JP2020088518A - Broadcast retransmission device and communication control method - Google Patents

Abstract

To construct an excellent system for retransmitting a broadcast wave to a subscriber's house via a network.SOLUTION: A broadcast retransmission device to be used for advanced broadband satellite digital broadcasting comprises a tuner that demodulates a received satellite broadcast wave including a frame and outputs demodulation data. A normal transmission system and a hierarchical transmission system having higher resistance are applied to the satellite broadcast wave as transmission systems for the frame. The transmission systems for the frame are switchable at a boundary of the frame. The broadcast retransmission device further comprises: a frame configuration retrieval unit that analyzes the demodulation data received from the tuner to perform retrieval processing of retrieving the beginning of the frame; a NTP detection unit that on the basis of a result of the retrieval processing, detects NTP data included in the demodulation data received from the tuner; and a switching unit that depending on a result of the detection, switches the transmission systems for the frame.SELECTED DRAWING: Figure 9

Description

The present invention relates to a broadcast retransmission device and a communication control method.

Conventionally, a technique for transmitting contents using MMTP (MPEG Media Transport Protocol) packets has been developed.

For example, the Japan Radio Industries Association, "Media transport method by MMT in digital broadcasting ARIB STD-B60 1.9 edition", March 24, 2017 (Non-patent document 1), broadcast using the MMT method. A system is disclosed.

In this broadcasting system, MMT packets containing program information such as audio information and video information are stored in the payload of IP packets. The IP packet is stored in the payload of a TLV (Type Length Value) packet.

Japan Association of Radio Industries and Businesses, "Media Transport Method by MMT in Digital Broadcasting ARIB STD-B60 1.9 Edition", March 24, 2017 Japan Radio Industry Association, "Transmission method of advanced broadband satellite digital broadcasting ARIB STD-B44 2.1 version", March 25, 2016 International Telecommunication Union Radiocommunications Sector, "Recommendation ITU-R BT.1869", March 2010, [online], [August 29, 2017 search], Internet <URL: http://www. itu. int/dms_pubrec/itu-r/rec/bt/R-REC-BT. 1869-0-201003-I! ! PDF-E. pdf〉

Advanced Broadband Satellite Digital according to the method disclosed in Japan Radio Industry Association, "Advanced Broadband Satellite Digital Broadcasting Transmission System ARIB STD-B44 2.1 version", March 25, 2016 (Non-Patent Document 2). A technique capable of constructing an excellent system for retransmitting broadcast waves such as broadcasts to the subscriber's home via a network is desired.

The present invention has been made to solve the above problems, and an object thereof is to provide a broadcast retransmitting device and communication capable of constructing an excellent system for retransmitting a broadcast wave to a subscriber's home via a network. It is to provide a control method.

(1) In order to solve the above problems, a broadcast retransmission device according to an aspect of the present invention is a broadcast retransmission device used for advanced wideband satellite digital broadcasting, and receives a satellite broadcast wave containing a frame and demodulates it. The satellite broadcast wave has a tuner for outputting demodulated data, and in the satellite broadcast wave, there are a normal transmission method and a hierarchical transmission method having a higher tolerance than the normal transmission method as the frame transmission method. The system can be switched at the boundary of the frame, and the broadcast re-transmission device further analyzes the demodulated data received from the tuner to perform a search process for searching the beginning of the frame. Section, an NTP detecting section for detecting NTP (Network Time Protocol) data included in the demodulated data received from the tuner based on a result of the search process by the frame configuration searching section, and a detection by the NTP detecting section. A switching unit that switches between the normal transmission method and the hierarchical transmission method according to the result.

(5) In order to solve the above problems, a communication control method according to an aspect of the present invention is a communication control method in a broadcast retransmission device used for advanced wideband satellite digital broadcasting, wherein the broadcast retransmission device comprises: The satellite broadcast wave includes a tuner that receives a satellite broadcast wave including a frame, demodulates the demodulated data, and outputs demodulated data. In the satellite broadcast wave, a normal transmission method is used as a transmission method of the frame, and a layer having higher tolerance than the normal transmission method. There is a transmission method, and the transmission method of the frame can be switched at the boundary of the frame, and a step of performing a search process for searching the head of the frame by analyzing the demodulated data output by the tuner And detecting the NTP data included in the output demodulated data based on the result of the search process, and switching the normal transmission method and the hierarchical transmission method according to the detection result.

The present invention can be realized not only as a broadcast retransmission device including such a characteristic processing unit, but also as a program for causing a computer to execute the steps of such characteristic processing. Further, the present invention can be realized as a semiconductor integrated circuit that realizes a part or all of the broadcast retransmission device, or can be realized as a system including the broadcast retransmission device.

According to the present invention, it is possible to construct an excellent system for retransmitting broadcast waves to the subscriber's home via the network.

FIG. 1 is a diagram showing a configuration of a broadcast retransmission system according to an embodiment of the present invention. FIG. 2 is a diagram showing an example of a protocol stack of data transmitted by broadcast waves in the broadcast retransmission system according to the embodiment of the present invention. FIG. 3 is a diagram showing an example of TLV packets transmitted by broadcast waves in the broadcast retransmission system according to the embodiment of the present invention. FIG. 4 is a diagram showing an example of frames of a stream transmitted in the broadcast retransmission system according to the embodiment of the present invention. FIG. 5 is a diagram schematically showing an example of a frame structure of a normal transmission method in the broadcast retransmission system according to the embodiment of the present invention. FIG. 6 is a diagram showing how satellite broadcast waves are received in different areas in the broadcast retransmission system according to the embodiment of the present invention. FIG. 7 is a diagram schematically showing an example of the frame structure of the hierarchical transmission system in the broadcast retransmission system according to the embodiment of the present invention. FIG. 8 is a diagram schematically showing another example of frame configurations of the normal transmission method and the hierarchical transmission method in the broadcast retransmission system according to the embodiment of the present invention. FIG. 9 is a diagram showing a configuration of a broadcast retransmission device in the broadcast retransmission system according to the embodiment of the present invention. FIG. 10 is a flowchart defining an operation procedure when the broadcast retransmission device according to the embodiment of the present invention switches the transmission method.

First, the contents of the embodiments of the present invention will be listed and described.

(1) A broadcast retransmission device according to an embodiment of the present invention is a broadcast retransmission device used for advanced broadband satellite digital broadcasting, receives a satellite broadcast wave containing a frame, demodulates it, and outputs demodulated data. A tuner is provided, and in the satellite broadcast wave, there are a normal transmission method as a transmission method of the frame, and a hierarchical transmission method having higher tolerance than the normal transmission method, and the transmission method of the frame is at a boundary of the frame. The broadcast re-transmission device is further configured to perform a search process for searching the beginning of the frame by analyzing the demodulated data received from the tuner, and the frame structure search. Based on the result of the search processing by the unit, the NTP detection unit that detects NTP (Network Time Protocol) data included in the demodulated data received from the tuner; and the normal transmission according to the detection result by the NTP detection unit. And a switching unit that switches the system and the hierarchical transmission system.

As described above, by the configuration in which the NTP data is separately detected together with the search process for searching the head of the frame, it is possible to switch between the normal transmission system and the hierarchical transmission system for the demodulated data without being limited by the performance of the search process. it can. This makes it possible to prevent data loss due to switching between the normal transmission method and the hierarchical transmission method. Therefore, it is possible to construct an excellent system for retransmitting the broadcast wave to the subscriber's home via the network.

(2) Preferably, the frame configuration search unit performs the search process by analyzing a plurality of the frames in the demodulated data received from the tuner.

As described above, in the configuration including the frame configuration search unit that requires a plurality of frames for the search process, the normal transmission method and the hierarchical transmission method can be switched for the demodulated data without being limited by the search process. It is possible to prevent frame-based data loss due to switching between the system and the hierarchical transmission system.

(3) More preferably, the broadcast retransmission device further includes a normal transmission buffer for accumulating the frame in the normal transmission method, and a hierarchical transmission buffer for accumulating the frame in the hierarchical transmission method. And the demodulated data output from the tuner are written in parallel to the normal transmission buffer and the hierarchical transmission buffer, and the switching target by the switching unit is the normal transmission buffer and the hierarchical transmission buffer. This is the read data from the buffer.

With such a configuration, it is possible to realize an appropriate hardware configuration capable of switching the data reading from each buffer using the detection result of the NTP data from the detection target frame.

(4) Preferably, the broadcast re-transmission device ensures broadcast identity.

With such a configuration, it is possible to prevent data loss due to switching between the normal transmission method and the hierarchical transmission method in the broadcast retransmission device that secures the broadcast identity.

(5) A communication control method according to an embodiment of the present invention is a communication control method in a broadcast retransmission device used for advanced wideband satellite digital broadcasting, wherein the broadcast retransmission device transmits a satellite broadcast wave including a frame. The satellite broadcast wave includes a tuner that receives and demodulates and outputs demodulated data. In the satellite broadcast wave, there are a normal transmission method as a transmission method of the frame, and a hierarchical transmission method having higher tolerance than the normal transmission method. A frame transmission method can be switched at a boundary of the frame, a step of performing a search process of searching the head of the frame by analyzing the demodulated data output by the tuner, and a result of the search process And detecting the NTP data included in the demodulated data that has been output, and switching the normal transmission method and the hierarchical transmission method according to the detection result.

As described above, by the configuration in which the NTP data is separately detected together with the search process for searching the head of the frame, it is possible to switch between the normal transmission system and the hierarchical transmission system for the demodulated data without being limited by the performance of the search process. it can. This makes it possible to prevent data loss due to switching between the normal transmission method and the hierarchical transmission method. Therefore, it is possible to construct an excellent system for retransmitting the broadcast wave to the subscriber's home via the network.

Embodiments of the present invention will be described below with reference to the drawings. It should be noted that the same or corresponding parts in the drawings are designated by the same reference numerals and the description thereof will not be repeated. Further, at least a part of the embodiments described below may be arbitrarily combined.

FIG. 1 is a diagram showing a configuration of a broadcast retransmission system according to an embodiment of the present invention.

Referring to FIG. 1, a broadcast re-transmission system 301 includes a broadcast re-transmission device 101, a subscriber network 10, and a plurality of STBs (Set Top Box) 131. The STB 131 is connected to the TV monitor 133.

The broadcast retransmission system 301 is not limited to the configuration including a plurality of STBs 131 and may have a configuration including one STB 131.

The broadcast re-transmission device 101 is provided, for example, in the station building 151 of a company that provides cable television broadcasting. The STB 131 and the TV monitor 133 are provided in the subscriber home 152.

An external antenna 81 is connected to the broadcast retransmission device 101, for example. The broadcast retransmitting device 101 receives a broadcast wave including a stream, for example.

The stream includes program information and the like. The program information includes, for example, audio information, video information, EPG (Electronic Program Guide) information, SI information (Service Information), and subtitle information.

The audio information and the video information are compressed and encrypted according to a predetermined method, for example.

The broadcast re-transmitting device 101 receives, for example, a satellite broadcast wave, which is a broadcast wave transmitted from a broadcast satellite for advanced wideband satellite digital broadcasting (not shown), for relaying a stream from a broadcast station via an external antenna 81. ..

FIG. 2 is a diagram showing an example of a protocol stack of data transmitted by broadcast waves in the broadcast retransmission system according to the embodiment of the present invention. In FIG. 2, a protocol stack using TLV packets is shown.

Referring to FIG. 2, a TLV packet is often used for transmission of 4K UHDTV (Ultra High Definition Television) or 8K UHDTV according to a standard such as 2160p or 4320p.

In the example illustrated in FIG. 2, the broadcast wave includes, for example, TMCC (Transmission & Multiplexing Configuration Control) information, AC information, and a TLV packet.

FIG. 3 is a diagram showing an example of TLV packets transmitted by broadcast waves in the broadcast retransmission system according to the embodiment of the present invention. 3 is an example of a packet having a header in which information indicating a data type is stored. Searched on October 12, 2017], Internet <URL: http://www. itu. int/dms_pubrec/itu-r/rec/bt/R-REC-BT. 1869-0-201003-I! ! PDF-E. pdf> (Non-patent document 3), the format of a TLV packet is shown.

The TLV packet includes a TLV header and a TLV payload. The TLV header includes a "start code" field in which a value of "01" is stored, a "future reservation" field, a "packet type" field, and a "length" field, and the length of these fields. Are 2 bits, 6 bits, 8 bits and 16 bits, respectively.

A value such as “0x01”, “0x02”, “0x03”, or “0xFF” is stored in the “packet type” field. Here, the numbers starting with "0x" mean that the numbers after "0x" are represented by hexadecimal numbers.

When “0x01” is stored in the “packet type” field, the TLV packet 61 includes an IPv4 packet having the total data length of the value stored in the “length” field in the TLV payload.

When “0x02” is stored in the “packet type” field, the TLV packet 62 includes an IPv6 packet having the total data length of the value stored in the “length” field in the TLV payload.

When “0x03” is stored in the “packet type” field, the TLV packet 63 includes an IP packet having the total data length of the value stored in the “length” field in the TLV payload. The compressed IP packet is, for example, an IP packet whose IP header is compressed.

When “0xFF” is stored in the “packet type” field, the TLV packet 64 includes null data that is the total data length of the value stored in the “length” field in the TLV payload. Hereinafter, a TLV packet including null data in the TLV payload is also referred to as a TLV null packet.

Referring again to FIG. 2, for example, NTP (Network Time Protocol) data for time synchronization, IP-SI data, time information, an MMT packet, or a data transmission method is stored in a UDP (User Datagram Protocol)/IP packet. To be done. Video information, audio information, MMT-SI data, and other information are stored in the MMT packet.

The TLV packets 61 to 63 (hereinafter, also referred to as TLV information packets) store such UDP/IP packets.

In addition, it is specified that the satellite broadcast wave includes one or a plurality of streams forming a frame. A plurality of streams can be efficiently transmitted by transmitting the stream using the satellite broadcast wave while maintaining the frame structure.

A frame can include a plurality of streams respectively corresponding to programs of up to 16 broadcasting stations. Each stream is distinguished by using the transport stream ID included in the MMT packet in the TLV packet, for example.

FIG. 4 is a diagram showing an example of frames of a stream transmitted in the broadcast retransmission system according to the embodiment of the present invention. FIG. 4 shows a structure of a frame according to the standard described in Non-Patent Document 2.

FIG. 4 shows a case where one frame includes three streams respectively corresponding to programs of three broadcasting stations.

Referring to FIG. 4, the frame is composed of 120 slots. That is, for example, 40 slots are assigned to one stream. For example, the stream ST1 with the stream number SN1 is assigned slots 1 to 40, the stream ST2 with the stream number SN2 is assigned slots 41 to 80, and the stream ST3 with the stream number SN3 is assigned from slot 81. Slots 120 are assigned.

The stream is divided and stored in the slots. Further, the length of time of the frame is 33 milliseconds.

The slot includes 44880-bit demodulated data and 1600-bit TMCC information in order from the beginning.

The demodulated data is composed of fields of a slot header, a main signal, a BCH code parity, a stuff bit, and an LDPC (Low Density Parity Check) code parity in order from the beginning.

The data length of the slot header is 176 bits.

The data length of the main signal is variable. One or a plurality of divided TLV packets and the like are stored in the field of the main signal.

The TLV packet includes NTP data when the TLV packet is the first TLV packet in the stream. Specifically, for example, the first TLV packet of stream ST1 includes NTP data NTP_1, the first TLV packet of stream ST2 includes NTP data NTP_2, and the first TLV packet of stream ST3 includes , NTP data NTP_3 is included.

When the demodulated data includes a TLV packet, the 16 bits from the head of the slot header indicate the head TLV instruction.

The head TLV instruction indicates the position of the head header of the first TLV packet in the main signal of each slot by the number of bytes from the head of the field of the main signal.

The data length of the BCH code parity is 192 bits. The data length of the stuff bit is 6 bits. The data length of the LDPC code parity is variable.

The TMCC information is composed of a field of basic TMCC information of fixed length of 280 bits and a field of transmission TMCC information of fixed length of 1320 bits, etc., in order from the beginning.

The field of the basic TMCC information includes, in order from the beginning, a 120-bit fixed-length synchronization signal field and a 160-bit fixed-length signal point arrangement information field.

The TMCC information is divided into a plurality of slots and stored. More specifically, the sync signal is stored over 24 slots. The signal point arrangement information is stored over 24 slots to 120 slots depending on the combination of modulation schemes.

In addition, 31480-bit information obtained by adding BCH code parity 192 bits and LDPC code parity 22066 bits to transmission 9CC-bit information of 9422 bits of 1320 bits x 7 slots and 182 bits of 8th slot is added to transmission TMCC information of 9422 bits. Stored across slots.

Referring again to FIG. 1, the broadcast re-transmission device 101 acquires program information from the broadcast wave, and transmits the broadcast wave including the acquired program information to each subscriber home 152 via the subscriber network 10. ..

The STB 131 receives, for example, the broadcast wave transmitted from the broadcast retransmission device 101 via the subscriber network 10.

Upon receiving the broadcast wave from the broadcast re-transmission device 101, the STB 131 acquires program information from the received broadcast wave, decodes audio information and video information based on the acquired program information, and decodes the audio information. And the video information is transmitted to the TV monitor 133.

The TV monitor 133 reproduces the program based on the audio information and the video information received from the STB 131.

[Hierarchical transmission]
For satellite broadcast waves for advanced wideband satellite digital broadcasting, there are a frame transmission system, a normal transmission system, and a hierarchical transmission system having higher tolerance than the normal transmission system.

FIG. 5 is a diagram schematically showing an example of a frame structure of a normal transmission method in the broadcast retransmission system according to the embodiment of the present invention.

Referring to FIG. 5, in the normal transmission method in 4K UHDTV, according to the standard described in Non-Patent Document 2, 16APSK (Amplitude and Phase Shift Keying) corresponding to programs of three broadcasting stations in order from the beginning of the frame. The stream ST1, the stream ST2 modulated with 16APSK, and the stream ST3 modulated with 16APSK are stored in the frame. The head TLV packet in the first slot of each of the streams ST1, ST2, ST3 includes NTP data NTP_1, NTP data NTP_2, and NTP data NTP_3, respectively.

For the sake of simplicity, the presence of the slot header is ignored, and the leading TLV packet in the first slot of the stream is also referred to as the beginning of the stream, and the leading TLV packet in the first slot of the frame is designated as the beginning of the frame. It may also be called.

Here, with 16APSK adopted in the normal transmission system, for example, it may be difficult for a tuner or the like to receive a satellite broadcast wave in bad weather.

FIG. 6 is a diagram showing how satellite broadcast waves are received in different areas in the broadcast retransmission system according to the embodiment of the present invention.

Referring to FIG. 6, for example, the weather in area A is fine and the weather in area B is heavy rain.

For example, a tuner (not shown) or the like provided in the area A can stably receive satellite broadcast waves according to the normal transmission method transmitted from a broadcast satellite (not shown) via the external antenna 81.

On the other hand, it is difficult for a tuner or the like (not shown) provided in the area B to stably receive the satellite broadcast wave according to the normal transmission method via the external antenna 81.

Therefore, it is conceivable to adopt a hierarchical transmission system in the case of bad weather, for example, in satellite broadcast waves. QPSK (Quadrature Phase Shift Keying) used in the hierarchical transmission system has higher noise resistance than 16APSK. Therefore, when QPSK is used, satellite broadcast waves can be received more stably in a tuner or the like during bad weather.

FIG. 7 is a diagram schematically showing an example of the frame structure of the hierarchical transmission system in the broadcast retransmission system according to the embodiment of the present invention.

Referring to FIG. 7, in the hierarchical transmission method in 4K UHDTV, according to the standard described in Non-Patent Document 2, modulation is performed with 16APSK of stream ST1 corresponding to programs of three broadcasting stations in order from the beginning of the frame. The other 35 slots (hereinafter, also referred to as higher layer stream), the stream ST2 modulated by 16APSK, the stream ST3 modulated by 16APSK, and the other 5 slots modulated by QPSK of the stream ST1 (hereinafter, low stream). (Also referred to as a hierarchical stream) is stored in the frame. The heads of the streams ST2 and ST3 include NTP data NTP_2 and NTP data NTP_3, respectively. NTP data NTP_1 is included at the beginning of the low-level stream.

The high-level stream includes, for example, video information of the program information included in the stream ST1, but does not include audio information and NTP data.

The lower layer stream includes the same program information as the higher layer stream. More specifically, since the amount of information that can be transmitted is small, the low-level stream includes video information of video of lower quality or reduced size than the video information included in the high-level stream. In addition, the low-level stream includes audio information, NTP data, and the like among the program information included in the stream ST1.

The transmission method of frames can be switched at frame boundaries. More specifically, when the weather changes to heavy rain in the area B shown in FIG. 6, the business operator who provides the advanced wideband satellite digital broadcasting normally transmits the transmission method at the boundary of the frame of the broadcast wave to be transmitted to the broadcasting satellite. Switch from the system to the hierarchical transmission system. The broadcast wave after switching is transmitted to area A and area B via a broadcasting satellite.

As a result, in the bad weather area B, for example, the tuner or the like can stably receive the low hierarchy stream included in the satellite broadcast wave complying with the hierarchy transmission method. That is, it is possible to continue viewing the program of the advanced broadband satellite digital broadcast in the area B in bad weather.

FIG. 8 is a diagram schematically showing another example of frame configurations of the normal transmission method and the hierarchical transmission method in the broadcast retransmission system according to the embodiment of the present invention.

Referring to FIG. 8, in the normal transmission method in 8K UHDTV, stream ST1 modulated by 16APSK is stored in a frame according to the standard described in Non-Patent Document 2. The head of the stream ST1 includes NTP data NTP_1.

In the hierarchical transmission method in 8K UHDTV, 100 slots modulated by 16APSK and 20 slots modulated by QPSK in the stream ST1 are stored in the frame in order from the beginning of the frame according to the standard described in Non-Patent Document 2. It The NTP data NTP_1 is included at the head of the 20 slots modulated by QPSK.

[Task]
When retransmitting satellite broadcast waves for advanced wideband satellite digital broadcasting, it is prohibited to change the contents of the frame, that is, it is required to ensure the identity of the broadcast. It is necessary to retransmit the satellite broadcast wave while ensuring the identity of the broadcast even when switching.

However, for example, in a configuration in which the slot configuration of a frame is analyzed and the satellite broadcast wave is retransmitted, when the transmission system of the satellite broadcast wave is switched and the slot configuration is changed, reanalysis of the slot configuration is required. Therefore, the satellite broadcast wave may not be retransmitted until the analysis is completed.

In this case, the broadcast wave to be transmitted is stopped even in an originally problem-free area, and it becomes difficult to continue viewing the program of the advanced wideband satellite digital broadcast.

On the other hand, in the broadcast re-transmission system according to the embodiment of the present invention, the above problems are solved by the following configurations and operations.

[Broadcast retransmission device]
FIG. 9 is a diagram showing a configuration of a broadcast retransmission device in the broadcast retransmission system according to the embodiment of the present invention.

Referring to FIG. 9, a broadcast retransmission device 101 includes a tuner 11, an NTP detection unit 12, a stream generation unit 15, a broadcast wave generation unit 16, a clock recovery unit 17, and a VCO (Voltage-Controlled Oscillator). 18 and a frame configuration search unit 19. The stream generation unit 15 includes a switching unit 13, a normal transmission buffer 22, a hierarchical transmission buffer 23, and a clock adjustment buffer 24. The switching unit 13 has a switch 31.

The normal transmission buffer 22 stores frames in the normal transmission method. More specifically, the normal transmission buffer 22 stores, for example, an amount of data corresponding to the amount of data of a frame in the normal transmission method.

The hierarchical transmission buffer 23 stores frames in the hierarchical transmission method. More specifically, the hierarchical transmission buffer 23 stores, for example, an amount of data corresponding to the amount of data of a frame in the hierarchical transmission method.

The clock adjustment buffer 24 stores one or a plurality of frames read from the normal transmission buffer 22 or one or a plurality of frames read from the hierarchical transmission buffer 23.

The VCO 18 generates a reference clock. More specifically, the VCO 18 can generate a clock having a frequency according to the magnitude of the voltage received from the clock reproducing unit 17 in a predetermined frequency range including 33.7571 megahertz.

For example, the tuner 11 receives a satellite broadcast wave containing a frame, demodulates it, and outputs demodulated data containing part or all of the frame contained in the satellite broadcast wave.

More specifically, the tuner 11 receives a satellite broadcast wave including information about a program transmitted from a broadcast satellite for advanced wideband satellite digital broadcasting via the external antenna 81, and outputs a stream included in the received satellite broadcast wave. get.

The satellite broadcast wave in the broadcast re-transmission system 301 is, for example, the above-mentioned TLV program packet which is a TLV packet including program information, time adjustment information for time adjustment between devices using Coordinated Universal Time, and the like. And includes the MMT method. The NTP data is an example of time adjustment information.

Specifically, the tuner 11 demodulates the received satellite broadcast wave and converts it into a digital signal. Then, the tuner 11 generates demodulation data including part or all of the TLV program packet, time adjustment information, and TMCC information based on the digital signal, and the generated demodulation data is detected by the stream generation unit 15 and NTP. It is output to the unit 12 and the frame configuration search unit 19.

Further, the tuner 11 outputs, for example, a clock corresponding to the demodulated data to the stream generation unit 15 and the frame configuration search unit 19.

The tuner 11 may store some or all of the acquired streams in the storage unit 21, for example.

Further, the tuner 11 is capable of discriminating and demodulating a satellite broadcast wave complying with a normal transmission scheme and a satellite broadcast wave complying with a hierarchical transmission scheme, and does not output a discrimination result of the normal transmission scheme and the hierarchical transmission scheme.

[Frame configuration search]
The frame configuration search unit 19 analyzes the demodulated data received from the tuner 11 to perform a search process for searching the beginning of the frame.

More specifically, the frame configuration search unit 19 detects the timing of a frame included in the received satellite broadcast wave. For example, the frame configuration search unit 19 detects the frame timing based on the demodulated data received from the tuner 11.

Specifically, the frame configuration search unit 19 detects the start timing of the frame in the demodulated data based on the NTP data and the transport stream ID included in the frame in the demodulated data received from the tuner 11.

The NTP data is included in the first TLV packet included in the frame in the normal transmission method. When detecting the NTP data, the frame configuration search unit 19 acquires the transport stream ID of the TLV packet by referring to the MMT packet in the TLV packet including the detected NTP data.

Then, the frame configuration searching unit 19 indicates an MH-SDT (MH-Service Description Table: MH service description table) indicating a correspondence relationship between the transmission stream ID included in the MMT packet and the numbers of a plurality of streams included in the frame. Is used to check which stream number in the frame the acquired transmission stream ID corresponds to.

When the acquired transmission stream ID is the stream of the stream number SN1 in the frame, that is, the stream ST1, the frame configuration search unit 19 sets the slot header of the slot including the NTP data NTP_1 in the leading TLV packet of the stream ST1 to the beginning of the frame. Then, the information TI1 indicating the timing of the beginning of the frame is output to the stream generation unit 15, the clock reproduction unit 17, and the NTP detection unit 12.

Then, the frame configuration search unit 19 measures the length of time of the frame included in the demodulated data received from the tuner 11. More specifically, the frame configuration search unit 19 counts the number of clock pulses received from the tuner 11 from the head of the determined slot header.

For example, the frame configuration search unit 19 performs a search process by analyzing a plurality of frames in the demodulated data received from the tuner 11.

More specifically, when the frame configuration search unit 19 detects the beginning of the frame next to the frame that started counting, it stops counting the clock and acquires the current count value V1. Then, the frame configuration search unit 19 resets the count value of the clock to zero and restarts counting.

Then, the frame configuration search unit 19 further detects the beginning of the next frame and acquires the count value V1, and if the acquired count value V1 is the same as the previous count value V1, the frame configuration search unit 19 sets the count value V1 in the frame. The length R is determined, and the information R1 indicating that the search process has been completed is output to the stream generation unit 15.

Then, the frame configuration search unit 19 resets the clock count value to zero and restarts counting, and determines that the slot header of the next slot at the timing when the clock count value reaches the count value V1 is the head of the frame. Then, the information TI1 is output to the stream generation unit 15, the clock reproduction unit 17, and the NTP detection unit 12.

After that, the frame configuration search unit 19 resets the count value of the clock to zero and restarts the count, and each time the count value of the clock reaches the count value V1, the information TI1 is added to the stream generation unit 15, the clock reproduction unit 17, and the clock reproduction unit 17. Output to the NTP detection unit 12.

In this way, the frame configuration search unit 19 performs a search process by analyzing a plurality of temporally consecutive frames in the demodulated data from the tuner 11.

Further, after detecting the frame start timing by the search process, the frame configuration search unit 19 outputs the information TI1 indicating the frame start timing to the NTP detection unit 12 without using the NTP data at the frame start. .. As a result, the NTP detecting unit 12 can identify a slot including NTP data, which will be described later, in a frame when the transmission method is switched from the normal transmission method to the hierarchical transmission method, for example.

The frame configuration search unit 19 is configured to determine that the count value V1 is the length of a frame based on the acquired first count value V1 and second acquired count value V1, but the present invention is not limited to this. Instead, the count value V1 may be determined to be the length of the frame based on one or a plurality of count values V1 after the third, where the frame where the counting is started is the first. Specifically, for example, when the first count value V1, the second count value V1, and one or more count values V1 after the third count value match, the frame configuration searching unit 19 sets the count value V1 to the frame count. Judge that the length.

[Clock playback]
The clock reproduction unit 17 reproduces the clock included in the satellite broadcast wave based on the timing of the frame detected by the frame configuration search unit 19.

More specifically, the clock reproduction unit 17 receives the information TI1 from the frame configuration search unit 19 and starts counting the pulses of the clock received from the VCO 18.

When the clock reproducing unit 17 receives the next information TI1 from the frame configuration searching unit 19, the clock reproducing unit 17 stops counting and acquires the current count value V2. Then, the clock reproducing unit 17 resets the count value to zero and restarts counting.

The clock reproduction unit 17 determines the magnitude of the output voltage to the VCO 18 for adjusting the oscillation frequency of the VCO 18, based on the acquired count value V2.

More specifically, the clock regenerator 17 determines whether the frame is longer than 33 milliseconds by counting 1115520 clock pulses output by the VCO 18, and based on the determination result, determines the oscillation frequency of the VCO 18. Determine the magnitude of the output voltage to VCO 18 for regulation.

Specifically, for example, when the count value V2 of the acquired clock is larger than 1115520, the clock reproduction unit 17 determines the magnitude of the output voltage to the VCO 18 so that the oscillation frequency of the VCO 18 becomes smaller.

In addition, for example, when the count value V2 of the acquired clock is smaller than 1115520, the clock reproduction unit 17 determines the magnitude of the output voltage to the VCO 18 so that the oscillation frequency of the VCO 18 increases.

The clock reproduction unit 17 may count the clock pulse until the information TI1 is received a plurality of times, and adjust the oscillation frequency of the VCO 18 based on the count value.

In this way, the clock reproduction unit 17 reproduces the clock included in the satellite broadcast wave by adjusting the frequency of the clock as described above.

The VCO 18 outputs a clock having a frequency according to the magnitude of the voltage received from the clock reproduction unit 17.

[Transmission method switching]
The stream generation unit 15 generates a stream included in the received satellite broadcast wave and stores it in the normal transmission buffer 22 and the hierarchical transmission buffer 23.

For example, the stream generation unit 15 generates a stream in which the demodulated data received from the tuner 11 includes a part or all of the demodulated data.

More specifically, when the stream generation unit 15 receives demodulation data including a part of a frame, for example, demodulation data not including TMCC information, the stream generation unit 15 holds the demodulation data.

Then, the stream generation unit 15 reads, for example, part of the data of the stream stored by the tuner 11 from the storage unit 21 in the tuner 11, and combines the read part of the data with the held demodulated data. , Generate a frame containing a stream.

The stream generation unit 15 receives the first information TI1 after receiving the information R1 indicating that the search processing has been completed from the frame configuration search unit 19, and writes the generated frame to the normal transmission buffer 22 and the hierarchical transmission buffer 23. To start.

The stream generation unit 15 uses, for example, a clock included in the satellite broadcast wave, that is, a clock received from the tuner 11, to generate a symbol rate of 33.7561 Mbaud, that is, 1115520 symbols per 33 milliseconds, a modulation method of TMCC information included in the frame. The data is written in parallel to the normal transmission buffer 22 and the hierarchical transmission buffer 23 at a bit rate according to the above.

Alternatively, for example, when the stream generation unit 15 receives demodulated data including all of the frames output from the tuner 11, that is, all of the streams, the stream generation unit 15 parallelizes the frames to the normal transmission buffer 22 and the hierarchical transmission buffer 23. Write it.

[NTP data detection]
The NTP detection unit 12 detects the NTP data included in the demodulated data received from the tuner 11 based on the result of the search processing by the frame configuration search unit 19.

More specifically, the NTP detection unit 12 determines the position of the NTP data in the frame based on the demodulated data received from the tuner 11 and the information TI1 indicating the timing of the beginning of the frame received from the frame configuration search unit 19. It is determined whether it is the head of the frame.

Specifically, for example, the NTP detection unit 12 counts the number of slot headers included in the demodulated data received from the tuner 11 from receiving one information TI1 from the frame configuration searching unit 19 to receiving the next information TI1. To start.

Then, when the NTP detection unit 12 detects the first NTP data included in the demodulated data received from the tuner 11 after receiving the certain information TI1, the NTP detection unit 12 acquires the current count value V3 of the number of slot headers, The slot including the detected NTP data is specified based on the acquired count value V3.

More specifically, for example, when the acquired count value V3 is 1, the NTP detection unit 12 determines that the slot containing the detected NTP data, in this case NTP data NTP_1, is the slot 1, that is, the head of the frame. ..

Further, for example, when the acquired count value V3 is 2 or more, the NTP detection unit 12 determines that the slot including the detected NTP data is a slot other than the slot 1, that is, a slot other than the head of the frame.

Then, the NTP detection unit 12 outputs a control signal for controlling the switch 31 in the switching unit 13 to the switching unit 13.

More specifically, the NTP detection unit 12 outputs a high-level or low-level control signal to the switching unit 13 depending on whether or not the position of the NTP data in the frame is the head of the frame.

Specifically, when the position of the NTP data in the frame is the head of the frame, the NTP detection unit 12 outputs a high-level control signal to the switching unit 13, and the position of the NTP data in the frame is other than the head of the frame. If it is a slot, it outputs a low-level control signal to the switching unit 13.

As described above, by the structure in which the frame structure searching unit 19 searches the head of the frame and the NTP detecting unit 12 separately detects the NTP data, the demodulated data in the demodulated data is not limited by the execution of the searching process. It is possible to determine whether the structure of the frame conforms to the normal transmission method or the hierarchical transmission method.

The switching unit 13 switches between the normal transmission system and the hierarchical transmission system according to the detection result of the NTP detection unit 12.

For example, the switching target of the switching unit 13 is the read data from the normal transmission buffer 22 and the hierarchical transmission buffer 23.

More specifically, the switch 31 in the switching unit 13 is connected between the normal transmission buffer 22 and the clock adjustment buffer 24 and between the hierarchical transmission buffer 23 and the clock adjustment buffer 24.

The switch 31 switches whether to connect the clock adjustment buffer 24 to the normal transmission buffer 22 or to the hierarchical transmission buffer 23 according to the control signal received from the NTP detection unit 12.

Specifically, for example, the switch 31 connects the clock adjustment buffer 24 and the normal transmission buffer 22 when receiving a high level control signal from the NTP detection unit 12.

As a result, the frame accumulated in the normal transmission buffer 22 is output to the clock adjustment buffer 24.

More specifically, the stream generation unit 15 reads the frame accumulated in the normal transmission buffer 22 using the clock included in the satellite broadcast wave, that is, the clock received from the tuner 11, and the read frame to the switch 31. It is output to and accumulated in the clock adjusting buffer 24.

Further, the switch 31 connects the clock adjustment buffer 24 and the hierarchical transmission buffer 23 when receiving a low level control signal from the NTP detection unit 12, for example.

As a result, the frames accumulated in the hierarchical transmission buffer 23 are output to the clock adjustment buffer 24.

More specifically, the stream generation unit 15 uses the clock included in the satellite broadcast wave, that is, the clock received from the tuner 11 to read the frame accumulated in the hierarchical transmission buffer 23, and the read frame to the switch 31. It is output to and accumulated in the clock adjusting buffer 24.

If the frame structure search unit 19 re-searches the beginning of a frame when the transmission method is switched from the normal transmission method to the hierarchical transmission method, the normal transmission buffer 22 and the hierarchy are used until the re-search is completed. Since a frame cannot be written in the transmission buffer 23, data loss occurs.

On the other hand, the configuration in which the NTP detection unit 12 specifies the slot containing the NTP data for each frame and controls the switch 31 is controlled by the buffers corresponding to the frame in the normal transmission system and the frame in the hierarchical transmission system, respectively. Since data corresponding to the transmission method can be read out for each frame, loss of data can be prevented.

[Generation of retransmission credit broadcast wave]
The broadcast wave generation unit 16 modulates the frame read from the clock adjustment buffer 24 and generates a retransmission credit broadcast wave.

More specifically, the broadcast wave generation unit 16 uses the clock received from the VCO 18, that is, the clock reproduced by the clock reproduction unit 17, for example, according to the transmission TMCC information included in the frame read from the clock adjustment buffer 24, Modulation processing of the frame is performed.

Then, the broadcast wave generation unit 16 converts the frequency of the modulated frame into a frequency corresponding to, for example, the subscriber network 10 to generate a retransmission credit broadcast wave.

As a result, the broadcast wave generation unit 16 is a retransmission credit broadcast wave that follows the timing of the clock having the same frequency as the transmission clock frequency of the frame included in the satellite broadcast wave, and has the same frame configuration as the frame included in the satellite broadcast wave. A broadcast wave for retransmission can be generated. That is, the broadcast retransmitting device 101 ensures the broadcast identity.

Then, the broadcast wave generation unit 16 transmits the generated retransmission credit broadcast wave to each subscriber home 152 via the subscriber network 10, for example.

[Operation flow]
Each device in the broadcast retransmission system 301 includes a computer including a memory, and an arithmetic processing unit such as a CPU in the computer reads and executes a program including some or all of the steps of the following flowchart from the memory. To do. The programs of these plural devices can be installed from the outside. The programs of these plural devices are distributed in a state of being stored in a recording medium.

FIG. 10 is a flowchart defining an operation procedure when the broadcast retransmission device according to the embodiment of the present invention switches the transmission method.

Referring to FIG. 10, first, tuner 11 in broadcast retransmission device 101 receives and demodulates a satellite broadcast wave including a frame transmitted from a broadcast satellite for advanced wideband satellite digital broadcasting, and partially or entirely of the frame. The demodulated data including is output (step S101).

Next, when the head of the frame included in the demodulated data output from the tuner 11 is not detected (NO in step S102), the broadcast re-transmission device 101 analyzes the demodulated data to detect the head of the frame. A search process for searching is performed (step S103). Then, the tuner 11 in the broadcast re-transmitting device 101 outputs demodulation data including the next frame included in the satellite broadcast wave transmitted from the broadcasting satellite for advanced wideband satellite digital broadcasting, in parallel with the search processing (step). S101).

On the other hand, when the head of the frame included in the demodulated data output from the tuner 11 has been detected (YES in step S102), the broadcast re-transmission device 101 sends the demodulated data to the normal transmission buffer 22 and the hierarchical transmission buffer. 23 (step S104).

Next, the broadcast re-transmission device 101 detects the NTP data included in the demodulated data based on the result of the search process (step S105).

Next, the broadcast retransmission apparatus 101 switches between the normal transmission method and the hierarchical transmission method according to the detection result (step S106).

When the broadcast retransmitting device 101 determines that the position of the detected NTP data is at the beginning of the frame (YES in step S106), it controls the switch 31 so that the frame is output from the normal transmission buffer 22 (step). S107).

Next, the broadcast re-transmission device 101 modulates the frame output from the normal transmission buffer 22 to generate a retransmission credit broadcast wave according to the normal transmission method (step S108).

Next, the broadcast retransmission device 101 transmits the generated retransmission credit broadcast wave to each subscriber home 152 via the subscriber network 10 (step S109).

On the other hand, when the broadcast retransmitting device 101 determines that the detected position of the NTP data is in a slot other than the beginning of the frame (NO in step S106), the switch 31 outputs the frame from the hierarchical transmission buffer 23. Is controlled (step S110).

Next, the broadcast re-transmission device 101 modulates the frame output from the hierarchical transmission buffer 23 to generate a retransmission credit broadcast wave according to the hierarchical transmission method (step S111).

Next, the broadcast re-transmission device 101 transmits the generated retransmission credit broadcast wave to each subscriber home 152, for example, via the subscriber network 10 (step S109). Then, the tuner 11 in the broadcast re-transmitting device 101 outputs demodulated data including the next frame included in the satellite broadcast wave transmitted from the broadcast satellite for advanced wideband satellite digital broadcasting (step S101).

In the broadcast retransmission device according to the embodiment of the present invention, the switching unit 13 is configured to have the switch 31, but the configuration is not limited to this. The switching unit 13 may not have the switch 31. In this case, the stream generation unit 15 further includes, for example, a buffer that stores one or a plurality of frames according to the normal transmission method and a buffer that stores one or a plurality of frames according to the hierarchical transmission method. Then, the NTP detection unit 12 outputs the above control signal to the broadcast wave generation unit 16 that functions as a switching unit. The broadcast wave generation unit 16 selects which of the two buffers to read the frame according to the control signal received from the NTP detection unit 12.

Further, in the broadcast retransmission system according to the embodiment of the present invention, the modulation schemes of the low-layer stream and the high-layer stream are different in the hierarchical transmission method, but the present invention is not limited to this. For example, the low-layer stream and the high-layer stream may have the same modulation scheme and different error correction schemes such as convolutional coding rates, or both.

Further, although the broadcast retransmission system according to the embodiment of the present invention is configured to adopt the normal transmission method and the hierarchical transmission method, the present invention is not limited to this. The broadcast retransmission system 301 may have a configuration in which another transmission system is adopted in addition to the normal transmission system and the hierarchical transmission system.

Further, in the broadcast retransmission system according to the embodiment of the present invention, the frame configuration search unit 19 is configured to perform a search process by analyzing a plurality of frames, but the configuration is not limited to this. The frame configuration search unit 19 may be configured to perform a search process by analyzing one frame. More specifically, the frame configuration search unit 19 may determine that the first count value V1 acquired is the length of the frame without comparing it with the count value V1 acquired next, for example.

By the way, there is a demand for a technology capable of constructing an excellent system for retransmitting broadcast waves such as advanced broadband satellite digital broadcasting to subscribers' homes via a network.

Therefore, in the broadcast retransmission device according to the embodiment of the present invention, tuner 11 receives a satellite broadcast wave containing a frame, demodulates it, and outputs demodulated data. In satellite broadcast waves, there are a normal transmission method and a hierarchical transmission method having a higher tolerance than the normal transmission method as a frame transmission method, and the frame transmission method can be switched at a frame boundary. The frame configuration search unit 19 analyzes the demodulated data received from the tuner 11 to perform a search process for searching the beginning of the frame. The NTP detection unit 12 detects the NTP data included in the demodulated data received from the tuner 11 based on the result of the search processing by the frame configuration search unit 19. The switching unit 13 switches between the normal transmission system and the hierarchical transmission system according to the detection result of the NTP detection unit 12.

As described above, by the configuration in which the NTP data is separately detected together with the search process for searching the head of the frame, it is possible to switch between the normal transmission system and the hierarchical transmission system for the demodulated data without being limited by the performance of the search process. it can. This makes it possible to prevent data loss due to switching between the normal transmission method and the hierarchical transmission method.

Therefore, the broadcast retransmission device according to the embodiment of the present invention can construct an excellent system for retransmitting broadcast waves to the subscriber's home via the network.

Further, in the broadcast retransmission device according to the embodiment of the present invention, frame configuration search unit 19 performs a search process by analyzing a plurality of frames in the demodulated data received from tuner 11.

As described above, in the configuration including the frame configuration search unit 19 that requires a plurality of frames for the search processing, the normal transmission method and the hierarchical transmission method can be switched for demodulated data without being limited by the search processing. It is possible to prevent data loss in frame units due to switching between the transmission method and the hierarchical transmission method.

Further, in the broadcast retransmission device according to the embodiment of the present invention, a normal transmission buffer 22 for accumulating frames in the normal transmission method and a hierarchical transmission buffer 23 for accumulating frames in the hierarchical transmission method are further provided. With. The demodulated data output from the tuner 11 is written in the normal transmission buffer 22 and the hierarchical transmission buffer 23 in parallel. The target to be switched by the switching unit 13 is the read data from the normal transmission buffer 22 and the hierarchical transmission buffer 23.

With such a configuration, it is possible to realize an appropriate hardware configuration capable of switching the data reading from each buffer using the detection result of the NTP data from the detection target frame.

Also, with the broadcast re-transmission apparatus according to the embodiment of the present invention, broadcast identity is ensured.

With such a configuration, it is possible to prevent data loss due to switching between the normal transmission method and the hierarchical transmission method in the broadcast re-transmission device 101 that secures the broadcast identity.

Further, in the communication control method in the broadcast retransmission device according to the embodiment of the present invention, first, the demodulated data output by the tuner 11 is analyzed to perform a search process for searching the beginning of the frame. Next, NTP data included in the output demodulated data is detected based on the result of the search process. Next, the normal transmission method and the hierarchical transmission method are switched according to the detection result.

As described above, by the configuration in which the NTP data is separately detected together with the search process for searching the head of the frame, it is possible to switch between the normal transmission system and the hierarchical transmission system for the demodulated data without being limited by the performance of the search process. it can. This makes it possible to prevent data loss due to switching between the normal transmission method and the hierarchical transmission method.

Therefore, the communication control method according to the embodiment of the present invention can construct an excellent system for retransmitting broadcast waves to the subscriber's home via the network.

It should be considered that the above-described embodiments are exemplifications in all respects and are not restrictive. The scope of the present invention is shown not by the above description but by the claims, and is intended to include meanings equivalent to the claims and all modifications within the scope.

The above description includes the following additional features.
[Appendix 1]
A broadcasting retransmitting device used for advanced broadband satellite digital broadcasting,
It has a tuner that receives satellite broadcast waves including frames, demodulates them, and outputs demodulated data.
In the satellite broadcast wave, there are a normal transmission method and a hierarchical transmission method having higher tolerance than the normal transmission method as a transmission method of the frame, and the transmission method of the frame can be switched at the boundary of the frame. Yes,
The broadcast retransmission device further includes
A frame configuration search unit that performs a search process for searching the beginning of the frame by analyzing the demodulated data received from the tuner;
An NTP detection unit that detects NTP data included in the demodulated data received from the tuner based on a result of the search processing by the frame configuration search unit;
A switching unit that switches between the normal transmission system and the hierarchical transmission system according to the detection result of the NTP detection unit;
A normal transmission buffer for accumulating an amount of data according to the data amount of the frame in the normal transmission method,
A hierarchical transmission buffer for accumulating an amount of data according to the amount of data of the frame in the hierarchical transmission system,
The tuner is capable of discriminating and demodulating the satellite broadcast wave of the normal transmission scheme and the satellite broadcast wave of the hierarchical transmission scheme, and does not output the determination result of the satellite broadcast wave and the hierarchical transmission scheme,
The frame configuration search unit performs the search process based on the NTP data and program information included in the frame,
The broadcast retransmission device, wherein the frame configuration search unit performs the search process by analyzing a plurality of temporally consecutive frames in the demodulated data received from the tuner.

10 Subscriber Network 11 Tuner 12 NTP Detection Section 13 Switching Section 15 Stream Generation Section 16 Broadcast Wave Generation Section 17 Clock Recovery Section 18 VCO
19 Frame Configuration Search Unit 21 Storage Unit 22 Normal Transmission Buffer 23 Hierarchical Transmission Buffer 24 Clock Adjustment Buffer 31 Switch 81 External Antenna 101 Broadcast Retransmission Device 131 STB
133 TV monitor 151 Station building 152 Subscriber house

Claims (5)

A broadcasting retransmitting device used for advanced broadband satellite digital broadcasting,
It is equipped with a tuner that receives satellite broadcast waves including frames, demodulates them, and outputs demodulated data.
In the satellite broadcast wave, there are a normal transmission method and a hierarchical transmission method having higher tolerance than the normal transmission method as a transmission method of the frame, and the transmission method of the frame can be switched at the boundary of the frame. Yes,
The broadcast retransmission device further includes
A frame configuration search unit that performs a search process for searching the beginning of the frame by analyzing the demodulated data received from the tuner;
An NTP detection unit for detecting NTP (Network Time Protocol) data included in the demodulated data received from the tuner, based on a result of the search process by the frame configuration search unit;
A broadcast retransmission device comprising: a switching unit that switches between the normal transmission method and the hierarchical transmission method according to the detection result of the NTP detection unit. The broadcast retransmission device according to claim 1, wherein the frame configuration search unit performs the search process by analyzing a plurality of the frames in the demodulated data received from the tuner. The broadcast retransmission device further includes
A normal transmission buffer for accumulating the frame in the normal transmission method,
A hierarchical transmission buffer for accumulating the frame in the hierarchical transmission system,
The demodulated data output from the tuner is written in parallel to the normal transmission buffer and the hierarchical transmission buffer,
The broadcast retransmission device according to claim 1 or 2, wherein the switching target by the switching unit is read data from the normal transmission buffer and the hierarchical transmission buffer. The broadcast retransmission device according to any one of claims 1 to 3, wherein broadcast identity is ensured in the broadcast retransmission device. A communication control method in a broadcast retransmission device used for advanced broadband satellite digital broadcasting, comprising:
The broadcast retransmitting device includes a tuner that receives and demodulates a satellite broadcast wave including a frame, and outputs demodulated data.
In the satellite broadcast wave, there are a normal transmission method and a hierarchical transmission method having higher tolerance than the normal transmission method as a transmission method of the frame, and the transmission method of the frame can be switched at the boundary of the frame. Yes,
Performing a search process for searching the beginning of the frame by analyzing the demodulated data output by the tuner,
Detecting NTP data included in the output demodulated data based on the result of the search process;
Switching the normal transmission method and the hierarchical transmission method according to a detection result.

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