KR100262947B1 - Network synchronous apparatus capable of providing satellite broadcasting satellite communication system - Google Patents

Abstract

PURPOSE: A network synchronous device of a multimedia satellite communication system having a satellite broadcasting supplying function is provided to make a central station deliver PCR(Program Clock Reference) data, and to make each set top box decide an inserting number of a broadcasting TS packet on the basis of an OPCR(Original Program Clock Reference) and the PCR data, to compensate a network synchronization. CONSTITUTION: A central station comprises as follows. A frequency generator(17) generates predetermined frequency signals. A PCR(Program Clock Reference) generator(18) counts the frequency signals and outputs counted value data. A TS packet generator(16) generates transmission data relating to set top boxes as a TS packet to output the transmission data, and registers the counted value data in the TS packet as a PCR value and an OPCR(Original Program Clock Reference) value, when the number of transmission times of the TS packet becomes a predetermined value. A multiplexer(20) delivers a TS packet of a broadcasting signal relating to the TS packet outputted from the TS packet generator(16), and adds a delay time by the inserted broadcasting signal to the PCR value, then registers a result value in the TS packet as a new PCR value. Each set top box comprises as follows. A demultiplexer receives the TS packet. A transmission timing generator generates a transmission timing signal of data for being transmitted to the central station. A transmission frame generator outputs a data frame for being transmitted to the central station. A controller calculates an inserting number of a broadcasting TS packet on the basis of the PCR value and the OPCR value of the received TS packet, and controls the transmission timing generator according to a calculated result.

Description

Network Synchronizer of Multimedia Satellite Communication System with Satellite Broadcasting Function

The present invention relates to a multimedia satellite communication system that is designed to match a synchronizer between set-top boxes using a PCR (Program Clock Reference) value, and in particular, to compensate for a network error generated by the insertion of a TS packet for satellite broadcasting. The present invention relates to a network synchronizer of a multimedia satellite communication system having a satellite broadcasting providing function.

At present, with the rapid development of wireless communication technology, a wireless communication system that enables a subscriber to execute voice and data communication with a counterpart through a wireless network rather than a conventional wired network is rapidly spreading. Accordingly, mobile communication systems or personal communication systems that allow communication subscribers to perform communication while moving are widely used, and communication devices of general households can be transferred to existing PSTN through WLL (Wireless Local Loop) system or satellite communication system. Connections with public switched telephone networks are also becoming more common.

In particular, in the case of a satellite communication system, there is an advantage in that it is possible to enable ultra-long distance communication such as communication between countries without providing a separate communication line. Therefore, a satellite broadcasting system has already been developed and spread to take advantage of such satellite communication system to directly receive satellite broadcasting in a general home through a set top box, etc. There is also a rapid research on a system for executing satellite communication through a device.

On the other hand, with the recent establishment of a communication method based on TCP / IP (Transport control protocol / Internet protocol), a global Internet network has been established. In satellite communication systems, the Internet service can be provided to the subscribers. The research on the multimedia satellite communication system that has been made possible is in earnest.

Accordingly, the present applicant has developed and applied for a multimedia satellite communication system that enables a subscriber to access the Internet through satellite communication, and also can receive a large amount of image data at high speed through such an Internet connection.

1 is a system configuration diagram showing the configuration of a multimedia satellite communication system filed by the present applicant.

In FIG. 1, reference numeral 1 denotes a central station connected to the Internet, which provides various multimedia services to terminal stations, and performs overall network operation management and control functions. In addition, reference numeral 3 is a terminal station antenna, 4 is a set top box as a terminal station providing multimedia services to a general subscriber, 5 is a personal computer as a terminal for a user to perform multimedia communication, and 6 is a satellite. to be.

In the above system, in the case of a forward link transmitted from the central station 1 to the set top box 4, a large amount of messages can be transmitted through the TDM method, and the set top box 4 to the central station 1 are transmitted. In the case of transmitting Return Link, a synchronous Code Division Multiple Access (CDMA) scheme is used to accommodate a large number of subscribers so that multimedia data can be transmitted to a large number of subscribers at high speed.

However, in the above-described multimedia satellite communication system, since the return link from the set top box 4 to the central station 1 is synchronous, in particular, the synchronization between the set top boxes 4 is very important. In this case, it is necessary to match the transmission time with other set-top boxes 4 in transmitting predetermined data to the central station 1.

Accordingly, the present applicant has applied for the network synchronizer of the multimedia satellite communication system through a patent application of the same applicant as the present application. In the above-described invention, the central station transmits predetermined PCR data for every predetermined TS packet and transmits it to the set-top box. In this case, the data transmission timing is set based on the PCR data received from the central station.

However, if satellite broadcasting is provided through the above-described satellite communication system, the MPEG-2 TS packet of the broadcast signal is inserted into a normal TS packet so that a predetermined delay time occurs in the value of the PCR data. Falling things can happen.

Accordingly, the present invention was created in view of the above circumstances, and a network of a multimedia satellite communication system having a satellite broadcasting providing function for easily matching data transmission time between set-top boxes even when transmitting a satellite broadcasting signal. The purpose is to provide a synchronization device.

1 is a system schematic diagram for explaining the outline of a general multimedia satellite communication system.

2 is a block diagram showing the configuration of a transmission data processing apparatus of a central station according to the present invention.

3 is a diagram showing the structure of a TS packet transmitted from a central station.

Figure 4 is a block diagram showing the configuration of a set-top box according to the present invention.

* Explanation of symbols for main parts of the drawings

1: central station 2, 3: antenna

4: set top box 6: satellite

16: TS packet generation unit 17: frequency generator

18: PCR generator 20: multiplexing device

In the network synchronizer of the multimedia satellite communication system with a satellite broadcasting providing function according to the present invention for realizing the above object, the central station inserts a TS packet of a broadcast signal into a TS packet for communication and transmits it to the set top box, each set top box. Is a multimedia satellite communication system configured to transmit data to a central station through a synchronous CDMA system, wherein the central station counts a frequency generating means for generating a predetermined frequency signal, and counts a frequency signal outputted from the frequency generating means and counts the count value thereof. PCR generating means for outputting data, and generating and outputting the transmission data for the set-top box as TS packets, and when the number of times of transmission of the TS packets reaches a predetermined value, the count data output from the PCR generating means as the PCR and the OPCR TS. TS packet generating means for registering the packet, and TS packet generating means. And a multiplexing means for inserting and transmitting the TS packet of the broadcast signal to the TS packet outputted from the MS packet, adding the delay time due to the insertion of the broadcast signal to the PCR value, and registering the result as a new PCR in the TS packet. The set top box comprises a demultiplexer for receiving the TS packet, a transmission timing generating means for generating a transmission timing signal of data to be transmitted to a central station according to a predetermined control signal, and a data frame to be transmitted to the central station. A transmission frame generating means for outputting a data frame generated based on the transmission timing signal, and calculating the insertion number of a broadcast TS packet based on the PCR and OPCR values of the received TS packet, and based on the transmission timing generating means It characterized in that it comprises a control means for controlling the.

의 연산처리를 실행함으로써 방송 TS패킷의 삽입수효를 판정하고, "최대 방송 TS패킷 삽입수효-방송 TS패킷 삽입수효"의 연산처리를 실행함으로써 망동기보정값을 산출하는 것을 특징으로 한다.In addition, the set top box is

It is characterized by calculating the insertion number of broadcast TS packets by executing arithmetic processing, and calculating a network synchronization correction value by executing arithmetic processing of " Maximum Broadcast TS Packet Insertion Number-Broadcast TS Packet Insertion Number ".

According to the present invention having the above configuration, the central station transmits PCR data having a variable value according to the insertion of a fixed value OPCR and broadcast TS packet, and the set-top box inserts a broadcast TS packet based on the OPCR and PCR data. By determining the number, the manipulator is corrected.

Therefore, even when the satellite broadcasting signal is transmitted to the TS packet from the central station, it is possible to synchronize transmission synchronization between each set-top box in a relatively simple manner.

Hereinafter, an embodiment according to the present invention will be described with reference to the drawings.

1 is a block diagram showing a configuration of the transmission data processing apparatus of a central station according to an embodiment of the present invention.

In the drawing, reference numeral 11 denotes an Ethernet interface for generating and outputting an IP packet based on an Ethernet frame input from an IP switch (not shown), and 12 denotes sequentially an IP packet data output through the Ethernet interface 11. The input buffer 13 to be stored determines the type of input data based on the header of the IP packet data stored in the input buffer 12, and the PS packet generation unit 15 to be described later based on the determined result. And an IP packet controller which controls the packet generation of the TS packet generation unit 16 and controls the transmission data processing apparatus based on the control data applied from the Ethernet interface 11.

In the drawing, reference numeral 14 denotes a subscriber information storage unit for storing PIDs allocated to each set top box 4, which maps the control PID and the traffic PID corresponding to the IP address of each set top box 4. To save it.

In the drawing, reference numeral 15 is a PS packet generation unit for generating a PS packet (Private Section Packet) based on data input from the IP packet controller 13, and 16 is a PS input from the PS packet generation unit 15. MPEG-2 TS packet is generated based on packet data and PID (control PID, traffic PID or information service PID) applied from the IP packet controller 16 and the traffic data stored in the input buffer 12. TS packet generation unit for outputting. In addition, the TS packet generation unit 16 counts the number of TS packets transmitted to the set-top box 4, and when the count value reaches a predetermined value, for example, 100, the PCR applied from the PCR generator 18 to be described later. OPCR (Original) and PCR data are generated based on the data and set in a predetermined area of the TS packet. When the PCR value is transmitted, the TS packet is transmitted through the information service PID so that all set top boxes 4 can receive the PCR value.

In the drawing, reference numeral 17 denotes a frequency generator for generating a frequency signal of 27 MHz, for example, and 18 denotes a PCR generator for counting the frequency signal output from the frequency generator 17 and outputting the count value data.

In the figure, reference numeral 20 denotes a TS packet input from the TS packet generation unit 16, inserts and transmits an MPEG-2 TS packet of a broadcast signal input from a broadcasting station, and inserts the broadcast signal. It is a multiplexing device that corrects PCR values of TS packets transmitted by counting the delay time generated.

That is, in the above-described configuration, the TS packet generation unit 16 generates TS packets continuously based on the PS packets input from the PS packet generation unit 15, and continuously outputs the TS packets. In this case, the PCR data applied from the PCR generator 18 is added to the predetermined field of the TS packet as PCR data and OPCR data for transmission.

3 shows a structure of a TS packet output from the TS packet generation unit 16, which has a header field of 4 bytes and a payload of 184 bytes. The header field stores a sync byte, a PID, and a continuous coefficient value.

On the other hand, when the PCR data and the OPCR data are added as described above, the TS packet generation unit 16 sets the extended field control data to, for example, "10" and then uses a predetermined byte of the payload portion as the extended header. In addition, the TS packet generation unit 16 sets the PCR and OPCR flags of the extension field to, for example, "1", and sets the coefficient data input from the PCR generator 18 for the option field to the PCR value. And OPCR value to register.

Subsequently, when the TS packet is output from the TS packet generator 16 and input to the multiplexer 20, the multiplexer 20 transmits the TS packet input from the TS packet generator 16 to the broadcast signal. The delay time is counted to correct the PCR value based on the count value. That is, when the delay time of the TS packet output from the TS packet generation unit 16 due to the insertion of the broadcast signal is "X", the PCR value of the TS packet including the PCR and OPCR data is "PCR value + X." Will be registered and printed.

The correction of the PCR value is output from the PCR generator 18 instead of the PCR value added by the TS packet generation unit 16 at the time of transmitting the TS packet to which the PCR and the OPCR are added, as indicated by the dotted line in the figure. This can be easily carried out by registering the PCR value as a new PCR.

Therefore, at this time, each set-top box 4 receives a TS packet including the corrected PCR value.

On the other hand, Figure 3 is a block diagram showing the configuration of a set-top box 4 according to the present invention.

In the drawing, reference numeral 41 denotes a frequency down-conversion and low-noise amplification of the high frequency signal transmitted from the central station 1, and a frequency up-conversion of the intermediate frequency signal output from the intermediate frequency generator 49, which will be described later. 42 is a tuner for frequency converting a high frequency signal output from the RF device 41 to output an intermediate frequency, and 43 is a QPSK for an intermediate frequency signal output from the tuner 42, that is, a central station 1. A demodulator demodulates a modulated signal.

In the drawing, reference numeral 44 denotes a demultiplexer for extracting a TS packet corresponding to the set-top box from the TS packet data output from the demodulator 44, which includes a register for storing PID information therein. PID applied from the processor 52 to be described later is stored in the register. The TS packet including the PID stored in the register is extracted from the TS packets applied from the demodulator 43 and applied to the processor 52.

In the drawing, reference numeral 45 denotes a network interface card (NIC) that performs an interface with the personal computer 5, which converts Ethernet packets applied from the processor 52 into IP packets to convert the personal computer (5). In addition to the above), the IP packet applied by the personal computer 5 is converted into an Ethernet packet and applied to the processor 52.

In the figure, reference numeral 46 denotes a serial transmission data frame based on the transmission data applied in parallel from the processor 52, and the transmission timing applied by the transmission timing generation unit 50 to be described later. A transmission frame generation unit sequentially outputs the transmission data frame in accordance with a signal. 47 is a CDMA modulation by mixing a CDMA code applied from the processor 52 with respect to transmission data output from the transmission frame generation unit 46. A CDMA channel transmitter for executing the data, 48 a modulator for modulating and outputting the data output from the CDMA channel transmitter 47, for example, QPSK, and 49 a modulator 48 based on the frequency data applied from the processor 52. Is an intermediate frequency generating unit for converting the modulated signal output from the predetermined frequency signal into a predetermined intermediate frequency signal.

In the drawing, reference numeral 50 denotes a transmission timing generator for generating a transmission timing signal for the transmission frame generator 46 under the control of the processor 50, and 51 denotes various data, in particular, from the central station 1. It is a data memory that stores the control PID, the traffic PID and the service information PID for receiving the service information (Service Information).

In addition, reference numeral 52 denotes a processor for controlling the overall operation of the set-top box 4, which converts the TS packet for the personal computer 5 received from the demultiplexer 44 into an IP packet and converts it into an IP packet. In addition to the output box, data from the personal computer 5 input from the network interface card 45 is output to the transmission frame generation unit 46 and transmitted to the central station 1.

In particular, the processor 52 determines whether PCR and OPCR are added to the TS packet currently received by reading the header of the TS packet transmitted from the central station 1, wherein the PCR and the OPCR are added. If it is determined that the predetermined timing is performed based on the PCR and OPCR values, the synchronous timing signal is generated and controlled.

That is, the processor 52 reads the PCR value and the OPCR value from the TS packet, calculates the delay time of the corresponding TS packet by executing the arithmetic processing of the PCR-OPCR, and uses this calculated value as the period of one TS packet. By dividing by the time corresponding to the number of TS packets of the embedded broadcast signal is calculated. For example, when the PCR value is 130, the OPCR value is 30, and one TS packet period is 50, the processor 52 performs two 130 broadcast signals by performing arithmetic processing (130-30) / 50. It is calculated that the TS packet is inserted.

Then, the transmission timing generation unit 50 is controlled to set the data transmission timing transmitted to the central station 1 on the basis of the obtained calculation result, where the processor 50 calculates a value of "2" as described above. When 2 is obtained, subtracting 2 from 10, which is considered as the maximum number of packet years due to the broadcast signal, sets the transmission timing at the value obtained at this time, that is, the timing at which 8 TS packets are received. That is, the transmission timing is synchronized with the TS packet reception time after the eighth time after the TS packet from which PCR and OPCR are detected.

In addition, the transmission timing control process is performed in the same manner in all the set-top boxes 4, so that even when the TS packet of the broadcast signal is inserted and transmitted to the general TS packet, the synchronism state of all the set-top boxes 4 is maintained. Will be.

On the other hand, in the above embodiment, since each set-top box 4 performs data reception based on the PID set in the demultiplexer 44, if the above-described PCR data is transmitted through a specific PID, the corresponding PID is not known. In the case of the set top box (4) can not receive the PCR data.

Therefore, when transmitting the above-described PCR data from the central station 1, it is required to send out the PIDs that can be received by all the set-top boxes 4, so that when the PCR data is sent out, for example, the information service PID is executed. It becomes preferable.

That is, in the central station 1, for example, the information service is executed every time a specific number of TS packets are transmitted. Thus, the PCR and OPCR data are sent in synchronization with the transmission time of the information service, and the set-top box 4 transmits the information service. When the information service data is input, when the PCR and OPCR data exist in a predetermined field of the TS packet, the synchronization of data transmission timing can be easily synchronized through the above-described calculation processing.

In addition, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the technical scope of the present invention.

As described above, according to the present invention, it is possible to realize a network synchronizer of a multimedia satellite communication system having a satellite broadcast providing function that enables easy data transmission time between each set-top box even when transmitting a satellite broadcast signal. do.

Claims (4)

In the multimedia satellite communication system in which the central station inserts a TS packet of a broadcast signal into a TS packet for communication and transmits it to a set top box, and each set top box transmits data to the central station through a synchronous CDMA method. The central station generates frequency output means for generating a predetermined frequency signal, PCR generating means for counting the frequency signal output from the frequency generating means, and outputs the count value data, and generates and outputs the transmission data for the set-top box as a TS packet. In addition, when the number of times of transmission of the TS packet reaches a predetermined value, the TS packet generation means for registering the count data output from the PCR generation means into the TS packet as PCR and OPCR, and the TS packet output from the TS packet generation means. And multiplexing means for inserting and transmitting the TS packet of the broadcast signal, adding the delay time due to the insertion of the broadcast signal to the PCR value, and registering the result as a new PCR in the TS packet. The set top box includes a demultiplexer for receiving the TS packet, transmission timing generating means for generating a transmission timing signal of data to be transmitted to a central station according to a predetermined control signal, transmission frame generating means for outputting a data frame to be transmitted to the central station; Multimedia with satellite broadcasting providing function comprising a control means for calculating the insertion number of the broadcast TS packet on the basis of the PCR and OPCR value of the received TS packet, and controlling the transmission timing generating means based on this Network synchronizer of satellite communication system. The method of claim 1, The central station is a network synchronizer of the multimedia satellite communication system with a satellite broadcast providing function, characterized in that the PCR data is transmitted through the information service PID. The method of claim 1, The set top box is

By determining the number of insertions of the broadcast TS packets, A network synchronizer of a multimedia satellite communication system with a satellite broadcast providing function, characterized in that a calculation for a network synchronizer is performed by executing a calculation processing of "maximum broadcast TS packet insertion number-broadcasting TS packet insertion number." The method according to claim 1 or 3, The set-top box is a multimedia satellite communication system with a satellite broadcasting providing function that sets the transmission timing for the central station from the input of the TS packet with the PCR and OPCR received from the TS packet corresponding to the correction value of the network synchronizer. , Synchronizer.

Images