JPH0664860B2 - Digital signal reproducing device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital reproducing apparatus for information such as PCM recorded audio signals.

Background art and its problems High-quality recording and reproduction can be performed by converting audio signals into PCM and recording and reproducing. This audio PCM recorder has a fixed head type and a rotary head type, but in both cases, it is used for recording monitors in addition to recording and reproducing heads in the field of commercial use where high reliability is especially required. A playback head is especially provided.

FIG. 1 and FIG. 2 respectively show a rotary head device and a recording / reproducing system of an example of this type of rotary head device.

This example is a two-head type device. In FIG. 1, HA ₁ and HB ₁ are rotary heads for both recording and reproduction, which are arranged 180 ° apart from each other, and the width directions of the gaps are different from each other, that is, azimuth. Are different from each other.

Further, HA ₂ and HB ₂ is a reproducing rotary head for recording the monitor, head HA ₂ is the head HA ₁ the same azimuth, also the head HB ₂ is a head HB ₁ and the same azimuth, the head HA ₁ respectively And HB ₁ are arranged at positions subsequent to each other and 180 ° angularly spaced from each other.

Then, the tape (1) is obliquely wound around the 90-degree angular range around the guide drum (2).
The rotary heads HA ₁ and HB ₁ scan alternately on the top to record and reproduce the PCM audio signal, and at the time of recording, the heads HA ₂ and HB ₂ generate signals from the recording tracks by the heads HA ₁ and HB ₁ , respectively. Is played,
A recording monitor is made.

That is, during recording, the audio signal through the input terminal (11) is supplied to the A / D converter (12) to be a digital signal and supplied to the PCM processor (13). This PCM
The processor (13) includes a PCM encoder and a PCM decoder, and the encoder works during recording. In this encoder, both heads HA ₁ and HB ₁ do not touch tape (1) 90
The time for the angle range of ° is used to add redundant data such as error correction codes and interleave processing, and for example, the audio signal for 180 ° rotation period is time-compressed for 90 ° rotation period and PCM is used. The data is read.
The read PCM data is recorded by the recording amplifier (14R), the recording / reproducing changeover switch (15), and the rotary transformer (16R).
It is supplied to heads HA ₁ and HB ₁ through A) and (16B) and recorded on the tape.

Then, at the time of this recording, the signals recorded by the heads HA ₁ and HB ₁ are reproduced by the heads HA ₂ and HB ₂ , and this is supplied to the reproduction amplifier (22) via the rotary transformers (21A) and (21B). The output is supplied to the PCM decoder (23), and the section in which the heads HA ₂ and HB ₂ do not contact the tape is used to perform PCM signal decoding processing such as error correction and de-interleaving, and the original Converted back to a digital signal,
This is converted back into an analog audio signal by the D / A converter (24), is supplied to the speaker (26) through the amplifier (25), and the sound is reproduced by this speaker (26) for recording monitoring. It As the PCM decoder (23), a decoder part of a PCM processor (13) having a PCM encoder and a decoder may be used.

During reproduction, the signals extracted from the tape by the heads HA ₁ and HB ₁ are rotated by the rotary transformers (16A) and (16B), and the recording / reproduction changeover switch (15) and the reproduction amplifier (17).
To the PCM processor (13). Then, in the decoder section, heads HA ₁ and HB
_The section where ₁ is not in contact with the tape is used to perform error correction, PCM signal decoding processing such as de-interleaving, and is returned to the original digital signal, which is supplied to the error correction circuit (18), Errors that could not be corrected are corrected. Then, the error correction output is returned to the analog audio signal by the D / A converter (19) and is led to the output terminal (20).

By the way, even when it is confirmed by the recording monitor that the recording is correctly performed as described above, the reproduced signal cannot be extracted due to the clogging of the head during reproduction, and a long burst error occurs in the reproduced data. Sometimes. If this happens, the correction capability of the error correction code and interleave will be exceeded. In this case, the data is error-corrected by an interpolation method or the like, but this is not sufficient for business use requiring a complete signal reproduction, and there is a problem in reliability.

SUMMARY OF THE INVENTION In view of the above points, the present invention is to provide a digital signal reproducing apparatus such as PCM, which is expected to improve reliability.

SUMMARY OF THE INVENTION The present invention aims to improve reliability by positively utilizing a reproduction system for recording monitor during reproduction.
First reproduction means HA for reproducing the digital signal recorded in the
₁ , HB ₁ , (22), second reproducing means HA ₂ , HB ₂ , (15) for delaying and reproducing a digital signal, and first reproducing means H
A _first decoder means (23) for detecting the error in the reproduced digital signal from A ₁ , HB ₁ , (22) and outputting the error-corrected first data signal and the first pointer, and the second reproduction. Second decoder means (13) for detecting the error in the reproduced digital signals from the means HA ₂ , HB ₂ , (15) and outputting the error-corrected second data signal and the second pointer
And the first and second regeneration means HA ₁ , HB ₁ , (22) and HA
The data or pointers from the first and second decoder means (23) and (13) are compared with the delay means (32) for delaying the time corresponding to the delay time of the reproduction output of ₂ , HB ₂ , (15). Means (3) for selecting a favorable output from the outputs of the first and second decoder means (23) and (13).
It is a digital signal reproducing device equipped with 1).

Embodiment FIG. 3 is an example in which the present invention is applied to the apparatus shown in FIG. 2 described above, and the operation at the time of recording is exactly the same as in the case of FIG.

In this example, even during reproduction, the recording monitor system is powered on, for example, to be in an operating state. Then, during this reproduction, the D / A converter (24)
The muting circuit (30) provided between the audio amplifier and the audio amplifier (25) operates, and the audio signal passing through this system is muted so as not to be output.

Then, the reproduced digital signal from the PCM decoder (23) is supplied to the selector (31). Also, PCM processor (1
The reproduced digital signal from 3) is delayed by the buffer memory (32) for a time corresponding to the delay time of the reproduction output due to the positional deviation between the head HA ₁ and HB ₁ and the head HA ₂ and HB _2, and the selector (31) Is supplied to.

Further, the signal D ₁ from the buffer memory (32) and the signal D ₂ from the PCM decoder (23) are both supplied to the comparison circuit (33) and compared for each sample, and the comparison output from the selector (31) Select the output to get. The selection is performed as follows, for example.

That is, the digital signals D ₁ and D ₂ are PCM
An error is detected in the processor (13) and the PCM decoder (23), and an error that can be corrected is corrected, but a pointer is set for the data sample in which the error is detected. Therefore, of whether the pointer is standing in signals D _1, D _2, selects the output by comparing the sample itself of signals D ₁ and D _2. An example of selection is shown below.

In this table, x indicates that the data is incorrect, o indicates that the data is correct, and the judgment is made using the pointer. In the fifth case, although both data are correct, the fact that D ₁ ≠ D ₂ means that the error error detection and error correction have been performed for any data. As the output, instead of the data D ₁ and D ₂ , the interpolation data created by the error correction circuit (18) is obtained as an output and supplied to the D / A converter (19).

In this way, correct data can be reproduced unless the outputs from the two reproducing heads are erroneous at the same time, and by comparing the data D ₁ and D ₂ themselves as described above, an error missed by the decoder is also found. And a reliable factory can be achieved.

In addition, the output of the amplifier (17) is delayed by a predetermined time and the output of the reproduction amplifier (22) is selectively supplied to the PCM decoder (23). Normally, one of the outputs is supplied to the PCM decoder (23). An error detection code in the data, for example, a CRC code, may be used to detect whether or not the head is clogged, and when the head is clogged, the output may be switched to the other output. In this case, whether or not the clogging has occurred is detected, for example, by detecting that the number of error detection samples by the CRC code has reached a predetermined number or more.

It should be noted that the present invention is not limited to the rotary head type reproducing apparatus, but can be applied to the fixed head type reproducing apparatus.

EFFECTS OF THE INVENTION According to the present invention, since the output of the reproducing system having two reproducing systems and one of which has a good reproducing output is taken out, clogging occurs simultaneously in the heads of the two systems. As long as there is no error or an error occurs, correct data can always be obtained and reliability can be greatly improved.

Moreover, in the conventional device having the recording monitor function, 2
Since this system has a system head and a reproducing system, this device has an advantage that it is not necessary to newly provide another head and a reproducing system.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a rotary head device applied to the device of the present invention, FIG. 2 is a system diagram of an example of a recording / reproducing device capable of recording and monitoring, and FIG. 3 is a recording / reproducing having an example of the device of the present invention. It is a systematic diagram of an example of an apparatus. HA ₁ and HB ₁ are recording / playback rotary heads, HA ₂ and HB ₂ are read-only rotary heads, (13) is a PCM processor including a PCM decoder, (17) and (22) are playback amplifiers, and (23) is PCM. A decoder, (31) is a selector, and (33) is a data comparison circuit.

Claims (1)

[Claims] 1. A first reproducing means for reproducing a digital signal recorded on a recording medium, a second reproducing means for delaying and reproducing the digital signal, and a reproduced digital signal from the first reproducing means. Error detecting and outputting a first data signal and a first pointer which have been error-corrected, and a first digital signal which is error-corrected by detecting a reproduced digital signal from the second reproducing device. Second decoder means for outputting the second data signal and the second pointer; delay means for delaying the time corresponding to the delay time of the reproduction output of the first and second reproducing means; A digital signal reproducing apparatus comprising means for selecting a favorable output from outputs of the first and second decoder means by comparing data or pointers from the two decoder means.