JPH04245819A - Information signal transmission equipment provided with error correcting function - Google Patents

Abstract

PURPOSE:To improve transmitting efficiency by transmitting a digital information signal from a base station to plural repeater stations by adding an error correcting code bit to an identification code itself including the designated repeater station code of each repeater station as well. CONSTITUTION:Information data to be transmitted from the base station to plural repeater stations is divided into the packet unit of 23l2-bytes, and is time-base-multiplexed to the channel of the information data. The synchronizing signal SYNC of 4-bytes is added to the head of the packet, identification for the acquisition of the data is executed accordingly. The header of 24-bytes is included in the head part of a data area. In ECC arithmetic operation, the error correction of the data can not be-executed before the portion of all 2280- bytes is received. However, if the repeater station knows that the data is not related to its own station by the identification code included in the ADR of the header immediately after the reception of the header, the receiving processing of the data of remaining 2256-bytes can be omitted.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information signal transmission device having an error correction function.

0002

[Background Art] Information consisting of a base station that divides a digital information signal into packets of a predetermined amount of information, adds error correction code bits to each divided information signal, and transmits the information signal, and a plurality of relay stations that receive the information signal. A transmission device was proposed. A correction code bit for error correction is added to the end of the packet, and an identification code containing the designated relay station code of each relay station is added to the header at the beginning of the packet. ing.

[0003] At each receiving station, the identification code of the packet is
The specified relay station code in the packet is decoded to determine whether the information in the packet belongs to the local station. However, since the correction code bit is added to the end of the packet, error correction of the packet is performed after receiving the entire packet, regardless of the designated relay station code of the identification code.
All packets from the base station must be captured, which may result in poor transmission efficiency.

0004

OBJECTS OF THE INVENTION Therefore, an object of the present invention is to provide a base station that divides a digital information signal into packets of a predetermined amount of information, adds an error correction code bit to each divided information signal, and transmits the divided information signal; An object of the present invention is to provide an information transmission apparatus having high transmission efficiency, in which each of the plurality of relay stations receives only the packets transmitted to itself.

[0005]

SUMMARY OF THE INVENTION An information signal transmission apparatus according to the present invention is an information transmission apparatus comprising a base station that transmits a digital information signal and a plurality of relay stations that receive the information signal.
The base station includes dividing means for dividing the digital information signal into packets having a predetermined amount of information, and a first correction code bit for error correction and a designated relay station code for each of the relay stations in each of the packets. and means for inserting a second correction code bit into the identification code for error correction of the identification code itself, the relay station and an error correction means for correcting errors in the identification code obtained from the extraction means based on the second correction code bits. .

[0006]

[Operation of the Invention] In the information signal transmission device according to the present invention, a digital information signal is divided into packets of a predetermined amount of information from a base station to a plurality of relay stations, and an error correction code bit is added to each packet before transmission. , an error correction code bit is added to the identification code itself, which includes the designated relay station code of each relay station, and then transmitted.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described below with reference to FIGS. 1 to 16. In FIG. 1, an information signal including video and audio information is transmitted from a base station 1 to a plurality of relay stations 2 using a communication satellite 3. The relay station 2 edits these information signals and retransmits them via the cable 4 to the CATV terminal station 5. Furthermore, at the base station 1, for example, AMeDAS,
Weather information transmitted from a weather satellite 6 such as Himawari is received and weather data serving as screen information to be retransmitted from the relay station 2 to the terminal station 5 is created.

In FIG. 2, the software transmission device 1a of the base station 1 transmits an information signal containing three types of information: a video signal as image information, a PCM audio signal as audio information, and information data. be done. Information data includes retransmission schedule data, video import information, and billing messages.
This includes data such as weather conditions and the weather data mentioned above. The contents of this information data can be selected according to the purpose. This information signal is supplied to a satellite communication transmitter 1b which is a transmitting means. The satellite communication transmitter 1b modulates the uplink carrier wave to the satellite using the supplied information signal, and transmits the modulated carrier wave toward the communication satellite 3. PCM
The audio signal is a PCM signal that includes not only audio for television moving images, but also BGM for still images and other independent audio data. The system controller 1c manages a series of controls in the base station 1.

[0009] The radio waves transmitted from the base station are subjected to carrier frequency conversion in the communication satellite 3 into carrier waves for downlinks to the ground, and then transmitted back to the ground. The modulated wave transmitted from the communication satellite is transmitted to the satellite communication receiver 2 in the relay station 2.
It is demodulated at a and separated for each of the transmitted channels to obtain information signals for each channel. This information signal is stored on a rewritable recording medium (not shown)
The retransmission schedule described below is stored in the retransmitter 2b.
CATV terminal station 5 via coaxial cable 4 according to the
will be resent. A system controller 2c manages a series of controls in the relay station 2.

The system controller 1c of the base station 1 and the system controller 2c of the relay station 2 are connected by a terrestrial public line 7, and can perform bidirectional communication. In this wired line, when the base station 1 transmits a diagnostic code via the satellite line, the relay station collects the data error status history and sends it to the base station, and the error information signal sent via the satellite line is transmitted. It can be used to request that the data be sent again.

Next, the baseband signal transmitted by each channel signal will be explained. As shown in FIG. 3, code signals such as time codes and attribute codes are inserted into the vertical blanking period of the video signal in the synthesis circuit 8, and then modulated in the FM modulation circuit 9. On the other hand, PCM
Audio signal (hereinafter simply referred to as audio signal)
is supplied to the time division multiplexing circuit 10, and multiplexed with the information data divided into packets by the format processing circuit 11. Thereafter, it is modulated into a digital subcarrier signal in a four-phase digital phase modulation circuit 12.

The modulated video signal and audio signal are multiplexed in a frequency multiplexing circuit 13 to form a baseband signal of the digital subcarrier audio addition system. Furthermore, the modulation circuit 14 modulates the carrier wave (27.50 to 29.25 GHz) of the uplink to the satellite into Ka band, which is power amplified and sent out.

The format of the baseband signal is as shown in FIG. 4, the video signal has a maximum modulation frequency of 4.5M.
It is an FM modulated wave of Hz. Furthermore, a digital subcarrier system is used for audio signals and information data, and is a four-phase DPSK (digital phase keying) system using subcarriers of 5.727272 MHz. Other specifications (specs) are shown in Table 1.

[0014]

[Table 1]

As mentioned above, the information signals transmitted from the communication satellite 3 include video signals, audio signals and information data.
It is divided into three channels: Among them, there are three types of image data in the video signal channel. One of them is the nationwide network image (V), which shows all relay stations 2
is retransmitted to all CATV terminal stations 5 in real time. The second type is a still image (S1), such as a still image created based on weather information obtained from a weather satellite, which is selectively captured by a predetermined relay station. The third is a local image (LV), which is also captured at the relevant relay station.

[0016] There are also three types of audio signals in the audio signal channel, and the above-mentioned national network (A)
There are two types of audio signals: one for local images (LA), and one for BGM (B1) when transmitting still images. Since these audio signals for the national network and local images are inseparable from the images, they are transmitted simultaneously with the video signals. On the other hand, as mentioned above, the information data channel includes image and audio information, retransmission schedule data, video import information for relay stations, billing messages, and diagnostic codes.
code and other messages.

[0017] Prior to transmitting the information signal, the base station 1 sends a schedule table of the information signal to be transmitted to the relay station 2, and based on this, preparations are made at the relay station 2 for smooth reception. will be carried out. After that, as shown in the transmission, reception, and retransmission timing diagram of FIG. 5, from the base station 1,
Video capture information (C) is sent first. Each relay station stores this video capture information.

Next, information data (D) such as retransmission schedule data, voice code, weather code, etc. is sent. Next, on the video channel, a still image (S1) and local video information (L) based on the retransmission schedule data are transmitted.
V) is transmitted. The decision to capture is made based on the code signal included in the vertical blanking period of the video signal and the previously stored video capture information, and the video signal is transferred to the rewritable recording medium at the corresponding relay station 2. recorded. In FIG. 5, since the video signal (V) for the national network and its audio signal (A) are subsequently transmitted, these are retransmitted as they are to the terminal station 5 in real time.

Retransmission from the relay station 2 to the terminal station 5 is performed while reading the video signal from the rewritable recording medium according to retransmission schedule data. Normally, the still image S1 is time-axis compressed, so when it is retransmitted, it is time-axis expanded and retransmitted as a still image S2. In addition, when necessary, local images (LV) and audio (LA)
) will be resent. Also, when retransmitting the still image (S2),
BGM (B2) is sent to the audio channel to the terminal station 5. Approximately 70 types of BGM are prepared at each relay station 2, and are selected and transmitted at the appropriate time.

[0020] The video signal from the base station is sent frame by frame, but depending on the video capture information sent in advance, it is determined whether or not the frame should be captured at each relay station. I know it in advance. For example, as shown in Figure 6, if there are three relay stations, the video capture information is included in the information data and transmitted in advance, and frame V1-1 is captured at relay station [1], so the relay A capture command for storing on a rewritable recording medium is issued at station [1]. Frame V2-1 and V
Since the two frames 2-2 are captured by the relay station [2], a capture command is issued by the relay station [2]. Similarly, at relay station [3], frames V3-1,
A capture command is issued for three frames, V3-2 and V3-3.

[0021] The time code inserted in the vertical blanking period of each frame of these video signals is an 8-digit BCD code, and the hour, minute, second and frame are
It represents the frame number of the frame. Also, the attribute code is also an 8-digit BCD code, and a 2-digit weather code.
It consists of a code, a 2-digit voice code, and a 4-digit backup code.

On the other hand, the information data is divided into packets of 2312 bytes, time-base multiplexed on the information data channel, and sent. As shown in FIG. 7, a 4-byte synchronization signal SYNC is added to the beginning of the packet, and is used for identification for data capture. This SYNC is a double sync method,
The same 2-byte synchronization signals are individually different and consecutive, and it is sufficient to capture one of them to ensure data capture. SYNC followed by HEADE
There are 2024 bytes of data including the R part, a 256 byte error correction code ECC (Error Correction Code), and finally a 4 byte error detection code EDC (Error Detect Code). is added. For example, a Reed-Solomon code is used for the ECC operation for error correction, and it is possible to correct an error of 1 byte out of 16 bytes of data. That is, the presence or absence of an error is detected in the data of a column (in the vertical direction in the figure) by arithmetic operations on the data group, and the error is corrected. On the other hand, EDC calculates errors for all data in columns and rows (horizontal direction in the figure) by calculating data groups.
In addition to detecting the presence or absence of
CC correction) is also detected. Error detection using EDC has a high detection ability and is more precise than error detection using ECC. Information regarding three types of data errors: the presence or absence of an error due to ECC, the presence or absence of an error due to EDC, and the presence or absence of ECC correction is utilized as error detection data to be described later. ED without performing ECC calculation
When only error detection using C is performed, the information data area has a capacity of 2280 bytes by adding 256 bytes of ECC to 2024 bytes of data.

A 24-byte header (HEADER) is included at the beginning of the data area, and is divided into five blocks: MODE, ATT, ADR, PAGE, and spare, as shown in FIG. MODE is an identification code indicating whether or not error correction is to be performed. ATT requires 8 bytes, the first and second bytes of which represent the attributes of the information data, in the case of weather data, identification of the type of meteorological satellite 6 (AMeDAS, Himawari, Meteor, etc.), season, typhoon. , is the code for lightning, etc. In addition, in the case of audio code, the stereo audio signal,
This is an identification code for bilingual, monaural, multiplexed audio, etc. Furthermore, identification codes such as retransmission schedule data, import permission, billing messages, error diagnosis, other messages, and local image data are also included here. Furthermore, month, day, and hour data indicating the transmission time are sent in the third to eighth bytes. ADR is a designated relay station code representing the area classification and address of the relay station. Each relay station 2 can determine whether the information signal is directed to its own station or not based on the contents of this ADR. ADR consists of 4 bytes, the 2nd byte indicates the area classification of the relay station, the 4th byte indicates the address of the relay station, and if the 2nd and 4th bytes are all "0", simultaneous reporting is performed for all relay stations. show. Note that the first and third bytes are reserved for future use.

[0024] Information data has a capacity of one packet22
The information data does not necessarily fit within 80 bytes, and is often composed of multiple packets for each piece of information data with the same attribute, that is, the same type of data. Furthermore, packets of the same type are not necessarily sent consecutively, and packets of different types may be sent randomly. Therefore, the base station 1 inserts a packet identification signal into each packet. In the packet format processing circuit 11 of FIG. 9, the information data written to the buffer memory 11a is 2024 or 2.
The packet is read out in units of 280 bytes and sent to the packet dividing means 1.
1b and is divided into packets. Next, the identification signal insertion means 11c inserts a packet identification signal, for example, 4 bytes as (packet number/total number of packets) into PAGE of the header, and supplies it to the time division multiplexing circuit 10. This packet identification signal is composed of the total number of packets of the same type and each packet number within the same type. At the relay station that received the information data, based on the total number and number of packets included in this PAGE,
A plurality of packets are arranged in order of packet number, and when the total number is complete, the data can be decoded as one package. Also, the packet numbers may not be sent in the order of their order, but may be sent in a random order. In this case,
Since the total number of packets is known, the receiving relay station rearranges the packets in order of their numbers, organizes packets of the same type, and performs data processing, that is, deciphering the information. This provides a kind of scrambling effect.

The identification code contained in the header is thus very important, but in the ECC calculation shown in FIG.
Data error correction can only be performed after all 2280 bytes have been received. However, due to the identification code included in the ADR header, relay stations can receive data unrelated to their own station.
If it is determined immediately after receiving the header that the data is a data header, the reception processing for the remaining 2256 bytes of data can be omitted. Therefore, in the spare block in the header, 2
By providing a byte redundancy code and correcting errors in the header itself, the contents of the header are decoded immediately after the header is received.

Next, the flow of information signals in each channel in the relay station will be explained. In FIG. 10, a modulated wave transmitted from a communication satellite 3 is received by a satellite tuner 15, which is a receiving means, and is supplied to a descramble decoder 16. Since the base station performs scrambling processing to prevent unauthorized viewing by persons other than subscribers, the descrambling decoder 16 performs descrambling to obtain information signals. Subsequently, the signal is separated into a video signal, an audio signal, and information data and demodulated.

The FM demodulated video signal is transferred to a VDR (video disc recorder) 17 as a recording medium playing means for recording and reproducing on and from an optical disc (not shown), which is a rewritable recording medium, and a time code decoder. 18 and video selector 19. In addition, the audio signal after digital phase demodulation is sent to the VDR 17 and the audio selector 2.
0. In the time code decoder 18, the time code and attribute code inserted into the vertical blanking of the video signal are extracted, decoded, and supplied to the recording/playback controller 21. The recording/playback controller 21 issues a recording command to the VDR 17 according to these time codes and attribute codes, and the video signal frames and audio signals to be retransmitted to the terminal station 5 are transferred to the VDR 17.
Recorded in R17. On the other hand, the video signal and
The information data received and demodulated prior to the audio signal is subjected to error detection and correction, and then sent to the retransmission scheduler 22.
is stored in the memory 25 by.

In FIG. 11, the information data in units of packets supplied to the retransmission scheduler 22 is extracted by the identification code extraction circuit 22a, and the identification code of the header in the packet is extracted, and the information data is sent to the error correction circuit 22b. The identification code is subjected to error correction and supplied to the memory controller 22c. When the memory controller 22c determines that the data is the captured information data of its own station, the data of the packet following the header is written to the memory 25 based on the packet identification signal as described above. .

[0029] Regarding the rewritable recording medium and its performance device, an application filed by the applicant of the present application, Japanese Patent Application No. 2-30067
No. 2, and although a detailed explanation will be omitted here, a video signal in a predetermined format such as NTSC or PAL is converted into a digital signal, then subjected to time axis compression and converted back to an analog signal. , FM modulation and recording on an optical disc. Furthermore, as shown in FIG. 12, a PCM audio signal is inserted into the vertical blanking period VB of the video signal for multiplex recording.

Not limited to the optical disc of this embodiment, but in general, when a video signal is recorded on a recording medium and played, and the original video signal is reproduced, so-called dropouts occur due to defects such as scratches and dirt on the recording medium. Therefore, dropout compensation is normally performed using the line correlation of the video signal. However, since the dropout video signal and the video signal to compensate for it are not exactly the same, it is difficult to perform complete compensation. Therefore, in an optical disc that has recording area addresses in advance as in this embodiment, the addresses of areas where scratches and dirt exist are searched in advance, and such scratches and dirt are not detected when recording video and audio signals. Address management of the optical disc to be recorded is performed by the recording/reproducing controller 21 in FIG. 10 so as to avoid recording areas. In this method, a search mode is set before recording the information signal, and a sine wave or a duty 50 wave is applied to the entire recording area of the optical disc.
After recording a predetermined reference signal such as a % digital pulse, if a dropout occurs in the read signal obtained by playing this, the address of that area is memorized. Next, in the recording mode, the information signal is recorded while detecting the address of the recording area, and is recorded in a normal area excluding the dropout area. By adopting such a recording method, it is possible to prevent dropouts from occurring.

FIG. 13 shows a flowchart of a subroutine executed by the recording/reproducing controller 21. Main route
When a mode is selected in a button (not shown), it is determined whether or not the search mode is selected (step S1), and the search mode is selected.
If it is determined that the disk is in the
Step S2), a reference signal is recorded at all addresses in the recording area of the disk (Step S3). After being recorded, the disc is played and the recorded signals are read and reproduced (step S4). It is determined whether or not there is a dropout in the read and reproduced signal (step S5), and when it is determined that there is a dropout, the address is stored as a dropout address (step S6).
Return to main routine. On the other hand, if it is determined in step S5 that there is no dropout, the process directly returns to the main routine.

Next, when recording the actual information signal, it is determined whether or not the recording mode is selected (step S7).
If it is determined that the disc is in a mode, the disc is rotated (step S8) and information signals are recorded. When recording this information signal, the address of the recording point is detected (step S9), and it is determined whether the address is a stored dropout address (step S10). If it is determined that the address is not a dropout address, an information signal is recorded (step S1).
1) If it is determined that the address is a dropout address, the recording point of that address is skipped (step S
12) The information signal is recorded only at a recording point that is not a dropout address, and then the process returns to the main routine.

When playing an optical disk on which video and audio signals have been recorded to obtain playback signals, signal processing that is opposite to that of recording is performed to obtain the playback video and audio signals. Not even. Note that the video (V) and audio signals (A) from the nationwide network are retransmitted as they are in real time to the terminal station 5 through the relay station 2 as described above, and therefore are not recorded on the VDR 17.

[0034] Still images and BGM are sent from the relay station 2 to the terminal station 5.
Furthermore, when local video and local audio signals are retransmitted, this is done based on the retransmission schedule stored in the retransmission scheduler 22. Retransmission scheduler 22
A retransmission command is given to the recording/playback controller 21 from
A reproduction performance command is issued from the recording and reproduction controller 21 to the VDR 17. In accordance with this playback command, the video and audio signals are played back while the still image is subjected to time axis expansion and other signal processing, and the video and audio selector 1
9, 20. In the video selector 19, according to a selection command from the retransmission scheduler 22, a national network video signal, a still image or a local video signal, or an external video signal independently produced at a relay station is transmitted to a transmitter (not shown). The signal is sent to the terminal station 5 via the . Similarly, the audio selector 20 outputs an audio signal such as a national network audio signal, BGM for still images, a local audio signal, or an external audio signal. external video,
The external audio signal is incorporated together with the retransmission schedule from the base station 1 by editing work for transmitting it to the terminal station 5 via the operation unit 23.

The error detection data from the descramble decoder 15 is supplied to the diagnostic data memory 24. In FIG. 14, diagnostic data is stored in a memory 24a, and in response to a diagnostic code, which is a command to return error diagnostic information from the base station 1, a transmitter 24b sends a line connecting means 24c such as a modem. Then, it is transmitted to the base station 1 via the public telephone line 7. This diagnostic code is included in ATT, which is an information data attribute of the header format shown in FIG. In response to the diagnostic data and the request from the relay station 2, the base station 1 retransmits the correct data, and based on the diagnostic data, for example, output power up from the base station 1, Performs maintenance of the entire satellite communication system, such as repeatedly sending data.

In the above embodiment, the video capture information is sent to each relay station in advance as shown in FIG. 6, but another embodiment in which the video capture information is sent each time a video signal is transmitted is shown in FIG. This will be explained with reference to FIG. In FIG. 15, data capture Q is transmitted one frame before the video frame V1-1 for relay station [1]. Relay station [1] issues a capture command based on the Q signal and captures the V1-1 frame. At relay station [2], one frame of video frame V2-1
Q signal is sent before frame, 2 frames (V2-1, 2)
is taken in. Similarly, relay station [3] captures three frames (V3-1, 2, and 3).

The signal format of this data acquisition Q is composed of 24 bytes as shown in FIG. The first 4 bytes of SYNC are in the data format of Figures 7 and 8.
Like the mat, it is a 2-byte continuous synchronization signal, and even if the first SYNC signal is failed to be captured, synchronization can be achieved by capturing the next SYNC signal as in the above embodiment. Particularly in the case of this embodiment, since a video frame is sent immediately after the Q signal, a detection error in the Q signal is not allowed, and supplementation of the SYNC signal becomes more important. MODE consists of 2 bytes and does not specify the data intake Q, and also indicates classification with or without correction code (ECC). ATT indicates the attribute of information data. Also, EDC
is an error detection code. This Q signal is transmitted at least three times in succession before the start of the frame to be captured,
During this time, the relay station 2 is controlled to complete the recording preparation of the VDR 17. Therefore, such so-called phase
By adopting the Rousafe method, highly reliable data acquisition is possible. The 6-byte FRAM indicates the number of consecutive video frames to be captured, and the number of still image frames to be captured in minutes, seconds, and frame numbers, and only the specified number of frames are written to the VDR 17.

[0038]

As explained above, in the information signal transmission device according to the present invention, a digital information signal is divided from a base station to a plurality of relay stations into packets of a predetermined amount of information, and error correction code bits are transmitted for each packet. Add and send,
Since the identification code, which includes the designated relay station code of each relay station, is transmitted with an error correction code bit added to it, each relay station that receives the data can receive only the packets sent to it. , information can be transmitted with high transmission efficiency.

[Brief explanation of the drawing]

FIG. 1 is a diagram of a CATV system using communication satellites according to the present invention.

FIG. 2 is a schematic block diagram of an information transmission device according to the present invention.

FIG. 3 is a block diagram of the satellite communication transmitter in FIG. 2.

FIG. 4 is a format diagram of the baseband signal in FIG. 3.

FIG. 5 is a timing chart for transmitting and receiving information signals in the information transmitting device according to the present invention.

FIG. 6 is a timing chart for capturing video frames in FIG. 5;

FIG. 7 is a diagram of the format of information data in the information transmission device according to the present invention.

[Figure 8] Format of information data header in Figure 7
mat diagram.

9 is a block diagram of the format processing circuit of FIG. 3. FIG.

FIG. 10 is a block diagram of a relay station according to the present invention.

FIG. 11 is a block diagram of retransmission scheduler 22 in FIG. 10.

12 is a format diagram of a recording signal in the block diagram of FIG. 10. FIG.

[Figure 13] Recording/playback controller 2 in Figure 10
1. Flowchart to be executed.

14 is a block diagram of the diagnostic data memory 24 in FIG. 10. FIG.

FIG. 15 is a timing chart for capturing video frames according to another embodiment of the present invention.

FIG. 16 is a format diagram of the uptake Q in FIG. 12.

[Explanation of symbols]

1...Base station
2...Relay station 3...Communication satellite
5...Terminal station 17...VDR
18... Time code decoder 21... Recording/playback controller 22... Retransmission scheduler

Claims (1)

[Claims] 1. An information transmission device comprising a base station that transmits a digital information signal and a plurality of relay stations that receive the information signal, the base station transmitting the digital information signal into packets of a predetermined amount of information. a dividing means for dividing into;
An identification code including a first correction code bit for error correction and a designated relay station code indicating a designated relay station is inserted into each of the packets, and the identification code includes its own error correction code. the relay station includes means for extracting the identification code from the received packet; and means for correcting errors in the identification code obtained from the extraction means. An information signal transmission device comprising: error correction means for making corrections based on the second correction code bits.