JPS6171478A - Digital data reproducing device - Google Patents

Abstract

PURPOSE:To obtain a digital data with high quality by selecting a highly reliable data between digital data of two systems obtained by reproducing a digital data at a prescribed time difference and using it as a re-output. CONSTITUTION:Decoders 6, 16 generate a reproduced digital audio signal from reproducing signals of magnetic heads 2, 3 and 12, 13. A comparator circuit 8 uses flag signals F11-F13, F21-F23 from the decoders 6, 16 to discriminate the propriety of reproduced digital audio signals DT1, DT2 from the decoders 6, 16 thereby generating a control signal. That is, a sample data without error or a correct sample data is selected by a switch circuit 9 from the comparator circuit 8. When the output data DT1 of the decoder 6 and the output data DT2 of the decoder 16 have the same priority, the output data DT11 of the decoder 6 via a delay circuit 7 is selected by the switch circuit 9.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a digital data reproducing device, and particularly to signal processing in a reproducing system of digital audio equipment.

[Conventional technology]

In the field of digital audio, fixed head audio tape recorders using magnetic tape and rotating head video tape recorders are used as recording devices. These devices record a digital audio signal on a magnetic tape as a recording medium using a magnetic head, and conversely, reproduce the digital audio signal using a magnetic head. However, since errors occur in the recording/reproducing system due to various causes, error detection and error correction codes are added to the digital audio signal. This is intended to reduce the influence of errors.

Furthermore, when error correction cannot be performed, pre-holding and average value interpolation are used to prevent digital data from being lost.

[Problem that the invention seeks to solve]

However, since the digital data reproducing device has a mechanical running system in its data transmission system, the occurrence of errors cannot be avoided no matter what code structure is used. Such data for which error correction cannot be performed may cause omissions in the reproduced data, and the quality of the reproduced data may deteriorate due to interpolation processing.

Accordingly, an object of the present invention is to provide a digital reproducing apparatus that can obtain higher reliability in a digital data reproducing system and, accordingly, can obtain high quality digital data.

[Means for solving problems]

The present invention provides a first reproducing means 2.3 and a second reproducing means 2.3 for reproducing digital data recorded on a recording medium at a predetermined time difference.
and error-corrected first data DT 1 and first error information F 11. which have been error-corrected by detecting errors in the reproduced digital signals from the reproduction means 12 and 13 and the first reproduction means 2 and 3.
F12. The first decoder 6 that outputs F13 and the second data DT that has been error-corrected by detecting errors in the reproduced digital signal from the second reproduction means 12.13.
2 and second error information F 21. F22. F
a second decoder 16 that outputs 23; a delay circuit 7 for matching the phases of the outputs of the first and second reproduction means;
A digital data reproducing device comprising means 8 and 9 for selecting a more correct output from the outputs of the first and second decoders 6.16 by comparing the first and second error information. .

[Effect]

Two systems of reproducing means are used to reproduce digital data recorded on a recording medium at a predetermined time difference, and among the two digital data DT 1° DT 2 obtained thereby,
Either the correct one or the more reliable one can be selected and reproduced as output.

〔Example〕

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a case where an embodiment of the present invention is applied to a digital audio signal recording and reproducing apparatus using a rotary head type video tape recorder will be described with reference to the drawings.

In Figure 1, ■ is a rotating drum, and rotating drum 1
A pair of recording/playback magnetic heads 2.3 are installed on the 180
They are installed with a square spacing of 6. In addition, the magnetic heads 2 and 3 are installed at a predetermined angle behind the rotation direction, for example, clockwise, with the magnetic heads 2 and 3 placed at an angular interval of 180°. It is also attached.

On the circumferential surface of the rotating drum 1, there is a magnetic tape 180 (not shown).
'The wrapping slightly larger than 'is a corner and is wrapped around. Although omitted in FIG. 1, a recording circuit is provided for recording a digital audio signal in the same signal form as a video signal using the magnetic head 2.3. That is, the recording signal has a horizontal synchronization signal, a vertical synchronization signal, and an equivalent pulse like a video signal, and an error correction encoded digital audio signal is inserted instead of the video signal.

In this manner, by making the digital audio signal have the same signal format as the video signal, it is possible to record and reproduce the digital audio signal using a rotary head type video tape recorder.

Of course, the present invention can also be applied to a dedicated recording/playback device for digital audio signals.

As the rotary drum 1 rotates, the magnetic heads 2 and 3 alternately output reproduction output every 172 rotation cycles of the rotary drum 1, for example, every 1 field. The output of the magnetic head 2 is supplied to one input terminal of the switch circuit 4, and the output of the magnetic head 3 is supplied to the other input terminal of the switch circuit 4.

Also, as the rotating drum 1 rotates, the magnetic helads 12, .
13, the reproduction output is taken out alternately every 1 or 2 rotation periods of the rotary drum 1. That is, the magnetic head 12
．． The reproduction output of the magnetic head 13 is delayed from the reproduction output of the magnetic heads 2 and 3 by an amount determined by the positional relationship between the magnetic heads 2 and 12 and the magnetic heads 3 and 13.

(i) The output of the air hand 12 is supplied to one input terminal of the switch circuit 14, and the output of the magnetic herad 13 is supplied to the other input terminal of the switch circuit 14.

The switch circuit 4 is supplied with a switch switching pulse from a terminal 10, and the switch circuit 14 is supplied with a switch switching pulse from a terminal 11. With this pulse, each of the switch circuit 4 and the switch circuit 14 performs a switching operation every 172 rotation cycles of the rotary drum l, and the pulse is supplied to two input terminals of the switch circuit 4 and the switch circuit 14, respectively. The reproduction output of the magnetic head is selected alternately to output a continuous reproduction signal. The output of the switch circuit 4 is supplied to a reproduction amplifier 5, and the output of the switch circuit 14 is supplied to a reproduction amplifier 15.

The reproduction signal amplified by the reproduction amplifier 5 is supplied to the decoder 6, and the reproduction signal amplified by the reproduction amplifier 15 is supplied to the decoder 16.

The decoder 6 generates a reproduced digital audio signal from the reproduced signal, and is composed of a synchronization signal extraction circuit, an error detection and correction circuit, an error interpolation circuit, and the like. The error detection circuit detects an error, and the error data is corrected by decoding the error correction code. Sample data that cannot be error corrected is corrected by the error interpolation circuit so that the error is not noticeable. In this example, average value interpolation and pre-hold interpolation are possible. If the sample data located in each position is correct, the error data is replaced by the average value of these two sample data.Also, if only the sample data located before the error data is correct, the error data is replaced with this correct data. Replaced with sample data.

Since average value interpolation has better interpolation accuracy than pre-hold, average value interpolation is performed preferentially over pre-hold. Furthermore, error data that cannot even be pre-held is muted.

The decoder 16 also has the same configuration as the decoder 6, and receives decoded digital audio signals DT1 from each of the decoders 6 and 16. Along with DT2, a flag signal F indicating processing regarding error data performed in each of the decoder 6 and the decoder 16.11.
F12. F 13 and F 21. F 22゜F
23 occurs. Flag signal F 11. F21 becomes high level corresponding to sample data subjected to average value interpolation, and the pufferfish signal F12. F22 becomes high level corresponding to the pre-held sample data, and the flag signal F13. F23 is at a high level corresponding to muted sample data. If there is no error, flag signal F11. F12. F13 or F21
°F 22. All F23 become low level.

The reproduced digital audio signal DT 1 output from the decoder 6 is delayed by the delay circuit 7 , and the delayed reproduced digital audio signal DTII is supplied to one input terminal of the switch circuit 9 .

Also, flag signal F11. F12. F13
is similarly delayed by the delay circuit 7 and supplied to the comparison circuit 8. As mentioned above, in this example, the magnetic head 2°3
It is assumed that the attachment of the magnetic heads 12 and 13 precedes the attachment of the magnetic heads 12 and 13, and the delay circuit 7 has a delay amount corresponding to the difference in the attachment positions of the magnetic heads. Therefore, the timings of the two reproduced data input to the switch circuit 9 are aligned, and the timings of the flag signals supplied to the comparison circuit 8 are aligned.

The reproduced digital audio signal DT2 output from the decoder 16 is supplied to the other input terminal of the switch circuit 9, and the flag signal F21. F22. F23
is supplied to the comparison circuit 8.

The switch circuit 9 normally selects the data reproduced by the magnetic head 2.3, that is, the output data DTII of the delay circuit 7. A reproduced digital audio signal DT 3 is taken out to an output terminal 12 of this switch circuit 9 . Although not shown, a D/A converter is connected to the output terminal 12.

Comparison circuit 8 receives flag signals F11 from decoder 6 and decoder 16. F, 12. F13. F
21. F22°F23 reproduces the reproduced digital audio signal DT from the decoder 6 and the decoder 16.
1. It is configured to determine the superiority or inferiority of DT 2 and generate a control signal.

In other words, the comparator circuit 8 selects error-free sample data or more correct sample data to the sinch circuit 9.
Selected by

The comparator circuit 8 determines whether the reproduced data is superior or inferior using the flag signal F11. F12. F13. F21
．． F22. This is done based on F23. To explain this order of priority, error-free data is given the highest priority, followed by average value interpolated data, pre-held data, and muted data. Further, when the output data DT 1 of the decoder 6 and the output data DT 2 of the decoder 16 are in the same order, the output data DT 11 of the decoder 6 via the delay circuit 7
is selected by the switch circuit 9.

FIG. 2 is a time chart showing the outputs of the various parts shown in FIG. 1. Referring to FIG. 2, the operation of one embodiment of the present invention will be described. 2A shows the reproduction output of the magnetic head 2, and FIG. 2B shows the reproduction output of the magnetic head 3. The reproduction output of the magnetic head 2.3 is connected to the switch circuit 4.
The data is serialized and subjected to reproduction processing such as error correction by the decoder 6, and the decoded reproduction data DT1 shown in FIG. 2C is obtained from the decoder 6. This playback data D
Reproduction data D obtained by delaying T1 by the delay circuit 7
TII (Fig. 2D) is obtained.

FIG. 2E shows the reproduction output of the magnetic head 12, FIG. 2F shows the reproduction output of the magnetic head 13, and FIG. 2G shows the reproduction output of the magnetic head 12.
The output of the reproduced data DT 2 after decoding from the decoder 16 is shown, and FIG.
3 is shown.

Normally, the reproduction data DT11 is generated by the inch circuit 9.
is selected and set as output data DT3.

Now, a dropout occurs in the output of the magnetic head 3 as shown by the shaded area in FIG. 2B, and
In the second diagram, it is assumed that an error due to dropout cannot be corrected, as shown by the shaded area, and the data in this area is muted. On the other hand, the magnetic head 12
．． It is assumed that no dropout occurs in the reproduced output of No. 13, and that the reproduced data DT 2 (G in FIG. 2) does not contain any errors. In this case, the comparison circuit 8 controls the switch circuit 9 to select the reproduced data DT 2 of the decoder 16 . Therefore, the output data DT3 is
As shown in FIG. 2H, the muted section is not included.

Furthermore, if there is digital data that cannot be error corrected in the output data corresponding to the respective outputs of the magnetic heads 2 and 3 and the magnetic heads 12 and 13, the data will be processed in accordance with the above-mentioned priority order. A control signal is supplied from the comparison circuit 8 to the switch circuit 9 so as to select highly reliable data.

〔Effect of the invention〕

According to this invention, two systems of reproducing means are used to reproduce digital data recorded on a recording medium at a predetermined time difference, and among the two digital data obtained thereby,
Since either the correct one or the more reliable one can be selected as the playback output, higher reliability can be obtained in the digital data playback system, and accordingly, high-quality digital data can be obtained. .

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention.
FIG. 2 is a time chart for explaining the operation of an embodiment of the present invention. 2.3.12, 13: magnetic head, 4, 9.14: switch circuit, 6, 16: decoder, 7: delay circuit, 8: comparison circuit.

Claims (1)

[Claims] first and second reproducing means for reproducing digital data recorded on a recording medium at a predetermined time difference; first data corrected by detecting errors in the reproduced digital signal from the first reproducing means; and a first decoder that outputs first error information; and a second decoder that detects errors in the reproduced digital signal from the second reproduction means and outputs error-corrected second data and second error information. a decoder, a delay circuit for matching the phases of the outputs of the first and second reproduction means, and a difference between the outputs of the first and second decoders by comparing the first and second error information. , means for selecting a more correct output.