Apparatus and method for receiving digital broadcast

The present invention relates to a digital broadcast receiving device and a digital broadcast receiving method, and particularly relates to a digital broadcast receiving device and a digital broadcast receiving method for receiving a digital broadcast using a plurality of antennas in a mobile body such as an automobile.

In Japan's terrestrial digital broadcasting, the frequencies of broadcast radio waves transmitted by each broadcasting station are different. For this reason, if a digital broadcast receiver mounted on a mobile body such as an automobile goes out of the reception area of a certain broadcast station while watching a program of a certain broadcast station, the digital broadcast receiver cannot receive the program that has been watched until then. I will end up. Therefore, when crossing the reception area of a broadcasting station, it is necessary to search for a receivable broadcasting station. This channel search process has a problem that it takes time because the process of confirming the presence or absence of broadcast waves is repeated for all 50 channels.

In order to reduce this time, for example, there is a broadcast receiving device as disclosed in Patent Document 1. In this broadcast receiving device, the control unit controls the tuner unit to detect one receivable broadcasting station, and the broadcasting receiving device is currently based on the identification information of this broadcasting station and the station-region conversion table. Identify the area where you are located. Then, the control unit detects the physical channels of the broadcasting stations that can be received in this area based on the specified area and the area-station conversion table, verifies whether each physical channel can actually receive, and actually Only the received physical channels are stored in the viewable frequency table, and the physical channels to be viewed by the user are selected from the physical channels stored in this table.

<patcit num="1"><text>JP-A-2007-288603</text></patcit>

<p> However, with the above-mentioned broadcast receiving device, the broadcast program cannot be viewed during the channel search. The present invention has been devised in view of the above problems, and an object of the present invention is to enable viewing of a program even during a channel search, and further, occurrence of reception failure such as interruption of video / audio signals of the program. It is an object of the present invention to provide a digital broadcast receiving device and a digital broadcast receiving method capable of suppressing the above.</p>

<p> In order to achieve the above object, the present invention is a digital broadcast receiving device that receives digital broadcast signals transmitted in a first layer in which video / audio signals are resistant to noise by layer transmission and a second layer in which video / audio signals are weak in noise immunity. From the plurality of receiving units having a receiving antenna, a channel selection unit, and a demodulating unit, a diversity synthesizing unit that diversity-synthesizes the output signals of the plurality of receiving units, and digital data output from the diversity synthesizing unit. A decoding unit that decodes the digital data of the first layer and the digital data of the second layer, respectively, and the video / audio signal of the first layer and the video / audio signal of the second layer output from the decoding unit. A switching unit that selects and outputs one of the audio signals, a program information extraction unit that extracts channel information from the digital data output from the diversity synthesis unit, and the current position of the digital broadcast receiving device. The reception area storage unit is a position information acquisition unit that acquires the indicated position information, a reception area storage unit that stores a channel list corresponding to the broadcast area, and the current position of the digital broadcast receiver indicated in the position information. When the broadcast area of the currently receiving channel stored in is exceeded, the channel search is started, and at the time of the channel search, the plurality of receiving units are divided into two and one of them is made to perform the channel search, and the other. Is characterized in that it is provided with a control unit for receiving the video / audio signal and instructing the switching unit to select the video / audio signal of the first layer.</p><p> Further, the present invention is a diversity receiving method for receiving a digital broadcast signal transmitted in a first layer in which video / audio signals are resistant to noise by layer transmission and a second layer in which video / audio signals are weak in noise immunity. From the reception step having a plurality of receivers that receive, select, and demote the digital broadcast signal, the diversity synthesis step that diversity-synthesizes the output signal of the reception step, and the digital data output from the diversity synthesis step. A decoding step that decodes the digital data of the first layer and the digital data of the second layer, respectively, and the video / audio signal of the first layer and the video / audio signal of the second layer output from the decoding step. A switching step of selecting and outputting one of the audio signals, a program information extraction step of extracting channel information from the digital data output from the diversity synthesis step, and the current position of the digital broadcast receiving device are set. It has a position information acquisition step for acquiring the indicated position information and a reception area storage step for storing a channel list corresponding to the broadcast area, and the current position of the digital broadcast receiving device shown in the position information step is the said. When the broadcast area of the currently receiving channel stored in the reception area storage unit is exceeded, the channel search is started, and at the time of the channel search, the plurality of reception units are divided into two and one of them performs the channel search. On the other hand, the video / audio signal is received, and the switching step is characterized in that the video / audio signal of the first layer is selected.</p>

<p> According to the present invention, it is possible to receive a program even during a channel search, and it is possible to suppress reception defects such as interruption of video / audio signals, and the user can receive a broadcast in a suitable state. There is.</p>

Hereinafter, embodiments of the present invention will be described with reference to the drawings. Regarding the digital broadcasting receiver according to the present invention, ISDB-T (Integrated Services Digital Broadcasting for), which is a transmission method for terrestrial digital broadcasting in Japan. Broadcast signals by Terrestrial) can be received. In ISDB-T, the transmission band of one channel can be divided into 13 segments, and each segment can be combined to perform layered transmission of up to 3 layers. Currently, using this tier transmission, 12 segments are used for high-quality broadcasting for fixed receiving terminals (hereinafter referred to as weak tier broadcasting), and the remaining 1 segment is used for mobile receiving terminals. Low-quality broadcasting for people (hereinafter referred to as strong-layer broadcasting) is being carried out. Weak-layer broadcasting and strong-layer broadcasting are simulcasts that broadcast the same program content. Here, the weak layer broadcast is a high-quality broadcast having a large transmission capacity, but is weak in noise immunity and cannot be received unless the received electric field strength of the broadcast radio wave is relatively large. On the other hand, strong-layer broadcasting is low-quality broadcasting with a small transmission capacity, but has strong noise immunity and is characterized in that it can be received even if the reception electric field strength of the broadcast radio wave is relatively small.

FIG. 1 shows a block diagram of the digital broadcast receiving device according to the first embodiment of the present invention. Here, the first receiving system 10a has an antenna unit 11a, a channel selection unit 12a, and a demodulation unit 13a. Further, the second receiving system 10b has an antenna unit 11b, a channel selection unit 12b, and a demodulation unit 13b. Further, the third receiving system 10c has an antenna unit 11c, a channel selection unit 12c, and a demodulation unit 13c. Further, the fourth receiving system 10d has an antenna unit 11d, a channel selection unit 12d, and a demodulation unit 13d.

The antenna units 11a to 11d receive the digital broadcast signal transmitted from the broadcasting station and supply the digital broadcasting signals to the channel selection units 12a to 12d, respectively. Based on the instruction from the control unit 21, the channel selection units 12a to 12d extract desired channel signals from the supplied digital broadcast signals and supply them to the demodulation units 13a to 13d, respectively. The demodulation units 13a to 13d demodulate the supplied desired channel signal to generate a demodulated signal, and supply the demodulated signal to the diversity synthesis unit 14. The diversity synthesis unit 14 performs diversity synthesis of the demodulated signals supplied from the demodulation units 13a to 13d (hereinafter, referred to as demodulation signals supplied from the reception systems 10a to 10d).

Here, the diversity synthesizing unit 14 can perform diversity synthesizing (hereinafter, referred to as 4 diversity synthesizing) by four demodulated signals supplied from the receiving systems 10a to 10d. Further, the diversity synthesizer 14 performs diversity synthesis using two demodulated signals supplied from any two receiving systems (for example, receiving systems 10a and 10b), and the remaining two receiving systems (for example, receiving systems 10c, 10c,) perform diversity synthesis. It is possible to perform a process of performing diversity synthesis using the two demodulated signals supplied from 10d) (hereinafter referred to as 2-2 diversity synthesis). Further, the diversity synthesizer 14 performs diversity synthesis using three demodulated signals supplied from any three receiving systems (for example, receiving systems 10a to 10c), and the remaining one receiving system (for example, receiving system 10d). The demodulated signal supplied from the above can be processed without diversity synthesis (hereinafter referred to as 3-1 diversity synthesis).

When the diversity synthesis unit 14 performs 4-diversity synthesis, the four channel selection units 12a to 12d select the same channel, and one demodulation signal is output from the diversity synthesis unit 14 and supplied to the error correction unit 15a. To. In addition, when performing 2-2 diversity synthesis or 3-1 diversity synthesis, since the four receiving systems are divided into two groups, each group selects different channels and the diversity synthesizer 14 Two demodulated signals are output from, and are supplied to the error correction units 15a and 15b, respectively.

Any method may be used for diversity synthesis. For example, a synthesis method such as a selective synthesis method, an equal gain synthesis method, or a maximum ratio synthesis method can be used. The selective synthesis method is a synthesis method in which only the signal of the antenna having the highest received power is selected and the signals of other antennas are not used. The equal gain synthesis method is a method of synthesizing signals with the same phase from each antenna. The maximum ratio synthesis method is a method in which the phases of the signals from each antenna are made the same, and weights proportional to the received power are added for synthesis.

The error correction units 15a and 15b perform error correction processing on the demodulated signals supplied from the diversity synthesis unit 14, respectively, and output a transport stream signal (hereinafter referred to as a TS signal). The strong layer decoding unit 16 decodes the TS signal including the strong layer video / audio data from the TS signal supplied from the error correction unit 15a, and outputs the strong layer video / audio signal. Further, the weak layer decoding unit 17 performs decoding processing of the TS signal including the weak layer video / audio data from the TS signal supplied from the error correction unit 15a, and outputs the weak layer video / audio signal. The switching unit 18 is of the strong layer video / audio signal supplied from the strong layer decoding unit 16 and the weak layer video / audio signal supplied from the weak layer decoding unit 17 based on the instruction from the control unit 21. , Either one is selected and supplied to the video / audio output unit 19. The video / audio output unit 19 supplies the supplied strong-layer video / audio signal or weak-layer video / audio signal to a video display device (not shown), an audio output device, or the like.

The program information extraction unit 20 uses the TS signal supplied from the error correction unit 15b to, for example, NIT (Network Information Table), BIT (Broadcaster Information Table), SDT (Service Description Table), EIT (Event Information Table), etc. The channel information is extracted and supplied to the control unit 21.

The control unit 21 holds various information about the receivable channel found by the channel search based on the supplied channel information such as NIT, BIT, SDT, and EIT. Further, the control unit 21 performs various controls on the channel selection units 12a to 12d, the diversity synthesis unit 14, and the switching unit 18.

The GPS (Global Positioning System) receiving system 22 has a GPS antenna unit 22a and a GPS receiving unit 22b. Here, it receives GPS signals, positions the current position of the vehicle, extracts position information by latitude and longitude, and outputs it to the control unit 21. The reception area storage unit 23 stores electronic map information with regional boundaries added. An area may be one prefecture or a collection of multiple prefectures. FIG. 2 shows an example of a specific area of the electronic map information held by the reception area storage unit 23. Hereinafter, this electronic map information will be referred to as a reception area map.

In addition, the reception area storage unit 23 stores various information of broadcasting stations broadcast in each area. FIG. 3 shows an example of a broadcasting station database held by the reception area storage unit 23. The broadcasting station database manages information such as an area name, a broadcasting station name broadcast in that area, a physical channel of a relay station for the broadcasting station, and a series ID of the broadcasting station. As shown in the figure, broadcasting stations of the same series are given the same series ID.

The arrow in FIG. 2 shows an example of the movement path of the vehicle equipped with the digital broadcast receiving device according to the first embodiment of the present invention. Below, as shown in Fig. 2, digital broadcasting when a vehicle equipped with a digital broadcast receiver moves from point A in Akita prefecture to point C in Iwate prefecture via point B on the prefectural border between the prefecture and Iwate prefecture. The processing of the receiving device will be described.

FIG. 4 is a flowchart showing an example of the processing operation of the digital broadcast receiving device according to the first embodiment of the present invention. The control unit 21 acquires the position information of the vehicle supplied from the GPS reception unit 22b. Then, the control unit 21 refers to the reception area map held by the reception area storage unit 23, and grasps where the current position is on the reception area map. When the vehicle is located at point A in Fig. 2, the channel selection unit 12a to 12d is instructed to select the channel specified by the user, and the diversity synthesis unit 14 is instructed to instruct the four reception systems 10a to 10d. 4 Diversity synthesis is performed using the demodulated signal of (S10). The demodulated signal output from the diversity synthesis unit 14 is supplied to the error correction unit 15a for error correction processing, and then the switching unit 18 outputs a strong layer video / audio signal output from the strong layer decoding unit 16. Then, either one of the weak layer video / audio signals output from the weak layer decoding unit 17 is selected and supplied to the video / audio output unit 19.

Here, any method may be used to determine which of the high-layer video / audio signal and the weak-layer video / audio signal is selected by the switching unit 18. For example, the reception status of broadcast radio waves is constantly monitored, when the reception status is good and stable, a weak layer video / audio signal is selected, and when the reception status deteriorates or fluctuates greatly and is unstable, it is strong. You can select the video / audio signal of the layer.

If the control unit 21 detects that the vehicle has reached point B and entered Iwate prefecture as shown in Fig. 2 (S11), there is a possibility that there is a broadcasting station with better reception than it is now. Start channel search (go to S12). First, the control unit 21 instructs the switching unit 18 to select a video / audio signal of a strong layer (S12). That is, the video / audio output unit 19 outputs a high-level video / audio signal.

Next, the control unit 21 instructs the diversity synthesis unit 14 to perform 2-2 diversity synthesis or 3-1 diversity synthesis (S13). 2-2 When performing diversity synthesis, the diversity synthesizer 14 performs diversity synthesis using demodulated signals supplied from any two receiving systems (here, receiving systems 10a and 10b), and after diversity synthesis. The demodulated signal of is supplied to the error correction unit 15a. Further, the diversity synthesis unit 14 performs diversity synthesis using the demodulated signals supplied from the remaining two receiving systems (here, the receiving systems 10c and 10d), and the demodulated signal after the diversity synthesis is corrected by the error correction unit 15b. Supply to.

Subsequently, the control unit 21 instructs the channel selection units 12a and 12b to continue selecting the channel currently being received, and also instructs the channel selection units 12c and 12d to search for the channel to be searched by the channel search. Channels are selected in order (S14). That is, even during the channel search, it is possible to receive a high-level video / audio signal having the same program content as that at the time of normal reception.

Here, the channel search processing procedure will be described. For example, if the channel currently being received is "NHK General Akita", the control unit 21 refers to the broadcasting station database of the reception area storage unit 23, and the broadcasting station in Iwate Prefecture says "NHK General Akita". Search the physical channels of the relay stations of "NHK General Iwate", which is a broadcasting station of the same series (series ID = 0), in order. If a receivable channel is found and it is found that the stations are in the same series based on various program information (NIT, BIT, SDT, EIT, etc.) of this channel acquired by the program information extraction unit 20 Instruct the channel selection section 12a to 12d to tune in to this channel. Alternatively, if the control unit 21 can currently receive "NHK General Akita", it retains the physical channel of the found broadcasting station of the same series in the memory, and "NHK General Akita" cannot receive it. In that case, this physical channel may be selected. Also, if you cannot find a broadcasting station of the same series by searching the physical channel of the relay station of "NHK General Iwate", you can search for another physical channel that has not been searched yet, or "" again after a predetermined time. You may search the physical channel of the relay station of "NHK General Iwate".

In addition, as another processing procedure of the channel search, the control unit 21 searches all physical channels in order, or searches the physical channels of the relay stations of each broadcasting station in order for all broadcasting stations broadcast in Iwate prefecture. You may find a receivable broadcast station, create a list of receivable broadcast stations at your current location, and present it to the user.

On the other hand, when performing 3-1 diversity synthesis, the diversity synthesizer 14 performs diversity synthesis using the demodulated signals supplied from any three receiving systems (here, receiving systems 10a to 10c), and the rest. The demodulated signal supplied from one of the receiving systems (here, the receiving system 10d) is not subjected to diversity processing.

When the control unit 21 wants to place more importance on the stable reception of the currently received channel than to perform the channel search stably, it instructs the diversity synthesis unit 14 to output the demodulated signal after the diversity synthesis. It is supplied to the error correction unit 15a, and the demodulated signal of the receiving system 10d is supplied to the error correction unit 15b. Subsequently, the control unit 21 instructs the channel selection units 12a to 12c to continue selecting the channel currently being received, and also instructs the channel selection unit 12d to sequentially search the channels to be searched by the channel search. Let me tune in.

Further, when the control unit 21 wants to place more importance on the stable and reliable execution of the channel search than to stably receive the currently received channel, the control unit 21 instructs the diversity synthesis unit 14 to perform diversity synthesis. The later demodulated signal is supplied to the error correction unit 15b, and the demodulated signal of the receiving system 10d is supplied to the error correction unit 15a. Subsequently, the control unit 21 instructs the channel selection units 12a to 12c to sequentially select the channels to be searched by the channel search, and also instructs the channel selection unit 12d to select the channel currently being received. To continue.

After that, when the channel search in S14 is completed, the control unit 21 instructs the diversity synthesis unit 14 to perform 4 diversity synthesis using the demodulated signals of the four reception systems 10a to 10d (S15). Finally, the control unit 21 instructs the switching unit 18 to cancel the selection of the video / audio signal of the strong layer (S16).

As described above, in the digital broadcast receiving device of the present invention, during normal reception, reception is performed by 4-diversity synthesis using demodulated signals from four receiving systems. When crossing the prefectural border of a prefecture, the four receiving systems are divided into two groups, one receiving system group receives the previously received channel, and the other receiving system group receives the channel search. To search for receivable channels. Therefore, the program can be received even at the time of channel search. By outputting a strong layer video / audio signal with strong noise immunity before the start of the channel search, it is possible to suppress the occurrence of reception defects such as interruption of the video / audio signal during the channel search. Channel search can be performed at an appropriate time, such as when crossing regional boundaries.

A second embodiment of the present invention will be described. Since the block diagram of the digital broadcast receiving device in the second embodiment is the same as the block diagram of the digital broadcast receiving device in the first embodiment shown in FIG. 1, the description thereof will be omitted.

In the second embodiment, the reception area storage unit 23 stores electronic map information to which a boundary line of the broadcast reception area is added for each area. FIG. 5 shows an example of a specific area of the electronic map information held by the reception area storage unit 23. Hereinafter, this electronic map information will be referred to as a reception area map. Further, the reception area storage unit 23 holds the same database as the broadcasting station database of the digital broadcasting receiving device according to the first embodiment shown in FIG.

FIG. 5 shows an example of a movement path of a vehicle equipped with a digital broadcast receiving device according to a second embodiment of the present invention. Below, as shown in Fig. 5, a vehicle equipped with a digital broadcast receiver goes from point D in Akita prefecture to point E, which enters the broadcast reception area in Iwate prefecture, and point F, which is outside the broadcast reception area in Akita prefecture. The processing of the digital broadcast receiver when moving to the G point in Iwate prefecture will be explained.

FIG. 6 is a flowchart showing an example of the processing operation of the digital broadcast receiving device according to the second embodiment of the present invention. The control unit 21 acquires the position information of the vehicle supplied from the GPS reception unit 22b. Then, the control unit 21 refers to the reception area map held by the reception area storage unit 23, and grasps where the current position is on the reception area map.

When the vehicle is located at point D in Fig. 5, the channel selection unit 12a to 12d is instructed to select the channel specified by the user, and the diversity synthesis unit 14 is instructed to instruct the four reception systems 10a to 10d. 4 Diversity synthesis is performed using the demodulated signal of (S10). The demodulated signal output from the diversity synthesis unit 14 is supplied to the error correction unit 15a for error correction processing, and then the switching unit 18 outputs a strong layer video / audio signal output from the strong layer decoding unit 16. Then, either one of the weak layer video / audio signals output from the weak layer decoding unit 17 is selected and supplied to the video / audio output unit 19.

Here, any method may be used to determine which of the high-layer video / audio signal and the weak-layer video / audio signal is selected by the switching unit 18. For example, the reception status of broadcast radio waves is constantly monitored, when the reception status is good and stable, a weak layer video / audio signal is selected, and when the reception status deteriorates or fluctuates greatly and is unstable, it is strong. You can select the video / audio signal of the layer.

If the control unit 21 detects that the vehicle has reached point E and entered the broadcast reception area of Iwate Prefecture as shown in Fig. 5 (S18), there is a possibility that there is a channel with better reception than it is now. Since there is, start the channel search (go to S12).

First, the control unit 21 instructs the switching unit 18 to select a video / audio signal of a strong layer (S12). That is, the video / audio output unit 19 outputs a high-level video / audio signal.

Next, the control unit 21 instructs the diversity synthesis unit 14 to perform 2-2 diversity synthesis or 3-1 diversity synthesis (S13). 2-2 When performing diversity synthesis, the diversity synthesizer 14 performs diversity synthesis using demodulated signals supplied from any two receiving systems (here, receiving systems 10a and 10b), and after diversity synthesis. The demodulated signal of is supplied to the error correction unit 15a. Further, the diversity synthesis unit 14 performs diversity synthesis using the demodulated signals supplied from the remaining two receiving systems (here, the receiving systems 10c and 10d), and the demodulated signal after the diversity synthesis is corrected by the error correction unit 15b. Supply to.

Subsequently, the control unit 21 instructs the channel selection units 12a and 12b to continue selecting the channel currently being received, and also instructs the channel selection units 12c and 12d to search for the channel to be searched by the channel search. Channels are selected in order (S14). That is, even during the channel search, it is possible to receive a high-level video / audio signal having the same program content as that at the time of normal reception.

Here, the channel search processing procedure will be described. For example, if the channel currently being received is "NHK General Akita", first refer to the broadcasting station database of the reception area storage unit 23, search for the physical channel of the relay station of "NHK General Akita", and then search. Search for channels that can be received by "NHK General Akita" other than the channels currently being received. The reception status of the newly found channel is better than the currently received channel, and it is relayed based on various program information (NIT, BIT, SDT, EIT, etc.) of this channel acquired by the program information extraction unit 20. If it turns out to be a station, instruct the channel selection units 10a to 10d to select this channel. Alternatively, the control unit 21 holds the physical channel of the found relay station in the memory when the currently received broadcast can be received, and when the currently received broadcast cannot be received, this is performed. The physical channel may be selected.

On the other hand, if the reception state of the broadcast currently being received is better than the reception state of the found relay station, or if the relay station is not found, the control unit 21 again broadcasts the broadcast station of the reception area storage unit 23. Refer to the database and search the physical channels of the relay stations of "NHK General Iwate", which is the same series (series ID = 0) as "NHK General Akita", in order at the broadcasting stations in Iwate Prefecture. If a receivable channel is found and it is found that the stations are in the same series based on various program information (NIT, BIT, SDT, EIT, etc.) of this channel acquired by the program information extraction unit 20 Instruct the channel selection section 10a to 10d to tune in to this channel. Or, the control unit 21, if the broadcast is currently received can be received, the physical channel of the broadcasting station of the found identical sequences may be held in the memory, the current can not be received broadcast being resident received In that case, this physical channel may be selected. Also, if you cannot find a broadcasting station of the same series by searching the physical channel of the relay station of "NHK General Iwate", you can search for another physical channel that has not been searched yet, or "" again after a predetermined time. You may search the physical channel of the relay station of "NHK General Iwate".

In addition, as another processing procedure for channel search, the control unit 21 searches all physical channels in order, or searches the physical channels of the relay stations of each broadcasting station in order for all broadcasting stations broadcast in Akita and Iwate prefectures. By doing so, it is possible to find a receivable broadcasting station, create a list of receivable broadcasting stations at the current position, and present it to the user.

On the other hand, when performing 3-1 diversity synthesis, the diversity synthesizer 14 performs diversity synthesis using the demodulated signals supplied from any three receiving systems (here, receiving systems 10a to 10c), and the rest. The demodulated signal supplied from one of the receiving systems (here, the receiving system 10d) is not subjected to diversity processing.

When the control unit 21 wants to place more importance on the stable reception of the currently received channel than to perform the channel search stably, it instructs the diversity synthesis unit 14 to output the demodulated signal after the diversity synthesis. It is supplied to the error correction unit 15a, and the demodulated signal of the receiving system 10d is supplied to the error correction unit 15b. Subsequently, the control unit 21 instructs the channel selection units 12a to 12c to continue selecting the channel currently being received, and also instructs the channel selection unit 12d to sequentially search the channels to be searched by the channel search. Let me tune in.

Further, when the control unit 21 wants to place more importance on the stable and reliable execution of the channel search than to stably receive the currently received channel, the control unit 21 instructs the diversity synthesis unit 14 to perform diversity synthesis. The later demodulated signal is supplied to the error correction unit 15b, and the demodulated signal of the receiving system 10d is supplied to the error correction unit 15a. Subsequently, the control unit 21 instructs the channel selection units 12a to 12c to sequentially select the channels to be searched by the channel search, and also instructs the channel selection unit 12d to select the channel currently being received. To continue.

After that, when the channel search in S14 is completed, the control unit 21 instructs the diversity synthesis unit 14 to perform 4 diversity synthesis using the demodulated signals of the four reception systems 10a to 10d (S15). Finally, the control unit 21 instructs the switching unit 18 to cancel the selection of the video / audio signal of the strong layer (S16).

When the control unit 21 detects that the vehicle has reached the F point and is out of the broadcast reception area of Akita Prefecture as shown in FIG. 5, the control unit 21 executes the channel search according to the processing operation shown in FIG. At this time, since the control unit 21 is out of the broadcast reception area of Akita Prefecture, it is not necessary to perform the process of searching the physical channel of the relay station of "NHK General Akita" in the processing operation shown in FIG. ..

As described above, in the digital broadcast receiving device of the present invention, during normal reception, reception is performed by 4-diversity synthesis using demodulated signals from four receiving systems. When crossing the reception area of a local broadcasting station, the four receiving systems are divided into two groups, one receiving system group receives the previously received channel, and the other receiving system group receives the channel. Perform a channel search to search for receivable channels. Therefore, the program can be received even at the time of channel search. By outputting a strong layer video / audio signal with strong noise immunity before the start of the search, it is possible to suppress the occurrence of reception defects such as interruption of the video / audio signal during channel search. In addition, by performing a channel search when the area crosses the broadcast reception area, the channel search is performed when the area is crossed, and the channel search is performed at an appropriate timing according to the actual reception environment as compared with the first embodiment. Channel search can be started.

Although the digital broadcast receiving device according to the embodiment of the present invention has been shown as a configuration example using four receiving systems, it is also possible to configure the digital broadcasting receiving device with two, three, or five or more receiving systems. Even in such a case, the digital broadcast receiving device is divided into two receiving system groups at the time of channel search, one receiving system group receives the same channel as during normal reception, and the other receiving system. The group performs a channel search and acquires the receivable channels. By outputting a strong layer video / audio signal with strong noise immunity before the start of the channel search, it is possible to suppress the occurrence of reception defects such as interruption of the video / audio signal during the channel search.

<figref num="1">It is a block diagram which shows the structure of the digital broadcasting receiving apparatus in Example 1 of this invention.</figref><figref num="2">This is an example of a reception area map held by the reception area storage unit 23 in the digital broadcast reception device according to the first embodiment of the present invention.</figref><figref num="3">This is an example of a broadcasting station database held by the reception area storage unit 23 in the digital broadcasting receiving device according to the first embodiment of the present invention.</figref><figref num="4">It is a flowchart which shows an example of the operation of the digital broadcasting receiving apparatus in Example 1 of this invention.</figref><figref num="5">This is an example of a reception area map held by the reception area storage unit 23 in the digital broadcast reception device according to the second embodiment of the present invention.</figref><figref num="6">It is a flowchart which shows an example of the operation of the digital broadcasting receiving apparatus in Example 2 of this invention.</figref>

Code description

10a ~ 10d Reception system 11a ~ 11d Antenna part 12a ~ 12d Channel selection department 13a ~ 13d Demodulation section 14 Diversity synthesis department 15a, 15b Error correction section 16 Strong layer decoding section 17 Weak layer decoding section 18 Switching part 19 Video / audio output 20 Program information extraction department 21 Control unit 22 GPS reception system 21a GPS antenna section 22b GPS receiver 23 Reception area storage.