JPH01116968A - Error correction system - Google Patents

Abstract

PURPOSE:To improve information protecting ability for errors by sending information continuously while shifting the multiplexing position and performing interleaving plural times, and making a majority decision on a reception side according to plural information sent which ought to be the sample. CONSTITUTION:A transmission part obtains a multiplex signal clock from the chrominance subcarrier signal of an input television video signal through a PLL circuit 2. Data received by a data receiving interface circuit 3, on the other hand, are put in packets by a packet generator 4, and error corrective encoding is performed; and a roll-off filter 5 limits the band and the data are multiplexed by a video inserter 6 to a specified video line. A reception part converts the multiplex video signal into a binary signal by using a clock obtained similarly to the transmission part, a data extractor 10 extracts a data part to obtain many successively sent data, and a majority deciding decoder 13 makes a majority decision to determine data, which is outputted 14. Consequently, the protecting ability of a transmission system and a recording system for errors is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an error correction method for multiplexing information on the vertical blanking portion of a television video signal and transmitting/receiving the multiplexed information.

[Summary of the Invention] The present invention multiplexes information into the vertical blanking portion of a television video signal and transmits the information continuously by changing the position where the information is multiplexed and performing interleaving a plurality of times. , On the receiving side, by taking a majority vote based on the transmitted multiple pieces of information that should be the same,
This improves the ability to protect information against errors that occur in the transmission or recording system.

[Prior Art] Conventionally, there is teletext broadcasting, which multiplexes and transmits information on the vertical blanking portion of a television video signal. In this teletext broadcast, the so-called BEST (
An error correction code called a H.272, 190) code is used, and has a practically sufficient error correction ability against errors in the transmission system.

However, this error correction code also prevents errors in recording systems such as VTRs (for example, bursts caused by dropouts).
It cannot be said that it has a practically sufficient correction ability for errors (errors).

[Problems to be Solved by the Invention] The error correction ability using only the conventional BEST code is practically sufficient as a protection ability against errors in the transmission system.
It cannot be said that the ability to protect against errors in the recording system is sufficient. This is because burst errors due to VTR tape dropouts, for example, often extend to an amount of information that exceeds the capabilities of the BEST code.

Therefore, the present invention makes it possible to correct errors with a relatively large amount of information such as burst errors in the recording system, and is practically sufficient to correct errors not only in the transmission system but also in the recording system. The purpose of this invention is to provide an error correction method that provides the ability to protect information.

[Means for Solving the Problems] In order to achieve the above object, the present invention continuously multiplexes data packets multiple times on a plurality of video lines in the vertical blanking portion of a television video signal according to a gate signal. and a majority decision/decoder that determines a single data packet by performing majority decision processing from a group of data packets that are multiplexed multiple times consecutively and should be the same, and performs error correction by majority decision processing. This is what we do.

[Function] In the present invention, the transmitting side performs continuous transmission while changing the multiplexing position of the information and performing interleaving multiple times, and the receiving side multiplexes multiple pieces of transmitted information that should be the same. A majority vote will be taken based on this.

[Example] Hereinafter, the present invention will be described in detail based on Examples.

FIG. 1 shows the overall configuration of an embodiment of the present invention. This embodiment is composed of a transmitting section and a receiving section. This transmitter includes a synchronous regenerator 1. PLL (Phase Lock)
ed Loop) circuit 2. Data reception interface circuit 3. Packet generator 4. Roll-off filter 5
．． It consists of a video inserter 6. The reception section also includes a synchronous regenerator 7° PLL circuit 8, a digital data regenerator 9. Data extractor 10. Line counter 11.
Data killer circuit 12. Majority decoder 13. It is composed of a data output interface circuit 14.

First, the overall operation of this embodiment will be explained.

In the transmitting section, 5.73MH2 (815MHz) is transmitted from the color subcarrier signal of the input television video signal through the PLL circuit 2.
xfsc (here, fsc: color subcarrier frequency) is obtained, and this is used as the multiplexed A8 clock. On the other hand, the data received by the data reception interface circuit 3 is packetized by the packet generator 4, and also subjected to error correction coding, band-limited by the roll-off filter 5, and then transferred to the designated video line by the video inserter 6. multiplexed by As a result, a video signal in which the data is converted to %m is obtained.

The multiplexed video signal obtained in this manner is sent to a receiving section through a transmission system or a recording system such as a VTR.

In the receiving section, 5.73MH obtained in the same manner as in the transmitting section
After the multiplexed video signal is binarized using z, the data portion is extracted by a data extractor IO to obtain multiple transmitted data. Next, the majority decision/decoder 13 determines the data by taking a majority decision from these data,
The data is output from the data output interface circuit 14.

Next, explanations will be added regarding each tapping operation of the transmitting section and the receiving section. Furthermore, a method of majority decision decoding in the receiving section will also be explained.

In the transmission section, the television video signal is sent to a synchronous regenerator 1.
is input to the video inserter 6.

A color subcarrier signal ftc is output from the synchronous regenerator 1, and this is input to the PLL circuit 2, which is 5.73 times 815.
MHz is obtained. This 5.73MIIz signal is
Used as a clock for multiplexed information.

On the other hand, data to be multiplexed is input to the packet generator N4 through the data receiving interface circuit 3. As a result, the data packet is encoded for error correction, further band-limited by the roll-off filter 5 according to the insert gate signal output from the video inserter 6, and the data packet is encoded by the video inserter 6 into the designated line of the television image. multiplexed into

The video signal in which the above data is multiplexed is sent to the synchronous regenerator 7 of the receiving section through a transmission system or a recording system. Data killer circuit 12. The data is manually input to the digital data regenerator 9. From the synchronization regenerator 7, the color subcarrier signal f le + horizontal synchronization signal fh and vertical synchronization signal fv are obtained, and f sc is the PLL signal.
In the circuit 8, fh and fv are input manually to a line counter 11.

In the PLL circuit 8, a 5.73 MHz signal is obtained similarly to the transmitter, and is used as a sampling clock for digital video signals and other purposes. The line counter 11 detects a video line in which data is multiplexed, generates a gate signal, and outputs it to the data extractor 10.

The video signal binarized by the digital data regenerator 9 is input to the data extractor 10, and only the data part is extracted. The obtained data group is input to the majority decision/decoder 13,
Desired data is obtained by decoding the error correction code and performing majority voting on the continuously transmitted data. This data is output to the outside through the data output interface circuit 14. On the other hand, the data killer circuit 12 removes only the data portion from the multiplexed video to obtain a normal video signal.

The operation of this embodiment has been described above, but the multiple transmission/majority decoding, which is a feature of the youngest son method, will be further explained.

It is well known that large burst errors occur in recording systems such as VTRs due to tape dropouts and the like. To avoid this, one embodiment of the present invention interleaves multiple lines to transmit the same data multiple times. An example of this situation is shown in FIG.

This allows errors due to dropouts to be distributed over multiple data packets, and also prevents data packets from being dropped.

On the other hand, on the receiving side, after each successively transmitted packet data is decoded, a majority decision is made between packets that should be the same (or, after a majority decision is made, decoding is performed). In this way, even if a single multiplex line is affected by a dropout, a correct data packet will be obtained if the other multiplex lines are intact. In addition, the validity of the data (
(correct or incorrect) can be detected by adding a CRC code to each data packet. FIG. 3 shows the state of this majority voting process. Further, FIG. 5 does not show an example of the format of packet data to be multiplexed.

As a second embodiment, a method will be described in which one packet data is divided and transported, and the receiving side combines the data and performs a majority vote to determine the packet data. According to this method, not only the above-mentioned effect is strengthened, but also the influence of l dropout on one packet is weakened, so that the interleaving effect is enhanced and the reliability of the system is improved. An example of data transmission using this method is shown in FIG.

In the example shown in FIG. 4, a data packet as one segment of data is divided into two, and each is interleaved twice and transported. On the receiving and receiving sides, a majority vote is taken on the data that should be the same for each part. Here, Ao is the first half of the data obtained by the majority vote from the mth line to the m+2 line, Ao is the second half of the data obtained by the majority vote from the m+3 line to the m+5 line, and the majority vote from the m+6 line to the m+8 line. The first half of the data obtained in B
, and the second half of the data obtained by majority vote from the m+9th line to the m+11th line is Bo. Then, on the receiving side, A+A'.

A combination of A+B', B+A' and B+B' is created and the validity of the data is checked using a CRC code to obtain valid data.

[Effects of the Invention] By implementing the present invention, the following effects can be obtained.

■ Even when passing through a recording system such as a VTR, the same information is interleaved and transmitted multiple times, so the VT
The influence of information loss due to drop-out of the R tape can be suppressed to a small level. Therefore, it is possible to obtain a practically sufficient protection capability against errors not only in the transmission system but also in the recording system.

■ By combining the VBL time information transmission method with the present invention, it becomes possible to control the time of data services in 1 millisecond units, making it possible to package and media synchronize data services with video. becomes possible. Similar services can be provided not only by using recording media but also by using transmission paths.

(2) Packet division and continuous transmission By adopting the 9-combination majority voting method, not only the error correction ability can be improved, but also scrambling becomes possible, and data that should be multiplexed can be kept secret. Therefore, when providing a paid service, it is advantageous from the viewpoint of system reliability and data confidentiality.

■ According to the second embodiment, the multiplex transfer/in increases, but the data transmission rate is halved, so the bandwidth of the transmission system or recording system is reduced to 2.86MHz (
f, cX415), it is also possible to record and play back on, for example, a consumer VTR.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a diagram showing an example of the relationship between data multiplexing positions and video fields in the case of three consecutive transmissions, and FIG. FIG. 4 is a diagram illustrating an example of majority decision for divided data, and FIG. 5 is a diagram illustrating an example of the format of data packets to be multiplexed. DESCRIPTION OF SYMBOLS 1... Synchronous regenerator (transmission section), 2... PLL circuit (transmission section), 3... Data reception interface circuit, 4... Packet generator, 5... Roll-off filter, 6 ...Video inserter, 7.. Synchronous regenerator (receiving section), 8.. PLL circuit (receiving section), 9.. Digital data regenerator, 10.. Data extractor, 11.. - Line counter, 12... Data killer circuit, 13... Majority decoder, 14... Data output interface circuit.

Claims (1)

[Scope of Claims] A packet generator that continuously multiplexes data packets multiple times on a plurality of video lines in a vertical blanking portion of a television video signal according to a gate signal; An error correction method characterized by comprising a majority decision/decoder that determines a single data packet from a group of data packets by performing majority decision processing, and performs error correction by majority decision processing.