JPH0831256B2 - Frame synchronization detection method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a frame synchronization detection system having a sector structure, and more particularly to a signal arrangement format suitable when an optical disc is used as a recording medium.

[Prior Art] Although an apparatus using a magnetic recording medium such as a magnetic tape or a magnetic disk is widely used as an auxiliary storage device of a computer system, in recent years, the recording density is remarkably higher than those of these magnetic recording media. There is a proposal to use a possible optical recording medium (for example, an optical disk) as an auxiliary storage device.

For example, in an optical disc, data is recorded by forming pits (small holes) with a diameter of about 1 μm on a recording track on the surface with a period (interval) of about 2 μm by a laser spot, and a storage capacity of about 30 cm diameter. For 10 ¹¹
It is about 10 ¹² bits. Usually, one recording track is set in a spiral shape.

In general, the access speed of the auxiliary storage device is much slower than that of the main storage device, so that data is recorded in a continuous area in blocks of a certain amount.

At that time, a predetermined block of data is formed into a sector so that reading and writing of data can be surely performed in a short time, and an address (sector address) is assigned to each sector for identification.

11 (a) and 11 (b) show an example of a data recording format in a track of an optical disc.

In the same figure (a), in the track TR, a plurality of sectors SC, each consisting of a pre-formatted area PF, a data area DF, and a gap GP1 separating the pre-formatted area PF and the data area DF, are separated from each other by a gap GP2. Is set automatically.

The pre-formatted area PF is formed in the track TR in advance with the number of bits including the data area DF and the gap GP2 combined.

Further, as shown in (b) of the figure, the pre-formatted area PF has a sync signal for matching the circuit conditions, that is, a bit sync signal for synchronizing the bit clock of the data write / read circuit with the generation timing of the recording data. It is composed of a preamble composed of BS, a sector synchronization signal SS composed of a bit example (pattern) having a sharp autocorrelation for detecting the preformatted area PF, and a sector address SA for identifying the sector SC.

The bit synchronization signal BS forming the preamble is a PLL (P-hase Locked L) for extracting a bit clock and data based on a read signal from the optical pickup unit.
oop) signal is used so that the circuit can be locked properly. For example, it is a signal that changes the state of the read signal at the minimum inversion cycle (that is, "010101 ..." In which the recording state on the optical disk is the repetition of the minimum pit length.

Further, the data area DF includes a plurality of data having a frame structure with a frame synchronization signal FS and a preamble (bit synchronization signal) added at the head of these data.
BS). The number of bits of the preamble in the data area DF is smaller than that of the preamble in the preformat area PF.
Has a sharp pattern of autocorrelation similar to the sector synchronization signal SS.

In addition, the preamble BS of the preformat area PF, the sector synchronization signal SS, the sector address SA, and the gap described above.
GP1, GP2, the preamble BS of the data area DF, and the frame synchronization signal FS are recorded on the optical disk in a non-modulated state, and the frame data of the data area DF is recorded in a state of being subjected to predetermined modulation.

Now, when recording data in such a recording format,
First, the sector synchronization signal SS is detected after bit synchronization is performed with the preamble of the preformat area PF, and the sector address SA is read based on the detection timing.

Gap GP1 if it represents the desired sector
After writing the preamble of the data area DF, the frame data of the first frame is written subsequent to the frame synchronization signal FS, and the frame synchronization signal FS and the frame data of each frame are sequentially recorded.

When reading data, the sector address SA is read in the same manner as described above, and when it indicates the desired sector, based on the timing at which the frame synchronization signal FS is detected after resynchronizing the bits with the preamble of the data area. Read the frame data for each frame.

Then, the read frame data is converted into the original data before modulation by a predetermined demodulation process.

In this way, the data is recorded and read by referring to the pre-formatted area recorded in advance.

By the way, although the optical disc has a remarkably large recording density as described above, it is considered that the optical disc is considerably susceptible to the bit error rate and the rotational fluctuation of the drive system.

On the other hand, in general, since a systematic error correction code is added to each frame data before modulation, even if a data error occurs, it can be completely recovered to some extent, and there is no major problem.

Also, considering the case where the frame synchronization signal FS could not be detected due to a bit error or rotation fluctuation, when the frame synchronization signal FS immediately before that is detected, an interpolation signal or the like is generated based on the detection timing. By doing so, it is possible to artificially generate the frame synchronization timing, but especially, the rotation fluctuation is detected between the end of the preformatted area PF and the detection of the first frame synchronization signal FS of the data area DF. If, for example, the values become large, the first frame synchronization signal FS may not be detected.

When such a situation occurs, the subsequent frame synchronization signal FS
It may take a relatively long time to detect
In the meantime, the frame synchronization cannot be detected with respect to the data frame, and as a result, the inconvenience may occur in that the data of that portion cannot be detected.

[Purpose] The present invention has been made in order to solve the above-mentioned disadvantages of the prior art, and an object of the present invention is to provide a frame synchronization detection method that is resistant to bit errors, drive system rotation fluctuations, and the like.

[Structure] The present invention arranges a preamble for establishing bit synchronization and a plurality of data frames separated by a frame synchronization signal having a sharp autocorrelation pattern, following a preformatted area indicating the start of a sector. In the frame synchronization detection method that detects the frame synchronization signal from the data recorded on the recording medium in the following recording format, the bit synchronization is detected based on the above preamble of the reproduction signal, and the bit clock synchronized with the detected bit synchronization is set. A bit synchronization means for extracting and outputting read data, a maximum detection window prediction function having a maximum detection window width for detecting the frame synchronization signal from the read data, and an optimum prediction function corresponding to the frame synchronization signal. Two prediction functions are generated in synchronization with the above bit clock and Prediction function generating means for generating an interpolation flag signal corresponding to the detection prediction timing of the frame synchronization signal, selection means for selecting either the maximum detection window prediction function or the optimum prediction function, the read data and the Matching filter means for detecting the matching state of the frame synchronization signal, and frame synchronization detection determining means for determining the detection state of the frame synchronization signal based on the output signal of the selecting means and the output signal of the matching filter means. After the bit synchronization detection means establishes bit synchronization, the frame synchronization detection determination means causes the selection means to select the maximum detection window prediction function until the frame synchronization signal is first detected. When the above-mentioned optimum prediction function is selected and the frame synchronization signal is detected, the detection of the frame synchronization signal is performed. When the frame synchronization detection signal synchronized with the imming is output and the frame synchronization signal is not detected, the frame synchronization detection signal synchronized with the output timing of the interpolation flag signal output from the prediction function generating means is output. It is the one. The preamble may be divided into a plurality of pieces by the frame synchronization signal.

In addition, following the preformatted area indicating the beginning of the sector, a preamble for establishing bit synchronization,
And a frame synchronization detection method for detecting a frame synchronization signal from data recorded on a recording medium in a recording format in which a plurality of data frames separated by a frame synchronization signal having a sharp autocorrelation are arranged, Bit synchronization is detected based on the preamble, a bit clock synchronized with the detected bit synchronization is extracted, and bit synchronization means for outputting read data, and detection for detecting the frame synchronization signal from the read data Two prediction functions, a maximum detection window prediction function having a maximum window width and an optimum prediction function corresponding to the frame synchronization signal, are generated in synchronization with the bit clock and correspond to the detection prediction timing of the frame synchronization signal. Prediction function generating means for generating an interpolation flag signal by
Selection means for selecting either the maximum detection window prediction function or the optimum prediction function, a matching filter means for detecting a matching state of the read data and the frame synchronization signal, an output signal of the selection means and the matching filter means. A frame synchronization detection discriminating means for discriminating the detection state of the frame synchronization signal based on the output signal of the above, and after the bit synchronization detecting means establishes bit synchronization, the frame synchronization detection discriminating means is Until the frame sync signal is detected, the selection means is caused to select the maximum detection window prediction function, and thereafter the optimum prediction function is selected, and when the frame sync signal is detected, the frame sync signal of the frame sync signal is detected. When outputting the frame synchronization detection signal synchronized with the detection timing and not detecting the frame synchronization signal, The frame synchronization detection signal synchronized with the output timing of the interpolation flag signal output from the prediction function generating means is output, and when the frequency of occurrence of the interpolation flag signal is larger than a predetermined value, the above selection It is so arranged that the means is restored to a state in which the maximum detection window prediction function is selected.

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

In the figure, the read signal SD output from a pickup (not shown) that reads data from the optical disk is the PLL.
It is added to the bit synchronization circuit 1 including a circuit and a data separator.

In the bit synchronization circuit 1, the PLL circuit is locked by the preamble in the data area DF, whereby the bit clock CP and the read data are changed from the read signal SD.
Separate the RD. This bit clock CP is matched filter 2
And a clock input terminal of the prediction function generator 3,
The read data DT is applied to the data input terminal of the matched filter 2.

The matched filter 2 compares the read data DT having a predetermined number of consecutive bits with the pattern forming the frame synchronization signal FS,
The number of coincident bits is counted and the counted value is output to one input terminal of the adder 4.

The prediction function generation unit 3 generates a maximum detection window prediction function Q1 having the largest detection window among the prediction functions for detecting the frame synchronization signal FS and an optimum prediction function Q2 corresponding to the frame synchronization signal FS, and The interpolation flag signal FI is generated based on the detection prediction timing of the frame synchronization signal FS.

The maximum detection window prediction function Q1 and the optimum prediction function Q2 are input to the input terminals A and B of the mode selector 5, and the interpolation flag signal F
I is output to each input terminal of the OR circuit 6.

The output signal of the mode selector 5 is added to the other input end of the adder 4, and the addition result of the adder 4 is output to the comparison input end of the comparator 7. The threshold signal (the bit length of the frame synchronization signal FS plus 1) set in the threshold setter 8 is applied to the reference input terminal of the comparator 7,
When the addition result of the adder 4 exceeds the threshold value, the comparator 7 raises the frame synchronization signal detection signal SF.

This frame synchronization signal detection signal SF passes through the OR circuit 6 and the frame synchronization detection signal FD together with the interpolation flag signal FI.
Is output to the next stage device (not shown). Further, the flip-flop 9 for controlling the switching of the mode selector 5 is set by the frame synchronization signal detection signal SF.

Note that the frame synchronization detection signal FD output from the OR circuit 6 is also output to the reset input terminal R of the prediction function generating unit 3, whereby the prediction function generating unit 3 is reset and the operation of the next cycle is performed. Be started.

With the above configuration, when the optical disc drive control unit (not shown) rotationally drives the optical disc and the sector address SA of the target sector is detected, the drive control unit outputs the initial reset signal IR and the start signal ST, respectively. It outputs at a predetermined timing to reset the flip-flop 9 and activate the prediction function generator 3.

As a result, the mode selector 5 selects the maximum detection window prediction function Q1 applied to the input terminal A and outputs it to the adder 4.

Therefore, immediately after the end of the pre-formatted area PF, as shown in FIG. 2, the search mode is in which frame synchronization detection is performed by the maximum detection window prediction function Q1.

In this search mode, until the frame synchronization signal FS is actually detected by the maximum detection window prediction function Q1 and the frame synchronization signal detection signal SF is output from the comparator 7, the interpolation flag signal FI remains unchanged from the frame synchronization detection signal FD. The synchronous interpolation state output as is repeated.

When the frame synchronization signal FS is actually detected and the frame synchronization signal detection signal SF is output from the comparator 7,
The flip-flop 9 is set and the selection state of the mode selector 5 is switched, whereby the search mode ends.

In this way, when the search mode ends and the selector 5 selects the optimum prediction function Q2 to be added to the input terminal B, the mode shifts to a synchronization mode in which frame synchronization detection is performed by the optimum prediction function Q2.

In this synchronization mode, when the frame synchronization signal FS is detected by the optimal prediction function Q2, the frame synchronization signal detection signal SF is generated from the comparator 7 and is output as the frame synchronization detection signal FD. If not detected, the interpolation flag signal FI is output as the frame synchronization detection signal FD (synchronization interpolation state; see FIG. 2).

In this way, the sync mode state is maintained after the frame sync signal FS is once detected.

Now, for example, if the pattern of the frame synchronization signal FS is "0011
[00111100] 12-bit sharp autocorrelation pattern, the maximum detection window prediction function Q1 that maximizes the detection window width for this frame synchronization signal FS is "11111111111111111" as shown in FIG. The optimum prediction function Q2 given to the frame synchronization signal FS is given as "112232211" as shown in FIG. Further, in this case, since the length of the frame synchronization signal FS is 12 bits, the threshold value set in the threshold value setting unit 8 is “13”.

Therefore, in this case, when the prediction function generator 3 is activated by the start signal ST, the first frame synchronization signal FS
So that the 9th bit of the first prediction function Q1 and the 5th bit of the second prediction function Q2 respectively occur at the generation timing of the 12th bit of the first prediction function Q1 and the second prediction function Q2. The operation timing is set so as to generate the second prediction function Q2.

According to the maximum detection window prediction function Q1, if the frame sync signal FS has no bit error, the frame sync signal FS can be detected even if the bit slip is ± 8 bits, and the bit error of 1 bit or more. The frame sync signal FS is not detected. That is, the frame sync signal FS is not erroneously detected.

Further, according to the optimum prediction function Q2, when the bit error does not occur in the frame synchronization signal FS, the frame synchronization signal FS can be detected even if the bit slip is ± 4 bits. Sync signal FS
The frame synchronization signal FS can be detected even if a 2-bit bit error occurs.

Here, considering the number of bits from the end of the preformatted area PF to the detection of the first frame synchronization signal FS, for example, from the preformatted area PF to the data area DF
If the length of the gap GP1 up to is 90 bytes and the length of the preamble of the data area DF is 128 bytes, the number of bits is 1744 bits (= (90 + 128) * 8).

Therefore, if the speed fluctuation rate of the read signal SD due to rotation fluctuation of the drive system is 0.4% at maximum, the selector address S
The maximum value of the bit slip amount that occurs from the time A is detected and the prediction function generator 3 is activated until the first frame synchronization signal FS appears in the read signal SD is 6.976 (= 1744 *
It becomes 0.004).

Since the bit slip amount does not exceed the detection capability of the maximum detection window prediction function Q1, in this case, if the bit error does not occur in the frame synchronization signal FS, the first frame synchronization signal FS of the data area DF is surely confirmed. Can be detected.

Next, consider a state in which the frame sync signal FS cannot be detected due to a burst error after the frame sync signal FS is once detected and the search mode is shifted to the sync mode.

For example, if the length of the frame data is 12 bytes, the length of the frame data after modulation, that is, the length of the data actually recorded on the optical disk is doubled to 24 bytes. Also, the frame synchronization signal FS is 12 bits,
When recording on an optical disc, it is recorded in a recording area of 2 bytes, that is, 16 bits. So, in this case,
The size of the recording area on the optical disc of the frame data including the frame synchronization signal FS is 208 bits.

As described above, with the optimum prediction function Q2 in the synchronous mode, the bit slip can be allowed up to ± 4 bits,
As described above, the maximum speed fluctuation rate of the read signal SD is 0.4%.
Then, the number of frames EN that can maintain the frame synchronization detection state by the interpolation flag FI is the maximum positive integer that satisfies the following formula.

208 * 0.004 * EN <4 Therefore, in this case, EN becomes 4. Therefore, as shown in FIG. 5, the burst error BE spans four frame data, and three frame synchronization signals FS continuously occur. Even if it cannot be detected, the frame synchronization signal FS that appears next can be surely detected.

In addition, the amount of bit slip that occurs between the detection of one frame sync signal FS and the detection of the next frame sync signal FS is 0.832 (= 208 * 0.004) bits. Prediction function Q2 allows frame sync detection to be sustained.

Thus, the first frame sync signal of the data area DF
If FS is detected with the maximum detection window and the detection is successful, the frame sync signal FS is detected from the next time using the optimum prediction function, so the preformat area PF to the data area DF are detected. It is possible to realize the frame synchronization detection that is strong against the speed fluctuation that occurs during Further, the frame synchronization can be pulled in quickly and the synchronization deviation can be reduced.

Note that the relationship between the length of the original frame data and the length of the modulated frame data is determined by the modulation method, and is not limited to the example described above.

By the way, even if the frame sync signal FS is detected in the search mode and the mode shifts to the sync mode, it can be considered that the sync loss may occur if the sync interpolation state continues.

An embodiment of the present invention which can deal with such a situation will be described below.

FIG. 6 illustrates an apparatus according to another embodiment of the present invention. In this embodiment, when the synchronous interpolation state continues for a predetermined number, the synchronous mode is returned to the search mode. The frame sync detection can be recovered.
In the figure, the same parts and corresponding parts as those in FIG. 1 are designated by the same reference numerals, and the description thereof will be omitted.

In the figure, the synchronization loss counter 11 counts the interpolation flag signal FI output from the prediction function generating unit 3 and resets the count value by the frame synchronization detection signal FD, and further, the count value is a predetermined value. For example, when the number is 4 or more, the sync loss detection signal DF is output.

The loss-of-synchronization detection signal DF is applied to the reset input terminal of the flip-flop 9 via the OR circuit 12, whereby the flip-flop 9 is reset. As a result, the mode selector 5 is switched so as to select the input terminal A, and the maximum detection window prediction function Q1 is returned to the selected search mode.

Therefore, similar to the above-described embodiment, when the initial reset signal IR and the start signal ST are applied, the frame sync detection is performed in the search mode, and when the first frame sync signal FS is detected, the search mode is shifted to the sync mode. . And in this synchronization mode, the synchronization interpolation state continues,
When the number of consecutive outputs of the interpolation flag signal FI reaches a predetermined value, the sync loss counter 11 outputs the sync loss detection signal DF, the mode selector 5 is switched again, and the frame sync detection returns to the search mode.

After returning to the search mode in this way, when the frame synchronization signal FS is detected again, the search mode is shifted to the synchronization mode as in the first state.

The predetermined value set in the sync loss counter 11 for determining the sync loss is not limited to 4, and the optimum prediction function Q2
It may be set according to the synchronization detection capability of.

The transition state of the operation mode of such frame synchronization detection is
This is shown in the state transition diagram of FIG.

Now, in each of the above-described embodiments, the frame synchronization detection is performed in the state of actually detecting the frame data of the data area DF, but the frame synchronization signal is arranged in the preamble of the data area DF, and this preamble is used in advance. By detecting the frame synchronization, the frame synchronization can be already completed before the detection of the frame data.

FIG. 8 shows a recording format of the data area DF in still another embodiment of the present invention.

In the figure, in the preamble PA of the data area DF, a plurality of frame synchronization signals FS are arranged at the same bit intervals as the frame data part FFD, and a bit synchronization signal BS is arranged between the frame synchronization signals FS. .

An example of an apparatus for detecting frame synchronization in the data area DF of such format is shown in FIG. In the figure, the same parts and corresponding parts as those in FIG. 1 are designated by the same reference numerals, and the description thereof will be omitted.

In the figure, the preamble determination unit 15 counts the bit clock CP when the start signal ST is applied, and outputs the preamble end signal EOP when the count value becomes a value corresponding to the length of the preamble PA. This preamble end signal EOP has a frame sync detection signal F at its one input end.
D is added to the other input of the AND circuit 16 to which it is added. Therefore, the frame synchronization detection signal FD is output to the next-stage device on condition that the preamble end signal EOP is output.

Therefore, the frame sync signal FS located in the preamble PA is detected, and the preamble PA
The frame synchronization detection signal FD resulting from the generation of the interpolation flag signal FI in the state of detecting (1) is masked by the AND circuit 16 and is not output.

The state transition diagram of FIG. 10 shows the transition status of the frame synchronization detection operation mode in this embodiment.

In this way, since the frame synchronization detection is executed in the preamble PA, the frame data FFD can be detected in the state where the frame synchronization detection has already been taken, and as a result, the frame synchronization detection is pulled in very quickly.

By the way, when a plurality of frame synchronization signals FS are arranged in the preamble PA of the data area DF as shown in FIG. 8, the frame synchronization can be achieved by the preamble PA, so that the frame synchronization signal FS has a sharp autocorrelation. In some cases, it is not necessary to use the pattern.

Note that the frame synchronization signal, the first and second prediction functions, and the like in each of the above-described embodiments are not limited to these, and other equivalent ones can be used.

[Effect] As described above, according to the present invention, a preformatted area indicating the beginning of a sector is followed by a preamble for establishing bit synchronization, and a frame synchronization signal having a sharp autocorrelation pattern. In the frame synchronization detection method that detects the frame synchronization signal from the data recorded on the recording medium in the recording format in which a plurality of data frames are arranged, the bit synchronization is detected based on the preamble of the reproduction signal, and the detection is performed. A bit synchronization means for extracting a bit clock synchronized with bit synchronization and outputting read data, a maximum detection window prediction function having a maximum detection window width for detecting the frame synchronization signal from the read data, and the frame synchronization The two optimal prediction functions corresponding to the signal are the same as the above bit clock. Prediction function generating means for generating an interpolation flag signal corresponding to the detection prediction timing of the frame synchronization signal, and selecting means for selecting one of the maximum detection window prediction function and the optimum prediction function. ,
Matching filter means for detecting the matching state of the read data and the frame synchronizing signal, and frame synchronization detection for judging the detecting state of the frame synchronizing signal based on the output signal of the selecting means and the output signal of the matching filter means. After the bit synchronization detection means establishes bit synchronization, the frame synchronization detection determination means selects the maximum detection window prediction function in the selection means until the frame synchronization signal is first detected. After that, the optimum prediction function is selected, and when the frame synchronization signal is detected, a frame synchronization detection signal synchronized with the detection timing of the frame synchronization signal is output and the frame synchronization signal is not detected. In this case, in synchronization with the output timing of the interpolation flag signal output from the prediction function generating means, Since so as to output a frame synchronization detection signal, even when the rotational fluctuation is increased between the preformat area of the data area, such an effect that can be rapidly frame synchronization.

In addition, following the preformatted area indicating the beginning of the sector, a preamble for establishing bit synchronization,
And a frame synchronization detection method for detecting a frame synchronization signal from data recorded on a recording medium in a recording format in which a plurality of data frames separated by a frame synchronization signal having a sharp autocorrelation are arranged, Bit synchronization is detected based on the preamble, a bit clock synchronized with the detected bit synchronization is extracted, and bit synchronization means for outputting read data, and detection for detecting the frame synchronization signal from the read data Two prediction functions, a maximum detection window prediction function having a maximum window width and an optimum prediction function corresponding to the frame synchronization signal, are generated in synchronization with the bit clock and correspond to the detection prediction timing of the frame synchronization signal. Prediction function generating means for generating an interpolation flag signal by
Selection means for selecting either the maximum detection window prediction function or the optimum prediction function, a matching filter means for detecting a matching state of the read data and the frame synchronization signal, an output signal of the selection means and the matching filter means. A frame synchronization detection discriminating means for discriminating the detection state of the frame synchronization signal based on the output signal of the above, and after the bit synchronization detecting means establishes bit synchronization, the frame synchronization detection discriminating means is Until the frame sync signal is detected, the selection means is caused to select the maximum detection window prediction function, and thereafter the optimum prediction function is selected, and when the frame sync signal is detected, the frame sync signal of the frame sync signal is detected. When outputting the frame synchronization detection signal synchronized with the detection timing and not detecting the frame synchronization signal, When outputting the frame synchronization detection signal synchronized with the output timing of the interpolation flag signal output from the prediction function generating means, and the occurrence frequency of the interpolation flag signal becomes larger than a predetermined value, the selecting means Since the system returns to the state in which the maximum detection window prediction function is selected, the frame synchronization can be quickly achieved even when the rotation fluctuation between the preformatted area and the data area becomes large. It is also possible to quickly resynchronize the frame synchronization even after the loss of the frame.

[Brief description of drawings]

FIG. 1 is a block diagram illustrating a device according to an embodiment of the present invention, and FIG. 2 is a state transition diagram showing a transition state of an operation mode of frame synchronization detection in the device shown in FIG.
FIG. 3 is a graph diagram showing an example of the first prediction function, FIG. 4 is a graph diagram showing an example of the second prediction function, FIG. 5 is a signal arrangement diagram showing an example of burst error occurrence, and FIG. FIG. 1 is a block diagram illustrating a device according to another embodiment of the present invention,
FIG. 7 is a state transition diagram showing a state of transition of an operation mode of frame synchronization detection in the apparatus shown in FIG. 6, and FIG. 8 is a signal arrangement diagram illustrating a preamble according to still another embodiment of the present invention. FIG. 9 is a block diagram illustrating a device according to still another embodiment of the present invention, FIG. 10 is a state transition diagram showing a transition state of an operation mode of frame synchronization detection in the device shown in FIG. FIG. 11A is a signal arrangement diagram showing an example of the recording format of the optical disc, and FIG. 11B is a signal arrangement diagram showing an example of the recording format per sector. 1 ... Bit synchronization circuit, 2, 20 ... Matched filter, 3 ...
Prediction function generator, 4 ... Adder, 5 ... Mode selector, 6,12,25 ... OR circuit, 7 ... Comparator, 8 ... Threshold setting device, 9 ... Flip-flop, 11 ... Synchronization Missing counter, 15 ... preamble discrimination circuit, 16, 22, 24 ... AND circuit, 21 ... detection window signal generator, 23 ... synchronization confirmation counter.

Claims (3)

[Claims] 1. A pre-formatted area indicating the beginning of a sector, followed by a preamble for establishing bit synchronization, and a plurality of data frames separated by a frame synchronization signal having a sharp autocorrelation pattern. In the frame synchronization detection method that detects the frame synchronization signal from the data recorded on the recording medium in the recording format, the bit synchronization is detected based on the above preamble of the reproduction signal, and the bit clock synchronized with the detected bit synchronization is extracted. At the same time, a bit synchronization means for outputting read data, a maximum detection window prediction function having a maximum detection window width for detecting the frame synchronization signal from the read data, and an optimum prediction function corresponding to the frame synchronization signal are provided. The prediction function is generated in synchronization with the bit clock, and Prediction function generating means for generating an interpolation flag signal corresponding to the detection prediction timing of the frame synchronization signal, selecting means for selecting one of the maximum detection window prediction function and the optimum prediction function, the read data and the Matching filter means for detecting the matching state of the frame synchronization signal, and frame synchronization detection determining means for determining the detection state of the frame synchronization signal based on the output signal of the selecting means and the output signal of the matching filter means. After the bit synchronization detection means establishes bit synchronization,
The frame synchronization detection determination means causes the selection means to select the maximum detection window prediction function until the frame synchronization signal is first detected, and thereafter selects the optimum prediction function, and the frame synchronization signal If detected, it outputs a frame synchronization detection signal synchronized with the detection timing of the frame synchronization signal, and if it does not detect the frame synchronization signal, outputs an interpolation flag signal output from the prediction function generating means. A frame synchronization detection method characterized by outputting a frame synchronization detection signal synchronized with timing. 2. A preformatted area indicating the beginning of a sector, followed by a preamble for establishing bit synchronization and a plurality of data frames separated by a frame synchronization signal having a sharp autocorrelation pattern. In the frame synchronization detection method that detects the frame synchronization signal from the data recorded on the recording medium in the recording format, the bit synchronization is detected based on the above preamble of the reproduction signal, and the bit clock synchronized with the detected bit synchronization is extracted. At the same time, a bit synchronization means for outputting read data, a maximum detection window prediction function having a maximum detection window width for detecting the frame synchronization signal from the read data, and an optimum prediction function corresponding to the frame synchronization signal are provided. The prediction function is generated in synchronization with the bit clock, and Prediction function generating means for generating an interpolation flag signal corresponding to the detection prediction timing of the frame synchronization signal, selecting means for selecting one of the maximum detection window prediction function and the optimum prediction function, the read data and the Matching filter means for detecting the matching state of the frame synchronization signal, and frame synchronization detection determining means for determining the detection state of the frame synchronization signal based on the output signal of the selecting means and the output signal of the matching filter means. After the bit synchronization detection means establishes bit synchronization,
The frame synchronization detection determination means causes the selection means to select the maximum detection window prediction function until the frame synchronization signal is first detected, and thereafter selects the optimum prediction function, and the frame synchronization signal If detected, it outputs a frame synchronization detection signal synchronized with the detection timing of the frame synchronization signal, and if it does not detect the frame synchronization signal, outputs an interpolation flag signal output from the prediction function generating means. A frame synchronization detection signal synchronized with the timing is output, and when the frequency of occurrence of the interpolation flag signal becomes larger than a predetermined value, it is possible to return to a state in which the selection means selects the maximum detection window prediction function. Characteristic frame synchronization detection method. 3. The frame synchronization detection method according to claim 1, wherein the preamble is divided into a plurality of sections by the frame synchronization signal.