JPH02214070A - Id protection device - Google Patents

Abstract

PURPOSE:To improve error correction efficiency by comparing ID data detected by a detecting means with the ID data generated by a generating means, and selecting either. CONSTITUTION:A signal string inputted from an input terminal 1 is inputted to an ID detector a 4, and the ID data in the signal string is detected by a synchronizing signal inputted from an input terminal 2. Also, an ID generator a 3 is reset to 0 at the switching timing of each track, and is comprised of a counter counted up by the synchronizing signal, and generates the ID data in prescribed sequence. And the ID data generated from the generator a 3 is compared with the ID data detected by the detector a 4 by an ID comparator a 5. When noncoincidence is obtained, an operation to substitute the ID data for data in a reproducing signal string is performed, and the signal string in which the ID data is substituted at a selector 6 is corrected at an error corrector 7. Thus, it is possible to heighten the error correction efficiency by performing error correction after substituting predicted ID data.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a transmission system for a digital signal string in which ID data is inserted in a predetermined order, and in particular, when a code error occurs in the ID data, related to data.

[Conventional technology]

As described in Japanese Unexamined Patent Publication No. 60-101766, the conventional device generates an I/I indicating the address of reproduced data as a result of error correction.
After detecting that there is an error in the D data, it is replaced with a predicted ID generated by an address counter operated by a synchronization signal detected by another means.

[Problem to be solved by the invention]

The above-mentioned conventional technology does not take into account erroneous detection of the synchronization signal, which is an immediate pulse of the address counter that generates the predicted ID, and even if an error is detected in the ID data as a result of error correction. Regardless, incorrect prediction I
There is a problem in that it is replaced with D data.

The purpose of the present invention is to reflect the result of error correction in the value of an address counter that generates a predicted ID, and when a correct ID is obtained by error correction, set the address counter to a value calculated from that value. , Furthermore, even before error correction, the predicted ID and the reproduced ID are replaced with each other to prevent synchronization signal detection errors [Means for solving the problem]. If the ID data detected in the signal string and the ID data generated in a predetermined order do not match before code error correction in the transmission system, the ID data in the signal string
This is achieved by performing number error correction after replacing the data with the generated ID data. Also, after code error correction, the ID of the code block that is determined to be uncorrectable.
Replace the data with the generated ID data, or
Depending on the comparison result of the magnitude relationship between the ID data in the code block and the generated ID data.

The above objective can also be achieved by switching whether or not to replace the ID.

[Effect]

In a signal string transmission system in which ID data is inserted in a predetermined order into a digital data string, an ID generating means generates ID data in a predetermined order using a synchronization signal detected from the signal string, and generates ID data to be transmitted. Predict ID data. I
The D data comparing means compares the ID data detected from the signal train and the generated ID data. If the comparison results do not match, it can be determined that there is a high possibility that a code error has occurred in the ID data of the transmitted signal string, so code error correction is performed after replacing it with the ID data predicted by the ID generation means. By doing so, it becomes possible to improve the correction efficiency of the code error correction circuit. After code error correction, if a code block that is determined to be uncorrectable occurs, there is a high possibility that a code error has occurred in the ID data in the code block, so it is replaced with ID data predicted by the ID generation means. By doing so, it is possible to avoid a situation in which the already transmitted signal train is destroyed in subsequent processing. In addition, the ID data after code error correction and the generated ID
Similarly, it is possible to avoid destruction of already transmitted signal strings by switching the processing of ID data based on the result of determining the magnitude relationship with the data.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a digital signal recording/reproducing apparatus that helically records a digital signal string on a magnetic tape will be described below with reference to FIGS. 1 and 2. FIG. 1 is a diagram showing the configuration of one embodiment. In FIG. 1, 1 is a playback data input terminal, 2 is a synchronization signal input terminal, 3 is an ID generation generation line, 4 is an ID detection detection line, 5 is an ID ratio comparison line, 6 is a selection line, 7 is an error corrector, and 8 is an error corrector. 9 is an ID detector, 10 is an ID comparator, and 11 is a selector. FIG. 2 is a diagram showing the recording order of 10 data in one track recorded on the tape in this embodiment. As shown in the figure, it is assumed that the ID data in each track increases sequentially from 0, and values up to 255 are recorded.

The signal string input from playback data input terminal 1 is input to ID detectors a and 4 and selector 6, and ID detector 4 inputs the signal string by the synchronization signal input from synchronization signal input terminal 2. Detect the ID data inside. The ID generator 3 consists of a counter that is reset to zero at each track switching retiming and counts up by the synchronization signal input from the synchronization signal input terminal 2, and generates ID data in the order shown in Figure 2. do. ID comparator 5 is
ID generated in back mountain 3 and ID detector 4
It is compared with the ID detected in , and it is determined whether or not -M has been detected. Alternatively, a configuration may be adopted in which a mismatch is determined only when the difference between the two types of ID exceeds a predetermined value. In this case, as a determination condition, for example, if the upper n bits of m-bit data match, Cm>n), a method may be adopted in which it is determined that the two types of ZD match. Selector 6 is
When the comparison result of the ID ratio comparison back pile 5 indicates that the detected ID and the generated ID do not match, it operates to replace the ID data in the reproduced signal sequence with the generated ID data. The signal string whose ID data has been replaced in selection return step 6 is passed to the error corrector 7, and if the ID data in the reproduced data string does not match the ID data predicted by the ID generation back step 3, the reproduced data string is replaced. Since there is a high probability that the ID data inside is incorrect, it is possible to equivalently increase the efficiency of error correction by performing error correction after replacing it with the predicted ID.

The ID generator b8 has the same structure as the ID generation generator 3, but generates ID data in the order shown in FIG. 2 in synchronization with the timing of the output data of the error corrector 7. I
The D detector b 9 detects I in the output data string of the error corrector 7.
Detect D data.

The ID comparator b 10 compares the ID data generated by the ID generator b 8 and the ID data detected by the ID detector b 9. Selector b 11 is ID comparator b
According to the determination result in step 10, the two types of IDs are switched.

If the ID data detected by ID detector b 9 is larger than the ID data generated by ID generator b 8, the ID data is not replaced and the detected ID data is replaced with the generated ID.
If the ID data is smaller than the ID data, the ID data in the signal string is replaced with the generated ID data. 6 By performing the operation after error correction as described above, when a code error occurs in the ID data, it is possible to replace the ID data in the signal string with the generated ID data. It is possible to prevent data destruction. Alternatively, the detected ID data may be the generated ID.
If the detected ID data is larger than the generated ID data, the ID data is replaced, and if the detected ID data is smaller than the generated ID data, the processing after error correction is stopped to prevent the destruction of the data that has already been transmitted. You can get the same effect on things.

FIG. 3 shows the configuration of another embodiment of the present invention, in which it is determined whether or not error correction is possible, and ID data is generated in a predetermined order according to five uncorrectable groups, and an uncorrectable discriminator 14 If the determination result shows that it is correctable, that is, no code error has occurred, the ID data detected by the ID detector b9 is loaded. When the result of the uncorrectable discriminator 14 indicates uncorrectable, the selector b 11 counts up by the synchronization signal input from the signal string input terminal 2, and selects the determination result of the uncorrectable discriminator 14. It is composed of a load counter that loads the ID data detected by the ID detector b9, and generates the ID data in the order shown in FIG. If uncorrectable correct ID data is obtained, the correct ID data is loaded every time, so it is possible to always generate correct ID data in a predetermined order, reducing the impact when a code error occurs in ID data. be able to. As in the above embodiment, by adding the error correction impossible flag to the ID data replacement condition,
It becomes possible to improve the operational accuracy of the ID generator.

Next, an example in which a demodulation error is applied to the ID data replacement condition will be described with reference to FIG. 4.

In FIG. 4, 16 is a demodulator, 17 is a demodulation error detector, and 18 is a selector. The signal string inputted from the reproduced data input terminal 1 is a signal string that has been modulated according to a certain rule so as to be suitable for recording on a magnetic tape. The demodulator 16 demodulates the signal string input from the reproduced data input terminal 1 and converts it into a signal string before modulation. When a code error occurs in the recording/reproducing system, a pattern that cannot exist under the original modulation/demodulation rules may appear, and in this case, it can be clearly determined that it is an error. The demodulation error detector 17 detects whether a demodulation error has occurred at the ID data position in the output signal sequence of the demodulator 16.

If an error occurs, a demodulation error flag is set.

When the output signal of the demodulation error detector 17 indicates a demodulation error, the selector 18 replaces the ID data in the signal string with the ID data generated by the ID generator 3. As mentioned above, if it is determined that the ID data in the output signal stream of the demodulator 16 is clearly erroneous, the error correction ability can be improved isometrically by replacing it with the correct ID data before error correction. It is possible to improve it.

Next, another embodiment to which the present invention is applied will be described using FIG. In FIG. 5, 20 is a synchronization detection circuit, 21 is a synchronization protection circuit, and 22 is a selector. Synchronization detection circuit 20
detects a synchronization signal inserted at a constant period in a reproduced signal sequence. When the synchronization detection circuit 20 cannot detect a synchronization signal due to a code error or a scratch on the tape magnetic material, the synchronization protection circuit 21 generates a synchronization signal at a predetermined synchronization position from the synchronization signal detected immediately before. At the same time as the insertion, a synchronization protection flag indicating that synchronization protection has been performed is output. When the synchronization protection flag indicating that synchronization protection has been performed is set, the selector 22 replaces the ID data in the signal train with the ID data generated by the ID generator 3. As mentioned above,
If the synchronization detection circuit 20 cannot detect a synchronization signal and the synchronization protection circuit 21 performs synchronization protection, there is a high possibility that the synchronization signal was not regenerated due to a code error or scratches on the magnetic material. teeth.

There is a high probability that the ID data will not be reproduced either. According to the present invention,
When synchronization protection is performed, the ID data in the signal train is
By performing error correction after replacing the generated ID data, it is possible to improve the efficiency of error correction.

The present invention has been described above in a case where the present invention is applied to a digital signal recording/reproducing device that helically records a digital data string on a magnetic tape. If it is a system, effects similar to those of this example can be obtained, and the essence of the present invention is not impaired. Furthermore, although the ID data in this embodiment is assumed to increase sequentially from O, the same effects as in this embodiment can be obtained as long as certain rules are followed. In this case, the ID generator can be configured by, for example, a counter that counts up with a synchronization signal and a ROM, or a counter and a decoding circuit. Even if an ID generator with this configuration is used, similar effects can be obtained, and the essence of the present invention is not impaired.

〔Effect of the invention〕

According to the present invention, in a transmission system for a signal string in which ID data is inserted in a predetermined order, predicted ID data is compared with ID data in a transmitted signal string before error correction. By adopting a configuration in which error correction is performed after ID data is replaced according to the result, the efficiency of error correction can be improved. In addition, after error correction, if the ID data in the signal string does not match the predicted ID data, or if it is determined that correction is impossible, the ID data in the signal string can be replaced with the predicted ID data. This makes it possible to prevent the signal train transmitted to the reed from being destroyed in the process after error correction.

[Brief explanation of the drawing]

1, 3, 4 and 5 are block diagrams of an embodiment of a digital signal transmission system to which the present invention is applied, and FIG. 2 is a block diagram of an embodiment of a digital signal transmission system to which the present invention is applied. ,
FIG. 3 is a diagram showing the order of ID data in each track. 3.8... ID generator, 5,10... ID comparator, 14... Uncorrectable discriminator, 17... Demodulation error detector, 21... Synchronization protection circuit. 4.9...ID detector, 7...Error corrector, 16...Demodulator, 20...Synchronization detection circuit, Takuman

Claims (1)

[Claims] 1. In a digital signal transmission system that transmits a signal string in which ID data is inserted in a predetermined position at a predetermined order in a digital data string via a code error correction circuit (7), ID data detection means (4, 9) for detecting first ID data from the signal train; and ID data generating means (3, 9) for generating second ID data from the signal train in a predetermined order. 8, 13, 15)
and a comparison means (5) for comparing the first and second ID data.
, 10), and selection means (6, 11, 18, 22) for selecting either the first ID data or the second ID data based on the comparison result by the comparison means. An ID protection device characterized by a configuration. 2. The ID data detection means (4, 9), the ID data generation means (3, 8, 13, 15), and the comparison means (5).
, 10) and the above selection means (6, 11, 18, 22)
The ID according to claim 1, wherein the ID is connected to at least a preceding stage or a succeeding stage of the code error correction circuit (7).
Protective device. 3. The signal train includes a synchronization signal, and the ID data generating means (3, 8, 13, 15) generates the second ID data by receiving the synchronization signal in the signal train. The ID protection device according to claim 1, wherein the ID protection device has a configuration of: 4. The comparison means (5, 10) compares the first ID data detected by the ID data detection means (4, 9) with the ID data generation means (3, 8,
13, 15), wherein the first ID data is replaced with the second ID data when the second ID data generated in steps 13 and 15) do not match. 3. The ID protection device according to 3. 5. The signal string is a reproduced signal reproduced from a recording medium, and the ID data detection means (4, 9) has a configuration for detecting errors that occur when the reproduced signal is subjected to recording modulation and demodulation. , The comparing means (5, 10) replaces the first ID data with the second ID data when the error is detected at the position of the first ID data in the reproduced signal. The ID protection device according to claim 1, 2 or 3, further comprising a configuration of. 6. The signal train includes ID data and a synchronization signal, and the ID data detection means (4, 9) is provided with a synchronization signal detection means (20) for detecting the synchronization signal at its front stage. and is connected to the preceding stage of the code error correction circuit (7), and is connected to the comparing means (5, 1).
0) is provided with a configuration for replacing the ID data in the signal train with the second ID data when an operation error occurs in the synchronization signal detection means (20), ID protection device according to 2 or 3. 7. The comparing means (5, 10) is connected to the subsequent stage of the code error correction circuit (7), and when a code block whose error cannot be corrected occurs in the code error correction circuit (7), the code 4. The ID protection device according to claim 1, further comprising a configuration for replacing ID data in a block with the second ID data. 8. The ID data generating means (3, 8, 13, 15) is connected to the subsequent stage of the code error correction circuit (7) and generates a code determined to have no code error in the code error correction circuit (7). When a block occurs, the value of the second ID data is changed to the first ID by the ID data in the code block.
Claim 7 comprising an arrangement to be made equal to the value of the data.
ID protection device described in . 9. The comparison means (5, 10) is connected to the subsequent stage of the code error correction circuit (7) and compares the first ID data detected from the code block generated by the code error correction circuit (7). 4. The ID protection device according to claim 1, further comprising a configuration for stopping a signal processing operation for the code block when the second ID data is smaller than the second ID data. 10. The comparison means (5, 10) is connected to the subsequent stage of the code error correction circuit (7), and is configured to detect the first ID detected from the code block generated by the code error correction circuit (7). Claims 1 and 2 further comprising a structure for replacing the ID data in the signal constituting the code block with the second ID data when the data is smaller or larger than the second ID data. or the ID protection device described in 3. 11. The comparison means (5, 10) is connected to the subsequent stage of the code error correction circuit (7) and compares the first ID data detected from the code block generated by the code error correction circuit (7). is larger than the second ID data, the ID data in the signal string constituting the code block is not replaced with the second ID data. ID listed in
Protective device. 12. The comparison means (5, 10) is connected before the code error correction circuit (7) and calculates the difference between the first ID data detected from the signal train and the second ID data. 5. The ID protection device according to claim 4, further comprising a configuration for replacing the first ID data with the second ID data when the first ID data exceeds a predetermined value.