JP4099559B2 - Signal processing apparatus and signal processing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a signal processing apparatus and a signal processing method for converting a first digital broadcast signal having a predetermined transmission frequency on a first network into a second digital broadcast signal on the second network. About.
[0002]
[Prior art]
Conventionally, for example, a digital broadcast broadcast on an arbitrary network such as a cable TV operator receiving a digital multi-channel broadcast program supplied via a satellite and distributing it to each home using its own network A program is distributed on another network.
[0003]
In this case, since the digital broadcast data has a network information table (NIT: Network Information Table) having physical information about the transmission path, simply converting the modulation method with a modulation conversion transmission device or the like, The digital broadcast program broadcast on the first network cannot be distributed on the second network, and the transmission frequency information included in the NIT of the digital broadcast data needs to be adapted to the second network. .
[0004]
The NIT also includes program information. For example, a set top box (in-home receiving device) connected to a cable television transmission path detects the NIT and determines a predetermined value based on the program information included in the NIT. It is configured to receive a program.
[0005]
Therefore, by detecting the NIT of the digital broadcast data in the first network, changing the detected NIT to be compatible with the second network, and replacing the NIT of the digital broadcast data in the first network with the changed NIT. The digital broadcast data in the second network is obtained.
[0006]
[Problems to be solved by the invention]
By the way, when a digital broadcast program broadcast on an arbitrary network is distributed on another network, the contents described in the NIT of the digital broadcast data corresponding to each network have an important meaning as described above. If there is an error in the correspondence between the physical information of each network and the service information to be transmitted, an appropriate distribution service cannot be performed. Therefore, the first network and the second network The NIT of the digital broadcast data in the first network is replaced with the NIT of the second network in accordance with the setting information in which the correspondence with the transmission frequency with the network and the service distributed to the second network are determined.
[0007]
However, if there is a change in the content of digital broadcast data in the first network, that is, the number of transport streams to be transmitted or the service, the setting information must be created again.
[0008]
Accordingly, an object of the present invention is to provide a signal processing apparatus and a signal processing method that can automatically reflect changes in the first network to the second network.
[0009]
In addition, an object of the present invention is to provide a signal processing apparatus and a signal processing method which can automatically cope with a change in the number of transport streams transmitted from the first network. Is to provide.
[0010]
Furthermore, an object of the present invention is to provide a signal processing apparatus and signal processing that can automatically cope with a change in the number of services in digital broadcast data transmitted from the first network. It is to provide a method.
[0011]
[Means for Solving the Problems]
The present invention is a signal processing apparatus for converting a first digital broadcast signal having a predetermined transmission frequency on a first network into a second digital broadcast signal on the second network, First frequency conversion means for performing frequency conversion processing on the first digital broadcast signal to obtain a first digital modulation signal, and demodulating the first digital modulation signal supplied from the first frequency conversion means And a demodulating means for obtaining digital broadcast data, a table detecting means for detecting a network information table having physical information relating to a transmission path from the digital broadcast data supplied from the demodulating means, and detected by the table detecting means. Analyzing means for analyzing information about the first network from the network information table, and Based on the comparison means for comparing the information on the first network analyzed by the analysis means with the information on the previous first network, and the information on the first network obtained as a comparison result by the comparison means, the first A table changing means for changing the network information table of one network so as to be adapted to the second network, and a network information table for digital broadcast data supplied from the demodulating means is supplied from the table changing means. Replacing the network information table, and the second digital modulated signal by modulating the digital broadcast data in which the network information table is replaced by the table replacing means. And obtaining modulating means, characterized by comprising a second frequency conversion means for obtaining said second digital modulated signal by performing frequency conversion on the second digital broadcast signal.
[0012]
The present invention is also a signal processing method for converting a first digital broadcast signal having a predetermined transmission frequency on the first network into a second digital broadcast signal having a predetermined transmission frequency on the second network. A first frequency conversion step of performing a frequency conversion process on the first digital broadcast signal to obtain a first digital modulation signal, and a first digital modulation signal obtained in the first frequency conversion step. A demodulating step for demodulating to obtain digital broadcast data; a table detecting step for detecting a network information table having physical information relating to a transmission path from the digital broadcast data supplied from the demodulating means; and the table detecting step. The information about the first network is separated from the detected network information table. An analysis step, a comparison step for comparing information on the first network analyzed in the analysis step with information on a previous first network, and a first network obtained as a comparison result in the comparison step A table changing step for changing the network information table of the first network so as to be adapted to the second network based on the information; and a network information table of the digital broadcast data obtained in the demodulating step. Replace the network information table with the network information table obtained in the above table change step, and the digital information with the network information table replaced in the table replacement step. A modulation step of modulating broadcast data to obtain a second digital modulation signal; and a second frequency conversion step of obtaining a second digital broadcast signal by frequency-converting the second digital modulation signal. Features.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0014]
The present invention is applied to, for example, a digital CATV (cable television) system 10 using satellite digital multi-channel broadcasting having a configuration as shown in FIG. The CATV system 10 uses an antenna 11 for receiving digital broadcast signals from a plurality of transponders (satellite repeaters) of a communication satellite 20, and changes the transmission frequency and modulation method of the received digital broadcast signals for CATV. From a modulation conversion sending device 12 that generates a digital broadcast signal and sends it to the transmission line 13, and set top boxes (in-home receiving devices) 14-1 to 14-m that are receiving terminals connected to the transmission line 13 Become. In the CATV system 10, images of channel numbers selected by the set top boxes 14-1 to 14-m are displayed on the monitors 15-1 to 15-m.
[0015]
Here, the digital broadcast signal transmitted from the communication satellite 20 will be described. In this embodiment, the digital broadcast signal corresponds to a DVB (Digital Video Broadcasting) system which is a European digital broadcasting standard. FIG. 2B shows a frame structure of digital broadcast data in the DVB system, and one frame is composed of eight MPEG2 transport packets (see FIG. 2A). In this case, the synchronization byte (= 47H) in the packet is used, and the synchronization byte is inverted (= B8H) once in 8 packets to obtain frame synchronization. Note that an error correction code according to Reed-Solomon (204, 188) is added to each MPEG2 transport packet (MPEG2TS packet). The digital broadcast data shown in FIG. 2B is modulated by QPSK (Quadrature Phase Shift Keying), and then frequency-converted to 27 MHz to be a digital broadcast signal transmitted from the communication satellite 20.
[0016]
FIG. 3 shows the packet structure of an MPEG2 transport packet, and the first 4 bytes of 188 bytes form a packet header. In the packet header, a PID (Packet Identification) indicating the attribute of the individual stream (data string) of the packet is arranged. As is well known, a PES (Packetized Elementary Stream) packet whose packet structure is shown in FIG. 4 is subdivided and arranged in the payload (data portion) of the MPEG2 transport packet, and is further defined in the MPEG2 system. Tables such as PAT (Program Association Table), PMT (Program Map Table), and NIT (Network Information Table) as PSI (Program Specific Information) are also arranged in a section format.
[0017]
Here, PSI is information necessary for realizing a simple channel selection operation and program selection. PAT indicates the PID of the PMT that transmits the information of the packets constituting the program for each program number (16 bits), and FIG. 5 shows the table structure of the PAT. As the PID of the PAT itself, PID = “0” is fixedly assigned.
[0018]
The main contents of PSI will be described. The table ID indicates the type of table, and is “0x00” (hexadecimal notation) in the PAT. The TS (Transport Stream) ID identifies a stream (multiplexed encoded data) and corresponds to a transponder in the case of a satellite. The version number is added every time the contents of the table are updated. The current next indicator is used for identification when the old and new versions are transmitted simultaneously. The program number identifies each channel. The network PID indicates the PID of the NIT when the program number is “0x0000”. The program map PID indicates the PID of the PMT.
[0019]
The PMT indicates, for each program number, the PID of a packet in which a stream of video, audio, additional data, etc. constituting the program is transmitted. The PID of the PMT itself is specified by the PAT as described above. FIG. 6 shows a table structure of the PMT. The main contents not overlapping with PAT will be described. The table ID indicates the type of table and is “0x02” in the PMT. The PCR PID indicates the PID of a packet including a clock (PCR: Program Clock Reference) that serves as a reference for decoding. The stream type indicates the type of signal transmitted in the stream, such as video, audio, and additional data.
[0020]
The NIT indicates physical information on the transmission path, that is, in the satellite, the orbit of the satellite, the polarization, the frequency for each transponder, and the like. The PID of the NIT itself is specified by the PAT as described above.
[0021]
FIG. 7 shows the NIT table structure. The table ID indicates the type of the table. The network is “0x40” and the other networks are “0x41”. The section syntax indicator indicates whether the NIT is composed of a single section or a plurality of sections. The section length represents the total data length thereafter. The network ID identifies the network. In the case of a satellite, it corresponds to an individual satellite. The version number is incremented when the contents of the NIT are changed. The current next indicator indicates whether the section is currently active. The section number indicates the current section number. The last section number indicates the last number of a plurality of sections constituting one table. The network descriptor length indicates the data length of the loop immediately after this. The TS loop length indicates the data length of the TS loop existing immediately after this. The TSID is an identification code of the TS, and corresponds to one transponder (27 MHz band) in the satellite method and one channel (6 MHz band) in CATV. The original network ID represents a network ID that is the origin when a certain digital broadcast signal is retransmitted from another network. The TS descriptor length indicates the total data length of a plurality of TS descriptors described immediately after this.
[0022]
Furthermore, a TS descriptor that plays an important role as part of the NIT will be described.
[0023]
First, the satellite delivery system descriptor will be described. This descriptor is used in NIT in digital satellite broadcasting.
[0024]
FIG. 8 shows the structure of the satellite delivery system descriptor. The descriptor tag is defined by DVB and indicates the type of descriptor. In this descriptor, “0x43” is set. The frequency indicates the transmission frequency for each stream (satellite is a transponder). The orbit / west longitude / east longitude flag / polarization indicates the orbit and polarization of the satellite. The modulation / symbol rate / inner error correction coding rate indicates a specification related to the transmission method.
[0025]
Next, the cable delivery descriptor will be described. This descriptor is used in a digital CATV system.
[0026]
FIG. 9 shows the structure of the cable delivery system descriptor. The descriptor tag indicating the type of descriptor is defined by DVB and is “0x44”. The frequency indicates a transmission frequency for each stream (one channel in the cable). The FEC outer code represents the outer code used, and is normally “0010” representing Reed-Solomon (200, 188). In this satellite delivery system descriptor, the description of the same part as the satellite delivery system descriptor is omitted.
[0027]
Further, the service list descriptor will be described. This descriptor indicates the ID of the service multiplexed in the stream (1 transponder for satellite, 1 channel for CATV).
[0028]
FIG. 10 shows the structure of the service list descriptor. The descriptor tag indicating the type of descriptor is defined by DVB and is “0x41”. The service ID identifies a service. The service type indicates the contents of the service such as video, audio, and data.
[0029]
FIG. 11 shows the configuration of the modulation conversion sending device 12 in the digital CATV system 10 of FIG. The sending device 12 changes the transmission frequency, modulation method, and the like of the digital broadcast signal sent from the first to Nth transponders (satellite repeaters) of the communication satellite 20, and further, satellite delivery / delivery in the NIT. The system descriptor is replaced with a cable delivery system descriptor to generate a CATV digital broadcast signal and send it to the transmission line 13.
[0030]
The sending device 12 includes a microcomputer, and is a digital broadcasting of SHF (Super High Frequency) band sent from a control unit 31 that controls the operation of the whole device and the first to Nth transponders of the communication satellite 20. The first to Nth signal processing units 32-1 to 32-N that process the signals and generate digital broadcast signals BS1 to BSN for CATV in the VHF (Very High Frequency) band or the UHF (Ultra High Frequency) band. And an adder 33 that adds these digital broadcast signals BS1 to BSN and sends them to the transmission line 13. The control unit 31 displays the operation unit 34 for setting the reception frequency in the tuners of the signal processing units 32-1 to 32-N, the status of the sending device 12, and the like, and a liquid crystal display or the like. The display part 35 comprised by these is connected.
[0031]
The display unit 35 includes information on the transmission path of the satellite-compatible NIT processed by the control unit 31 (information in the satellite delivery system descriptor) and the broadcast service ID (information in the service list descriptor). Is displayed as information about the satellite. Also, information on the transmission path of the cable-compatible NIT generated by the control unit 31 (information in the cable delivery system descriptor) and the service ID transmitted to the cable are displayed.
[0032]
The signal processing unit 32-1 selects a digital broadcast signal transmitted from the first transponder of the communication satellite 20 from a plurality of SHF band digital broadcast signals received by the antenna 11, and outputs the digital broadcast signal to the digital broadcast signal. A tuner 41 that performs frequency conversion processing to obtain a QPSK modulated signal S1, a demodulator 42 that demodulates the QPSK modulated signal S1 to obtain a signal S2 having a DVB frame structure, and a DVB output from the demodulator 42 An ECC (Error Correction Code) decoder 43 that performs error correction on the frame-structured signal S2 and sequentially obtains MPEG2 transport packets S3 as digital broadcast data is provided.
[0033]
The signal processing unit 32-1 also includes a NIT detection circuit 44 that detects NIT from the MPEG2 transport packet S3 sequentially output from the ECC decoder 43, and a memory 45 that stores a table NITa detected by the NIT detection circuit 44. And a memory 46 for storing a table NITb obtained by changing the table NITa stored in the memory 45 so as to conform to the CATV by the control unit 31. The NIT detection circuit 44 detects NIT based on a fixed PID.
[0034]
The contents of the table NITa detected by the NIT detection circuit 44 and stored in the memory 45 are analyzed by the control unit 31. As a result of the analysis of the table NITa by the control unit 31, detailed information such as the number of satellite transponders, the transmission frequency, and the services multiplexed in the transport stream transmitted from one transponder can be obtained.
[0035]
In addition, the control unit 31 holds information on a CATV system where a distribution service is performed in advance.
[0036]
The control unit 31 stores, as setting information, which channel of the CATV the transponder with the satellite is transmitted to, which of the services multiplexed therein is distributed to the CATV, and the like. The satellite NITA is changed to the CATV NITb.
[0037]
At this time, if the number of transponders transmitted for some reason increases or decreases, the setting information held in the control unit 31 does not match, and the satellite NITa cannot be changed to the CATV NITb. End up. In such a case, the control unit 31 analyzes the NITa from the satellite again according to the procedure shown in the flowchart of FIG. 12, finds the difference from the previous setting information, and for example, the satellite − of FIG. New setting information as shown in the CATV frequency correspondence table and the distribution service setting table shown in FIG. 13B is automatically recreated.
[0038]
That is, the control unit 31 acquires the NIT (step S1), determines whether or not the version number included in the NIT has been updated (step S2), and if updated, the number of transponders It is determined whether or not has changed (step S3).
[0039]
When the number of transponders has decreased, the control unit 1 deletes the setting information related to the cable channel corresponding to the transponder that is desired to be transmitted (step S4), and deletes the setting information related to the cable channel. By updating the setting information to the state (step S5), it is prevented from being distributed to CATV. If the number of transponders has increased, a cable channel for transmitting the digital broadcast data is allocated in order to distribute the digital broadcast data transmitted from the newly increased transponder to CATV (step S6). ), New setting information is created, and NIT is changed based on the new setting information (step S7). Also, the control unit 31 controls the signal processing units 32-1 to 32-N that are reserved through the interface 47 so as to operate normally based on the setting information (step S8). If the digital broadcast data transmitted from the newly increased transponder is not distributed to CATV when the number of transponders has increased, the control unit 31 updates the setting information and changes the NIT based on this. (Step S9).
[0040]
In addition, when the number of services multiplexed in a transport stream transmitted from a certain transponder increases or decreases, the control unit 1 automatically updates the setting information in the same manner as when the number of transponders increases or decreases. Based on this, the NIT is changed.
[0041]
As described above, since the NIT table structure in the digital broadcast data related to the communication satellite 20 is as shown in FIG. 7, the table structure of the table NITa detected by the NIT detection circuit 44 is the same. In obtaining the table NITb, the control unit 31 changes the satellite delivery system descriptor in the table NITa to a cable delivery system descriptor.
[0042]
Writing to and reading from the memories 45 and 46 are controlled by the control unit 31 via the interface 47. The reception frequency of the tuner 41 described above is also controlled by the control unit 31 via the interface 47.
[0043]
Further, the signal processing unit 32-1 has an NIT replacement circuit 48 that detects NIT from the MPEG2 transport packet S3 sequentially output from the ECC decoder 43 and replaces the NIT with a table NITb stored in the memory 46. ing. The NIT replacement circuit 48 also detects NIT based on a fixed PID.
[0044]
Further, the signal processing unit 32-1 adds a Reed-Solomon (204, 188) error correction code to the MPEG2 transport packet S4 in which the NIT is replaced by the NIT replacement circuit 48, etc. ECC encoder 49 that obtains the signal S5 (see FIG. 2B), a modulator 50 that performs 64QAM (Quadrature Amplitude Modulation) modulation processing on the signal S5 having the DVB frame structure, and 64QAM modulation output from the modulator 50 A frequency converter 51 for converting the frequency of the signal to obtain a digital broadcast signal BS1 for CATV in the VHF band or UHF band.
[0045]
The signal processing units 32-2 to 32-N are respectively the tuner 41, the demodulator 42, the ECC decoder 43, the interface 47, the NIT replacement circuit 48, the ECC encoder 49, and the modulator 50 in the signal processing unit 32-1. The frequency converter 51 is provided. Then, in the NIT replacement circuit 48 of the signal processing units 32-2 to 32-N, the NIT replacement is performed by using the table NITb stored in the memory 46 of the signal processing unit 32-1, respectively. In the tuners of the signal processing units 32-2 to 32-N, the digital broadcast signals transmitted from the second to Nth transponders of the communication satellite 20 are selected from the plurality of digital broadcast signals received by the antenna 11, respectively. Then, frequency conversion processing is performed on the digital broadcast signal to obtain a QPSK modulated signal S1. The reception frequencies of the tuners of the signal processing units 32-2 to 32-N are controlled by the control unit 31 via the interface 47. Further, the frequency converter 51 of the signal processing units 32-2 to 32-N performs frequency conversion so that the transmission frequencies of the digital broadcast signals BS1 to BSN are different from each other.
[0046]
As described above, in the CATV system 10, the modulation conversion transmission device 12 detects the NITa from the MPEG2 transport packet as digital broadcast data in the satellite digital broadcast (first network) by the NIT detection circuit 44, and The control unit 31 obtains at least the transmission frequency information of the above-mentioned NITa detected by the NIT detection circuit 44 from the control unit 31, and the NITa of the MPEG2 transport packet as digital broadcast data in satellite digital broadcasting is obtained. Is replaced with NITb by the NIT replacement circuit 48 to obtain MPEG2 transport packets as digital broadcast data in CATV, so that the digital multi-channel broadcast program supplied via the communication satellite 20 is converted into CATV. It can be delivered by
[0047]
Even when the digital broadcast from the communication satellite 20 is changed for some reason, the control unit 31 analyzes the NITa detected by the NIT detection circuit 44 to read the change contents and automatically By updating the setting information, the NIT can be changed based on the new setting information, and the NIT replacement circuit 48 can replace the NITb with the new digital broadcast data to be distributed to the CATV system. .
[0048]
【The invention's effect】
As described above, according to the present invention, the network information table of the first network is analyzed, and when there is a change compared with the contents of the network information table analyzed before, the network information table is automatically The setting information is updated, the network information table is changed based on the updated setting information, and the network information table of the digital broadcast data is replaced with a new network information table of the second network. Changes in one network can be automatically reflected in the second network.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a digital CATV system to which the present invention is applied.
FIG. 2 is a diagram illustrating a frame structure of an MPEG2 transport packet and a DVB system.
FIG. 3 is a diagram illustrating a packet structure of an MPEG2 transport packet.
FIG. 4 is a diagram illustrating a packet structure of a PES packet.
FIG. 5 is a diagram showing a table structure of a program association table (PAT).
FIG. 6 is a diagram showing a table structure of a program map table (PMT).
FIG. 7 is a diagram showing a table structure of a network information table (NIT).
FIG. 8 is a diagram showing a structure of a satellite delivery system descriptor in the NIT.
FIG. 9 is a diagram showing a structure of a cable delivery system descriptor in the NIT.
FIG. 10 is a diagram illustrating a structure of a service list descriptor in the NIT.
FIG. 11 is a block diagram showing a configuration of a modulation conversion sending apparatus constituting a digital CATV system.
FIG. 12 is a flowchart showing NIT analysis and setting processing by the control unit of the modulation conversion sending apparatus;
FIG. 13 is a diagram illustrating an example of correspondence between a satellite frequency set to NIT by the control unit and a CATV frequency and contents of a distribution service.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 CATV system, 11 Antenna, 12 Modulation conversion transmission apparatus, 13 CATV transmission line, 14, 14-1-14-m set top box, 15-1-15-m monitor, 20 Communication satellite, 31 Control part , 32-1 to 32-N signal processing unit, 33 adder, 34 operation unit, 35 display unit, 41 tuner, 42 demodulator, 43 ECC decoder, 44 NIT detection circuit, 45, 46 memory, 47 interface, 48 NIT Replacement circuit, 49 ECC encoder, 50 modulator, 51 Frequency converter

Claims (16)

A signal processing device for converting a first digital broadcast signal having a predetermined transmission frequency on a first network into a second digital broadcast signal on a second network,
First frequency conversion means for performing frequency conversion processing on the first digital broadcast signal to obtain a first digital modulation signal;
Demodulation means for demodulating the first digital modulation signal supplied from the first frequency conversion means to obtain digital broadcast data;
A table detection means for detecting a network information table having physical information on a transmission path from the digital broadcast data supplied from the demodulation means;
Analyzing means for analyzing information about the first network from the network information table detected by the table detecting means;
Comparing means for comparing information relating to the first network analyzed by the analyzing means with information relating to the previous first network;
Table changing means for changing the network information table of the first network so as to be adapted to the second network based on information on the first network obtained as a comparison result by the comparing means;
Table replacement means for replacing the network information table of the digital broadcast data supplied from the demodulation means with the network information table supplied from the table changing means;
Modulation means for modulating the digital broadcast data in which the network information table is replaced by the table replacement means to obtain a second digital modulation signal;
A signal processing apparatus comprising: second frequency conversion means for converting the frequency of the second digital modulation signal to obtain the second digital broadcast signal. The table changing means, when the number of transport streams to be transmitted is increased based on the information on the first network obtained as a comparison result by the comparing means, the increased number of transport streams 2. The signal processing according to claim 1, wherein the information is reflected in the setting, and the network information table of the first network is changed so as to be adapted to the second network based on the setting. apparatus. The table changing means changes the setting so as to assign the transmission frequency to an unused transmission frequency corresponding to the second network among the increased transport stream information. Item 3. The signal processing device according to Item 2. The table changing means, when the number of transport streams to be transmitted is increased based on the information about the first network obtained as a comparison result by the comparing means, the information on the increased transport streams 2. The signal processing apparatus according to claim 1, wherein the setting is changed so as not to be included in the network information table of the first network. The table changing means, when the number of transport streams to be transmitted is reduced based on the information about the first network obtained as a comparison result by the comparison means, the reduced number of transport streams 2. The signal processing according to claim 1, wherein the information is reflected in the setting, and the network information table of the first network is changed so as to be adapted to the second network based on the setting. apparatus. The table changing means sets the increased service information when the service information in a certain transponder stream is increased based on the information about the first network obtained as a comparison result by the comparing means. 2. The signal processing apparatus according to claim 1, wherein the network information table of the first network is changed so as to be adapted to the second network based on this setting. The table changing means includes service information for the increased amount of service information in a certain transponder stream based on information about the first network obtained as a comparison result by the comparing means. 2. The signal processing apparatus according to claim 1, wherein the network information table of the second network is changed so as not to be present. The table changing means sets service information for the reduced amount when the service information in a transponder stream is reduced based on the information about the first network obtained as a comparison result by the comparing means. 2. The signal processing apparatus according to claim 1, wherein the network information table of the first network is changed so as to be adapted to the second network based on this setting. A signal processing method for converting a first digital broadcast signal having a predetermined transmission frequency on a first network into a second digital broadcast signal on a second network,
A first frequency conversion step of performing a frequency conversion process on the first digital broadcast signal to obtain a first digital modulation signal;
A demodulation step of demodulating the first digital modulation signal obtained in the first frequency conversion step to obtain digital broadcast data;
A table detection step of detecting a network information table having physical information about a transmission path from the digital broadcast data supplied from the demodulation means;
An analysis step for analyzing information on the first network from the network information table detected in the table detection step;
A comparison step comparing the information about the first network analyzed in the analysis step with the information about the previous first network;
A table changing step for changing the network information table of the first network so as to be adapted to the second network based on the information about the first network obtained as a comparison result in the comparing step;
A table replacement step for replacing the network information table of the digital broadcast data obtained in the demodulation step with the network information table obtained in the table changing step;
A modulation step of modulating the digital broadcast data in which the network information table is replaced in the table replacement step to obtain a second digital modulation signal;
And a second frequency conversion step of obtaining the second digital broadcast signal by converting the frequency of the second digital modulation signal. In the table changing step, when the number of transport streams to be transmitted is increased based on the information on the first network obtained as a comparison result in the comparing step, 10. The signal according to claim 9, wherein the stream information is reflected in the setting, and the network information table of the first network is changed so as to be adapted to the second network based on the setting. Processing method. In the table changing step, among the increased transport stream information, the setting is changed so that the transmission frequency is assigned to an unused transmission frequency corresponding to the second network. Item 11. The signal processing method according to Item 10. In the table changing step, when the number of transport streams to be transmitted is increased based on the information about the first network obtained as a comparison result in the comparing step, the increased number of transport streams is 10. The signal processing method according to claim 9, wherein the setting is changed so that the information is not included in the network information table of the first network. In the table changing step, when the number of transport streams to be transmitted is decreasing based on the information about the first network obtained as a comparison result in the comparing step, 10. The signal according to claim 9, wherein the stream information is reflected in the setting, and the network information table of the first network is changed so as to be adapted to the second network based on the setting. Processing method. In the table changing step, when the service information in a certain transponder stream is increased based on the information on the first network obtained as a comparison result in the comparing step, the increased service information is displayed. 10. The signal processing method according to claim 9, wherein the signal processing method is reflected in settings, and the network information table of the first network is changed so as to be adapted to the second network based on the settings. In the table changing step, when the service information in a certain transponder stream is increased based on the information on the first network obtained as a comparison result in the comparing step, the increased service information is displayed. 10. The signal processing method according to claim 9, wherein the network information table of the second network is changed so as not to be included. In the table changing step, when the service information in a certain transponder stream is reduced based on the information on the first network obtained as a comparison result in the comparison step, the reduced service information is displayed. 10. The signal processing method according to claim 9, wherein the signal processing method is reflected in settings, and the network information table of the first network is changed so as to be adapted to the second network based on the settings.

Images