JP3338810B2 - Program selection device for digital television receiver and frequency conversion data acquisition method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a program selection device for a digital television receiver, and more particularly to a program selection device for a digital television receiver that receives digital terrestrial broadcasting via a cable television system (hereinafter referred to as CATV). It relates to an acquisition method of frequency conversion data to be registered.

[0002]

2. Description of the Related Art As a system for re-broadcasting terrestrial digital broadcasting on CATV, the present applicant has previously filed Japanese Patent Application No. Hei 11-2.
No. 07349 proposes a system in which only the carrier frequency is changed and the broadcast is re-broadcasted on a CATV transmission channel without changing the transmission line modulation system of digital terrestrial broadcasting.

In digital terrestrial broadcasting and CATV digital television broadcasting, the former is based on OFDM (Orthogonal
Frequency Division Multiplex)
The modulation method is 64QAM (Quadrature Amplitude M
odulation: Quadrature amplitude modulation (modulation) and transmission path modulation are different, but both are MPEG (Moving Picture ExpartGro).
up) An encoding method called a transport stream is adopted, and by converting only the carrier frequency,
A terrestrial digital broadcast signal can be distributed using a CATV transmission channel without deteriorating transmission quality. In addition, CATV viewers often watch digital terrestrial broadcasting, in which case, even if a digital television receiver equipped with an OFDM demodulator is prepared, the burden on the CATV viewer will not be substantially increased. .

[0004] Therefore, according to the above-mentioned proposed system in which only the carrier frequency is changed and the broadcast signal is re-broadcasted on the CATV transmission channel without changing the transmission line modulation system of the terrestrial digital broadcasting, the CATV receiver side It is possible to suppress the capital investment on the CATV transmitting station side while minimizing the substantial burden on the CATV service, and to provide the CATV service at lower cost.

FIG. 5 is a block diagram showing a configuration of such a CATV. FIG. 5A shows a transmitting station, and FIG.
(B) shows a configuration example of a receiver. With reference to FIG. 5, a conventional transmitting station of such a CATV includes a distributor 1, an n-group (n
Are positive integers) frequency converters 2-1 to 2-n and a mixer 3. The receiver includes a tuner 4, a transmission line demodulator 5, an MPEG separator 6, an MPEG decoder 7, a control unit 8 And a memory 9.

On the transmitting side, the received terrestrial digital broadcast wave is distributed or branched by the distributor 1 for each transmission channel.
The signal is sent to each of the frequency converters 2-1 to 2-n. The frequency converters 2-1 to 2-n convert the carrier frequencies of the respective transmission channels of the terrestrial digital broadcasting into the carrier frequencies of the CATV transmission channels assigned to them, and the mixer 3 converts these frequency-converted terrestrial channels. The digital broadcast transmission channel is frequency-multiplexed with the CATV's own transmission channel (not shown) and output to the transmission path.

On the receiving side, a signal in a frequency band of a specific transmission channel is selected from signals input from the transmission line by the tuner 4 in accordance with an instruction of the control unit 8 and output to the transmission line demodulator 5 as a selected channel signal. Then, the transmission path demodulator 5 performs transmission path demodulation corresponding to the transmission path modulation method of the selected channel signal, and if the selected channel signal is a digital television signal, decodes it into an MPEG transport stream and sends it to the MPEG separator 6. Output.

[0008] The MPEG separator 6 extracts program arrangement information from the MPEG transport stream in accordance with an instruction from the control unit 8 and outputs it to the control unit 8, and also extracts video and image program element information instructed by the control unit 8. And outputs the result to the MPEG decoder 7. The MPEG decoder 7 decodes the program element information extracted by the MPEG separator 6 into video and audio signals, respectively, and sends them to a display / output circuit (not shown).

At this time, if the selected channel signal is a rebroadcasting transmission channel for terrestrial digital broadcasting, the program arrangement information extracted by the MPEG separator 6 is the same as that at the time of transmission from the terrestrial digital broadcasting station. MP
It is the program arrangement information itself of the EG transport stream, and the frequency information included in the program arrangement information and the CAT
The actual carrier frequency of the transmission channel received via V will be different.

Therefore, in such a conventional CATV,
In the memory 9, for example, a frequency information conversion table indicating correspondence between frequency information of an original broadcast channel in digital terrestrial broadcasting and frequency information of an actual transmission channel in CATV is prepared. If the program is for rebroadcasting of digital broadcasting, the control unit 8 refers to the frequency information conversion table in the memory 9 to obtain the frequency information of the corresponding CATV transmission channel, and controls the tuner 4 using this. Configuration.

However, in the above-mentioned conventional example, the data of the frequency information conversion table is directly input by a viewer or the like using a remote control of the digital television receiver, a switch of the receiver itself, or the like. For example, the frequency conversion information separately distributed from the CATV service provider is downloaded from the outside or the like.

[0012]

Therefore, the conventional CATV program selection method has the following problems. The first problem is that it takes a lot of time and labor to manually input frequency information conversion tables for dozens of channels to each digital television receiver. The second problem is that transmission channels in digital terrestrial broadcasting and C
To change the correspondence with the transmission channel in the ATV, it is necessary to correct the frequency information conversion table held by each digital television receiver. It is difficult to modify the receivers all at once, which hinders flexible modification of the CATV distribution service, for example.
The present invention solves these problems and automatically prepares a frequency information conversion table registered in a program selection device of a digital television receiver for receiving terrestrial digital broadcasting via CATV without requiring any manual operation. It is an object of the present invention to provide a creating method and a program selecting device having the function.

[0013]

According to the present invention, there is provided a terrestrial terrestrial rebroadcast signal receiving system which converts a carrier frequency without changing a transmission line modulation method and distributes the terrestrial terrestrial broadcasting signal according to the present invention. A program selecting device of a digital television receiver extracts a frequency component of a specified transmission channel from a CATV distribution signal and outputs the selected channel signal as a selected channel signal, and the selected channel signal is a terrestrial rebroadcast signal. In this case, a transmission path demodulator for demodulating the selected channel signal on a transmission path and outputting an MPEG transport stream, and an MPEG for extracting program sequence information and program element information to be decoded into video and audio signals from the MPEG transport stream. A separator, and controls the tuner and the MPEG separator, so that CA By scanning the transmission channel distributed by V, the transmission channel for transmitting the terrestrial rebroadcast signal is detected. For each of the transmission channels for transmitting the terrestrial rebroadcast signal, the original channel included in the program sequence information is detected. A control unit is provided for acquiring correspondence information between frequency information of terrestrial digital broadcasting and a carrier frequency being selected by the tuner, and registering the information as a frequency information conversion table.

[0014] In addition, the detection of the transmission channel for transmitting the terrestrial rebroadcast signal is performed when the signal level of the selected channel signal is equal to or higher than a predetermined threshold value and the selected channel signal is transmitted over a terrestrial digital broadcast transmission path. When demodulation is possible according to the modulation scheme, the transmission channel is determined to be a transmission channel for transmitting a terrestrial rebroadcast signal.

Further, the control unit controls the tuner to select one transmission channel when scanning the transmission channel distributed by the CATV,
It is characterized in that after a first fixed time has elapsed, it is determined whether or not the output level of the selected channel signal is equal to or higher than the certain threshold value.

Further, the control unit determines that the signal level of the selected channel signal is equal to or higher than the predetermined threshold value when scanning the transmission channel distributed by the CATV, and after a lapse of a second predetermined time period. By checking the pull-in signal, it is determined whether or not the selected channel signal can be demodulated in accordance with a terrestrial digital broadcast transmission channel modulation method.

Still further, according to the present invention, a digital television receiver for receiving a terrestrial rebroadcast signal, which is a terrestrial digital broadcast signal distributed by CATV by converting a carrier frequency without changing a transmission line modulation method. The method of obtaining the frequency conversion data to be registered in the program selection device of
A transmission channel selection step of extracting a frequency component of one CATV transmission channel from the V distribution signal and controlling a tuner to output the frequency component as a selected channel signal;
A rebroadcast channel detecting step of detecting whether or not the selected channel signal is a terrestrial rebroadcast signal; and, when the selected channel signal is a terrestrial rebroadcast signal, transmission channel demodulation of the selected channel signal. Obtaining correspondence information between the original terrestrial digital broadcast frequency information included in the program arrangement information of the MPEG transport stream and the carrier frequency of the transmission channel selected by the tuner, and registering the information as frequency information conversion table data; Is repeated for each of the CATV transmission channels.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a configuration example of a digital television receiver according to one embodiment of the present invention. Compared to the conventional configuration example of FIG. 5B, the digital television receiver of FIG. 1 further includes a detector 104 for detecting the output level 121 of the tuner 4 and a timer 110. Also, instead of the transmission line demodulator 5 and the control unit 8 in FIG. 5B, a transmission line demodulator 105 that outputs a synchronization pull-in signal 122 indicating whether or not synchronization of the OFDM modulation signal is performed, and a timer 110 are used. A control unit 108 for controlling a digital television receiver so as to scan a CATV transmission channel while referring to the output level 121 and the synchronization pull-in signal 122 and automatically acquire data of a frequency information conversion table to be registered in the memory 9. ing.

On the transmitting station side, for example, as shown in FIG.
And converts only the carrier frequency of each transmission channel of the received terrestrial digital broadcast wave into the carrier frequency of the transmission channel to be transmitted by CATV, multiplexes the frequency, and outputs it to the transmission path.

On the receiving side, as in the conventional example shown in FIG.
The control unit 108 which receives the program selection information from the viewer
Obtains the frequency information of the original transmission channel from the program arrangement information corresponding to the program, and, if the original transmission channel is a terrestrial digital broadcast transmission channel, stores the frequency information conversion table held in the memory 9. This is converted into the frequency information of the transmission channel of the CATV,
A transmission channel in ATV is indicated.

The tuner 4 selects a CATV transmission channel corresponding to the program in accordance with frequency information specified by the control unit 108 from signals transmitted from the transmission path,
The signal is output to the transmission path demodulator 105 as a selected channel signal. The transmission channel demodulator 105 demodulates the selected channel signal on the transmission channel in accordance with the transmission channel modulation method.
And outputs it to the MPEG separator 6. When the selected channel signal is an analog television signal, for example, VSB (Vestigial Side)
Band) demodulated by a demodulator and output to an analog video circuit (not shown).

In this case, the control unit 108 of the digital television receiver according to the present embodiment performs the CATV at an initial setting such as turning on the power of the receiver or at an appropriate timing such as a specific switch operation of the viewer. The frequency information conversion data to be registered in the frequency information conversion table stored in the memory 9 is automatically acquired by performing scanning on each transmission channel.

When the control unit 108 receives program selection information from a viewer using a remote controller of the digital television receiver or a switch of the receiver itself, the program is rebroadcast on CATV. If the program is a terrestrial digital broadcast program, the corresponding C is obtained based on the frequency information conversion table automatically acquired and held in the memory 9.
The frequency information of the ATV transmission channel is obtained, and the tuner 4 is instructed on the frequency of the CATV transmission channel to be selected.

Hereinafter, the operation of the digital television receiver of FIG. 1 for automatically acquiring frequency information conversion data will be described with reference to the flowchart shown in FIG. 2 and the time chart shown in FIG.

For example, at the time of initial setting such as turning on the power of the receiver or when a viewer operates a specific switch or the like, the control unit 108 activates the tuner 4 when the frequency information conversion table creation / update routine is started. (Step A).
1). Further, the control unit 108 sets a time T1 required for the tuner 4 to take in the selected channel signal after the transmission channel is switched, in the timer 110, and waits for the elapse of the time T1 (step A2). When the timer 110 counts T1, the control unit 108 outputs an output level 121 that represents whether the level of the selected channel signal is equal to or higher than a specified value in two levels (301, 301: high level when specified level or higher, specified value An example in which the following is set to the low level is received from the detector 104, and it is determined whether or not the level of the selected channel signal is equal to or higher than a specified value (step A3).

When the level of the selected channel signal is equal to or higher than the specified value (YES in step A3), the control unit 108
The time T2 required from when the transmission path demodulator 105 starts to fetch the selected channel signal to when it pulls in the synchronization.
Is set in the timer 110, and the elapse of the time T2 is waited (step A4). When the timer 110 counts T2, the control unit 108 generates a synchronization pull-in signal 122 (see FIG. 3) that expresses in binary whether or not the transmission line demodulator 105 has locked the OFDM modulation signal into the selected channel signal.
-302: Transmission line demodulator 105 when sync pull-in is set to high level and sync pull-in is set to low level
Then, it is determined whether or not the transmission path demodulator 105 has performed synchronization pull-in on the selected channel signal (step A5).

When the transmission path demodulator 105 performs synchronization pull-in on the selected channel signal (Y in step A5)
ES), the control unit 108 determines that the transmission channel is a transmission channel for rebroadcasting a terrestrial digital broadcast, and arranges a program arrangement from the MPEG transport stream output from the transmission path demodulator 105 via the MPEG separator 6. Information is extracted and frequency information conversion data is obtained.

The MPEG transport stream includes program element information such as video and audio compressed data streams of a plurality of programs served by the transmission channel and PAT (Program Associative) associated with these programs.
ation Table), PMT (Program Map Table), NIT
(Network Information Table) and the like, which is composed of packet data of program arrangement information, and a unique packet ID is assigned to each of the packet data. P
The packet ID of the AT is standardized to '0x0000' (where 0x represents a hexadecimal number; the same applies hereinafter). The packet ID of the program element information of each program is described in the PMT, and the packet ID of the PMT of each program is described in the PAT of the transport stream. Further, information such as the frequency and the modulation method for each of the plurality of transport streams serviced from the same network is described in the NIT, and the NIT having the same content is packet-multiplexed into each of the plurality of transport streams. The packet ID of the NIT and the transport stream ID together with the PA of each transport stream
It is described in T.

Therefore, the control unit 108 sends the standardized PAT packet ID '0x000
The PAT is separated and extracted by designating 0 ′, and the transport ID is acquired by referring to the PAT, and the PAT is acquired.
The packet ID of the NIT described in T is converted to an MPEG separator 6
(Step A6).

In this way, the control unit 108
Of the terrestrial digital transmission channel information (frequency information) and the service ID information described in (1), are stored in the memory 9 as a frequency information conversion table in association with the currently selected CATV transmission channel information (frequency information). (Step A7).

Therefore, when the level of the selected channel signal is equal to or higher than the specified level and the transmission line demodulator 105 performs synchronization pull-in of the OFDM modulation signal (YES in step A3, Y in step A5)
ES), the frequency information conversion data for the selected channel signal is registered in the frequency information conversion table.
(FIG. 2, route step A3 → step A4 → step A
5 → Step A6 → Step A7). The time T3 from the determination of the synchronization pull-in of the transmission channel Cn to the switching of the transmission channel in FIG. 3 indicates the time required for acquiring the PAT / NIT and writing the frequency information conversion data to the memory. When the level of the selected channel signal is equal to or lower than the specified value (NO in step A3), the synchronization pull-in determination and the writing of the frequency information conversion data are skipped (FIG. 2, paths 201 and 3, transmission channel Cn + 1). If the level of the selected channel signal is equal to or higher than the specified level, but the transmission line demodulator 105 cannot pull in the OFDM modulated signal (YES in step A3, step A5).
NO), the writing of the frequency information conversion data is skipped assuming that the selected channel signal is not a terrestrial rebroadcast signal (FIG. 2, path 202 and FIG. 3, Cn + 2).

In this way, after scanning is performed on any one of the above three routes, the control unit 108 sets a CA which may be assigned to all terrestrial rebroadcast signals.
It is determined whether or not scanning has been performed on the TV transmission channel (step A8). If there is a transmission channel on which scanning has not been performed, the control unit 108 instructs the tuner 4 to move (select a channel) to the next transmission channel (step A9).

The control unit 108 repeats the control flow of steps A2 to A9 in this way to scan the transmission channels that may be allocated to all terrestrial rebroadcast signals, To complete.

The reason why the above-described level determination of the selected channel signal and the synchronization pull-in determination are performed is to create a conversion table only for a normal terrestrial rebroadcast signal.
When multiple modulation schemes are mixedly broadcast, OFDM
It performs the function of distinguishing modulation signals from other signals.

The frequency information conversion table creation / update timing has been described as being started, for example, at the time of initial setting such as turning on the power of a receiver or by a specific switch operation of a viewer. A method of transmitting a signal of a start command from the transmitting station at the time of reorganization or the like and starting up by the start command may be considered, but the present invention does not particularly limit the method of instructing the start of the conversion table creation.

The order of scanning may be a sequence from a low-frequency transmission channel to a high-frequency transmission channel, a sequence from a high-frequency transmission channel to a low-frequency transmission channel, and a sequence from a given channel to one round. However, the present invention does not limit the order of the scanning.

As a method for determining whether or not all the transmission channels have been scanned, a mark is placed on the transmission channel from which scanning has been started, scanning is performed in the order of arrangement of the channels, and the circuit is circled once. How to end scanning after detecting transmission channel,
A method may be considered in which the scanned transmission channels are marked, and the scanning is terminated when there are no unmarked transmission channels. However, the present invention does not limit the method of determining whether all the transmission channels have been scanned.

Next, the operation performed by the receiver shown in FIG. 1 for normal program selection will be described with reference to the flowchart shown in FIG. When the viewer inputs an instruction to select a specific program, the control unit 108 instructs the MPEG separator 6 to acquire the PAT from the MPEG transport stream of the currently received transmission channel (step B1). ).
The control unit 108 determines whether or not the program to be selected exists in the currently received transport stream with reference to the PAT (step B2). If it does not exist in the transport stream, it controls the MPEG separator 6 in the same manner as described above to acquire the NIT,
Transmission channel information (frequency information,
Service ID) (step B3). Control unit 108
Obtains the frequency information of the transmission channel to be actually selected by referring to the frequency conversion table automatically acquired and held in advance in the memory 9 based on the transmission channel information (step B4).

The control unit 108 instructs the tuner 4 on the obtained frequency information to move (select) a transmission channel (step B5), and instructs the MPEG separator 6 to perform PA transmission.
T is acquired (step B6). When the program to be selected is present in the currently received transport stream (YES in step B2), or when the mobile station moves to a transmission channel containing the program and acquires the PAT (step B5), the control unit 108 also stores the PAT. At the same time, the packet ID of the PMT of the program to be selected is instructed to the MPEG separator 6, and
The PMT in the transport stream is obtained (step B7).

The control unit 108 acquires the packet ID of the program element information such as video and audio of the selected program from the PMT (step B8), and
The MPEG separator 6 selects the program element information of the selected program based on the packet ID,
Output to the EG decoder 7 (step B9). The MPEG decoder 7 decodes the video / audio signal from the program element information and outputs it to the display circuit (Step B10).

[0041]

As described above, according to the program selection device of the present invention, the following effects can be obtained. A first effect is that the program arrangement information and its frequency conversion information can be automatically acquired on the receiver side. For this reason, when re-broadcasting terrestrial digital broadcasting on the CATV transmitting station side, re-broadcasting while leaving the program arrangement information such as NIT as it is does not cause an increase in the burden on the viewer side. Since the change of the program arrangement information can be omitted, the device configuration on the transmitting station side can be simplified.
If the transmitting station changes the program arrangement information, M
Only after decoding to PEG transport stream can operation be performed. For this reason, the transmitting station demodulates the received signal from an RF signal to a baseband signal, decodes the transmission path, changes the program sequence information, performs transmission path coding and modulation again, and outputs the result to the transmission path. Will be needed. Therefore, the equipment configuration on the transmitting station side becomes complicated, which leads to an increase in the cost of the CATV transmitting station, which in turn leads to an increased burden on the user.

The second effect is that there is almost no increase in the circuit on the receiver side and the increase in the processing software is small.
There is almost no cost impact.

The third effect is that, by automatically creating a conversion table in a digital television receiver, the operation of inputting the correspondence between frequency information of terrestrial digital broadcasting and transmission frequency information in CATV to the receiver is omitted. it can.

A fourth effect is that when the correspondence between a transmission channel in digital terrestrial broadcasting and a transmission channel in CATV is changed, the digital television receiver is again instructed to start creating a conversion table. Thus, the conversion table can be easily renewed to the latest one.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration example of a digital television receiver according to an embodiment of the present invention.

FIG. 2 is a flowchart illustrating an operation performed by the digital television receiver in FIG. 1 to create a conversion table.

FIG. 3 is a time chart illustrating an operation performed by the digital television receiver in FIG. 1 in creating a conversion table.

FIG. 4 is a flowchart illustrating an operation performed by the digital television receiver in FIG. 1 for normal program selection.

FIG. 5 is a block diagram showing a conventional configuration of a CATV for rebroadcasting terrestrial digital broadcasting without changing the transmission line modulation method.

[Explanation of symbols]

 Reference Signs List 1 distributor 2-1 to 2-n frequency converter 3 mixer 4 tuner 5, 105 transmission line demodulator 6 MPEG separator 7 MPEG decoder 8, 108 control unit 9 memory 104 detector 110 timer 121 output level 122 pull-in signal

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-2001-36887 (JP, A) JP-A-2000-350180 (JP, A) JP-A-2000-115742 (JP, A) JP-A-11-150719 (JP, A) JP-A-11-32318 (JP, A) JP-A-10-200886 (JP, A) JP-A-10-285571 (JP, A) (58) Fields studied (Int. Cl. ⁷ , DB Name) H04N 5/38-5/46 H04N 7/10 H04N 7/14-7/173 H04N 7/20-7/22 H04N 7/00-7/088

Claims (11)

(57) [Claims] 1. A cable television system (hereinafter referred to as CAT) by converting a carrier frequency without changing a transmission line modulation method.
It is called V. A terrestrial digital broadcasting signal (hereinafter referred to as a terrestrial rebroadcasting signal) distributed by a digital television receiver is provided. The program selecting device converts a frequency component of a designated transmission channel from a CATV distribution signal. A tuner that extracts and outputs a selected channel signal as a selected channel signal; and a transmission path demodulator that demodulates the selected channel signal and outputs an MPEG transport stream when the selected channel signal is a terrestrial rebroadcast signal. An MPEG separator for extracting program sequence information and program element information to be decoded into video and audio signals from an MPEG transport stream; and controlling the tuner and the MPEG separator so that a transmission channel for CATV distribution at a required timing. Transmit terrestrial rebroadcast signals by scanning For each of the transmission channels for detecting the transmission channel and transmitting the terrestrial rebroadcast signal, the correspondence information between the original terrestrial digital broadcast frequency information included in the program arrangement information and the selected carrier frequency of the tuner. And a control unit for acquiring the information as a frequency information conversion table. 2. The program selection device for a digital television receiver according to claim 1, wherein the detection of a transmission channel for transmitting the terrestrial rebroadcast signal includes a threshold at which the signal level of the selected channel signal is constant. If the selected channel signal is equal to or more than the value and the selected channel signal can be demodulated according to the terrestrial digital broadcast transmission channel modulation method, it is determined that the transmission channel is a transmission channel for transmitting a terrestrial rebroadcast signal. Characteristic program selection device for digital television receiver. 3. The detector according to claim 2, further comprising a detector for detecting whether a signal level of the selected channel signal is equal to or higher than the predetermined threshold value and outputting the detected signal level to the control unit. A program selection device for a digital television receiver as described in the above. 4. The transmission path demodulator outputs a synchronization pull-in signal indicating whether synchronization pull-in is possible or not to the control unit, so that the selected channel signal can be demodulated according to a transmission path modulation scheme of terrestrial digital broadcasting. 3. The program selection device for a digital television receiver according to claim 2, wherein the control unit is notified of whether or not there is a program. 5. The control unit controls the tuner to select one transmission channel when scanning a transmission channel distributed by the CATV, and then controls the first tuner.
4. The digital television according to claim 3, wherein the output of the detector is checked after a lapse of a predetermined time to determine whether the output level of the transmission channel is equal to or higher than the predetermined threshold. Receiver program selection device. 6. The control unit according to claim 1, wherein the control unit determines that the signal level of the selected channel signal is equal to or higher than the predetermined threshold value when scanning the transmission channel distributed by the CATV, and after a lapse of a second predetermined time period. 6. The digital television receiver according to claim 5, wherein by checking the synchronization pull-in signal, it is determined whether the selected channel signal can be demodulated in accordance with a terrestrial digital broadcast transmission channel modulation method. Machine program selection device. 7. A timer which is referred to by the control unit and measures the first fixed time and the second fixed time,
The program selection device for a digital television receiver according to claim 6, further comprising: 8. A program selection device for a digital television receiver which receives a terrestrial rebroadcast signal, which is a terrestrial digital broadcast signal distributed by CATV, by changing a carrier frequency without changing a transmission line modulation method. A transmission channel selection step of extracting a frequency component of one transmission channel of the CATV from a CATV distribution signal and controlling a tuner to output the selected channel signal as a selected channel signal; A rebroadcast channel detecting step of detecting whether or not the channel signal is a terrestrial rebroadcast signal; and an MPE obtained by demodulating the selected channel signal when the selected channel signal is a terrestrial rebroadcast signal.
Acquiring correspondence information between the original terrestrial digital broadcast frequency information included in the program arrangement information of the G transport stream and the carrier frequency of the transmission channel selected by the tuner, and registering the information as frequency information conversion table data; The method of acquiring frequency conversion data, comprising: repeating the above for each of the CATV transmission channels. 9. The re-broadcast channel detecting step includes: a signal level detecting step of detecting whether a signal level of the selected channel signal is equal to or higher than a predetermined threshold value; A modulation scheme detection step of detecting whether demodulation is possible according to the transmission path modulation scheme of the transmission channel modulation scheme, wherein the signal level of the selected channel signal is equal to or higher than a predetermined threshold value, and the selected channel signal is 9. The frequency conversion data according to claim 8, wherein when the demodulation is possible according to the transmission channel modulation method of the digital broadcast, the transmission channel is determined to be a transmission channel for transmitting a terrestrial rebroadcast signal. Acquisition method. 10. The method according to claim 9, wherein the signal level detecting step is performed after a lapse of a first fixed time after the transmission channel selecting step. 11. The method according to claim 1, wherein, if the signal level of the selected channel signal is equal to or higher than the predetermined threshold value in the signal level detection step, the selection is performed after a lapse of a second predetermined time. The method according to claim 9, wherein the method is performed by checking whether or not a transmission line demodulator that demodulates a channel signal in accordance with a transmission line modulation method of digital terrestrial broadcasting can perform synchronization.