JPH0785337B2 - Signal processing circuit for rotary head type magnetic recording device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary head type recording / reproducing apparatus, a signal processing circuit and a magnetic tape used therefor, and in particular, interleaves (digitizes) digitized data and generates during recording / reproducing. The present invention relates to one using an error correction code for correcting an error in data.

[0002]

2. Description of the Related Art Conventionally, as a device of this kind, there is a rotary head type PCM recording / reproducing device for converting an audio signal into a digital signal and recording / reproducing it on a magnetic tape by a rotary head. Generally, an error correction code is used in the above device to correct an error in data that occurs during recording and reproduction, and when the number of errors exceeds the correction capability and cannot be corrected, the average value of the preceding and following data is taken and interpolated. Correction processing such as turning on is performed. Since an error on the magnetic tape is often a burst error, it is effective to perform an interleave process to randomize error data in order to make full use of the ability of the error correction code.

In the correction processing as described above, the method with a simple circuit and less noise is the mean value interpolation. However, since the preceding and following data must be correct for this, the data of the odd sample group and its adjacent The interleaving is performed so that the data of the even sample groups are placed as far apart as possible. In the following description, as an example, a two-head helical scan rotary head type P that handles two-channel signals
Consider a CM recorder. FIG. 1 is a diagram showing a magnetization pattern recorded on a magnetic tape by a conventional rotary head PCM recorder.

In the figure, T is a magnetic tape, S is a head scan direction, D is a tape running direction, and L and R are also shown.
Indicates two channels, a indicates an even sample group, b indicates an odd sample group, and P indicates an error correction code group. In this example, as an interleaving method for arranging the even sample group and the odd sample group at positions separated from each other,
This is a method in which the samples that can enter a scan are divided into an even sample group and an odd sample group, and these are arranged with an error correction code group P interposed therebetween. If such interleaving is performed, even if a burst error Y of about half the width of the tape shown in the figure occurs, consecutive sample errors do not occur, so that average value interpolation is possible.

[0005]

Is Toko filtration [0005] In the interleaving of the conventional method, when momentarily rise to Medzu Mari magnetic powder one head is peeled off, i.e., the reproduced signal from one of the heads However, in the case of missing or extremely deteriorated state, errors occur in consecutive samples, so that average value interpolation cannot be performed, and there is a drawback that noise that is audible to the ear is generated.

[0006]

The present invention has been made in view of the above conventional problems, and controls the input / output operation of a memory for storing a plurality of words sequentially input within a unit time. A word stored in said memory
To a coding means for generating a redundant signal for error control.
A rotary head having memory control means for storing the supplied and generated redundant signal in the memory, and outputting the word and the redundant signal rearranged in a predetermined order by the memory control means through an output terminal. in shape the magnetic recording apparatus for signal processing circuit, pre SL memory control hand stage, when the input sequence of words which is first input as the 0th to the signal processing circuit, the input order to the signal processing circuit is 4n th A first word group that is composed of a plurality of (n is an integer) words and is repeatedly allocated one word at a time corresponding to the input order in m frames (m is a natural number) from 0 to m−1,
At least a part of the redundant signal is composed of a plurality of 4n + 3th words and is arranged in the order of a fourth word group which is repeatedly allocated one word at a time corresponding to an input order of m frames 0 to m-1. The rearranged first digital signal sequence is output from the output terminal, and the input sequence to the signal processing circuit is composed of a plurality of 4n + 1th words and corresponds to the m sequence of 0 to m-1 in the input sequence. Second word group, which is sequentially and repeatedly allocated one word at a time, at least a part of the redundant signal, 4n +
The second digital data, which is composed of the second plurality of words and is rearranged in the order of the third word group, which is repeatedly allocated one word at a time corresponding to the input order to m frames from 0 to m-1 A signal sequence is output from the output terminal, and the words assigned to the m frames in the first to fourth word groups are output from the output terminal in the order of frames 0 to m-1. Thus, it is an object of the present invention to obtain a signal processing circuit for a rotary head type magnetic recording device, which has a low probability of continuous error and a low probability of concentrated data loss.

[0007]

For the rotary head type magnetic recording apparatus according to the present invention
According to the signal processing circuit, the probability of continuous error and
The probability of data loss can be reduced.

[0008]

2 is a magnetization pattern diagram on a tape recorded by a rotary head type PCM magnetic recording / reproducing apparatus according to an embodiment of the present invention. The symbols in the figure are the same as those in FIG. In the interleaving by the device of the present invention, the odd sample groups and the even sample groups of the same channel are alternately arranged for each adjacent scan and arranged at positions separated in the width direction of the tape. Even if the signal loss of one scan described above occurs due to such an arrangement, consecutive sample errors do not occur in each channel.
Correction by average value interpolation is possible.

The construction and operation of a two-head helical scan rotary head type PCM recorder having a tape winding angle of 90 ° will be described below as an embodiment of the present invention with reference to FIG . Further, FIG . 4 is a timing chart showing the operation of the memory circuit included in FIG . In FIG. 4 , WT is a memory writing period, EN is a coding period, RD is a memory reading period, and DE is a decoding period. In FIG. 3 , the recording system includes a 2-channel input terminal 1, a low-pass filter (LPF) 2, a sample hold (S / H) circuit, and an analog-digital (A / D) conversion circuit 3.
A memory circuit 4 and a recording system memory address control circuit 5
An encoding circuit 6, a modulation circuit 7, a recording amplifier 8,
It comprises a first switch 9 and heads 10 and 11.

An analog signal of two channels of LR is input to the input terminal 1 and each band is limited by the LPF 2. The output of the LPF 2 is given to the S / H and A / D conversion circuit 3, and digital signals WLn and WRn (n = 0, 1,
2, ...). Here, n indicates the order of sampling, and the signals of the two channels of L and R are sampled alternately and are sequentially output as WL0, WR0, WL1, .... This signal is given to the memory circuit 4 and sequentially written in the addresses on the memory designated by the recording system memory address control circuit 5. The samples stored in the memory circuit 4 are read by the recording system memory address control circuit 5 in a required order and given to the encoding circuit 6. In the encoding circuit 6, an error correction code and an error detection code are generated,
It is written in the memory circuit 4. The information signal and the error correction code are sequentially read by the recording system memory address control circuit 5 and given to the modulation circuit 7. The memory circuit 4 is practically divided into two systems, and while one system memory is writing samples, the other one system memory performs encoding and reading. This is shown in Figure 4,
Since the recording / reproduction is performed by two heads by winding the 90 ° tape, a 90 ° signal recording / reproducing section and a 90 ° resting section are alternately present. That is, the 90 ° signal recording / reproducing period is 1
It supports recording and playback of scans. WT in FIG. 4 (b)
Of the signals for 2 scans sampled in the period of 1), the signal of 1 scan read in the period of the next RD is first encoded in the period of EN and is read in the period of RD, and then the remaining 1 The signals for the scan are encoded in the next EN period and read out in the RD period.

In the modulation circuit 7, the signal read from the memory is converted into a data string suitable for recording on the magnetic tape, amplified by the recording amplifier 8, and then the two heads are passed through the first changeover switch 9. It is recorded on a magnetic tape from Nos. 10 and 11. The first changeover switch 9 operates to switch the circuit connected to the head during recording and during reproduction.
Next, the structure and operation of the reproducing system will be described. The reproducing system includes heads 10 and 11, and a second changeover switch 12.
, Reproduction amplifier 13, demodulation circuit 14, and memory circuit 1
5, a reproduction system memory address control circuit 16, a decoding circuit 17, a correction circuit 18, and a digital-analog (D / D)
A) Conversion circuit 19 and low-pass filter (LPF) 20
And a two-channel output terminal 21. Second
The changeover switch 12 is for applying the output signals of the heads 10 and 11 to the reproduction amplifier 13 as a signal of one system. The signals reproduced by the heads 10 and 11 are amplified by the reproduction amplifier 13 via the first changeover switch 9 and the second changeover switch 12, and are given to the demodulation circuit 14. The signal is returned to the digital signal before being modulated by the demodulation circuit 14 and given to the memory circuit 15. This digital signal is sequentially written in the memory circuit 15 by the reproducing system memory address control circuit 16. Further, the memory address control circuit 16 reads out necessary samples from the memory circuit 15 and gives them to the decoding circuit 17. The decoding circuit 17 uses the error correction code to perform error detection and correction. The corrected samples in the memory are sequentially read by the memory address control circuit 16 and given to the correction circuit. The samples in which an error is detected but cannot be corrected are corrected by the above-mentioned average value interpolation. It Memory operation during reproduction is shown in FIG. 4 (c). 1 played during WT
Scan samples are written to the memory circuit 15, decoded during the next 90 ° open period (denoted by DE), and held in memory. During the next WT period, the remaining one-scan samples are written to the memory and decoded during the next DE period. The samples for the two scans for which decoding has been completed are read during the RD period. The memory circuit 15 is divided into two systems, and while one is writing and decoding, the other memory is reading, as in the case of recording.

The corrected and corrected sample is D /
The LPF is converted into the original analog signal by the A conversion circuit 19.
After the unnecessary frequency component is removed at 20, it is output from the output terminal 21. The clock pulse generation circuit 22 has a function of giving a necessary clock to each part of the recording system and the reproducing system. Next, a concrete description of the memory circuits 4 and 15 in the block shown in FIG. 3 and a detailed sample on the tape will be described. FIG. 5 shows a memory configuration diagram in an embodiment of the present invention. In the figure, WLn and WRn indicate the nth sample occurring in the L channel and the R channel, respectively, as described above, CLn, CRn and Pn are error correction codes, and lLn and lRn are four vertical information signal samples. And the frame number composed of the correction code. Further, a horizontal number fa indicates a memory address in a frame unit (hereinafter referred to as a frame address), and a vertical number sa indicates a memory address in a row unit (hereinafter referred to as a sample address). Each A indicates data to be recorded in one scan, and the memory is composed of data for two scans, here 32 samples of each information signal LR and 26 words of error correction code. During recording, WL0, WR0, WL
Samples given as 1, ... are stored in the memory by controlling the memory addresses so that the array shown in the figure is obtained. At this time, the even sample group a and the odd sample group b are separated for each channel.

Next, lL0, lL2, l to be recorded first
The error correction code P is obtained by performing encoding on the 8 × 4 matrix sample of L4, IL6, IL1, IL3, IL5, IL7.
0-P4 and CL0, CL2, CL4, CL6, CR1, CR3, CR
5, CR7 is generated. There are many error correction codes, and the encoding method and the like are also different, but they are not the gist of the present invention, and therefore will be omitted. Coded frame address 0 to
The data of No. 8 are sequentially read in the order of frame numbers in frame units, and only the error correction code frame lP0 is La and Lb.
It is read after the frame number 3 so as to be inserted in the interval and recorded on the tape. After the reading of one scan is completed, the same coding is performed on the remaining samples of one scan, and the samples are recorded in the next scan. That is, continuous samples on each channel are distributed to two scans, but the error correction code is completed for one scan of data recorded on the tape and does not extend to two scans. At the time of reproduction, data is written in the memory on a frame-by-frame basis and is corrected using an error correction code, and then WL
0, WR0, WL1, ... are sequentially read. As described above, the error correction code can decode the scan when the data of one scan is read.

This operation is as described with reference to FIG. 4, and if the code extends over two scans, the data for two scans must be collected and then the decoding for two scans must be performed in the 90 ° open section. In contrast to this, since the decoding can be performed for each scan in this method, the clock rate required for encoding and decoding does not increase even if the data interleaving of 2 scans is performed. FIG. 6 is a magnetic pattern diagram recorded on a tape having the memory configuration of FIG. In the figure, X1 indicates the width of the tape, and X2 indicates the width of the burst error that can be interpolated by the average value. In this example, the error correction code frames lP0 and lP5 are controlled so that the read address during recording is located at the center of one scan, but this may be placed anywhere in the scan. As described above, in the magnetization pattern shown in FIG. 6, continuous sample errors occur even when a signal loss of one scan occurs or when a burst error in the tape running direction of about half the tape width from the tape edge occurs. Since there is no average value correction is possible.

FIG. 7 is a diagram showing another example of the magnetization pattern according to the present invention. It is clear that this example also has the same effect as that shown in FIG. In the above description, the case of handling the information signals of two channels is shown, but it is applicable to the case of handling the information signals of a plurality of channels. Furthermore, in the above example, the device for the audio signal is described, but it is possible to cover all signals for which the correction by the mean value interpolation is effective. As a digital signal recording / reproducing system, it goes without saying that a system other than the PCM system can be applied.

[0016]

As it is evident from the foregoing description, according to the rotary head type magnetic recording apparatus for signal processing circuit of the present invention, which controls input and output operations of the memory for storing a plurality of words which are sequentially inputted in a unit time And the word stored in the memory
Code as a coding means for generating a redundant signal for error control.
A rotary head having memory control means for storing the supplied and generated redundant signal in the memory, and outputting words and redundant signals rearranged in a predetermined order by the memory control means through an output terminal. in shape the magnetic recording apparatus for signal processing circuit, pre SL memory control hand stage, when the input sequence of words which is first input as the 0th to the signal processing circuit, the input order to the signal processing circuit is 4n th A first word group that is composed of a plurality of (n is an integer) words and is repeatedly assigned one word at a time corresponding to the input order in m frames (m is a natural number) from 0 to m−1, at least the above A part of the redundant signal, which is composed of a plurality of 4n + 3rd words and is sequentially allocated one word at a time to m frames from 0 to m-1 corresponding to the input order. The first digital signal sequence rearranged in the order of the word group is output from the output terminal, and the input sequence to the signal processing circuit is composed of a plurality of 4n + 1th words and m from 0 to m-1. Second word group, which is sequentially and repeatedly allocated one word at a time corresponding to the input order in the frame, at least a part of the redundant signal, 4
It is composed of a plurality of n + 2nd words and 0 to m-
The second digital signal sequence rearranged in the order of the third word group, which is sequentially and repeatedly assigned one word at a time corresponding to the input order to m frames of 1 is output from the output terminal, and the first to In the fourth word group, the words assigned to the m frames are set to 0.
Since it is configured to output from the output terminal in the order of frames from m to m-1, it is possible to easily form a digital signal sequence of two systems suitable for recording a specific recording pattern as in the present application by helical scan recording by a rotary head. Further, since a predetermined digital signal sequence is formed from the digital signals input within the unit time, it is possible to easily rewrite the information with the digital signal sequence as one information unit. There is an effect.
Further, in signal recording using the rotary head type magnetic recording device configured by incorporating this signal processing circuit, the following effects can be obtained. (B) Even if the signal is lost in one scan, no large continuous word is lost. Therefore, the information is not concentrated and lost, and there is no problem in deciphering the content of the information. (B) Large continuous word loss does not occur even with a burst error in the tape running direction having a size about half the tape width. (C) Even if a continuous error of a sub-region length or less at a distance of more than half the tape width occurs simultaneously in the first and second tracks, a large continuous error is unlikely to occur.

[Brief description of drawings]

FIG. 1 is a magnetization pattern state diagram of a conventional rotary head type recording / reproducing apparatus.

FIG. 2 is a magnetization pattern state diagram according to an embodiment of the present invention.

FIG. 3 is a schematic block diagram according to an embodiment of the present invention.

FIG. 4 is a timing diagram showing an operation state of a memory circuit included in one embodiment of the present invention.

FIG. 5 is a memory configuration diagram of a memory circuit included in an embodiment of the present invention.

FIG. 6 is a magnetization pattern state diagram showing a frame arrangement on the tape of the present invention.

FIG. 7 is a magnetization pattern state diagram according to another embodiment of the present invention.

[Explanation of symbols]

1 input terminal 2 recording side low pass filter 3 sample hold and analog-digital conversion circuit 4 recording side memory circuit 5 recording system memory address control circuit 6 encoding circuit 7 modulation circuit 8 recording amplifier 9 first changeover switch 10 head 11 head 12 Second selector switch 13 Reproduction amplifier 14 Demodulation circuit 15 Reproduction side memory circuit 16 Reproduction system memory address control circuit 17 Decoded signal 18 Correction circuit 19 Digital-analog conversion circuit 20 Reproduction side low-pass filter 21 Output terminal 22 Clock generation circuit

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location G11B 20/18 G 9074-5D

Claims (2)

[Claims] 1. A be one that controls input and output operations of the memory for storing a plurality of words which are sequentially inputted in a unit time
The word stored in the memory for error control
The redundant signal is generated by supplying it to the encoding means for generating a redundant signal.
Comprising a memory control means for storing a signal in said memory, in a rotary head type magnetic recording apparatus for signal processing circuit for outputting through the output terminal of the word and the redundant signals rearranged in a predetermined order by the memory control means, before serial memory control hand stage, when the input sequence of words that is first input to the signal processing circuit and the 0-th input sequence to the signal processing circuit is 4n th (n is an integer)
First word group, which is made up of a plurality of words and is repeatedly assigned one word at a time corresponding to the input order in m frames (m is a natural number) from 0 to m−1, at least a part of the redundant signal. The first word rearranged in the order of the fourth word group, which is composed of a plurality of 4n + 3rd words and is repeatedly allocated one word at a time corresponding to the input order in m frames from 0 to m−1. A digital signal sequence is output from an output terminal, and the signal processing circuit is sequentially composed of a plurality of 4n + 1th words and is repeated one word at a time corresponding to the input order in m frames from 0 to m-1. The assigned second word group, at least a part of the redundant signal, is composed of a plurality of 4n + 2nd words, and is included in m frames 0 to m-1. Corresponding to power order, 1
The second digital signal sequence rearranged in the order of the third word group repeatedly assigned word by word is output from the output terminal, and in the first to fourth word groups, the m number of frames A signal processing circuit for a rotary head type magnetic recording device, wherein the assigned words are output from an output terminal in the order of frames 0 to m-1. 2. The rotary head type magnetic recording apparatus according to claim 1, wherein the encoding means generates an error control code that is completed in each of the first and second digital signal sequences. Signal processing circuit.