JPS5957540A - Data transmitter - Google Patents

Abstract

PURPOSE:To simplify hardware and to attain low cost, by using the result of error detection of a main data for the error detection of control information data. CONSTITUTION:A reproducing data from a demodulation circuit 1 is applied to a sub-code separating circuit 2, where the data is divided into the data of the main channel and the sub-code. The data of the main channel is applied to an error correction circuit 3 and the sub-code is applied to a buffer memory 7. The sub- code delayed at the memory 7 is applied to a sub-code processing circuit 8 and the sub-code discriminated as correct at the circuit 8 is applied to a system controller 9. Further, an error pointer formed at the circuit 3 is applied to a pointer buffer memory 11, interleaved and applied to a discrimination circuit 12, where the number of error pointers representing the error is counted, and when the number exceeds the number of prescribed threshold values, a falg representing that the corresponding sub-code makes an error is produced and applied to the circuit 8.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a data transmission device that is applied when reproducing digital information signals such as digital audio signals and digital video signals from, for example, a recording medium.

"Background Art and Problems Therewith" For example, when a digital audio signal is recorded on an optical digital audio disc (hereinafter referred to as a compact disc), control information data called a subcode is added. This subcode is
A signal indicating the division of a program such as a song recorded on a compact disc, the address of this program (referred to as a track number), and the division within the program.

Time code that displays program and pause times;
It consists of a signal that distinguishes between channel 2 and channel J, a signal including control data indicating whether or not pre-emphasis is applied, still image data, audio data related to this, and the like. The sub-food is used to select a desired program during reproduction and to reproduce still images associated with the main audio information.

This subcode is as important as the main data, which is the digital audio signal, and is subjected to error correction encoding so that it is not affected by errors during playback. Digital audio signals are recorded on compact discs in a different order from the nine-dimensional signal order in order to disperse the effects of burst errors caused by dropouts and the like. Such processing is called interleaving. In practice, double interleaving is performed and error correction encoding using Reed-Solomon codes is used in conjunction with each interleave. It is also conceivable to perform error detection using CRC or error correction encoding using Reed-Solomon code for the subcode.

Error correction encoding for this subcode is simpler and has greater redundancy than for digital audio signals.

This prevents the processing time from increasing and one circuit from becoming large-scale.

By the way, on compact discs, subcodes are located at the beginning of each predetermined length of main data consisting of a digital audio signal and a redundant code for error correction, so there is a very high correlation regarding errors between the main data and subcodes. Strong against

By utilizing this fact, it is possible to extend the results of main data error detection to subcode error detection.

``Object of the Invention'' This invention uses the results of error detection in main data to detect errors in control information data. It is valid even if it has been done.

In other words, the results of error detection of main data can be used to further increase the reliability of the results of error detection of control information data. Or.

According to the present invention, in the case of realizing a configuration in which circuits for error detection and error correction for subcodes are omitted in order to reduce costs as one of the compact disc digital cameras, the present invention is applicable.

Error detection for subcodes can be substantially performed.

"Summary of the Invention" The present invention detects errors in a received digital information signal in a data transmission device in which control information data is added to and transmitted for each predetermined length of an error correction encoded digital information signal. The circuit and the error detection results output from the circuit are used to detect errors in the control information data added.

Furthermore, the present invention is also applicable to cases where the digital information signal has been subjected to interleaving processing, while the control information data has not been subjected to interleaving processing, or has been subjected to simpler interleaving processing that is different from the digital information signal. .

That is, the present invention uses interleaving in an order different from the original order, and in a data transmission apparatus in which control information data is added to and transmitted for each predetermined length of an error correction encoded digital information signal,
received con).

further comprising a buffer memory for storing information data, a circuit for performing dinterleaving to restore the order of the received digital information signal, and a circuit for error detection and error correction of the dinterleaved digital information signal, Based on the result of this error detection, errors in the control information data stored in the buffer memory are detected.

"Embodiment" Hereinafter, an embodiment in which the present invention is applied to a compact disc player will be described.

In FIG. 1, reference numeral 1 denotes a demodulation circuit for demodulating data reproduced from a compact disc. Compact discs use a modulation method that converts g bits into 74' bits according to a predetermined algorithm.
From the demodulation circuit 1, reproduced data returned to 1g bits appears. This reproduced data is supplied to the subcode separation circuit 2 and is separated into main channel data and subcode.

The main channel data is supplied to the error correction circuit 3. This error correction circuit 3 performs dinterleaving to restore the original data order and error correction using a Reed-Solomon code.

Dinterleaving is performed twice, at a first stage and a second stage, and the Reed-Solomon code is decoded at each stage. As a result of this error correction, the error pointer for the /word of data containing an uncorrectable error is set to a high level, for example. The error pointer for the word whose error has been corrected is set low. In this way, the digital A audio signal to which the error pointer has been added is supplied to the interpolation circuit 4 and subjected to, for example, average value interpolation processing so that the error is not noticeable.

The output data of this interpolation circuit 4 is supplied to a D/A:l inverter 5, and an analog audio signal is obtained at an output terminal 6.

7, - of the data recorded on the compact disc. ,show. 77-A (7) At the beginning, 2
A 4'-bit frame synchronization signal (shaded) is added, followed by an l symbol subcode, and
/2 symbol digital audio signal, redundant data for error correction of g symbol, /2 symbol digital audio signal, and redundant data for error correction of t symbol are located in this order. The l symbol is converted into g bits by passing through the demodulation circuit 1 as /4' bits.

Although not shown in the drawings, the frame synchronization signal and symbols, and the subcodes separated by each subfood separation circuit 2, are delayed in a buffer memory 7 and supplied to a subcode processing circuit 8.

The subcode determined to be correct by the subcode processing circuit 8 is supplied to the system controller 9. In addition to detecting this error, the sub-food processing circuit 8 performs a process of dividing the subcode into a plurality of channels. The system controller 9 is supplied with key signals from a keyboard 10 provided with operation keys, and also generates system control signals for controlling the feeding of the optical pickup.

Further, in the error correction circuit 3, an error pointer formed by performing the first stage of dinterleaving and decoding is supplied to the pointer buffer memory 11. This pointer buffer memory 11 stores an error pointer (/
bits) and return them to data locations on a compact disc. In this way, the interleaved error pointer is supplied to the determination circuit 12. As mentioned above, in the case of a compact disc, since the digital audio signal of 2t symbols is included in 1 frame, the pointer buffer memory 11
An error pointer of 2t bits is supplied to the determination circuit 12 per +/frame. Then, the 9 judgment circuit 12 counts the number of error pointers indicating an error among the 21I bit error pointers, and when the number exceeds a predetermined threshold, a flag indicating that the corresponding subcode is in error is set. Occur. This flag is supplied to the subcode processing circuit 8.

The operation of the embodiment of the invention described above will be explained with reference to FIG. To simplify the explanation, it is assumed that l symbols of main data exist in seven frames, and l symbols of subcodes are added to the beginning of the main data.

FIG. 3 shows a sequence of subcodes and main data before being interleaved. In Figure 3, the subcode symbol S8 and the main data symbols W+, 'V/2+''3+W4 are interleaved and recorded on the compact disc as shown in tg3uB. In other words, the main data's l symbol/1' WI HW2 , Wl HW
4 are recorded on the compact disc at intervals of t symbols including the subfood symbol.

Reproduction data similar to that shown in FIG. 3B is reproduced from the compact disc. Then, the subcode S of frame F1 of the reproduced data is written into the memory area 13 of the buffer memory 7, as shown in FIG.
The /inchers (the three shaded symbols and the symbol W1) of this frame F are written in the memory area 14 of the buffer memory of the error correction circuit 3 in a diagonal direction. The main data is read out from the memory area 14 in the vertical direction. In the period of frame F,
Seven previously written symbols (indicated by cross marks) are read out in the vertical direction and error detection and error correction processing is performed. In this way, the dinterleaving process is performed by controlling the write address and the read address.

Then, the main data subjected to error detection and error correction is taken out from the error correction circuit 3 as an output data series and supplied to the interpolation circuit 4, as shown in the third diagram. Each of the output data series of this error correction circuit 3 is /
A bit error pointer is appended to the 0 bit. At this timing.

Subcode S is not read out from buffer memory 7.

In the next frame F2, the subcode is written into the memory area 13 of the buffer memory T, and at the same time, the symbol W! is written into the memory area 14 of the buffer memory of the error correction circuit 3. The number of symbols containing the number is written. At this time, one symbol of the main data that has already been written is read out.

After error detection and error correction processing is performed, an output data series is obtained as shown in Figure 3. As shown in the third rffl C, the data processing described above results in frame F3. Frame F4. Similarly, in each of the frames F, there are a large number of symbols W,, W, in the period of the frame Fl+, as shown in the third diagram.

W8. W4 is extracted as output data - The error pointer can be found regarding the main data (three hatched symbols and symbol W1) included in the same frame F1 as the subcode s1 on the compact disc during the period of frame F. It is. This error pointer is written in the pointer buffer memory 11, and the number of related error pointers that indicate an error is counted, and if the 1 value exceeds the threshold number, the corresponding subcode is Determined as an error symbol.

In the example shown in FIG. 3, the buffer memory 7 for the subcode needs to have a capacity of at least S symbols. Also.

In the example shown in FIG. 3, the pointer buffer memory 11 stores at least 10 symbol error pointers (70 bits) in order to store error pointers necessary for error determination of the subcode next to subcode S1. It is necessary to have a capacity of

Interleaving is performed by controlling the address when writing the error pointer to this pointer buffer memory 11 and the address when reading the error pointer,
Unlike this, the pointer buffer memory 11 is configured to collect error pointers of main data symbols included in the same frame on a compact disc.
may be used simply for delay, and error pointers of symbols included in the same frame may be extracted from this output for determination.

In actual compact disc error correction encoding, 9.
Because there is a 2-claw interleave in row 4.

Detection regarding subcodes is performed using error pointers generated by the first stage of dinterleaving and error correction. In other words, the first stage of dinterleaving and error correction are performed.

Furthermore, after the λ-th stage of dinterleaving and error correction, most errors are corrected because the error correction code has a high error correction ability.

There is a possibility that the error pointer cannot be used to detect errors in the subcode. In this respect, the number of thresholds to be compared with the count value of the number of error pointers is determined by taking into account the correction ability of the error correction code. Furthermore, if an error detection code such as a CRC code is added to the main data for error detection, the result of this error detection is used. Furthermore, the compact disc subcode contains 9 subcode sync patterns.
The unit is g frames. This (!r bit ×
The present invention may be applied only to a part of the subcodes of the 9g frame).

"Effects of the Invention" According to the present invention, errors in control information data are detected using the results of error detection in main data. There is no need to provide a code, and it is possible to simplify the hardware and reduce the p-cost.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an embodiment in which the present invention is applied to a compact disc player, and FIG. 2 is a route diagram showing the frame format of data recorded on the compact disc. FIG. 3 is a route map used to explain the operation of an embodiment of the present invention. 2... Subcode separation circuit, 3... Error correction circuit, 7... Buffer memory, 8...
...Subcode processing circuit, 11... Pointer no.: Rafa memory 0 Agent Masaru Sugiura Tomo Figure 2 Figure 3

Claims (1)

[Scope of Claims] A circuit for detecting errors in a received digital information signal in a data transmission device in which a digital information signal subjected to fil error correction encoding is transmitted with control information data added to each predetermined length. and a data transmission device configured to detect errors in the control information data added using the error detection results output from this circuit. (2) The above data received in a data transmission device that uses interleaving in a different order from the original order and transmits control information data added to every predetermined length of an error correction encoded digital information signal. hun) A panzer memory for storing zero-file information data, a circuit for performing dinterleaving to restore the order of the received digital information signals, and a circuit for detecting and correcting errors in the dinterleaved digital information signals. 1. A data transmission device comprising a circuit, and detects an error in control information data stored in the buffer memory based on the result of the error detection.