff frequency and rotational phase amount can be varied independently of each other, as is generally known. In this digital filter 2, an external switch 3a
By 3C, the 2-rotation phase amount is switched to a predetermined state of 3fl. For example, when switch 3a is closed, the low-pass filter installed in the recording system of Company X is used. The amount of phase rotation is set to a value that cancels out the amount of phase rotation 11, and when switch 3b is closed, the amount of phase rotation is set to a value that cancels out the amount of phase rotation caused by the low-pass filter installed in the recording system of Company Y. The amount of phase rotation is predetermined so that when the switch 3c is closed, the amount of phase rotation is set to a value that cancels out the amount of phase rotation in the low-pass filter 6. Therefore, for example, when a digital audio disc made by Company Y is played back, the playback signal is subject to the phase rotation given by the low-pass filter installed in Company Y's recording system.
ing. On the other hand, the digital filter 2 selected by the switch 3a will forcefully apply an amount of phase rotation that cancels out the amount of phase rotation received in the Y recording system.

The digital signal that has undergone this kind of processing is
The phase rotation received in the recording system also cancels out the phase rotation applied by the digital filter 2, so that it is not affected by the phase rotation. In this way, the output signal of the digital filter 2, whose phase rotation has been corrected, is changed into an analog signal in the digital-to-analog conversion circuit 4, and then the stabilized portion is extracted in the aperture circuit 5. After averaging processing is performed, the signal is outputted as a reproduced audio signal B via a low-pass filter 6 for removing high-frequency noise. Therefore, since this reproduced audio signal B has to correct the phase rotation received in the recording system of the digital audio disc in the reproduction system, a reproduced sound that is faithful to the original sound at the time of recording can be obtained. .

Next, when playing a digital audio disc produced by Company Y, by closing only switch 3a, the amount of phase rotation of digital filter 2 is set to a value that can cancel out the phase rotation received by Company Y's recording system. By simply switching to 2, you will be able to obtain reproduced sound that is faithful to the original sound.

Incidentally, the rotary filter provided at the output stage also applies phase rotation to the reproduced audio signal B. Therefore, if it is desired to also correct the influence of phase rotation caused by the low-pass filter 6, it is sufficient to close the switch 3c in addition to closing the switch 3a or 3b. In this way, an amount of phase rotation is added that cancels out the phase rotation received by the low-pass filter 6 when the switch 3c is closed, and as a result, both the recording system and the playback system Any phase rotations received will be corrected.

In addition, in the above embodiment, the case where it is applied to a digital audio disc playback device has been described, but the present invention is not limited to this, but can be applied to all digital audio playback devices. It is.

As explained above, in the digital audio playback frame according to the present invention, since the phase rotation received in the recording system can be corrected in the playback system, playback sound that is faithful to the original sound can be obtained. It has excellent effects.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing an embodiment of a digital audio playback device according to the present invention. 1...Signal processing amount Pi! ! , 2... Digital filter', 32-3C... Switch, 4... Digital-to-analog converter, 5... Anozochar circuit, 6...
... Sufilta in Rono. Applicant: ShinNippon Electric Co., Ltd.

Claims (1)

[Claims] (1) In a digital audio playback device that reproduces an audio signal by reading out an audio signal digitally recorded on a recording medium and supplying it to a digital/analog converter, the input of the analog/digital converter A digital audio playback device, characterized in that a digital filter is provided on the side, and an amount of phase rotation that cancels phase rotation applied to the digital audio signal in a recording system is set in advance as a characteristic of the digital filter. .