JPS60219678A - Rotary head magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To obtain a reproducing sound with less noise by coding a signal independently at even and odd number order sample groups of each channel, recording one group of each channel to one track in the unit of group and recording the other group on a different track while parting it in the tape width direction. CONSTITUTION:Coding is applied independently to an even and odd number order sample group at each channel in the unit of groups and the same channel odd and even number order sample groups are different on the different tracks at recording. Since the even number order and odd number order sample groups of the same channel are recorded at a position parted mutually in the broadwise direction of a tape, and even if the burst of a width K2 corresponding to nearly a half of the recording region is caused, since the sample group of other channel is recorded to the same location of the adjacent track, consecutive sample missing is prevented. Since the code is independent between channels and between the even and odd number of sample groups, not only the rewrite at each channel but also the rewrite in the unit of groups is attained.

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to a rotary head type magnetic recording/reproducing device, and in particular to a rotary head type PCM which converts information signals into digital signals.
This invention relates to improvements in data interleaving and encoding in magnetic recording and reproducing devices.

[Prior art]

In general, a rotating head type PCM magnetic recording/reproducing device converts an audio signal into a digital signal, and records and reproduces this onto a magnetic tape using a rotating head, and an error correction code is generally used in this type of device. . The purpose of the error correction code is to correct errors in data that occur during recording and reproduction of magnetic tape, and to reproduce high-quality audio signals.

However, if the number of errors exceeds the correction capability and cannot be corrected, correction processing such as interpolation by taking the average value of previous and subsequent data is performed. Furthermore, errors on magnetic tape are often burst errors, and in order to improve the performance of error correction codes, interleaving (crossing) processing is performed to disperse error data. As mentioned above, when an error cannot be corrected, a correction process is performed, and an effective method using a simple circuit is average value interpolation. This average value interpolation is effective only when there are correct samples before and after an incorrect sample. Therefore, when performing interleaving, it is important to separate the data of the odd sample group and the data of the even sample group as much as possible. It is done.

1 and 2 are diagrams showing magnetization patterns recorded on a magnetic tape by a conventional rotary head type PCM magnetic recording/reproducing device, and FIG. 3 is a diagram showing a code structure.

In the following description, as an example, a case will be considered in which a two-channel (Lch, Rch) signal is recorded using a PCMfi sound reproducing device of the 2-to-7 helical force scan rotary head type.

In FIG. 1, T indicates the magnetic tape, ■ indicates the tape running direction, H indicates the scanning direction of the rotary head, and A and B indicate the even and odd sample groups I for two channels, respectively. As shown in Figure 1, by recording even-numbered samples and odd-numbered samples on separate tracks, even if the signal of one channel is completely lost due to head clogging, there will be no consecutive missing samples, and the average value will be The correction means can prevent the generation of audible clicking noise or sound interruptions due to muting.

Next, the data arrays in A and B in FIG. 1 will be explained using FIGS. 2 and 3.

Figure 3 shows the structure of a transmission signal when recording a signal of 32 samples per channel on a magnetic tape with a 2-scan length.
n=0 to 31) are samples of the L channel and R channel, respectively, and n indicates the order of occurrence. X and Y indicate an even sample group and an odd sample group, respectively.

P indicates an error detection code, each consisting of 4 vertical samples (W
O to W3) are added column by column. Q is a code for correcting an error of 2 samples per row by combining with the above code P, and for 16 horizontal samples (FO to F15), two codes QII are used per row.
I, o, Qll, 1 are added.

Above Q*, O% Qs+, 1 is the nth (0≦m≦3)
It shows the code of the row.

Note that there are various methods of generating codes, but they are not the gist of the present invention, so they will not be discussed here. In the following explanation, symbols P and Q will also be expressed as samples.

The encoded samples as shown in FIG. 3 are recorded on a magnetic tape with one frame consisting of five vertical samples (WO to W4). Fn (n=Q~17) in the figure is the nth
Showing the frame.

FIG. 2 shows the magnetization pattern when the encoded sample shown in FIG. 3 is recorded on the magnetic tape 1, and N
indicates the magnetization pattern of the N-th scan, and M indicates the magnetization pattern of the N+1-th scan.

In the Nth scan, from the bottom edge of the tape
The codes of even sample groups from O to F7 are recorded, and one of the two Q codes (F16) is recorded at the top.

Also, in the M-th (N+1) scan, from the bottom edge of the tape,
The codes of the odd sample groups from 8 to F15 are recorded, and the Q code (F17) is recorded at the top.

Until now, only the input signals have been referred to as even sample groups and odd sample groups, but from now on, the signals including the codes recorded accompanying each group will also be referred to as even sample groups and odd sample groups. In the above example, Fl6 belongs to the even sample group, and F
l7 belongs to the odd sample group.

Since the conventional recording/reproducing pattern is configured as described above, it has the following two drawbacks.

That is, (1) If a burst error with a width K of about 2 frames as shown in FIG. 2 occurs, FO.

Data of Fl, FB, and F9 are missing. In this case, the third
Since there is an error of 4 samples in each row shown in the figure, P,
Correction by Q becomes impossible, and even if correction is made, LO,
Consecutive sample errors occur, as seen in the missing LL, resulting in an audible sound.

■ Since the Q code is generated from the samples of both channels, when rewriting one channel, the reproduced signals of both channels are written to memory and decoded, then the samples of one channel are rewritten, further encoded, and the tape is re-recorded. Because of the time difference between playback and re-recording, the sample of the fixed channel will be re-written at a position shifted by several scans. For this reason, in language practice machines and the like, each time the fixed channel (teacher's voice) is rewritten, it approaches the end of the tape, causing the inconvenience that samples of the fixed channel are eventually lost.

[Summary of the invention]

This invention was made in order to eliminate the above-mentioned drawbacks of the conventional method.It encodes independently the even number sample group and the odd number sample group of each channel, and when recording this on tape, one By recording one group of each channel on a track as a group, and recording the other group of the same channel on a different track separated from the above one group in the tape direction, playback sound with fewer voices can be produced. It is an object of the present invention to provide a rotary head type magnetic recording/reproducing device which is capable of not only rewriting on a channel-by-channel basis but also rewriting on a group-by-group basis.

[Embodiments of the invention]

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 4 shows a schematic block diagram of an embodiment of the present invention, in which 1 is an L channel analog signal input terminal;
21 is an analog signal input terminal of the R channel, 2 is a low-pass filter, 3 is an analog-digital (A/D) conversion circuit that converts the input analog signal into a digital signal, 4 is a memory, and the fifth FI! As shown in J.
The four areas are address control circuits that perform address control for writing and reading, and the memory 4 and address control circuit 23 are used as sample group creation means for dividing sampling data for each channel into an odd sample group and an even sample group. is configured.

5 is an encoding circuit that reads sample data in the memory 4 and performs complete encoding in groups; 6 is a modulation circuit; 7
is the first selector switch, and 8.9 is the magnetic hand A, respectively.
, B. and the address control circuit 23. Erotic circuit 6. A recording means is constituted by the first changeover switch 7 and the magnetic head 8.9, and the recording means records the encoded data of each channel group by group, as well as the odd sample group and the even sample group of the same channel. The sample group is recorded so that it is separated from the sample group in the width direction of the tape on a different trunk.

Further, 11 is a second changeover switch, 12 is a demodulation circuit, and 1
3 is a memory, 14 is a decoding circuit that reads data in the memory 13 and corrects data errors in groups, and 15 is a digital-to-analog (D/A) conversion circuit that converts the decoded reproduced digital signal into an analog signal. , 16 is a low-pass filter, 17 is an output end terminal for the reproduced analog signal of the L channel, and 24 is an address control circuit for controlling writing and reading of the memory 13.

FIG. 5 shows the signal structure obtained by dividing the 64 samples shown in FIG. This is the added block. Similarly, LS, RE
, R3 indicates a block in which a complete error detection code P and error correction code Q are added to each of the odd sample group of the L channel, the even sample group of the R channel, and the odd sample group of the R channel, respectively. Signals encoded for each block are recorded on a magnetic tape.

Further, FIG. 6 shows a magnetization pattern when the data group shown in FIG. 5 is recorded on a magnetic tape.

Next, the operation will be explained.

First, the operation during recording will be explained. Input terminal 1.21
The 2-channel signal input to is passed through low-pass filter 2.
After high frequency components are removed, the signal is time-divisionally converted into a digital signal by the A/D conversion circuit 3 and written into the memory 4. As mentioned above, the memory 4 is divided into four blocks shown in FIG. 5, and each sampling data is stored in this block.

The addresses are specified by the address control circuit 23 and written into the memory 4 so as to have the arrangement shown in FIG. Once the 64 samples have been written, the encoding circuit 5 writes the memory 4
This reads the samples in 7. Generate two Q check signals for the 4 horizontal samples in the y-axis and write them into the memory 4, further generate P check signals for the 4 vertical samples (including Q), and write them into the memory 4. .

The signal encoded in this manner is first read out from the memory 4 in block R3 and then in block LS. The read signal is modulated by the modulation circuit 6 and then recorded on the tape by the magnetic head A via the first changeover switch 7.

The signal shown in the Nth scan in FIG. 6 is the signal recorded by this magnetic head A. Next, blocks LE and RE are respectively read from the memory 4 and modulated, and then the modulated signals are recorded on the tape by the head B via the first changeover switch 7. The signal of the Nth scan in FIG. 6 is the signal recorded by head B. The above writing and reading of the memory 4 is carried out by the address control circuit 23.
controlled by

Next, during reproduction, the signals read from heads A and B are applied to the second changeover switch 11 via the first changeover switch 7. The second changeover switch 11 provides the head A and the path 12. The reproduced signal demodulated by the demodulation circuit 12 is stored in the memory 13 as the fifth
The array is written as shown in the figure. The decoding circuit 14 reads necessary signals from the memory 13 and performs error correction on a group-by-group basis. The memory address for writing and reading data at the time of writing demodulated data and error correction is as follows:
The samples in the memo I713 suppressed by the address control circuit 24 and corrected in this way are LO, RO, Ll, R1, . . . by the address control circuit 24.
, L31. R31 is read out sequentially, and the D/A conversion circuit 1
5, the signal is converted back to an analog signal and output from the output terminal 17.22.

In this embodiment, even-numbered sample groups and odd-numbered sample groups are independently encoded on a group-by-group basis for each channel, and during recording, even-numbered and odd-numbered sample groups of the same channel are encoded in different trunks. Since the data is recorded in the same way, even if there is a signal dropout for one track due to head clogging, correction processing can be performed using one of the sample groups recorded in the adjacent track. Furthermore, since even and odd sample groups of the same channel are recorded at positions separated from each other in 11 directions of the tape, as is clear from Figure 6, approximately 1/2 of one recording area
Even if a burst with a width of 2° corresponding to
Since sample groups of different channels are recorded at the same position on adjacent tracks, consecutive sample omissions can be prevented. Furthermore, as mentioned above, since the codes are independent between channels, even sample groups, and odd sample groups, it is possible to rewrite not only each channel but also each group, and the data of one channel can be rewritten as before. Even when rewriting only the fixed channel, positional shift of the fixed channel will not occur.

In addition, in the above embodiment, a case was explained in which an even numbered sample group of the R channel was recorded on the N trunk, and an odd numbered sample group of the R channel was recorded on the M) rack.
If the odd and even sample groups of the same channel are not adjacent to each other in the first half or the second half of the track, record the odd sample group of the L channel and the even sample group of the R channel on the N track, and record the odd sample group of the R channel on the M track. The sample group and the even sample group of the L channel may be recorded.

Similarly, in the case of multiple channels, each channel is encoded in groups of even samples and odd samples to form small blocks, and either the even sample group or the odd sample group of each channel is assigned to each track. The same effect as in the above embodiment can be obtained by recording odd and even sample groups of the same channel while separating them from each other in the lJ direction of the tape.

〔Effect of the invention〕

As described above, according to the present invention, even-numbered sample groups and odd-numbered sample groups of each channel are encoded in group units, and when recording, one track includes even-numbered sample groups and odd-numbered sample groups of the same channel.
By recording only one of the odd-numbered sample groups, and recording the odd-numbered sample group and the odd-numbered sample group on separate tracks on the same channel, at positions separated from each other in the middle of the tape, Correction processing can be performed for signal loss for 2 troughs due to head clogging and burst errors extending in the tape running direction with a width of approximately 1/2 in the tape center direction, resulting in low-noise playback sound. There is an effect that can be obtained.

Furthermore, since each channel is encoded in units of groups, it is possible to rewrite not only each channel but also each group.

[Brief explanation of drawings]

1 and 2 are block diagrams of a rotary head type magnetic recording and reproducing device using a conventional two-head helical scan type rotary head PCM magnetic recording and reproducing device, and FIG. 5 is a signal configuration diagram according to an embodiment of the present invention. FIG. 6 is a diagram of the magnetization pattern on the magnetic tape produced by the apparatus of FIG. 4. 3... A/D conversion circuit, 4... Memory (sample group creation means), 5... Encoding circuit, 6... Modulation circuit, 7... Changeover switch, 8, 9... magnetic head, 2
3...Address control circuit. Note that the same reference numerals in the figures indicate the same or equivalent parts. Agent Masuo Oiwa Figure 1 Gi; ν No oath Figure 5 Figure 6 Procedural amendment (spontaneous) Mr. Commissioner of the Japan Patent Office 1, Indication of case: Patent application No. 59-75227, 1972, Name of invention: Rotating head type Magnetic recording and reproducing device 3, relationship with the amended person case Patent applicant address: 2-2-3 Marunouchi, Chiyoda-ku, Tokyo Name:
(601) Mitsubishi Electric Co., Ltd. Representative: Hitoshi Katayama 4, Agent address: 2-2-3-5 Marunouchi, Chiyoda-ku, Tokyo, Detailed description of the invention column 6 of the specification to be amended, Contents of the amendment <t) Change “approximately 2 frames” on page 7, line 8 of the specification to “
The correction is made to j, which causes approximately 2 frames of signal loss. (2) On page 9, line 20, "Modulation circuit 6." is corrected to "Memory 4. Modulation circuit 6." (3) Correct "4 samples" in the second line of page 12 to "16 samples."that's all

Claims (2)

[Claims] (1) In a rotary head magnetic recording and reproducing device that converts n-channel information signals into digital signals and sequentially scans them with m rotary heads to record and reproduce the digital signals on a magnetic tape, A sample group generating means for dividing the sampling data into an odd sample group, which is a group of odd-numbered sampling data, and an even-numbered sample group, which is a group of even-numbered sampling data; the coded information signal of each channel in the group unit, and the even number sample group and the odd number sample group of the same channel are separated in the middle direction of the tape on different trunks on the magnetic tape. What is claimed is: 1. A rotary head type magnetic recording/reproducing device, comprising: a recording means for recording data at a certain position. (2) The number of channels is 2. The number of rotary heads is 2 channels and 2, respectively, the encoding means performs encoding completed for each channel, and the recording means is for the first channel. Either the encoded even sample group or the odd sample group is recorded in the first half of the first track by the first rotary head, and the other group is recorded in the second half of the second trunk by the second rotary head. A patent characterized in that either an even number sample group or an odd number sample group of a second channel is recorded in the latter half of the first track, and the other group is recorded in the first half of the second track. A rotary head type magnetic recording/reproducing device according to claim 1.