JPH114221A - Data distribution system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To distribute program data for data broadcasting to slave stations from a master station and to receive same data at same timing in the plural slave stations. SOLUTION: Broadcastomg data are transmitted to the plural local stations 2-1 to 2-n, which are the slave stations, from a key station 1, which is the master station, by using a frame format and the like by a high level data link control procedure. The key station 1 does not receive a response from the local stations 2-1 to 2-n. Thus, program data for data broadcasting is distributed to the local stations 2-1 to 2-n from the key station 1 and same data can be received at same timing in the slave local stations 2-1 to 2-n.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a data distribution system, and more particularly to a data distribution system for distributing broadcast data from a key station as a master station to a plurality of local stations as slave stations.

[0002]

2. Description of the Related Art In recent years, in addition to video and audio, data used for broadcasting, such as program data, may be distributed from a key station to a local station. FIG. 7 shows a first example of a conventional distribution system.

In FIG. 1, a high-speed digital line is provided between a key station 1 and n local stations 2-1 to 2-n. The key station 1 passes program data to be distributed to the local stations 2-1 to 2-n to each CCU, and each local station transmits the program data. In this case, since the CCU controls the protocol, there is little deviation in the timing at which the program data arrives at each local station.

FIG. 8 shows a second example of a conventional distribution system. In the system shown in the figure, a branch function of a high-speed digital line is used. Therefore, only one CCU on the key station side is required.

[0005] In FIGS. 7 and 8, CC
U (Communication Control Un
it) is a line control unit, TA (Terminal Ada)
ptor) is a terminal adapter, DSU (Digit)
al Service Unit) is a digital line termination device.

[0006]

In the first conventional example of the above-mentioned distribution system, it is necessary to prepare the number of CCUs and high-speed digital lines as line control units by the number of local stations, which is costly. There is a disadvantage that.

In the second conventional example, a high-speed digital line is used, and one CCU and n local stations and HD
LC (High level Data Link C
protocol communication (communication 20), n protocol sequences (communication 20)
0-1 to 200-n), data cannot be distributed to all local stations. Therefore,
There is a disadvantage that program data cannot be simultaneously received by each local station.

In the data communication system described in Japanese Patent Application Laid-Open No. 2-47948, a communication system having a command / response communication protocol is employed. In such a communication system, the same data cannot be simultaneously delivered to a plurality of secondary stations.

In the broadcast communication system described in Japanese Patent Application Laid-Open No. Hei 6-232865, it is necessary to perform data distribution processing for the number of connected secondary stations. Therefore,
The same data cannot be received simultaneously by the other party (secondary station), and the real-time property of broadcasting cannot be satisfied.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned drawbacks of the prior art, and has as its object to distribute program data for data broadcasting from a master station to slave stations, and a plurality of slave stations each having the same data. An object of the present invention is to provide a data distribution system capable of receiving data at the same timing.

[0011]

SUMMARY OF THE INVENTION A data distribution system according to the present invention is a data distribution system for distributing broadcast data used for broadcasting, comprising: a master station for broadcasting the broadcast data; And a plurality of slave stations each receiving the broadcast data.

That is, the present system has the following configuration to solve the above-mentioned problem.

First, in order to satisfy the broadcasting property of broadcasting, it is necessary to make the program data reach the local station (secondary station) at the same time. For that purpose, it is necessary that the program data reach all the secondary stations from the key station by transmitting the program data only once. Also, since the key station and each local station are far from each other (for example, the key station is located in Tokyo and the local stations are all over Japan), a high-speed digital line is required to satisfy long-distance transmission and high-speed transmission. Must be delivered using.

Next, to distribute data to a high-speed digital line, it is necessary to use a synchronous system protocol (for example, HDLC) that satisfies the line system. However, the protocol such as HDLC is a command / response method and is not suitable for broadcasting.

Therefore, in order to solve the above problem, a branching function of a high-speed digital line is used. The high-speed digital line connected to the key station is branched by the number of local stations that distribute program data, and connected to each local station.

Further, in order to solve the above problems,
It uses an HDLC frame format, enables connection to a high-speed digital line, and does not receive a response in the frame format, thereby satisfying broadcast characteristics.

In short, the present system uses a frame format according to a high-level data link control procedure when broadcasting data is broadcast from a master station to a plurality of slave stations. Since the master station does not receive a response from the slave station, a plurality of slave stations can receive the same data at the same timing.

[0018]

Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of a data distribution system according to the present invention. In the figure,
7 and 8 are denoted by the same reference numerals, and detailed description of those portions will be omitted.

In this figure, in the present system, program data is transmitted from the CCU of the key station 1 to the high-speed digital line in the HDLC frame format. At this time, the same data is simultaneously transferred to each local station to use the branch function of the high-speed digital line. In this case, the one-way communication 100 in which the key station 1 does not receive a response. For this reason, the program data to each of the local stations 2-1 to 2-n can be simultaneously received by each local station by a single transmission process.

FIG. 2 shows an example of a data transfer format used in the present system. This frame format is a known HDLC frame format. That is, the data broadcast program data is loaded on the variable length information section 204. Then, a flag 201 (01111110), an 8-bit address 202, and an 8-bit control unit 203 are added to the front part A of the information section 204. Further, a flag check sequence part (FCS; Frame Check) is added to the rear part B of the information part 204.
Sequence) 205 and a flag 206 (0111)
1110) is added. These front part A and rear part B
Is added in the HDLC interface logic of the key station 1 as described later, and the HD of each local station is
Deleted in LC interface logic.

As described above, by using the HDLC frame format, it is possible to cope with synchronous communication on a high-speed digital line.

FIG. 3 is a block diagram showing the configuration of the CCU on the key station side. In the figure, a CCU 11 has a physical interface with a high-speed digital Y interface TA 12 as an ITU-TX. 21 compatible interface 1
1-3 are provided. In this interface 11-3, T
The data is transmitted in synchronization with A12. The CPU interface 11-1 is a CPU unit 10 that performs transmission processing.
And writes program data to the HDLC interface logic, controls data transmission, and the like. The HDLC interface logic 11-2 is
A flag, an address, a control unit and an FCS are added to the program data as shown in FIG. 2 to generate an HDLC frame format.

FIG. 4 is a block diagram showing the configuration of the CCU on the local station side. In the figure, the CCU 21 has a physical interface with the high-speed digital Y interface TA 22 as an ITU-TX. 21 corresponding interface 21-3. This interface 21-3
Synchronizes with the TA 22 to receive data. C
The PU interface 21-1 is a CPU that performs reception processing.
It manages an interface with the unit 20, reads program data from the HDLC interface logic, and controls data reception. HDLC interface logic 21-2
Deletes the flag, address, control unit, and FCS from the received data (see FIG. 2), and extracts only the program data.

Here, the program data transmission control operation in the CPU section of the key station 1 which is the master station will be described with reference to the flowchart of FIG.

In the figure, the CPU unit waits for transmission data (step 51). If there is transmission data, data is written into the HDLC interface logic (step 52). Next, the written data is transmitted (step 53). After this transmission, other processing is performed (step 54), and step 5
Return to 1.

Next, the program data reception control operation in the CPU section of each local station, which is a slave station, will be described with reference to the flowchart of FIG.

In the figure, the CPU unit waits until there is received data (step 61). If there is received data, data is read from the HDLC interface logic (step 62). Next, the read received data is stored (step 63). After this storage, another process is performed (step 64), and the process returns to step 61.

In short, the present system uses an HDLC frame format to distribute program data, does not use a command / response protocol,
The key station performs only transmission and the local station performs only reception. The transmission path uses a line branch function of a high-speed digital line. For this reason, the key station can distribute the same data to all the receiving stations (local stations) at the same timing by transmitting the program data only once in the HDLC format.

As described above, the program data of the data broadcast is
Key stations can broadcast to multiple local stations.

The timing at which program data is received at a plurality of local stations is the same at each local station, and since there is no time lag, data broadcasting can be performed without losing the character as a broadcast.

The present invention can take the following aspects in connection with the description of the claims.

(4) The data distribution system according to claim 1 or 2, wherein said transmitting means includes means for adding a flag, an address and a control unit, and a frame check sequence and a flag to said broadcast data.

(5) The data distribution according to (4), wherein each of the slave stations includes means for deleting a flag, an address and a control unit, and a frame check sequence and a flag added by the transmitting means. system.

[0035]

As described above, according to the present invention, broadcast data is transmitted from a master station to each of a plurality of slave stations using a frame format or the like according to a high-level data link control procedure. By not receiving a response, there is an effect that the data broadcast program data is distributed from the master station to a plurality of slave stations, and the plurality of slave stations can receive the same data at the same timing.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a data distribution system according to an embodiment of the present invention.

FIG. 2 is a diagram showing an example of a data transfer format.

FIG. 3 is a block diagram showing a configuration of a CCU on a key station side.

FIG. 4 is a block diagram showing a configuration of a CCU on the local station side.

FIG. 5 is a flowchart showing a program data transmission control operation in a CPU unit of a key station.

FIG. 6 is a flowchart showing a program data reception control operation in a CPU unit of each local station.

FIG. 7 is a block diagram showing a configuration of a first conventional example of a data distribution system.

FIG. 8 is a block diagram showing a configuration of a second conventional example of a data distribution system.

[Explanation of symbols]

 1 Key station 2-1 to 2-n Local station 10, 20 CPU section 11, 21 CCU 12, 22, TA for high-speed digital Y interface

Claims (3)

[Claims] 1. A data distribution system for distributing broadcast data used for broadcasting, comprising: a master station that broadcasts the broadcast data; and a plurality of slave stations each receiving the broadcast data. A data distribution system comprising: 2. The master station includes transmitting means for transmitting the broadcast data to each of the plurality of slave stations in a frame format according to a high-level data link control procedure, and the master station receives a response from the slave station. The data distribution system according to claim 1, wherein the data distribution system does not perform the operation. 3. A transmitting means for transmitting broadcast data to be used for broadcasting to a plurality of slave stations, wherein the transmitting means transmits the broadcast data to each of the plurality of slave stations in a frame format according to a high-level data link control procedure. A master station that does not receive a response from the slave station.