JPH04339362A - Method and device for synchronization detection - Google Patents

Abstract

PURPOSE:To prevent the occurrence of erroneous synchronization and to improve reliability by using data which follow a synchronization pattern as a synchronization detection pattern as a synchronizing signal and improving autocorrelation. CONSTITUTION:An AM pattern is set in a second shift register 5, inputted in a shift register 1 and compared with the synchronization pattern of a synchronization pattern register 2. When the AM pattern of a first sector cannot be read, synchronization is performed with the AM pattern of the next sector. Once the synchronization is established, a track address and a sector address are recognized, and the track address and the sector address for the next sector can be estimated. Then the track address and the sector address for the just preceding sector are inputted in a pattern generation part 6 and the pattern following the AM is used as a synchronization detection pattern.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a synchronization detection method and apparatus using a synchronization pattern suitable for use in devices that record and reproduce information in units of sectors such as magneto-optical disks, optical disks, magnetic disks, and magnetic tapes. In particular,
As a synchronization detection pattern, the data following the synchronization pattern (
The present invention relates to a synchronization detection method and apparatus that improve data reliability by increasing autocorrelation and preventing false synchronization by using ID data (for example, ID data) as a synchronization signal.

0002

[Prior Art] As a conventional synchronization detection method, firstly,
The second method is to use a third value in addition to the binary values used for digital information.The third method is to create a synchronization pattern consisting of two values, "0" and "1", and insert it between data. There are three known methods: 1, 2, and 3, which use a pattern that does not appear in modulated data.

The first method is originally used in devices intended for recording and transmitting analog signals. For example, when recording and transmitting digital signals using television signals,
Use the horizontal sync signal and vertical sync signal. The third method is used, for example, in CDs (compact discs) and can reliably synchronize as long as no bit errors occur, but it does not require changing 8-bit data to 14-bit data. However, since it is necessary to perform EFM modulation using a combination of patterns with a minimum length of 3 bits and a maximum length of 11 bits, the apparatus becomes complicated.

[0004]The second synchronization detection method is generally adopted in devices that record and reproduce information in units of sectors, such as magneto-optical disks and optical disks. The second method, that is, the synchronization detection method in which a synchronization pattern consisting of two values of "0" and "1" is created and inserted between data, has the advantage that clock extraction is easy. On the other hand, if the same pattern as the synchronization pattern occurs in the data, there is an inconvenience that erroneous synchronization occurs.

For example, the ISO standard sector format of a magneto-optical disk is as shown in FIGS. 2 and 3 below. FIG. 2 is a diagram showing a sector format with 1,024 user bytes. In Figure 3, the user bytes are 512
FIG. 2 is a diagram showing a sector format of . The numbers in the diagram indicate the number of bytes.

In FIGS. 2 and 3, SM is a sector mark, VFO1 to VFO3 are continuous data patterns for PLL lock, AM is an address mark, and ID is an address (2 bytes as track number, 1 byte as sector number). , CRC is a code for error detection in the ID section, ODF (Offset Detection Flag) is a mark for offset detection in tracking error detection using the push-pull method, Gap is a gap with no data within a 3-byte length, Flag is a flag indicating that writing has been performed, ALPC (Auto Laser Power
Control) is a test section for controlling the laser power level, Sync is a synchronization signal for the data section, and Da
a Field is an area where user data is written, 1,
024 bytes of user data and 235 bytes of DM
It consists of P, ECC, CRC, and Resync (a special code for synchronization in the Data area), and Buffer is an area for a disk rotation fluctuation margin.

For example, in a magneto-optical disk having the sector format shown in FIG. 2, its ID (track address...2 bytes, sector address...1 byte)
In order to read accurately, AM (address mark...
1 byte of 16 code bits). If this synchronization is out of sync, it becomes impossible to record and reproduce information.

FIG. 4 is a functional block diagram showing an example of the main structure of a conventional synchronization detection device. In the figure, 1 is a shift register, 2 is a synchronization pattern register, 3 is a match counter that counts the number of matches, and 4 is a comparator.

The input data is input to the shift register 1 and compared with the synchronization pattern held in the synchronization pattern register 2. However, the ISO standard AM pattern has a weak synchronization ability with respect to a pattern shifted by around 3 bits, so there is a problem in that erroneous synchronization is likely to occur.

[0010] In this second method, a method is also known in which a matched filter is used to detect synchronization and a prediction function is used to detect synchronization. However, in this synchronization detection method, a prediction function is generated. However, there is a problem in that synchronization cannot be achieved reliably.

As described above, the method of detecting synchronization using a synchronization pattern (second synchronization detection method) is adopted in conventional devices for recording and reproducing information in units of sectors such as magneto-optical disks and optical disks. However, there is a drawback in that the synchronization ability is weak for patterns in which the AM pattern is shifted by around 3 bits, but since no countermeasures have been taken, it is not possible to reliably prevent the occurrence of erroneous synchronization. There was an inconvenience.

0012

SUMMARY OF THE INVENTION The present invention solves these inconveniences in conventional synchronization detection devices, and
By increasing the number of synchronization detection patterns in order to increase the autocorrelation of these 3-bit shifts for patterns that are shifted around 3 bits, false synchronization can be reliably prevented and data reliability can be improved. The purpose of the present invention is to provide a synchronization method and device with improved performance.

[0013]

[Means for solving the problems] In this invention, firstly,
In a synchronization detection device that detects synchronization using a specific synchronization pattern, this method detects synchronization using the synchronization pattern and some or all of the information written following the pattern.

Second, in an information reproducing apparatus using an optical disc having a format in which an ID signal such as a sector address is recorded following an address mark in a sector header, the address mark and the address This is a method of detecting synchronization using part or all of the information of the ID signal written following the mark.

Thirdly, in the second synchronization detection method, the ID signal pattern is generated from the track address and sector address of the immediately preceding sector.

[0016]

[Operation] In this invention, for patterns in which the AM (address mark) pattern is shifted around 3 bits, in order to improve the autocorrelation of these 3 bit shifts, the synchronous detection pattern is used as a synchronization detection pattern that follows the synchronization pattern. Data (for example, ID data) is also used as a synchronization signal, increasing the number of synchronization detection patterns, and following this AM pattern, continuously changing ID (track address, sector,
using some of the address) information along with the AM pattern,
Detection capability is improved by synchronous detection.

Specifically, in the sector format of a magneto-optical disk, the ID following the AM (address mark)
Since (track address, sector address) changes continuously, we focused on the fact that this ID information is predictable, and by using part or all of this ID information together with the AM pattern, Detection of false synchronization is prevented by increasing the autocorrelation of synchronization detection patterns.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the synchronization detection method and apparatus of the present invention will be described in detail with reference to the drawings. This embodiment corresponds to claims 1 to 3 of the invention.

FIG. 1 is a functional block diagram showing an embodiment of the main structure of a synchronization detection device according to the present invention. Reference numerals in the drawing are the same as those in FIG. 4, and 5 indicates a second shift register, 6 a pattern generator, 7 a second comparator, and 8 a mask circuit.

In the synchronization detection device of the present invention shown in FIG.
The difference from the conventional example shown in FIG. a mask circuit 8 consisting of a group of gate circuits for masking the output of and the comparison result with input data;
, and a second shift register 5 to which input data (received data) is set.

The operation of the synchronization detection device of the present invention is as follows. First, when reading data on a disc for the first time, its ID information, that is, the track address,
Since none of the sector addresses are known, a mask signal (given from a CPU (not shown) or the like) is set to "1", for example, and synchronization is achieved using only the AM (address mark) pattern.

That is, the AM pattern is once set in the second shift register 5, but then at the timing,
Input to shift register 1, synchronization pattern register 2
(as before). The mask circuit 8 uses, for example, a NAND gate circuit, and acts so that the output of the second shift register 5 is not output to the match number counter 3 during this period. In this case, if the AM pattern of the first sector cannot be read due to a defect or the like, synchronization is achieved using the AM pattern of the next sector. The same applies when the AM pattern of the next sector cannot be read due to a defect etc.
Synchronize using M pattern.

[0023] As shown in FIGS. 2 and 3, this AM pattern starts with the first preformat part (52 bytes).
It is recorded in four locations. Therefore, it is actually extremely rare that the entire AM pattern cannot be read across several sectors like this.

Once synchronization is achieved, the track address and sector address are known, so the track address and sector address of the next sector can be predicted. Therefore, a pattern following AM is generated as a synchronization detection pattern by inputting it to the pattern generator 6 generated from the track address and sector address of the immediately preceding sector (from a CPU or the like (not shown)).

Therefore, as patterns for synchronization detection, the track address and sector address (ID information) patterns generated by this pattern generator 6 and the AM pattern of the synchronization pattern register 2 are used. become. Next, by setting the mask signal to "0", the comparison result by the second comparator 7 and the comparison result by the comparator 4 are counted by the match number counter 3, and based on the obtained number of matches, synchronization is performed. Detect.

[0026] In this way, by using the AM pattern and the predictable ID information that follows it as a pattern for synchronization detection, simple and accurate synchronization detection becomes possible.

[0027] Note that the data (ID data) following the AM pattern (synchronization pattern) does not necessarily need to use all of the track address and sector address information in the case of ID data, but only some of them. Even if , the autocorrelation is similarly increased, thereby preventing the occurrence of false synchronization.

[0028] Furthermore, as described in the embodiment, the address
It is not always necessary to use the mark and part or all of the information of the ID signal written following the address mark; in general, the synchronization pattern and
It is easily conceivable for those skilled in the art to perform synchronization detection using part or all of the information written following the pattern, and the present invention encompasses all of these cases.

[0029]

[Effects of the Invention] In this invention, the data (ID data) following the synchronization pattern is also used as a synchronization signal as a synchronization detection pattern, thereby increasing the autocorrelation and preventing the occurrence of false synchronization. Reliability is significantly improved (effects corresponding to the inventions of claims 1 to 3)
, an excellent effect can be achieved.

[Brief explanation of drawings]

FIG. 1 is a functional block diagram showing an embodiment of the main configuration of a synchronization detection device of the present invention.

FIG. 2 is a diagram showing a sector format with 1,024 user bytes.

FIG. 3 is a diagram showing a sector format with 512 user bytes.

FIG. 4 is a functional block diagram showing an example of the configuration of main parts of a conventional synchronization detection device.

[Explanation of symbols]

1 Shift register 2 Synchronization pattern register 3 Match number counter 4 Comparator 5 Second shift register 6 Pattern generator 7 Second comparator 8 Mask circuit

Claims (3)

[Claims] 1. A synchronization detection device that detects synchronization using a specific synchronization pattern, in which synchronization is detected using the synchronization pattern and part or all of information written subsequent to the pattern. A synchronous detection method characterized by: 2. In an information reproducing apparatus using an optical disc having a format in which an ID signal such as a sector address is recorded following an address mark in a sector header, the address mark and an ID signal such as a sector address are recorded in the sector header. A synchronization detection method characterized by performing synchronization detection based on information on part or all of ID signals that are subsequently written. Claim 3: In the synchronization detection method according to claim 2,
A synchronization detection device characterized in that a D signal pattern is generated from the track address and sector address of the immediately preceding sector.