JP4538888B2 - Transmission / reception system and method, and reception apparatus and method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention uses a transmission line to transmit a digital terrestrial broadcast signal received by a common antenna, such as a hearing facility installed in an apartment house such as an apartment, or a small CATV (Cable Television) system. The present invention relates to a transmission / reception system and method and a receiving apparatus and method suitable for use in a system that distributes video to each home.
[0002]
[Prior art]
Digital terrestrial broadcasting is being developed. In digital terrestrial broadcasting, a video signal is compressed by, for example, MPEG (Moving Picture Coding Experts Group) 2 method, modulated by OFDM (Orthogonal Frequency Division Multiplex), and transmitted. OFDM uses a plurality of carrier waves orthogonal to each other, and is a modulation system that is resistant to multipath causing ghosts. As the frequency used for digital terrestrial broadcasting, it has been studied to use the lower frequency of current UHF broadcasting in relation to the current analog terrestrial broadcasting.
[0003]
When receiving such digital terrestrial broadcasting, NIT (Network Information Table) is usually acquired. Frequency information is obtained from the NIT table, the reception frequency is set to a desired frequency, and then a PAT (Program Association Table) is referred to. From the PAT information, a packet identifier (PID) of a channel in the carrier wave is obtained. Video packets and audio packets are extracted and a desired channel is received.
[0004]
[Problems to be solved by the invention]
In this way, in digital terrestrial broadcasting, the reception frequency can be set to the frequency of a desired channel by referring to this NIT. As long as the digital terrestrial broadcast is directly received and reproduced, the reception frequency can be set using the information of the NIT as it is.
[0005]
However, in condominiums such as condominiums, a hearing system is used that transmits signals received by a common antenna to each home via a cable. In such a hearing system, an empty channel and transmission capacity are used. For the reasons described above, it may be considered that the channel is retransmitted after being changed to a channel having a frequency different from the channel used in broadcasting. When the frequency of the channel is changed in this way, the frequency information indicated by NIT and the frequency of the signal actually transmitted via the cable do not match, and the receiving operation cannot be performed. For this reason, it is considered that the NIT needs to be rewritten in accordance with the frequency of the changed channel in the re-transmission equipment of the common hearing system.
[0006]
However, in order to rewrite the NIT information, when the frequency is converted on the re-transmission equipment side of the common hearing system, the received signal is demodulated, the NIT information is rewritten, remodulated, and converted to the desired frequency. And have to retransmit. In particular, in digital terrestrial broadcasting, OFDM is adopted as a modulation method. OFDM demodulation and modulation processing involves complicated processing.
[0007]
For retransmission, it is conceivable to use, for example, 64-value QAM (Quadrature Amplitude Modulation) used in the current digital CATV without using OFDM modulation. However, if the modulation method is changed from OFDM to 64-value QAM when retransmitting, the processing becomes complicated, and an ordinary digital terrestrial broadcast receiver cannot be used when receiving a transmitted signal. A dedicated receiver is required.
[0008]
Accordingly, an object of the present invention is to allow digital terrestrial broadcast signals received by a shared antenna to be transmitted via a transmission line without rewriting NIT information when retransmitting after changing the frequency in a hearing system. An object of the present invention is to provide a transmission / reception system and method and a receiving apparatus and method that can be retransmitted.
[0009]
Another object of the present invention is a transmission / reception system which does not require a dedicated receiver and can retransmit a digital terrestrial broadcast signal received by a shared antenna via a transmission line without much capital investment. And a method and a receiving apparatus and method.
[0010]
[Means for Solving the Problems]
  The present invention includes a shared antenna for receiving digital broadcasting,
  A re-transmission facility that inputs a digital broadcast reception signal received by a shared antenna, changes the frequency of the digital broadcast reception signal as necessary, and retransmits the signal via a transmission line;
  In a digital broadcast transmission / reception system comprising a receiving facility in each home that receives and reproduces a signal sent via a transmission line,
  The digital broadcast reception signal contains information indicating the frequency of each channel.
  The receiving device is provided with a conversion table indicating the correspondence between information indicating the frequency of each channel included in the received signal and the frequency of the signal transmitted via the transmission path,
  When receiving the signal of the desired channel with the receiver,
Extract the frequency of the channel on which the program of the desired channel is sent from the information indicating the frequency of each channel included in the received signal,
The frequency obtained from the information indicating the frequency of each channel included in the received signal is converted into the frequency of the signal sent via the transmission path based on the conversion table,
Convert received frequency to converted frequencySet
  This is the transmission / reception system.
[0011]
  The present invention receives a digital broadcast with a shared antenna,
  Input the digital broadcast reception signal received by the shared antenna, change the frequency of the digital broadcast reception signal as necessary, retransmit through the transmission line,
  In a digital broadcasting transmission / reception method in which a signal sent via a transmission path is received and reproduced by a receiving facility in each home,
  The digital broadcast reception signal contains information indicating the frequency of each channel.
  Provided in the receiving apparatus a conversion table indicating the correspondence between the information indicating the frequency of each channel included in the received signal and the frequency of the signal transmitted via the transmission path,
  When receiving the signal of the desired channel with the receiver,
Extract the frequency of the channel on which the program of the desired channel is sent from the information indicating the frequency of each channel included in the received signal,
The frequency obtained from the information indicating the frequency of each channel included in the received signal is converted into the frequency of the signal sent via the transmission path based on the conversion table,
Convert received frequency to converted frequencySet
  This is the transmission / reception method.
[0012]
  The present invention relates to a receiving apparatus for receiving a digital broadcast signal received by a shared antenna, having a frequency changed as necessary, and sent via a transmission line.
  The digital broadcast reception signal contains information indicating the frequency of each channel.
  Provided with a conversion table indicating the correspondence between the information indicating the frequency of each channel included in the received signal and the frequency of the signal transmitted via the transmission path,
  When receiving the signal of the desired channel,
Extract the frequency of the channel on which the program of the desired channel is sent from the information indicating the frequency of each channel included in the received signal,
The frequency obtained from the information indicating the frequency of each channel included in the received signal is converted into the frequency of the signal sent via the transmission path based on the conversion table,
Convert received frequency to converted frequencySet
  This is the receiving apparatus.
[0013]
  The present invention relates to a receiving method for receiving a digital broadcast signal received by a shared antenna, having a frequency changed as necessary, and sent via a transmission line.
  The digital broadcast reception signal contains information indicating the frequency of each channel.
  Create a conversion table showing the correspondence between the frequency information of each channel included in the received signal and the frequency of the signal sent via the transmission line,
  When receiving the signal of the desired channel,
Extract the frequency of the channel on which the program of the desired channel is sent from the information indicating the frequency of each channel included in the received signal,
The frequency obtained from the information indicating the frequency of each channel included in the received signal is converted into the frequency of the signal sent via the transmission path based on the conversion table,
Convert received frequency to converted frequencySet
  This is the receiving method.
[0014]
The signal of the terrestrial digital broadcast is retransmitted, and only the frequency is converted as necessary, and sent to the receiving facility of each home via the transmission line. Each home receiver is provided with a conversion table indicating the correspondence between the NIT frequency and the frequency of the signal sent via the transmission line. A reception frequency is set based on this conversion table.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. In the present invention, a digital terrestrial broadcast signal received by a common antenna is imaged to each home using a transmission line, such as a hearing facility installed in an apartment house such as an apartment, or a small CATV system. Is used in a system that distributes
[0016]
FIG. 1 shows an example of a receiving system to which the present invention is applied. In FIG. 1, a digital terrestrial broadcast signal is received by an antenna 1. The reception output of the antenna 1 is supplied to the retransmission facility 2.
[0017]
The re-transmission facility 2 performs frequency conversion as necessary in order to transmit the reception signal of each channel of digital terrestrial broadcasting received by the antenna 1 through each frequency channel for CATV.
[0018]
In digital terrestrial broadcasting, a video signal is compressed by, for example, the MPEG2 system, modulated by OFDM, and transmitted. As the frequency used for digital terrestrial broadcasting, it has been studied to use the lower frequency of current UHF broadcasting in relation to the current analog terrestrial broadcasting. As a frequency for CATV, a VHF mid band (108 MHz to 170 MHz) and a super high band (222 MHz to 470 MHz) are mainly used.
[0019]
  The retransmission facility 2 includes tuner circuits 22A, 22B, 22C,..., Frequency conversion circuits 23A, 23B, 23C,. The reception output of the antenna 1 is supplied to the tuner circuits 22A, 22B, 22C,. Each of the tuner circuits 22A, 22B, 22C,... Selects a reception signal having a frequency of each channel from the reception signals from the antenna 1. Tuner circuit 22A,The output of 22B, 22C, ...Frequency conversion circuit23A, 23B, 23C,. In the frequency conversion circuits 23A, 23B, 23C,..., The frequency of the received signal of each channel of digital terrestrial broadcasting isConverted as needed.The outputs of the frequency conversion circuits 23A, 23B, 23C,... Are supplied to the mixing circuit 24. In the mixing circuit 24, the outputs of the frequency conversion circuits 23A, 23B, 23C,.
[0020]
The transmission path 3 is derived from the mixing circuit 24 of the retransmission facility 2. The signal frequency-converted by the re-transmission facility 2 is supplied to the receiving facilities 4A, 4B, 4C,.
[0021]
The receiving equipment 4A, 4B, 4C,... Of each home includes receiving devices 31A, 31B, 31C,... And receivers 32A, 32B, 32C,. The signals sent via the transmission line 3 are decoded by the receiving devices 31A, 31B, 31C,... Of the receiving facilities 4A, 4B, 4C,. The outputs of the receivers 31A, 31B, 31C,... Are supplied to the receivers 32A, 32B, 32C,. The screens based on the video signals decoded by the receiving devices 31A, 31B, 31C,... Are reproduced by the receivers 32A, 32B, 32C,.
[0022]
The receivers 31A, 31B, 31C,... And the receivers 32A, 32B, 32C,... May be integrated into a television receiver capable of receiving digital terrestrial broadcasts. 31A, 31B, 31C,... Are set top boxes for receiving digital terrestrial broadcasts, and receivers 32A, 32B, 32C,. The devices 31A, 31B, 31C,... May be connected.
[0023]
Thus, in the system to which the present invention is applied, the frequency of the received signal of each channel of the digital terrestrial broadcast received by the antenna 1 is converted into the frequency of each channel for CATV by the retransmission facility 2. This signal is transmitted to the receiving facilities 4A, 4B, 4C,...
[0024]
Retransmission facility 2 performs frequency conversion, but does not rewrite NIT or the like. For this reason, the frequency information of each channel indicated by NIT may not match the actual frequency of each channel transmitted via the transmission path 3.
[0025]
In normal terrestrial digital broadcasting, the NIT is acquired, the frequency information is obtained from the NIT table, the reception frequency is set to a desired frequency, the PAT is referenced, and the PAT information The PID video packet and audio packet of the selected channel are taken out and the desired channel is received. For this reason, the frequency information of each channel indicated by NIT and the actual frequency transmitted through the transmission path 3 (hereinafter referred to as the frequency of the transmission channel) do not match. This makes it impossible to set the frequency of a desired channel.
[0026]
Therefore, in the present invention, the correspondence between the frequency information indicated by NIT and the frequency of the transmission channel in the receiving devices 31A, 31B, 31C,... In the receiving facilities 4A, 4B, 4C,. A frequency conversion table showing the relationship is provided.
[0027]
This frequency conversion table is created by setting the receiving devices 31A, 31B, 31C,... To the frequency search mode at the time of initial setting of the receiving equipment, for example.
[0028]
That is, the receiving devices 31A, 31B, 31C,... Are set to a frequency search mode in order to search for channels on which broadcasting is performed, at the time of initial setting. When the frequency search mode is set, the NIT is acquired, and the correspondence between the frequency information indicated by the NIT and the frequency information set at that time indicates the correspondence between the frequency information of the NIT and the frequency of the transmission channel. A frequency conversion table is created. As a result, the receivers 31A, 31B, 31C,... In the receiving facilities 4A, 4B, 4C,... The reception frequency can be set.
[0029]
FIG. 2 shows the configuration of the receiving devices 31A, 31B, 31C,... In the receiving facilities 4A, 4B, 4C,. As described above, the receiving devices 31A, 31B, 31C,... Are provided with a frequency conversion table in which the correspondence between the frequency information indicated by NIT and the frequency of the transmission channel is written. The rest of the configuration is basically the same as a normal digital terrestrial broadcast receiver.
[0030]
In FIG. 2, the signal from the input terminal 50 is supplied to the front end unit 51. The front end unit 51 includes a tuner circuit 52, an OFDM demodulation circuit 53, and an ECC decoder 54.
[0031]
A signal from the input terminal 50 is supplied to the tuner circuit 52 of the front end unit 51, and a signal having a desired frequency is selected from the signals sent via the transmission path 3 by the tuner circuit 52. The output of the tuner circuit 52 is supplied to the OFDM demodulation circuit 53. The OFDM demodulation circuit 53 performs OFDM demodulation processing. The output of the OFDM demodulation circuit 53 is supplied to the ECC decoder 54. The ECC decoder 54 performs an error correction process using a Reed-Solomon code.
[0032]
The output of the ECC decoder 54 is supplied to the descrambler 56. The descrambler 56 is supplied with the descrambling key data stored in the IC card 58 mounted in the IC card slot 57. The descrambler 56 descrambles the MPEG transport stream using the key data of the IC card 58. The descrambled MPEG2 transport stream is sent to the demultiplexer 60.
[0033]
  The demultiplexer 60 separates a desired packet from the stream from the descrambler 56 based on a command from the controller 61. A packet identifier (PID) is described in the header part of the transmission packet. In the demultiplexer 60, based on this PID, video packets and audio packets of a desired program, PSI (Program Specific)Information) Is extracted. The video packet of the desired program is sent to the video processing circuit 62, and the audio packet is sent to the audio processing circuit 63. The PSI is sent to the controller 61.
[0034]
The video processing circuit 62 receives the video signal packet from the demultiplexer 60 and performs MPEG2 decoding to form a video signal. This video signal is supplied to the adder circuit 64. An on-screen display signal is supplied from the OSD circuit 65 to the adder circuit 64. This on-screen display signal is generated based on a signal from the controller 61. The output of the adder circuit 64 is output from the video output terminal 66.
[0035]
The audio processing circuit 63 receives the audio packet from the demultiplexer 60, performs MPEG audio decoding processing, and forms an audio signal. The output of the audio processing circuit 63 is output from the audio output terminal 67.
[0036]
Input for operating the receiving device 31 is performed by the input key 71, and the input from the input key 71 is supplied to the controller 61. Further, an infrared signal from a remote controller (not shown) is received by the light receiving unit 73, and this signal is supplied to the controller 61. Further, the output of the controller 61 is supplied to the display unit 72, and various setting states are displayed on the display unit 72. The controller 61 can be connected to a telephone line by a modem 74.
[0037]
Furthermore, an EEPROM (Electrically Erasable and Programmable Read Only Memory) 75, an SRAM (Static Random Access Memory) 76, and a ROM (Read Only Memory) 77 are provided for the controller 61. In the SRAM 76, a frequency conversion table indicating the correspondence between the frequency information indicated by NIT (Network Information Table) and the frequency of the transmission channel is created. When the reception frequency is set by the tuner circuit 52, this frequency conversion table is referred to.
[0038]
As described above, in the receiving apparatuses 31A, 31B, 31C,... To which the present invention is applied, the frequency conversion table indicating the correspondence between the frequency information indicated by NIT and the frequency of the transmission channel is used. This will be described in detail below.
[0039]
  FIG. 3 is an example of an NIT table sent by digital terrestrial broadcasting. In this NIT tableincludedImportant information includes a terrestrial distribution descriptor and a service list descriptor.
[0040]
FIG. 4A shows a terrestrial distribution descriptor. The terrestrial distribution descriptor includes a descriptor tag (descriptor_tag), a descriptor length (descriptor_length), an area code (area_code), a guard interval (guard_interval), and a transmission mode (transmission_mode). (Frequency) is described. The guard interval (guard_interval) is defined as shown in FIG. 5B. Further, the transmission mode (transmission_mode) is defined as shown in FIG. 5C.
[0041]
FIG. 4B shows a service list. In the service list, a descriptor tag (descriptor_tag), a descriptor length (descriptor_length), a service ID (service_id), and a service type (service_type) are described. The service type (service_type) is defined as shown in FIG. 5A.
[0042]
The important information in the NIT table is the frequency (FIG. 4). This frequency indicates the center frequency of a channel (physical transmission frequency) through which a terrestrial digital broadcast signal is transmitted.
[0043]
Normally, when receiving a broadcast of a desired channel, first, an NIT table is acquired, and a frequency is obtained from the NIT table, and the reception frequency is set to a desired frequency. Then, the PAT packet is referenced. The PAT describes channel information in each frequency and PMT PID indicating the contents of each channel. From this PAT information, the video packet and audio packet of the PID of the channel in the carrier wave are extracted, and the desired channel is received.
[0044]
Thus, normally, the NIT table is acquired and the reception frequency is set, but in this system, the frequency conversion circuits 23A, 23B, 23C,... Of the retransmission equipment 2 in FIG. Therefore, the frequency of the channel sent via the transmission path 3 may not match the frequency information of the NIT. Here, a frequency conversion table indicating the correspondence between the frequency information obtained from the NIT and the frequency of the transmission channel sent via the transmission path 3 is created.
[0045]
This frequency conversion table is created as follows in the frequency search mode.
[0046]
FIG. 6 is a conceptual diagram showing generation of a frequency conversion table. As shown in FIG. 6A, a frequency table is prepared in which all channel information in the VHF and UHF bands including channels used in domestic terrestrial digital broadcasting is registered.
[0047]
When the frequency search mode is set, the channel selection data is transmitted from the controller 61 to the tuner circuit 52 based on the frequencies registered in the frequency table shown in FIG. 6A, for example, from the lower frequency to the higher frequency. It is done.
[0048]
Then, it is determined whether or not the signal can be received at the set frequency. If the signal can be received, the NIT is acquired from the received signal, and the frequency set at that time in the tuner circuit 52 and the frequency obtained from the NIT A frequency conversion table is generated based on the correspondence relationship with the information.
[0049]
For example, in FIG. 6A, when the tuner circuit 52 is set to the frequency of 105 MHz of “J3ch”, it is assumed that frequency information of 333 MHz is acquired from the NIT information as shown in FIG. 7B. In this case, as shown in FIG. 7C, if the NIT frequency information is 333 MHz, a frequency conversion table indicating that the reception frequency of the tuner circuit 52 is set to 105 MHz is created.
[0050]
  In the reception mode, the receivers 31A, 31B, 31C,...Tune inAs a method, (a) a method of allocating a reception frequency appropriately corresponding to a channel selection button of a remote controller as in the case of reception of a current terrestrial analog broadcast, and (b) a service using a remote controller similar to a method of receiving a CS digital broadcast How to enter the ID,You could think so.
[0051]
In the method (a), after the frequency conversion table is generated as described above in the frequency search mode, the channel selection button number of the remote controller corresponds to the reception frequency set in the tuner in the frequency information after conversion. .
[0052]
  For example, the channel selection button “8” is set to a frequency of 105 MHz and can be received by selecting the channel with the channel selection button. A program can be displayed by determining a default service ID. The default service ID is, for example, the method of storing the service ID of the last viewed program or the program with the smallest service ID number in the receiving channel.To chooseIt is possible.
[0053]
When a program with another service ID is received within the reception channel, the corresponding NIT table is referenced using the frequency conversion table, and the service descriptor is obtained from the corresponding NIT table. For example, if the reception frequency is 105 MHz, the NIT frequency information of 333 MHz is referred to by the conversion table shown in FIG. 6C. As shown in FIG. 6B, a service descriptor is acquired from the 333 MHz NIT table.
[0054]
  In the method (b), the channel including the input service ID is searched from the NIT table, and the channel frequency including the service ID is obtained from the distribution descriptor, as in the case of an existing digital CS broadcast receiver. And6C.By converting the frequency indicated by NIT into the frequency of the corresponding transmission channel by using the frequency conversion table shown in FIG. 6 and transmitting the channel selection data based on the frequency, the desired program can be received.
[0055]
FIG. 7 is a flowchart showing processing in the frequency search mode. When the frequency search mode is set, the channel selection data is transmitted from the controller 61 to the tuner circuit 52 based on the frequencies registered in the frequency table (FIG. 6A), for example, from the lower frequency to the higher frequency. In the tuner circuit 52, the frequency is set based on the channel selection data (step S1).
[0056]
The tuner circuit 52 tries whether or not a signal can be received at a set frequency. When the tuner circuit 52 can receive a signal, an F / E lock signal can be acquired from the front end unit 51. The F / E lock signal is a flag indicating that the demodulation circuit and the error correction circuit have correctly operated and the transport stream has been correctly output. Therefore, whether or not a signal can be received at the set frequency can be determined based on whether or not an F / E lock signal can be acquired from the front end unit 51 (step S2). If the F / E lock signal cannot be received in step S2, the process returns to step S1 and is set to the next frequency based on the frequency table, and the F / E lock signal is acquired at the set frequency in step S2. It is determined whether or not it can be performed.
[0057]
If the F / E lock signal can be received in step S2, it is determined whether or not NIT can be acquired (step S3). When the F / E lock signal can be received, the transport stream is output from the front end unit 51, so that the NIT can be acquired. If the NIT cannot be acquired, the transport stream is not output correctly or broadcast data is not included in the transport stream. In this case, the process returns to step S1.
[0058]
When the NIT is acquired in step S3, the NIT frequency information is acquired with reference to the distribution descriptor in the NIT (step S4).
[0059]
At this time, the reception frequency set in the tuner circuit 52 and the NIT frequency information obtained in step S4 are associated with each other, and a frequency conversion table is generated (step S5).
[0060]
Then, it is determined whether or not all the frequencies have been searched (step S6). If all the frequencies have not been searched, the process returns to step S1, is set to the next frequency, and the same processing is repeated. When the frequency search for all channels is completed, the frequency search mode is terminated.
[0061]
In this manner, in the frequency search mode, a frequency conversion table indicating the correspondence between the frequency indicated by NIT and the frequency of the transmission channel is created.
[0062]
FIG. 8 is a flowchart showing the operation in the reception mode. This example is an example of setting a channel by inputting a service ID with a remote controller as in the CS digital broadcast receiving method.
[0063]
In FIG. 8, when an input for receiving the service ID of the “M” channel is given, a channel including the service ID is searched from the NIT table (step S11). It is determined whether or not there is a channel including the service ID (step S12). If there is no channel including the service ID, a display indicating that reception is impossible is performed (step S13).
[0064]
If there is a channel including the service ID in step S12, the frequency conversion table is referred to, and the frequency indicated by NIT is converted into the frequency of the corresponding transmission channel (step S14). Based on this frequency, the reception frequency of the tuner circuit 52 is set (step S15).
[0065]
Then, a PAT packet is acquired (step S16). The PAT describes channel information in each frequency and PMT PID indicating the contents of each channel. From this PAT information, the PID corresponding to the channel “M” is recognized (step S17). Then, the recognized PID video packet and audio packet are separated (step S18). As a result, the desired “M” channel is received.
[0066]
As described above, in the system to which the present invention is applied, the signal of the terrestrial digital broadcasting is converted by the re-transmission facility 2 only as necessary, and the reception facility 4A of each home is transmitted via the transmission path 3. , 4B, 4C,. Each home receiving device 31A, 31B, 31C,... Is provided with a conversion table indicating the correspondence between the NIT frequency and the frequency of the signal transmitted via the transmission path. A reception frequency is set based on this conversion table. For this reason, the retransmission facility 2 does not need to perform NIT change processing, and does not require an OFDM demodulation circuit or modulation circuit. In addition, the receiving facilities 4A, 4B, 4C,... In each home use ordinary digital data except that a conversion table indicating the correspondence relationship between the NIT frequency and the frequency of the signal transmitted via the transmission path is provided. Those for receiving terrestrial broadcasts can be used.
[0067]
In this example, OFDM is used as a modulation method for digital terrestrial broadcasting, but the present invention can be similarly applied to other modulation methods.
[0068]
【The invention's effect】
According to the present invention, the terrestrial digital broadcast signal is converted by the re-transmission facility as necessary only for the frequency, and is sent to the receiving facility in each home via the transmission path, and is sent to the receiver in each home. Is provided with a conversion table indicating the correspondence between the frequency of the NIT and the frequency of the signal transmitted via the transmission path. A reception frequency is set based on this conversion table.
[0069]
For this reason, it is not necessary to perform NIT change processing in the retransmission facility, and an OFDM demodulation circuit and modulation circuit are not required.
[0070]
In addition, the receiving equipment for each home uses a receiver for receiving ordinary digital terrestrial broadcasts except that a conversion table indicating the correspondence between the frequency of the NIT and the frequency of the signal transmitted via the transmission path is provided. Can and does not require a dedicated receiver.
[0071]
A conversion table showing the correspondence between the NIT frequency and the frequency of the signal sent via the transmission path is created in the frequency search mode at the initial setting, and can be easily realized by software. Once created, there is no need to create it later, so there is no confusion for the recipient.
[0072]
When the channel is set, the reception frequency is automatically set based on this conversion table. Therefore, the receiver operates the desired channel in exactly the same manner as when receiving a normal digital terrestrial broadcast. Can be received.
[Brief description of the drawings]
FIG. 1 is a block diagram of an example of a transmission / reception system to which the present invention is applied.
FIG. 2 is a block diagram of an example of a receiving apparatus in a transmission / reception system to which the present invention is applied.
FIG. 3 is a schematic diagram used to describe an NIT table.
FIG. 4 is a schematic diagram used to describe an NIT table.
FIG. 5 is a schematic diagram used to describe an NIT table.
FIG. 6 is a schematic diagram used for explaining a frequency conversion table;
FIG. 7 is a flowchart used for explaining the operation of a frequency search mode in a receiving apparatus in a transmission / reception system to which the present invention is applied.
FIG. 8 is a flowchart used for explaining a reception operation in a reception apparatus in a transmission / reception system to which the present invention is applied.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Antenna, 23A, 23B, 23C ... Frequency conversion circuit, 3 ... Transmission path 3, 4A, 4B, 4C ... Reception equipment, 31A, 31B, 31C ... Reception apparatus, 53. ..OFDM demodulation circuit, 76 ... SRAM

Claims (4)

A shared antenna for receiving digital broadcasts;
Retransmission equipment for inputting a digital broadcast reception signal received by the shared antenna, changing the frequency of the digital broadcast reception signal as necessary, and retransmitting it via a transmission line;
In a digital broadcasting transmission / reception system comprising a receiving facility in each home that receives and reproduces a signal sent via the transmission path,
The digital broadcast reception signal includes information indicating the frequency of each channel,
The receiving device is provided with a conversion table indicating the correspondence between the information indicating the frequency of each channel included in the received signal and the frequency of the signal transmitted through the transmission path,
When receiving a signal of a desired channel by the receiving device ,
Extracting the frequency of the channel on which the program of the desired channel is sent from the information indicating the frequency of each channel included in the received signal,
The frequency obtained from the information indicating the frequency of each channel included in the received signal is converted into the frequency of the signal sent via the transmission path based on the conversion table,
A transmission / reception system in which the reception frequency is set to the converted frequency . Receive digital broadcasts with a shared antenna,
Input the received signal of the digital broadcast received by the shared antenna, change the frequency of the received signal of the digital broadcast as necessary, retransmit via the transmission line,
In a digital broadcast transmission / reception method in which a signal transmitted via the transmission path is received and reproduced by a receiving facility in each home,
The digital broadcast reception signal includes information indicating the frequency of each channel,
A conversion table indicating correspondence between information indicating the frequency of each channel included in the received signal and the frequency of the signal transmitted via the transmission path is provided in the receiving device,
When receiving a signal of a desired channel by the receiving device ,
Extracting the frequency of the channel on which the program of the desired channel is sent from the information indicating the frequency of each channel included in the received signal,
The frequency obtained from the information indicating the frequency of each channel included in the received signal is converted into the frequency of the signal sent via the transmission path based on the conversion table,
A transmission / reception method in which the reception frequency is set to the converted frequency . In a receiving apparatus for receiving a digital broadcast signal received by a shared antenna, having a frequency changed as necessary, and sent via a transmission path,
The digital broadcast reception signal includes information indicating the frequency of each channel,
A conversion table indicating the correspondence between the information indicating the frequency of each channel included in the received signal and the frequency of the signal transmitted via the transmission path;
When receiving the signal of the desired channel ,
Extracting the frequency of the channel on which the program of the desired channel is sent from the information indicating the frequency of each channel included in the received signal,
The frequency obtained from the information indicating the frequency of each channel included in the received signal is converted into the frequency of the signal sent via the transmission path based on the conversion table,
A receiving apparatus configured to set the receiving frequency to the converted frequency . In a receiving method for receiving a digital broadcast signal received by a shared antenna, having a frequency changed as necessary, and sent via a transmission path,
The digital broadcast reception signal includes information indicating the frequency of each channel,
Create a conversion table indicating the correspondence between the information indicating the frequency of each channel included in the received signal and the frequency of the signal transmitted via the transmission path,
When receiving the signal of the desired channel ,
Extracting the frequency of the channel on which the program of the desired channel is sent from the information indicating the frequency of each channel included in the received signal,
The frequency obtained from the information indicating the frequency of each channel included in the received signal is converted into the frequency of the signal sent via the transmission path based on the conversion table,
A reception method in which the reception frequency is set to the converted frequency .

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