JPS6151666A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To obtain a magnetic recording and reproducing device which has a code structure for appropriate correction capability and removes the effect on a pattern effect, by adding a pseudo-random signal of long cycle for each subblock with an address signal for a repetitive long cycle. CONSTITUTION:A subblock signal, which has an added correction code in a parity generator 10 of a recording processor 1, is added in a scrambler 11 the pseudo-random signal of the long cycle relative to a repetitive address signal of the long cycle having the same length as the correcting range of a time axis corrector 6 for correcting a time base of a decoding signal in an exclusive OR system. After the addition of a synchronizing signal, the signal is recorded on a magnetic tape through a modulator 2. The same processing as for the scrambler 11 is done in a descrambler 19 of a reproducing processor 7, and the pseudo- random signal of the long cycle is added for each subblock to obtain the magnetic recording reproducer which has the code mechanism for appropriate correction capability and removes the affection of pattern effect.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic recording and reproducing apparatus suitable for recording from digitized images. In particular, the present invention relates to a magnetic recording/reproducing device that eliminates the effects of signal repetition.

[Conventional technology]

In magnetic recording of digital signals, NRZ (NonRe
Turn to Zero) recording has a narrow signal band and is suitable for high-density recording, but since the maximum magnetization reversal interval is infinite, if "0" or "1" continue, there will be a section with no reproduction pulse. This makes clock recovery difficult. Therefore, signal randomization or block coding is used as a method to limit the number of consecutive "0"s or "1s". Furthermore, when recording a signal with a strong periodic correlation, such as a digitized video signal, certain combinations of codes that are likely to cause word errors may appear in succession, worsening the overall error rate. This is called the "pattern effect." In order to reduce this pattern effect, it is effective to randomize the signal even when block codes are used.

In magnetic recording of digital signals, in order to most efficiently restore the original data against data errors caused by so-called dropouts and jitters, a synchronization signal and a check code are added to an information word of about 200 to 1000 bits to create one subblock. Error correction is performed for each subblock. Conventionally, this signal randomization has been performed by adding a pseudorandom signal that is manipulated back every subblock or every several tens of subblocks to the input signal by exclusive OR (MOD2).

[Problem that the invention seeks to solve]

However, using each subblock does not have sufficient effect on the pattern effect, and if it is repeated for multiple subblocks, all data for one period will be in error unless the first reset is taken, which is not practical. There was a problem.

The present invention solves the above problem, and includes an address signal that repeats at the same cycle as the length of the correction range of the time base corrector in the synchronization signal so as to increase the repetition cycle of the pseudo-random signal to several tens of subblocks. It is an object of the present invention to provide a magnetic recording and reproducing apparatus which has a code structure having an appropriate correction ability and which eliminates the influence of pattern effects by adding different pseudo-random signals for each sub-block.

Means for Solving Problem C] The present invention provides a recording processor that adds necessary information to an input signal at least in the process of recording and reproduction, a modulator that converts the output of the recording processor into a recording signal, and a recording signal that converts the output of the recording processor into a recording signal. A magnetic head that records on a magnetic recording medium or reproduces a reproduced signal from the magnetic recording medium, a demodulator that extracts a clock from the reproduced signal or demodulates the reproduced signal, and a time axis corrector that corrects the time axis of the demodulated signal. , a magnetic recording and reproducing device comprising a reproducing processor for restoring the original input signal from the output signal, wherein the synchronization signal of the recording signal includes an address signal that is repeated at a cycle of the same length as the correction range of the time axis corrector. In addition, the recording processor is equipped with a scrambler that adds a pseudo-random signal with MOD2 that is repeated with the same length as the correction range of the time axis corrector, and the playback processor adds the same pseudo-random signal as above with MOD2. It is characterized by the addition of a descrambler.

[Effect]

The present invention improves the randomness and signal correction ability by making the repetition period of the so-called pseudo-random signal sufficiently longer than the conventional one based on the randomness, and also reduces the pattern effect caused by the repetition signal. The effects can also be removed.

〔Example〕

The invention will now be described in detail with reference to embodiments of the accompanying drawings.

FIG. 1 is a block diagram of an embodiment in which the present invention is implemented in a PCM-VTR. This device has a serial configuration of a recording processor 1, a modulator 2, a magnetic node 3, a magnetic tape 4, a demodulator 5, a time axis corrector 6, and a reproduction processor 7.

Furthermore, the recording processor 1 includes an AD converter 8, a time axis compression memory 9, a parity generator 10, and a scrambler 1.
1 and a 5YNC generator 12 in series, with a variable g
The M unit 2 includes an encoder 13 and a recording amplifier 14.

The magnetic head 3 consists of a recording head 15 and a reproducing head 16, and the demodulator consists of a reproducing amplifier 17 and a decoder 18. The reproduction processor 7 also includes a descrambler 19, a correction/correction circuit 20, a time axis expansion memory 21, and a DA converter 22. Figure 2 shows a circuit that can be used for both the scrambler 11 and descrambler 19, #0 to l115.
registers and a MOD'2 adder.

The video input signal is converted into a digital signal by an AD converter 8, and converted into a recording format as shown in FIG. 3 by a time-base compression memory 9. The above recording format divides 768 bytes of valid data (at the time of 4fcc sampling) in one horizontal section (H) of the video input signal into 8 equal parts, and divides it into 8 equal parts, 5YNC 40bits and CI? C code 16
A bit is added to form a sub-block (SB), and a correction code 83B is added to data 643B to form a block (SB).
B), and one vertical section (V) section is composed of 32B.

The signal output from the time axis compression memory 9 is sent to the parity generator 1
0 adds a correction code and a CRC code, and the scrambler 11
is input. The scrambler can be constructed, for example, by a circuit as shown in FIG. 2, and SET is set for each block (B).

A 5YNC generator 12 adds synchronization information to the scrambled signal. As shown in Figure 3, 5YNC has a total of 5 bytes (=40b
It consists of The output of the 5YNC generator is converted into a recording code by an encoder 13, converted into a recording current by a recording amplifier 14, and recorded on the magnetic tape 4 by a recording head 15.

The information recorded on the magnetic tape is taken out as a reproduction signal from the reproduction head 16, and after a certain gain is obtained by the reproduction amplifier 17, it is equalized, and the decoder 18 extracts the clock and detects the pulse. This output is adjusted to ±
After correction is made for fluctuations in the time axis within 0.5B, the signal is returned to the original signal by a descrambler 19. The descrambler 19 can be constructed of a circuit similar to the scrambler 11 shown in FIG. 2, and can be used for descrambling. The signal obtained in this way is converted by a time axis expansion memory 21 after data errors are removed by a correction/correction circuit 20.
The DA converter 22 restores the original video signal.

〔Effect of the invention〕

As explained above, the present invention has the effect of increasing the signal correction ability and eliminating the influence of pattern effects by using a different pseudo-random signal for each sub-block and making the repetition period sufficiently long.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an apparatus according to an embodiment of the present invention. FIG. 2 is a block configuration circuit diagram of a portion of FIG. 1. FIG. 3 is a diagram showing the relationship between input signals, subblocks, and blocks. FIG. 4 is a configuration diagram of the 5YNC signal. DESCRIPTION OF SYMBOLS 1... Recording processor, 2... Modulator, 3... Magnetic head, 4... Magnetic tape, 5... Demodulator, 6...
... Time axis corrector, 7... Playback processor, 8...
AD converter, 9... Time axis compression memory, 10... Parity generator, 11... Scrambler, 12... 5
YNC generator, 13... Encoder, 14... Recording amplifier, 15... Recording head, Engineering 6... Playback head, 17... Playback amplifier, 18... Decoder, 19.
... Descrambler, 20 ... Correction/correction circuit, 21
...Time axis expansion memory, 22...DA converter.

Claims (1)

[Claims] (1) A recording processor including means for taking in an input signal and adding information necessary for recording and reproduction to this input signal, a modulator that converts the output of this recording processor into a recording signal, and a magnetic recording medium that converts this recording signal into a recording signal. a magnetic head that reads information recorded on the magnetic recording medium and generates a reproduced signal; a demodulator that extracts a clock signal from this reproduced signal and demodulates this reproduced signal; and an output of this demodulator. A magnetic recording and reproducing device for digital signals, comprising: a time axis corrector for correcting the time axis of a demodulated signal obtained from the demodulated signal; and a reproduction processor including means for restoring an output signal corresponding to the input signal from the demodulated signal. means for inserting into the synchronization signal of the recording signal an address signal that is repeated at a cycle equal to the correction range of the time base corrector, and the recording processor is provided with a pseudo signal that is repeated at a cycle equal to the correction range of the time base corrector. a scrambling means for adding MOD2 to a signal passing through a random signal, and the reproduction processor is provided with a scrambling means for adding MOD2 to a signal passing through a random signal;
A magnetic recording/reproducing device comprising a descrambling means for adding at OD2.