Patent Publication Number: US-2018054643-A1

Title: Digital broadcast reception device

Description:
TECHNICAL FIELD 
     The present disclosure relates to a digital broadcast reception device that receives a digital broadcast such as a terrestrial digital television broadcast and the like. 
     BACKGROUND ART 
     There is known a technology for receiving a digital broadcast in a mobile body such as an automobile (for example, PTL 1). 
     PTL 1 discloses a digital broadcast receiver capable of switching and using plural types of received services. In the digital broadcast carried out in Japan, hierarchical transmission of simultaneously transmitting a plurality of hierarchies different in transmission characteristics is possible. 
     Then, the digital broadcast receiver disclosed in PTL 1 can receive different types of encoded digital data (MPEG2, MPEG4/H.264 and the like) from a broadcast wave of a same channel by the digital broadcast, and can switch digital data, which is viewed by a user, in the received digital data. 
     Moreover, in the digital broadcast receiver disclosed in PTL 1, the plural types of received services can be switched based on network follow information. 
     CITATION LIST 
     Patent Literature 
     PTL 1: Unexamined Japanese Patent Publication No. 2006-270208 
     SUMMARY OF THE INVENTION 
     In the digital broadcast receiver of PTL 1, in a case where the network follow information is not present, it is difficult for the user to continuously view a service while the user is moving. 
     Moreover, for example, in a digital broadcast carried out in Europe and the like, unlike the hierarchical transmission in Japan, the different types of encoded digital data are not sometimes present in the broadcast wave of the same channel. In this case, the digital broadcast receiver cannot decode digital broadcast data encoded for each of the plurality of hierarchies different in transmission characteristics. 
     The present disclosure provides a digital broadcast reception device that enables the user to continuously view the service in response to a receiving state of the digital broadcast while the user is moving. 
     The digital broadcast reception device in the present disclosure includes: a first received signal processor; a second received signal processor; and a controller. The first received signal processor receives a signal, which indicates a first channel in a digital broadcast, and outputs a first channel signal obtained by demodulating the received signal. The second received signal processor receives a signal, which indicates a second channel different from the first channel, and generates a second channel signal obtained by demodulating the received signal. The controller controls operations of the first received signal processor and the second received signal processor. In a period while the first received signal processor is outputting the first channel signal, the controller selects the second channel based on pieces of information regarding services provided by respective channels, the pieces of information being individually included in the first channel signal and the second channel signal. The controller switches a signal to be outputted from either one signal of the first channel signal and the second channel signal to other one of the first channel signal and the second channel signal based on individual receiving states of the first channel under output and the selected second channel. 
     The digital broadcast reception device in the present disclosure enables the user to continuously view the service while the user is moving. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a block diagram schematically showing a configuration example of a digital broadcast reception device in a first exemplary embodiment. 
         FIG. 2  is a view schematically showing a receiving state of a digital broadcast in the digital broadcast reception device mounted on a mobile body. 
         FIG. 3  is a flowchart showing an example of operations of the digital broadcast reception device in the first exemplary embodiment. 
         FIG. 4  is a flowchart showing an example of a main reception system demodulation processing executed in the digital broadcast reception device in the first exemplary embodiment. 
         FIG. 5  is a flowchart showing an example of a sub reception system demodulation processing executed in the digital broadcast reception device in the first exemplary embodiment. 
         FIG. 6A  is a diagram showing an example of a display video by a video signal output from the digital broadcast reception device in the first exemplary embodiment. 
         FIG. 6B  is a diagram showing an example of the display video by the video signal output from the digital broadcast reception device in the first exemplary embodiment. 
         FIG. 6C  is a diagram showing an example of the display video by the video signal output from the digital broadcast reception device in the first exemplary embodiment. 
         FIG. 6D  is a diagram showing an example of the display video by the video signal output from the digital broadcast reception device in the first exemplary embodiment. 
         FIG. 7  is a block diagram schematically showing a configuration example of a digital broadcast reception device in a second exemplary embodiment. 
         FIG. 8  is a flowchart showing an example of a sub reception system demodulation processing executed in the digital broadcast reception device in the second exemplary embodiment. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, exemplary embodiments will be described in detail while appropriately referring to the drawings. However, a description more in detail than necessary is omitted in some cases. For example, a detailed description of a well-known item and a duplicate description of substantially the same configuration are omitted in some cases. These omissions are made in order to avoid unnecessary redundancy of the following description and to facilitate the understanding of those skilled in the art. 
     Note that the accompanying drawings and the following description are provided in order to cause those skilled in the art to fully understand the present disclosure, and it is not intended to thereby limit the subject of the description of the scope of claims. 
     Moreover, the respective drawings are schematic views, and are not illustrated necessarily exactly. Furthermore, in the respective drawings, in some cases, the same reference numerals are assigned to the same constituents, and a description thereof may be omitted or simplified. 
     FIRST EXEMPLARY EMBODIMENT 
     Hereinafter, a first exemplary embodiment will be described with reference to  FIG. 1  to  FIG. 6D . 
     [1-1. Configuration] 
     [1-1-1. Outline] 
     A description will be made of an outline of digital broadcast reception device  100  in a first exemplary embodiment with reference to  FIG. 1  and  FIG. 2 . 
     Note that, in the present disclosure, a service received in digital broadcast reception device  100  means a content such as a program provided from a broadcast station through a broadcast wave. 
       FIG. 1  is a block diagram schematically showing a configuration example of digital broadcast reception device  100  in the first exemplary embodiment. 
     As shown in  FIG. 1 , a digital broadcast reception system includes: digital broadcast reception device  100 ; and antenna device  101 . Digital broadcast reception device  100  includes: first received signal processor  110 ; second received signal processor  120 ; controller  130 ; and buffer memory  102 . 
     The digital broadcast reception system in this exemplary embodiment is, for example, a reception system capable of receiving a digital broadcast such as a terrestrial digital television broadcast. In the terrestrial digital television broadcast, logical channels, each of which is composed of a video signal, an audio signal and a data signal, are encoded and multiplexed based on a standard such as MPEG (Moving Picture Experts Group), and are subjected to digital modulation by the OFDM (Orthogonal Frequency Division Multiplexing) system, whereby a digital broadcast wave of one broadcast channel is generated. A plurality of the broadcast channels are broadcast from a plurality of the broadcast stations, and a broadcast network is composed of the plurality of broadcast stations. 
     Moreover, this digital broadcast reception system is mountable on a mobile body, for example, such as a vehicle. 
       FIG. 2  is a view schematically showing a receiving state of the digital broadcast in digital broadcast reception device  100  mounted on mobile body  200 . 
     In  FIG. 2 , mobile body  200  on which the digital broadcast reception system is mounted is passing through a boundary region between service area  215  and service area  225 . Service area  215  is an area (range) where a digital broadcast wave by first transmitting station  210  is receivable. Service area  225  is an area (range) where a digital broadcast wave by second transmitting station  220  is receivable. By using first received signal processor  110  and second received signal processor  120 , digital broadcast reception device  100  in this exemplary embodiment selects a digital broadcast wave, in which a receiving state is good, from among the digital broadcast waves individually sent out from transmitting station  210  and transmitting station  220 . In this way, a user who uses digital broadcast reception device  100  can continuously view a desired service during a period of moving by mobile body  200  on which digital broadcast reception device  100  is mounted. 
     [1-1-2. Configuration of Digital Broadcast Reception Device] 
     Hereinafter, a description will be made of a configuration of digital broadcast reception device  100  in this exemplary embodiment with reference to  FIG. 1 . 
     Digital broadcast reception system in this exemplary embodiment receives the digital broadcast wave, which is broadcast from the broadcast station, by antenna device  101 , and demodulates a received digital broadcast signal by digital broadcast reception device  100 . Then, digital broadcast reception device  100  outputs a channel signal, which is obtained as a result of the demodulation, to a display device (not shown) or the like viewable by the user. The display device may be provided in digital broadcast reception device  100 , or may be provided separately from digital broadcast reception device  100 . 
     For example, antenna device  101  includes a plurality of antennas capable of composing a diversity antenna. Antenna device  101  receives digital broadcast waves of channels (physical channels), which are formed of different frequency bands, by the plurality of antennas, outputs digital broadcast signal Sd 1  to first received signal processor  110 , and outputs digital broadcast signal Sd 2  to second received signal processor  120 . 
     In digital broadcast reception device  100 , each of first received signal processor  110  and second received signal processor  120  is composed of a tuner module that performs signal processing for selecting one channel from the digital broadcast and generating a channel signal. 
     First received signal processor  110  includes: demodulating circuit  111 ; demultiplexing circuit  112 ; and signal decoding circuit  113 . 
     Demodulating circuit  111  demodulates digital broadcast signal Sd 1  regarding the selected channel, and outputs digital broadcast signal Sd 1 , which is thus demodulated, to demultiplexing circuit  112 . The digital broadcast signal output from demodulating circuit  111  is in a state of being multiplexed and encoded. 
     Demultiplexing circuit  112  performs demultiplexing for the digital broadcast signal, which comes from demodulating circuit  111 , and outputs a digital broadcast signal, which is obtained as a result of the demultiplexing, to signal decoding circuit  113 . 
     Signal decoding circuit  113  decodes the digital broadcast signal, which comes from demultiplexing circuit  112 , and outputs, to controller  130 , channel signal Sc 1  including a video signal, an audio signal and a data signal, which are obtained as a result of decoding the digital broadcast signal. 
     In a similar way to first received signal processor  110 , second received signal processor  120  includes: demodulating circuit  121 ; demultiplexing circuit  122 ; and signal decoding circuit  123 . Configurations and operations of the respective circuits in second received signal processor  120  are substantially the same as those of the respective circuits in the first received signal processor  110 , and accordingly, a description thereof is omitted. 
     Buffer memory  102  is composed of a storage device, for example, such as a flash memory. Buffer memory  102  temporarily stores (holds) the audio signal, the video signal and the like, which are included in each of channel signal Sc 1  and channel signal Sc 2 . Either one of channel signal Sc 1  and channel signal Sc 2 , which are held in buffer memory  102 , is output as output signal So to an outside. 
     Controller  130  is composed, for example, of a CPU (Central Processing Unit), an MPU (Micro Processing Unit) or the like, and controls a whole operation of digital broadcast reception device  100 . Controller  130  includes an internal memory, and realizes predetermined functions in cooperation with software. For example, controller  130  realizes functions as same signal identifier  131 , signal strength determiner  132 , and delay synchronizer  133 . 
     Same signal identifier  131  reads out varieties of information, which are included individually in channel signal Sc 1  and channel signal Sc 2 , from buffer memory  102  or the internal memory (not shown), and determines a uniformity between the services by the respective channels of channel signal Sc 1  and channel signal Sc 2 . Note that the uniformity determination refers to determining whether or not the services by the respective channels are mutually the same services. 
     As an example of the varieties of information usable by same signal identifier  131 , there is a broadcast ID (Identification) that is identification information imparted to the digital broadcast. For example, the broadcast ID includes a Network ID (hereinafter, referred to as “NID”), an Original Network ID (hereinafter, referred to as “ONID”), a Transport Stream ID (hereinafter, referred to as “TSID”), and a Service ID (hereinafter, referred to as “SID”). The NID is an ID that identifies the broadcast network, and is defined in the NIT (Network Information Table). The ONID is an ID that identifies, for example, a whole of the broadcast network for each country. The TSID is an ID of each multiplex. The SID is an ID that identifies the service in the digital broadcast. 
     In addition to the broadcast ID, or in place of the broadcast ID, same signal identifier  131  may determine the uniformity between channel signal Sc 1  and channel signal Sc 2  based on a service name and an event name. In the standard such as ISDB (Integrated Services Digital Broadcasting) and DVB (Digital Video Broadcasting), the service name and the event name are defined in the SDT (Service Description Table), and are embedded as text data in each of channel signal Sc 1  and channel signal Sc 2 . Moreover, same signal identifier  131  may determine the uniformity between channel signal Sc 1  and channel signal Sc 2  by using the audio signal and the video signal, which are included in each of channel signal Sc 1  and channel signal Sc 2 . A determination method of the uniformity, which is based on information described in the SDT and information (content information) regarding contents of the service, such as the audio data and the image data, will be described later. 
     Signal strength determiner  132  measures individual signal strengths of two channel signals Sc 1  and Sc 2  between which the uniformity is determined by same signal identifier  131 , and determines which of two channel signals Sc 1  and Sc 2  is a signal having a higher signal strength. As such a signal strength to be measured, for example, there are a field intensity of the signal, a value of a bit error rate (BER), and the like. 
     For example, delay synchronizer  133  adjusts a period of holding each of channel signal Sc 1  and channel signal Sc 2  in buffer memory  102  (hereinafter, this period is referred to as “buffer period”), and thereby synchronizes delays of channel signal Sc 1  and channel signal Sc 2  with each other. In this way, in a case of switching output signal So between channel signal Sc 1  and channel signal Sc 2 , output signal So can be switched (for example, output signal So is switched from channel signal Sc 1  to channel signal Sc 2 ) in a state where channel signal Sc 1  and channel signal Sc 2  synchronize with each other. 
     Note that the description is made above of such an example where controller  130  is composed of a CPU; however, controller  130  is not limited to the CPU, and may be a dedicated electronic circuit designed to realize a predetermined function or a hardware circuit such as a reconfigurable electronic circuit. Controller  130  may be composed of a variety of semiconductor integrated circuits such as an MPU, a microcomputer, a DSP (Digital Signal Processor), an FPGA (Field Programmable Gate Array), and an ASIC (Application Specific Integrated Circuit). For example, same signal identifier  131 , signal strength determiner  132  and delay synchronizer  133  may be composed of separate circuit devices. 
     [1-2. Operations] 
     [1-2-1. Outline of Operations] 
     Next, a description will be made of an outline of operations of digital broadcast reception device  100  in this exemplary embodiment. 
     Digital broadcast reception device  100  is mounted on the mobile body, for example, such as an automobile, and receives a digital broadcast broadcast by a broadcast station. The mobile body sometimes moves across a plurality of service areas provided by a plurality of broadcast stations. In this case, in order to enable the user to continuously view a service which the user desires, two reception systems composed of first received signal processor  110  and second received signal processor  120  are used in digital broadcast reception device  100 . For example, in digital broadcast reception device  100 , while one of the reception systems (hereinafter, this is referred to as “main reception system”) is stably receiving a digital broadcast signal that indicates a specific channel as a viewing target, a candidate for a next station to be selected is selected in other of the reception systems (hereinafter, this is referred to as “sub reception system”). In this way, when the mobile body goes out of the service area of the broadcast station from which the mobile body is receiving a broadcast service at present, and enters the service area of the adjacent broadcast station, then digital broadcast reception device  100  can automatically switch the channel. 
     Here, in the sub reception system, from among plural types of the received services in the digital broadcast receivable by digital broadcast reception device  100 , an equivalent service (that is, a same program) to the broadcast service, which is being received (viewed) at present in the main reception system, is determined by same signal identifier  131 . In this way, the above-mentioned uniformity is determined. 
     Such determination processing by same signal identifier  131  may be performed based on network information included in the NIT configured for each of broadcasters in the area. For example, the specific IDs (TSID, SID, NID and the like) indicate an affiliated broadcasting station. Therefore, in a country where these pieces of the network information are arranged (for example, Japan), the network information is extracted from the digital broadcast waves, whereby the digital broadcast signals from the broadcast stations of the same group can be determined. However, for example in newly emerging countries and the like, it is frequent that the network information such as in the NIT is not arranged, and reliability of the network information concerned is low in some cases. 
     In this connection, in digital broadcast reception device  100  of this exemplary embodiment, the uniformity of the service is determined between the main reception system and the sub reception system based on the SDT (Service Description Table) in which a service name and the like are described and based on the content information including the audio data and the image data, the SDT and the content information being included in the digital broadcast signal. In this way, even in a case where the network information is not usable, or even in a case where the reliability of the network information is low, digital broadcast reception device  100  can make it possible to find the service, which is equivalent to the service now being viewed by the user, from the whole of the receivable services, thus making it possible for the user to continuously view the same service in a case where the user moves across a variety of broadcast areas. 
     Moreover, in digital broadcast reception device  100  of this exemplary embodiment, in a case of switching the service between the main reception system and the sub reception system, timing of switching output signal So (for example, timing of switching output signal So from channel signal Sc 1  to channel signal Sc 2 ) is adjusted based on each of the content information. In this way, at a time when output signal So is switched, the user can continuously view a desired service without feeling that something is wrong. 
     Hereinafter, a description will be made of the operations of digital broadcast reception device  100  in this exemplary embodiment. 
     [1-2-2. Operations of Digital Broadcast Reception Device] 
     A description will be made of the operations of digital broadcast reception device  100  in this exemplary embodiment with reference to  FIG. 3 . 
       FIG. 3  is a flowchart showing an example of the operations of digital broadcast reception device  100  in the first exemplary embodiment. 
     The flowchart of  FIG. 3  is executed by controller  130  of digital broadcast reception device  100 . The flowchart of  FIG. 3  is started in a state where the specific channel (specific service) in the digital broadcast is selected by an operation of the user, and the like in digital broadcast reception device  100 . 
     First, controller  130  performs main reception system demodulation processing (Step S 101 ). 
     The main reception system demodulation processing is processing, in the main reception system, for performing signal processing such as demodulation of a signal that indicates the channel selected by the user, and for outputting a main signal that represents the service to be viewed by the user. Details of the main reception system demodulation processing will be described later. 
     Hereinafter, a description will be made of an example where the main reception system is sequentially switched between first received signal processor  110  and second received signal processor  120 . Note that the main reception system in an initial state is assumed to be set to first received signal processor  110 . In this case, channel signal Sc 1  is output as the main signal. 
     Next, controller  130  performs sub reception system demodulation processing (Step S 102 ). 
     The sub reception system demodulation processing is processing, in the sub reception system, for selecting a channel different from the channel selected in the main reception system, and for selectively demodulating a sub signal that represents the same service as that of the main signal. In this operation example, the sub reception system in the initial state is set to second received signal processor  120 , and channel signal Sc 2  becomes the sub signal. 
     Note that the main reception system may be set to second received signal processor  120 , and the sub reception system may be set to first received signal processor  110 . In that case, channel signal Sc 2  is output as the main signal, and channel signal Sc 1  is output as the sub signal. 
     In the sub reception system demodulation processing, controller  130  functions as same signal identifier  131 , and compares respective pieces of the content information, which are included in the main signal and the sub signal, with each other, and thereby determines whether or not the contents of the services of the main signal and the sub signal are the same. Details of the sub reception system demodulation processing will be described later. 
     Note that the main reception system demodulation processing (Step S 101 ) and the sub reception system demodulation processing (Step S 102 ) may be executed concurrently (in parallel). 
     Next, controller  130  functions as signal strength determiner  132 , and checks receiving states of both of the signals, which are main signal Sc 1  and sub signal Sc 2  (Step S 103 ). Note that this main signal Sc 1  refers to channel signal Sc 1 , and this sub signal Sc 2  refers to channel signal Sc 2 . 
     Specifically, controller  130  measures individual signal strengths of channel signal Sc 1  demodulated in first received signal processor  110  and channel signal Sc 2  demodulated in second received signal processor  120 . 
     Next, controller  130  functions as signal strength determiner  132 , and compares the receiving states of main signal Sc 1  and sub signal Sc 2 , which are checked in Step S 103 . Then, controller  130  determines whether or not the received state of sub signal Sc 2  is better than the receiving state of main signal Sc 1  (Step S 104 ). 
     Specifically, the determination of controller  130  (signal strength determiner  132 ) in Step S 104  is performed based on whether or not the signal strength of sub signal Sc 2  is higher than the signal strength of main signal Sc 1 . In a case of having determined in Step S 104  that the received state of sub signal Sc 2  is not better than the receiving state of main signal Sc 1  (No in Step S 104 ), controller  130  returns to Step S 101 , and repeats the processing of Step S 101  and after. 
     Meanwhile, in a case of having determined in Step S 104  that the receiving state of sub signal Sc 2  is better than the receiving state of main signal Sc 1  (Yes in Step S 104 ), controller  130  functions as delay synchronizer  133 , and performs processing of Steps S 105  and S 106 . 
     That is, in a case of having determined that the receiving state of second received signal processor  120  is better than the receiving state of first received signal processor  110  (Yes in Step S 104 ), controller  130  switches the main reception system and the sub reception system so that an output of second received signal processor  120  can become “main signal” in Steps S 105 , S 106 . At this time, if timing (output timing of main signal Sc 1 ) when main signal Sc 1  is output from first received signal processor  110  and timing (output timing of sub signal Sc 2 ) when sub signal Sc 2  is output from second received signal processor  120  as a switching destination are not synchronized in advance with each other, then it is possible that both of the output timing may be shifted from each other. 
     Accordingly, controller  130  functions as delay synchronizer  133 , and synchronizes both of the output timing with each other, which are: the timing of outputting main signal Sc 1  from first received signal processor  110 ; and the timing of outputting sub signal Sc 2  from second received signal processor  120  (Step S 105 ). 
     Specifically, first, controller  130  compares audio data of main signal Sc 1  and audio data of sub signal Sc 2  with each other, and senses which output timing of main signal Sc 1  and sub signal Sc 2  is earlier. In a case where the output timing of sub signal Sc 2  is earlier than the output timing of main signal Sc 1 , controller  130  extends a buffer period of holding sub signal Sc 2  in buffer memory  102  so as to delay the output timing of sub signal Sc 2  in matching with the output timing of main signal Sc 1 . Meanwhile, in a case where the output timing of main signal Sc 1  is earlier than the output timing of sub signal Sc 2 , controller  130  reduces the buffer period for sub signal Sc 2  so as to advance the output timing of sub signal Sc 2  in matching with the output timing of main signal Sc 1 . 
     In a case where a delay time between main signal Sc 1  and sub signal Sc 2  is larger than a maximum value of the buffer period, and the like, it is possible that the pieces of the output timing of both of the signals cannot be synchronized with each other. Accordingly, based on the content information included in main signal Sc 1 , controller  130  senses timing of changing a scene, and so on in a program under broadcast in main signal Sc 1 , and switches output signal So from main signal Sc 1  to sub signal Sc 2  at the timing sensed (Step S 106 ). 
     For example, controller  130  may determine such switching timing from main signal Sc 1  to sub signal Sc 2  based on a change of the audio data of main signal Sc 1 . Alternatively, for example, controller  130  may compare IDR (Instantaneous Decoding Refresh) pictures (frames) with each other, may thereby sense a large change of the image data across the whole of the screen, and may determine the timing concerned. Alternatively, controller  130  may perform the switching from main signal Sc 1  to sub signal Sc 2  in a period of a commercial message or at start timing of the commercial message based on a predetermined flag that indicates a broadcast period of the commercial message. 
     As described above, digital broadcast reception device  100  switches output signal So from main signal Sc 1  to sub signal Sc 2  in matching with the timing of the scene change in the service being viewed by the user at present, and can thereby switch the channel while reducing such a feeling of discomfort, which is given to the user. 
     After Step S 106 , controller  130  sets second received signal processor  120  as the main reception system, and in addition, sets first received signal processor  110  as the sub reception system, and performs the processing of Step S 101  and after one more time. 
     By the processing described above, in digital broadcast reception device  100 , the main reception system and the sub reception system are alternately switched in response to a change of the receiving state, and accordingly, it becomes possible for the user who gets in the mobile body to continuously view the same service while the user is moving. 
     Moreover, in digital broadcast reception device  100 , data substantially equivalent to a few seconds is held in buffer memory  102 , whereby it becomes possible to restore a signal from the data in buffer memory  102  in a case of performing the switching from main signal Sc 1  to sub signal Sc 2 . In this way, it becomes possible to reduce the feeling of wrongness, which is given to the user in the case of switching output signal So from main signal Sc 1  to sub signal Sc 2  by delay synchronizer  133 . 
     Note that, in digital broadcast reception device  100 , at a time of switching output signal So from main signal Sc 1  to sub signal Sc 2 , the delays of main signal Sc 1  and the delay of sub signal Sc 2  do not have to be synchronized with each other. For example, output signal So is switched from main signal Sc 1  to sub signal Sc 2  in matching with the period of the commercial message, and the like, whereby such a feeling of discomfort, which may be possibly sensed by the user due to a time shift between main signal Sc 1  and sub signal Sc 2 , can be reduced. Moreover, in a case where the signal strength of main signal Sc 1  falls down below a predetermined threshold value, controller  130  may instantaneously switch output signal So from main signal Sc 1  to sub signal Sc 2  without synchronizing the delays of main signal Sc 1  and sub signal Sc 2  with each other. 
     [1-2-2-1. Main Reception System Demodulation Processing] 
     Next, a description will be made of the main reception system demodulation processing of step S 101  of  FIG. 3  with reference to  FIG. 4 . 
       FIG. 4  is a flowchart showing an example of the main reception system demodulation processing executed in digital broadcast reception device  100  in the first exemplary embodiment. 
     The flowchart of  FIG. 4  is executed by controller  130 , and is repeatedly performed in a predetermined cycle (for example, 30 fps (frames per second)). Hereinafter, a description will be made of a case where the main reception system is first received signal processor  110 . Note that second received signal processor  120  may be the main reception system. In that case, following first received signal processor  110  just needs to be interpreted as second received signal processor  120 , and digital broadcast signal Sd 1  just needs to be interpreted as digital broadcast signal Sd 2 . 
     First, controller  130  controls first received signal processor  110  to demodulate a channel, which is selected in advance by the user, from digital broadcast signal Sd 1  received by antenna device  101  (Step S 201 ). 
     At this time, for digital broadcast signal Sd 1  of the selected service, first received signal processor  110  sequentially implements the demodulation, the demultiplexing and the decoding in demodulating circuit  111 , demultiplexing circuit  112  and signal decoding circuit  113  (refer to  FIG. 1 ), and outputs the signal, which is subjected to these pieces of the processing, as main signal Sc 1  to controller  130 . 
     Next, controller  130  outputs main signal Sc 1 , which is demodulated by first received signal processor  110 , as output signal So to the outside while holding main signal Sc 1  in buffer memory  102  at any time (Step S 202 ). 
     In this way, controller  130  ends the processing of Step S 101  of  FIG. 3 , and proceeds to the processing of Step S 102 . 
     [1-2-2-2. Sub Reception System Demodulation Processing] 
     Next, a description will be made of the sub reception system demodulation processing of step S 102  of  FIG. 3  with reference to  FIG. 5 . 
       FIG. 5  is a flowchart showing an example of the sub reception system demodulation processing executed in digital broadcast reception device  100  in the first exemplary embodiment. 
     The flowchart of  FIG. 5  is executed by controller  130 . Hereinafter, a description will be made of a case where the sub reception system is second received signal processor  120 . Note that first received signal processor  110  may be the sub reception system. In that case, following second received signal processor  120  just needs to be interpreted as first received signal processor  110 , and digital broadcast signal Sd 2  just needs to be interpreted as digital broadcast signal Sd 1 . 
     First, controller  130  controls second received signal processor  120  to demodulate a channel, which is other than that of the main signal, from digital broadcast signal Sd 2  received by antenna device  101  (Step S 301 ). 
     Next, controller  130  functions as same signal identifier  131 , analyzes respective pieces of the content information, which are included in main signal Sc 1  and sub signal Sc 2 , and compares individual analysis results of main signal Sc 1  and sub signal Sc 2  with each other (Step S 302 ). 
     For example, controller  130  extracts the individual service names as the pieces of the content information, which are included in main signal Sc 1  and sub signal Sc 2 , and compares the extracted service names with each other. A determination method for the same service, which is based on other content information (audio data or image data), will be described later. 
     Next, controller  130  functions as same signal identifier  131 , and based on a comparison result of main signal Sc 1  and sub signal Sc 2 , determines whether or not the service of sub signal Sc 2  is the same as (or similar to) the service of main signal Sc 1  (Step S 303 ). 
     For example, it is assumed that the service name extracted from main signal Sc 1  is “MHK Osaka”, and that the service name extracted from sub signal Sc 2  is “MHK Kyoto”. In a case where the extracted service names are similar to each other like “MHK Osaka” and “MHK Kyoto”, then based on a fact that text data “MHK” in head portions coincide with each other, controller  130  determines that the service of sub signal Sc 2  is the same as (or similar to) the service of main signal Sc 1  (Yes in Step S 303 ). 
     In this example, “MHK” in the head portions of the text data represent a key station. Then, based on a fact that the text data, each of which represents the key station (that is, first three characters of each of the text data), coincide with each other, controller  130  determines that the service of sub signal Sc 2  is the same as (or similar to) the service of the main signal Sc 1  (Yes in Step S 303 ). For example, in controller  130  as same signal identifier  131 , the uniformity (or similarity) between the service of main signal Sc 1  and the service of sub signal Sc 2  may be determined in this way. That is, in such a case where a plurality of characters (for example, three characters) predetermined from the head in each of the text data which represent the service names coincide with those from the head in the other text data, controller  130  as same signal identifier  131  may determine that the service of sub signal Sc 2  is the same as (or similar to) the service of the main signal Sc 1  (Yes in Step S 303 ). However, such a criterion of the determination is merely an example, and the present disclosure is never limited to this operation example. 
     In a case of having determined that the service of sub signal Sc 2  is not the same as (or similar to) the service of main signal Sc 1  (No in Step S 303 ), controller  130  changes the channel being selected in second received signal processor  120  (Step S 304 ). Controller  130  repeats the processing of Step S 301  and after in the changed channel. 
     In a case of having determined that the service of sub signal Sc 2  is the same as (or similar to) the service of main signal Sc 1  (Yes in Step S 303 ), controller  130  ends the processing of Step S 102  of  FIG. 3 , and proceeds to the processing of Step S 103 . 
     Until it is determined by the above-described processing that the service of sub signal Sc 2  is the same as (or similar to) the service of main signal Sc 1 , controller  130  repeatedly changes the channel of sub signal Sc 2 . In this way, in digital broadcast reception device  100 , such a channel that supplies substantially the same service as that of main signal Sc 1  is selected (searched) in the sub reception system. 
     [1-2-2-3. Regarding Determination Method for Same Service] 
     Hereinafter, a description will be made of a modification example of the determination method for the same service in the sub reception system demodulation processing. 
     In the sub reception system demodulation processing, the determination of the same service may be performed by using the video signals included in main signal Sc 1  and sub signal Sc 2 . For example, in Step S 302  of  FIG. 5 , controller  130  may extract image data of a logotype and the like of the broadcast station from the individual video signals included in main signal Sc 1  and sub signal Sc 2 , and may compare the extracted image data with each other. 
     A description will be made of an extraction method for the image data of the logotype with reference to  FIG. 6A  to  FIG. 6D . 
       FIG. 6A  to  FIG. 6D  are diagrams showing an example of a display video by the video signal output from digital broadcast reception device  100  in the first exemplary embodiment.  FIG. 6A  to  FIG. 6D  show a first display example to fourth display example of the video signal by the digital broadcast. 
     In image data D 1  of the whole the screen, logotype D 2  is usually fixed to the screen, and does not move on the screen. Accordingly, in this exemplary embodiment, for example, based on information of motion vectors included in main signal Sc 1  and sub signal Sc 2 , controller  130  may take out image data in which a vector quantity becomes substantially zero (an image stills), and may extract the image data of the logotype. 
     Moreover, as shown in  FIG. 6A  to  FIG. 6D , a display position of logotype D 2  is usually disposed on a corner of the screen. Therefore, such an extraction target of logotype D 2  does not have to be image data D 1  of the whole of the screen. In this exemplary embodiment, as shown in  FIG. 6A  to  FIG. 6D , controller  130  may set, as such extraction targets, predetermined regions  601  to  604  on four corners of image data D 1 , and may extract logotype D 2 . Controller  130  may compare shapes, colors, locations and the like of the image data of logotypes D 2 , which are individually extracted from main signal Sc 1  and sub signal Sc 2 , with each other, and may determine whether or not the services are the same service. 
     Note that the image data of such comparison targets are not limited to the image data of logotype D 2 . For example, still images (images in which vector quantities of motion vectors become substantially zero), which are individually included in main signal Sc 1  and sub signal Sc 2 , may be compared with each other. 
     Moreover, in the sub reception system demodulation processing, the determination as to whether or not the services are the same service may be performed by using the audio signals individually included in main signal Sc 1  and sub signal Sc 2 . For example, controller  130  may hold, in buffer memory  102 , individual audio data of a predetermined period (for example, five seconds) in main signal Sc 1  and sub signal Sc 2 , may compare the held audio data with each other, and may determine whether or not portions similar to each other are present between main signal Sc 1  and sub signal Sc 2 . 
     The above-described determination may be performed, for example, when controller  130  determines that the service names are similar to each other. In this way, controller  130  can omit the comparison of the audio data (or the image data) when the service names are not similar to each other, and the determination as to whether or not the services are the same service can be performed efficiently. 
     [1-3. Effects and the Like] 
     As described above, in this exemplary embodiment, a digital broadcast reception device includes: a first received signal processor; a second received signal processor; and a controller. The first received signal processor receives a signal, which indicates a first channel in a digital broadcast, and outputs a first channel signal obtained by demodulating the received signal. The second received signal processor receives a signal, which indicates a second channel different from the first channel, and generates a second channel signal obtained by demodulating the received signal. The controller controls operations of the first received signal processor and the second received signal processor. The controller selects the second channel based on pieces of information regarding services provided by respective channels, the pieces of information being individually included in the first channel signal and the second channel signal, in a period while the first received signal processor is outputting the first channel signal. The controller switches a signal to be outputted from either one signal of the first channel signal and the second channel signal to other one of the first channel signal and the second channel signal based on individual receiving states of the first channel under output and the selected second channel. 
     Note that digital broadcast reception device  100  is an example of the digital broadcast reception device. First received signal processor  110  is an example of the first received signal processor. Second received signal processor  120  is an example of the second received signal processor. Controller  130  is an example of the controller. Digital broadcast signal Sd 1  is an example of the signal that indicates the first channel. Channel signal Sc 1  is an example of the first channel signal. Digital broadcast signal Sd 2  is an example of the signal that indicates the second channel. Channel signal Sc 2  is an example of the second channel signal. 
     For example, in the example shown in the first exemplary embodiment, digital broadcast reception device  100  includes: first received signal processor  110 ; second received signal processor  120 ; and controller  130 . First received signal processor  110  receives digital broadcast signal Sd 1 , which indicates the first channel in the digital broadcast, and outputs the first channel signal (channel signal Sc 1 ) obtained by demodulating received digital broadcast signal Sd 1 . Second received signal processor  120  receives digital broadcast signal Sd 2 , which indicates the second channel different from the first channel, and generates the second channel signal (channel signal Sc 2 ) obtained by demodulating received digital broadcast signal Sd 2 . Controller  130  controls operations of first received signal processor  110  and second received signal processor  120 . In a period while first received signal processor  110  is outputting the first channel signal (channel signal Sc 1 ), controller  130  selects the second channel based on the pieces of information regarding the contents of the respective services, which are individually included in the first channel signal (channel signal Sc 1 ) and the second channel (channel signal Sc 2 ). Controller  130  switches a signal to be outputted from channel signal Sc 1  to channel signal Sc 2  based on the individual receiving states of the first channel under output and the selected second channel. 
     In this way, in digital broadcast reception device  100 , the second channel (channel signal Sc 2 ) is selected based on the information regarding the services provided by the respective channels, which are individually included in the first channel signal (channel signal Sc 1 ) and the second channel signal (channel signal Sc 2 ). In this way, the user who views the service by using digital broadcast reception device  100  mounted on the mobile body can continuously view the same service in response to the receiving state of the digital broadcast while the user is moving. 
     Based on the pieces of information regarding the services, which are individually included in the first channel signal and the second channel signal, the controller of the digital broadcast reception device may select the second channel so that the service provided by the second channel can have the same content as the content of the service provided by the first channel. 
     For example, in the example shown in the first exemplary embodiment, in digital broadcast reception device  100 , based on the pieces of information regarding the services, which are individually included in the first channel signal (channel signal Sc 1 ) and the second channel signal (channel signal Sc 2 ), controller  130  selects the second channel so that the service provided by the second channel can have the same content as the content of the service provided by the first channel. 
     In this way, the user who views the service by using digital broadcast reception device  100  mounted on the mobile body can continuously view the same service in response to the receiving states of the first channel signal (channel signal Sc 1 ) and the second channel signal (channel signal Sc 2 ) while the user is moving. 
     Each of the pieces of information regarding the service concerned may include at least one of (i) the service name, (ii) the event name, and (iii) the audio data and the image data in the service concerned. Moreover, the image data may include image data which indicates a logotype regarding the service. 
     Note that the content information is an example of the information regarding the service. The logotype (logotype D 2 ) of the broadcast station is an example of the logotype regarding the service concerned. 
     For example, in the example shown in the first exemplary embodiment, in digital broadcast reception device  100 , the content information regarding the service concerned includes at least one of (i) the service name, (ii) the event name, and (iii) the audio data and the image data in the service concerned. Moreover, the image data includes the image data which indicates the logotype regarding the service. 
     In this way, digital broadcast reception device  100  can select the second channel, which is provided by the sub reception system, based not on the network information but on the content information. 
     The controller of the digital broadcast reception device may select the second channel by using the broadcast IDs individually included in the first channel signal and the second channel signal. 
     For example, in the example shown in the first exemplary embodiment, in digital broadcast reception device  100 , controller  130  may select the second channel (channel signal Sc 2 ) by using a plurality of broadcast IDs, which are individually included in the first channel signal (channel signal Sc 1 ) and the second channel signal (channel signal Sc 2 ). For example, controller  130  may limit a selection target of the second channel, which is provided by the sub reception system, to a range where the ONID is the same as that of the first channel. Under this condition, controller  130  may compare the TSIDs and the SIDs, which are individually included in channel signal Sc 1  and channel signal Sc 2 , with each other. In this way, in digital broadcast reception device  100 , efficiency can be brought to the selection of the second channel, which is performed in controller  130 . 
     Moreover, in the example shown in the first exemplary embodiment, in digital broadcast reception device  100 , controller  130  selects the second channel while analyzing the information regarding the service concerned in the period of outputting the first channel signal (channel signal Sc 1 ). Controller  130  compares the individual receiving states of the first channel under output and the selected second channel with each other, and based on a result of this comparison, switches the signal to be outputted from the first channel signal (channel signal Sc 1 ) to the second channel signal (channel signal Sc 2 ). 
     In this way, in digital broadcast reception device  100 , at any time while the first channel signal (channel signal Sc 1 ) is being output, the information regarding the service concerned is analyzed, and the second channel is selected. Therefore, the user who views the service by using digital broadcast reception device  100  can continuously view the service in response to the individual receiving states of channel signal Sc 1  and channel signal Sc 2  while the user is moving. 
     In the case of switching the signal to be outputted from the first channel signal to the second channel signal, the controller of the digital broadcast reception device may synchronize the delays of the first channel signal and the second channel signal with each other. 
     For example, in the example shown in the first exemplary embodiment, in digital broadcast reception device  100 , in the case of switching the signal to be outputted from the first channel signal (channel signal Sc 1 ) to the second channel signal (channel signal Sc 2 ), controller  130  synchronizes the delays of the first channel signal (channel signal Sc 1 ) and second channel signal (channel signal Sc 2 ) with each other. 
     In this way, when the channel being viewed at present by the user is switched from the first channel to the second channel, digital broadcast reception device  100  can reduce the feeling of discomfort, which may be possibly sensed by the user due to a shift of the timing, which occurs by a fact that the first channel signal and the second channel signal are not synchronized with each other. 
     The controller of the digital broadcast reception device may switch the signal to be outputted from the first channel signal to the second channel signal at the time of the scene change or during the period of the commercial message in the program under broadcast in the first channel signal. 
     For example, in the example shown in the first exemplary embodiment, in digital broadcast reception device  100 , controller  130  switches the signal to be outputted from the first channel signal (channel signal Sc 1 ) to the second channel signal (channel signal Sc 2 ) at the time of the scene change or during the period of the commercial message in the program under broadcast. 
     In this way, when the channel being viewed at present by the user is switched from the first channel to the second channel, even in the case where the first channel signal and the second channel signal are not synchronized with each other, digital broadcast reception device  100  can switch the service in response to the scene or content of the service, and accordingly, the feeling of discomfort, which may be possibly sensed by the user, can be reduced. 
     SECOND EXEMPLARY EMBODIMENT 
     Hereinafter, a second exemplary embodiment will be described with reference to  FIG. 7  and  FIG. 8 . 
     In the first exemplary embodiment, the description has been made of the operation example where the channel of the same service as that of the main reception system is searched in the sub reception system. In this exemplary embodiment, a description will be made of a method for accumulating search results for the channel of the same service by using position information. 
     [2-1. Configuration] 
     Hereinafter, next, a description will be made of digital broadcast reception device  100 A in the second exemplary embodiment. 
     Note that, in digital broadcast reception device  100 A shown in the second exemplary embodiment, the same reference numerals are assigned to constituents which perform substantially the same operations as those of the constituents provided in digital broadcast reception device  100  shown in the first exemplary embodiment, and a description of these constituents of digital broadcast reception device  100 A is omitted. Hereinafter, different points from those of digital broadcast reception device  100  shown in the first exemplary embodiment will be mainly described, and in some cases, a description of substantially the same operations as those of digital broadcast reception device  100  shown in the first exemplary embodiment is omitted. 
       FIG. 7  is a block diagram schematically showing a configuration example of digital broadcast reception device  100 A in the second exemplary embodiment. 
     As shown in  FIG. 7 , digital broadcast reception device  100 A has substantially the same configuration as that of digital broadcast reception device  100  described in the first exemplary embodiment. In addition to this configuration, digital broadcast reception device  100 A further includes: position information acquisition device  140 ; and channel information storage device  150 . 
     Position information acquisition device  140  is composed, for example, of a GPS (Global Positioning System) module. Position information acquisition device  140  receives a radio wave (GPS information) from a GPS satellite, and determines position information that indicates a latitude and longitude of a location where the radio wave is received. Position information acquisition device  140  is an example of a position information acquisition controller that acquires a position of digital broadcast reception device  100 A (subject device). 
     Channel information storage device  150  is composed, for example, of a storage medium such as a flash memory. Channel information storage device  150  stores channel information table Da. Channel information table Da is a data table for associating (at least) two channels, which are determined to be the same service in same signal identifier  131 , and position information, which indicates a position where this determination is made, with each other, and managing the associated two channels and position information. Channel information storage device  150  is an example of a storage that stores search results of the channel of the same service. 
     [2-2. Operations] 
     Hereinafter, operations of digital broadcast reception device  100 A in this exemplary embodiment will be described with reference to  FIG. 8 . 
       FIG. 8  is a flowchart showing an example of sub reception system demodulation processing executed in digital broadcast reception device  100 A in the second exemplary embodiment. 
     Digital broadcast reception device  100 A in this exemplary embodiment acquires a current position of digital broadcast reception device  100 A, which is mounted on the mobile body, at any time by position information acquisition device  140 , and performs the sub reception system demodulation processing while referring to and updating channel information table Da. Specifically, controller  130  of digital broadcast reception device  100 A executes the flowchart shown in  FIG. 3 , and in Step S 102  shown in  FIG. 3 , performs the sub reception system demodulation processing shown in  FIG. 8 . 
     In the flowchart of  FIG. 8 , controller  130  first acquires position information, which indicates the current position of digital broadcast reception device  100 A, from position information acquisition device  140  (Step S 310 ). 
     Next, controller  130  refers to channel information table Da, and determines whether or not the channel, which is being viewed at present in main signal Sc 1 , is stored in channel information table Da in association with position information within a predetermined range (for example, a radius of 1 km) from the position information acquired in Step S 310  (Step S 311 ). 
     In a case of having determined in Step S 311  that the channel being viewed in main signal Sc 1  is not stored in channel information table Da (No in Step S 311 ), controller  130  executes the respective pieces of the processing of Step S 301  to Step S 304  in a similar way to the first exemplary embodiment. 
     In a case of having made a determination of Yes as a result of executing the processing of Step S 303 , controller  130  associates the respective channels of main signal Sc 1  and sub signal Sc 2 , which are determined in Step S 303  to be the same service, and the position information (position information acquired in Step S 310 ) of the current position, with each other, and stores the associated channels and position information in channel information table Da (Step S 312 ). 
     In a case of having determined in Step S 311  that the channel being viewed in main signal Sc 1  is stored in channel information table Da (Yes in Step S 311 ), controller  130  demodulates another channel, which is associated with the channel of main signal Sc 1  in channel information table Da, by the sub reception system (Step S 313 ). 
     In this way, controller  130  ends the sub reception system demodulation processing (Step S 102 ) of  FIG. 3 , and advances the processing to Step S 103 . 
     In digital broadcast reception device  100 A, when two channels, which are different from each other and provide substantially the same service, are determined between the main reception system and the sub reception system by a fact that the processing described above is executed (Yes in Step S 303 ), then a correspondence relationship (search result) between these channels is accumulated in channel information table Da in association with the position information (position information acquired in step S 310 ) of the current position (Step S 312 ). 
     Thereafter, in a case where the mobile body on which digital broadcast reception device  100 A is mounted passes through a same position as (or a position close to) the position concerned (that is, the position accumulated in channel information table Da), if the user who uses digital broadcast reception device  100 A views the same service as the service concerned (that is, the service provided by the channel accumulated in channel information table Da), then, without performing the processing of Step S 301  to Step S 304  one more time, controller  130  of digital broadcast reception device  100 A can demodulate another channel, which provides the same service as the service being viewed by the user at present, by the sub reception system (Step S 313 ). Therefore, in digital broadcast reception device  100 A, a processing time can be reduced, and a load related to the sub reception system demodulation processing can be reduced. 
     [2-3. Effects and the Like] 
     As described above, in this exemplary embodiment, the digital broadcast reception device further includes: a position information acquisition controller; and a storage. The position information acquisition controller acquires position information that indicates a position of the digital broadcast reception device concerned. The storage stores the position information when the second channel is selected and the first channel and the second channel in association with each other. The controller selects the second channel based on the position information acquired by the position information acquisition controller and based on the information stored in the storage. 
     Note that digital broadcast reception device  100 A is an example of the digital broadcast reception device. Position information acquisition device  140  is an example of the position information acquisition controller. Channel information storage device  150  is an example of the storage. 
     For example, in the example shown in the second exemplary embodiment, digital broadcast reception device  100 A further includes: position information acquisition device  140 ; and channel information storage device  150  in addition to the configuration of digital broadcast reception device  100  shown in  FIG. 1 . Position information acquisition device  140  acquires the position information that indicates the position of digital broadcast reception device  100 A. Channel information storage device  150  stores the position information when the second channel is selected and the first channel and the second channel in association with each other. Controller  130  selects the second channel based on the position information acquired by position information acquisition device  140  and based on the information stored in channel information storage device  150 . 
     In this way, in digital broadcast reception device  100 A, every time when the second channel is selected by the analysis for the information regarding the service mentioned above, the position information and the first channel and the second channel are stored in channel information storage device  150  in association with each other. After such storing is performed, controller  130  can select the second channel based on the information stored in channel information storage device  150 . Therefore, efficiency when the second channel is selected can be enhanced. 
     OTHER EXEMPLARY EMBODIMENT 
     As described above, the description is made of the first and second exemplary embodiments as illustration of the technology disclosed in the present application. However, the technology in the present disclosure is not limited to this, and is applicable also to exemplary embodiments, which are subjected to alteration, replacement, addition, omission, and the like. Moreover, it is also possible to constitute new exemplary embodiments by combining the respective constituent elements, which are described in the foregoing first and second exemplary embodiments, with one another. 
     Accordingly, hereinafter, other exemplary embodiment will be illustrated. 
     In the first and second exemplary embodiments described above, the description is made of the configuration example where digital broadcast reception device  100  ( 100 A) is mounted on the mobile body such as a vehicle. However, the present disclosure is never limited to this configuration. Digital broadcast reception device  100  ( 100 A) may be mounted, for example, on a mobile terminal. In this case, in a case where a holder of the mobile terminal moves by walk, bicycle or the like, or uses a vehicle, a train, a vessel, an aircraft or the like, the switching of output signal So (the switching from main signal Sc 1  to sub signal Sc 2 ) may be performed. Moreover, the mobile body on which digital broadcast reception device  100  ( 100 A) is mounted is not limited to the vehicle, and for example, may be a train, a vessel, an aircraft or the like. 
     Moreover, in the first and second exemplary embodiments described above, the description is made of the operation example where, when the switching of output signal So (the switching from main signal Sc 1  to sub signal Sc 2 ) is performed in digital broadcast reception device  100  ( 100 A), the main reception system and the sub reception system are interchanged with each other between first received signal processor  110  and second received signal processor  120 . However, the present disclosure is never limited to this configuration. In digital broadcast reception device  100  ( 100 A), in first received signal processor  110  and second received signal processor  120 , the main reception system and the sub reception system may be fixed, respectively. 
     Moreover, in the first and second exemplary embodiments described above, the description is made of the configuration example where digital broadcast reception device  100  ( 100 A) includes two reception system, which are first received signal processor  110  and second received signal processor  120 . However, the present disclosure is never limited to this configuration. Digital broadcast reception device  100  ( 100 A) may include three or more reception systems. In this case, one reception system among the plurality of reception systems may be set as the main reception system, and the rest thereof may be set as the sub reception systems. Moreover, controller  130  may search a plurality of the channels of the same service as that of the main reception system by using a plurality of the sub reception systems. 
     Moreover, the digital broadcast to be received by digital broadcast reception device  100  ( 100 A) may be a terrestrial digital broadcast, or may be a BS (Broadcasting Satellite) broadcast or a CS (Communications Satellite) broadcast. Moreover, the standard of the digital broadcast may be ISDB (ISDB-T, ISDB-TB, ISDB-TS) or DVB, or may be ATSC (Advanced Television Systems Committee). 
     As described above, the description is made of the first and second exemplary embodiments as illustration of the technology in the present disclosure. For this purpose, the accompanying drawings and the detailed description are provided. 
     Hence, the constituent elements described in the accompanying drawings and the detailed description can include not only constituent elements, which are essential for solving the problems, but also constituent elements, which are mentioned for illustrating the above-described technology and are not essential for solving the problems. Therefore, it should not be immediately recognized that such inessential constituent elements are essential by the fact that the inessential constituent elements are described in the accompanying drawings and the detailed description. 
     Moreover, the above-mentioned first and second exemplary embodiments illustrate the technology in the present disclosure, and accordingly, can be subjected to various types of alterations, substitutions, additions, omissions and the like within the scope of claims or equivalents thereof. 
     INDUSTRIAL APPLICABILITY 
     The present disclosure is applicable to a receiver of a digital broadcast. 
     Specifically, the present disclosure is applicable to a receiver such as an in-vehicle receiver, which is mounted on a mobile body (for example, a vehicle, a train, a vessel, an aircraft or the like), a receiver mounted on a mobile terminal, or the like. 
     REFERENCE MARKS IN THE DRAWINGS 
     
         
           100 ,  100 A digital broadcast reception device 
           101  antenna device 
           102  buffer memory 
           110  first received signal processor 
           111 ,  121  demodulating circuit 
           112 ,  122  demultiplexing circuit 
           113 ,  123  signal decoding circuit 
           120  second received signal processor 
           130  controller 
           131  same signal identifier 
           132  signal strength determiner 
           133  delay synchronizer 
           140  position information acquisition device 
           150  channel information storage device