JPS6217313B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a PCM recording and reproducing apparatus, and more particularly to a tape format with high error correction capability for a fixed head type multi-channel PCM recording and reproducing apparatus.

Here, the PCM recording and playback device has the function of digitizing the audio signal and recording and playing back the PCM.
is an abbreviation for Pulse Cord Modulation.

The tape formats of fixed head type multi-channel PCM recording and reproducing devices (hereinafter referred to as multi-recorders) that have been proposed up to now are one-track, two-track, and four-track formats per audio signal channel. FIG. 1 shows an example of a one-track system. In the figure, magnetic tape 2 is a recording track 1, and the number of recording tracks 2 is equal to the number of channels of the recorder. 3 is a recorded audio information signal, 4 is a redundant signal for error correction generated in response to the audio information 3, and each signal is interleaved on the track, so that even on one track, signals can be placed at distant locations. recorded. On the other hand, in the experience of the inventors, when the recording condition of a tape is poor, it is rare for all tracks to deteriorate equally, and rather, it is common for code errors to occur concentrated on some track. Therefore, in that case, one of the channels becomes unusable, which is a drawback.

In the present invention, in order to improve such drawbacks,
Furthermore, a track for recording redundant signals for error correction is provided to correct code errors in the width direction of the tape. FIG. 2 shows one example of this, in which the information track is one track per audio channel, and two redundant signals for error correction are provided for each eight audio tracks 2-1 to 2-8.
Tracks 5-1 and 5-2 have been added. In the figure, 5 indicates the added redundant signal 5-1 and redundant signal 5-2. FIG. 3 explains the method of generating the redundant signals 5-1 and 5-2. From each track 2-1 to 2-8, extract b bits from adjacent positions in the tape width direction, _a1 to _a8.
The redundant signals c ₁ , c ₂ are obtained from the b×8 bits.
get. The generation of c ₁ and c ₂ may be simple parity, Hamming code, or Reed-Solomon code.

Similar operations are performed for the next b bits of each track, and then the next b bits are successively performed. FIG. 4 shows an example in which interleaving is applied, in which each b bit is taken out at an angle slightly deviating from the tape width direction, and redundant signals are recorded at positions further apart.

Figure 5 shows an example in which a redundant signal is further added to the tape running; in this example, each track 2-1 to 2-8, 5-
For both 1 and 5-2, a redundant signal _d1 is added for every 7×b bits. The algorithm for the generation of _d1 is also CRC,
Various simple Hallity codes have been devised. In this way, if it is possible to correct up to two tracks using the error correction redundant signals c ₁ and c ₂ , even if one track is in a bad recording state and code errors occur frequently, it can be sufficiently corrected. Even if one track completely fails and becomes inoperable, and dropouts occur in other tracks, it can be corrected, so the recorder's operation will not be affected, greatly increasing the stability of the recorder. That means you did it.

Next, let's talk about overdubbing.

Figure 6 shows the tape running system and its circuit of a multi-recorder. In the figure, 6 is a multi-track recording head (hereinafter referred to as a recording head), and 7 is a multi-track synchronized playback head (hereinafter referred to as a playback head).
The tape 1 runs in the direction of arrow 8. 9
is a digital circuit on the playback side, and the inside of the playback circuit 9 is as shown below.The output from the playback head 7 is an amplifier 10.
The signal is amplified by 1, code errors are corrected by an error correction circuit 102, converted back to an analog signal by a D/A converter 103, and amplified by an audio amplifier 104 to output audio. One of the outputs of the error correction circuit 102 and the other
It is supplied to the switch 12 through a digital delay 105 in the form of a PCM signal. The audio signal input from the input terminal 11 is sent to the input side digital circuit 10.
Converted to PCM signal.

Inside the input circuit 10, the input audio signal is amplified by the audio amplifier 106 and amplified by the A/D converter 107.
It is converted into a PCM signal and output via digital delay 111. Reference numeral 15 denotes a recording side digital circuit, which internally generates a redundant signal for error correction in an error correction code adding circuit 108 to the PCM signal from the switch 12, amplifies this signal in a recording circuit 109, and outputs the tape 1 to the recording head 6. Record above.

The switch 12 and the recording circuit 109 are controlled by an operation button 110.

As shown in the figure, a recording head 6, a reproducing head 7, a reproducing side digital circuit 9, an input side digital circuit 10,
The switch 12 and the recording side digital circuit 15 are configured as many as the number of channels.

Next, the overdubbing operation will be explained with reference to FIG. 7, taking as an example the case where the error correction redundant signals c ₁ and c ₂ are created in the width direction of the tape.

If the second channel is now overdubbed, the shaded portion of the second track 2-2 is re-recorded. In this case, it is naturally necessary to re-record the redundant signals c ₁ and c ₂ corresponding to that portion as well.

In FIG. 6, during overdubbing, the digital signal of the second channel is supplied to the input side digital circuit 10, and the other channels 1 to 8 are supplied from the reproduction side digital circuit 9 to the recording side digital circuit 15.
c ₁ and c ₂ are generated by the recording side digital circuit 15.
In this case, if other information signals of channels 1 to 8 are newly recorded, deterioration due to code errors increases, so it is necessary to rerecord only the channels to be overdubbed and the parity track portions corresponding thereto.

In this example, the error correction code is generated in the tape width direction, but the fourth interleaved
In the case of the figure, it is sufficient to overdub the shaded area in FIG. Also, in this example, audio channel 1
Although one track is recorded for each track, the same holds true even when multiple tracks are recorded. Figure 9 is audio 1
This is an example of recording two tracks per channel.

Also, in this example, 2 redundant signals are provided for each 8 channels of audio.
Although it was a track, it can be done in exactly the same way with other combinations of numbers.

As mentioned above, in a fixed head multichannel recorder, redundant signals for error correction are generated across multiple audio channels, each audio channel and redundant signal are recorded on separate tracks, and when overdubbing, the overdubbing track is By simultaneously re-recording the redundant signal portion corresponding to the overdubbing portion, it is possible to provide a format that has high error correction ability and also allows overdubbing.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing a format in which one track is recorded per audio channel in a conventional example, Fig. 2 is a block diagram showing a tape format according to an embodiment of the present invention, and Fig. 3 is an algorithm for creating redundant signals. FIG. 4 is a block diagram showing an example of recording by interleaving codes, FIG. 5 is a block diagram showing a format when a redundant signal is added in the tape running direction, and FIG. 6 is a block diagram showing an example of recording by interleaving codes. FIG. 7 is a configuration diagram showing the tape running system and digital signal processing of a PCM multi-channel recorder according to an embodiment;
FIGS. 8 and 9 are block diagrams showing each overdubbing, and are examples in which two tracks are recorded per audio channel. In the figure, 2 is a recording track, 5 is a track, 6 is a recording head, 7 is a reproduction head, 9 is a reproduction side digital circuit, 10 is an input side digital circuit, and 15 is a recording side digital circuit. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] 1. Means for converting an audio signal into a digital signal, allocating one or more recording tracks per channel of the audio signal and recording the digital signal on the recording track, and generating an error correction code from the plurality of audio signals. , means for recording this on a track different from the above-mentioned information track, and when re-recording only a specific part of a specific audio signal that has already been recorded, means for re-recording only that part and the error correction code corresponding to it. A PCM recording and playback device equipped with