JP2010141420A - Apparatus and method for receiving digital broadcast - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a digital broadcast receiving apparatus executing channel search at appropriate timing, allowing viewing of a program even during the channel search, and suppressing reception failure such as interruption of the video/sound signals of a program. <P>SOLUTION: Broadcasting station information corresponding to a broadcasting area for each region is held, and when detecting that a vehicle is located out of the reception area of the region by a GPS reception part, the channel search is started on the basis of the broadcasting station information. A control part 21 instructs a switching part 18 to select the video/sound signals of one-segment broadcasting, divides a plurality of reception systems into two groups, one for the channel search and the other for receiving a program. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

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

  In Japanese terrestrial digital broadcasting, the frequency of broadcast radio waves transmitted by each broadcasting station is different. For this reason, if a digital broadcast receiver mounted on a mobile object such as an automobile is watching a program of a certain broadcast station and is out of the reception area of this broadcast station, it cannot receive the program that has been viewed until then. End up. Therefore, when straddling the receiving 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 since the process of confirming the presence or absence of broadcast waves is repeated for all 50 channels.

  In order to shorten this time, for example, there is a broadcast receiving apparatus 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 based on the identification information of the broadcasting station and the station-region conversion table, the broadcast receiving device Identify the location. Then, the control unit detects the physical channel of the broadcasting station that can be received in this region based on the specified region and the region-station conversion table, verifies whether each physical channel can actually be received, and actually Only the physical channels that can be received are stored in the viewable frequency table, and the physical channel that the user views is selected from the physical channels stored in this table.

JP 2007-288603 A

  However, the above-described broadcast receiving apparatus cannot watch broadcast programs during channel search. The present invention has been devised in view of the above problems, and its purpose is to enable viewing of a program even during a channel search, and also to cause poor reception such as interruption of the video / audio signal of the program. It is an object of the present invention to provide a digital broadcast receiving apparatus and a digital broadcast receiving method that can suppress the above-mentioned problem.

  In order to achieve the above object, the present invention provides a digital broadcast receiving apparatus for receiving a digital broadcast signal transmitted in a first layer in which video / audio signals are highly resistant to noise and a second layer that is weak in noise resistance by hierarchical transmission. A plurality of receiving units having a receiving antenna, a channel selection unit and a demodulation unit, a diversity combining unit for diversity combining the output signals of the plurality of receiving units, and the digital data output from the diversity combining unit, A decoding unit that decodes the first layer digital data and the second layer digital data, respectively, the first layer video / audio signal output from the decoding unit, and the second layer video / From the switching unit that selects and outputs one of the audio signals and the digital data output from the diversity combining unit, A program information extracting unit for extracting channel information, a position information acquiring unit for acquiring position information indicating a current position of the digital broadcast receiving device, a receiving area storing unit for storing a channel list corresponding to a broadcasting area, When the current position of the digital broadcast receiving device indicated by the position information exceeds the broadcast area of the currently received channel stored in the reception area storage unit, a channel search is started. The receiving unit is divided into two parts, one is subjected to channel search, the other is received the video / audio signal, and the switching unit is instructed to receive the first layer video / audio signal. And a control unit for selection.

  Further, the present invention is a diversity reception method for receiving a digital broadcast signal transmitted in a first layer in which video / audio signals are strong in noise resistance and in a second layer weak in noise resistance by hierarchical transmission, From the reception step having a plurality of reception units for receiving, selecting and demodulating the digital broadcast signal, the diversity combining step for diversity combining the output signal of the reception step, and the digital data output from the diversity combining step, A decoding step for decoding the first layer digital data and the second layer digital data, respectively, the first layer video / audio signal output from the decoding step, and the second layer video / A switching step of selecting and outputting one of the audio signals; and the diversity. A program information extracting step for extracting channel information from the digital data output from the synthesizing step, a position information acquiring step for acquiring position information indicating the current position of the digital broadcast receiver, and a channel corresponding to the broadcast area A reception area storage step for storing a list, wherein the current position of the digital broadcast receiving device indicated in the position information step exceeds the broadcast area of the channel currently received stored in the reception area storage unit. In the case of channel search, the plurality of receiving units are divided into two, one performs channel search, the other receives the video / audio signal, and the switching step includes the first step. It is characterized by selecting video / audio signals in the hierarchy.

  According to the present invention, it is possible to receive a program even at the time of channel search, suppress reception failures such as interruption of video / audio signals, and the effect that a user can receive a broadcast in a suitable state. There is.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
The digital broadcast receiving apparatus according to the present invention can receive broadcast signals by ISDB-T (Integrated Services Digital Broadcasting for Terrestrial), which is a transmission system for Japanese terrestrial digital broadcasting. In ISDB-T, a transmission band of one channel is divided into 13 segments, and each segment can be combined to perform hierarchical transmission of up to three layers. Currently, using this hierarchical transmission, 12 segments are used for high-quality broadcasting for fixed reception terminals (hereinafter referred to as weak hierarchical broadcasting), and the remaining one segment is used for portable reception terminals. Broadcasts of low quality (hereinafter referred to as strong broadcast). Weak broadcasts and strong broadcasts are simulcasts that broadcast the same program content. Here, the weak hierarchical broadcast is a high-quality broadcast with a large transmission capacity, but is weak in noise resistance and cannot be received unless the received electric field strength of the broadcast radio wave is relatively high. On the other hand, strong broadcasts are low-quality broadcasts with a small transmission capacity, but are strong in noise resistance and can be received even when the reception electric field strength of broadcast radio waves is relatively small.

FIG. 1 shows a block diagram of a digital broadcast receiving apparatus in Embodiment 1 of the present invention.
Here, the first reception system 10a includes an antenna unit 11a, a channel selection unit 12a, and a demodulation unit 13a. The second reception system 10b includes an antenna unit 11b, a channel selection unit 12b, and a demodulation unit 13b. The third reception system 10c includes an antenna unit 11c, a channel selection unit 12c, and a demodulation unit 13c. Further, the fourth reception system 10d includes an antenna unit 11d, a channel selection unit 12d, and a demodulation unit 13d.

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

  Here, the diversity combining unit 14 can perform diversity combining (hereinafter referred to as “4 diversity combining”) using four demodulated signals supplied from the receiving systems 10a to 10d. The diversity combining unit 14 performs diversity combining using two demodulated signals supplied from any two receiving systems (for example, the receiving systems 10a and 10b), and performs the remaining two receiving systems (for example, the receiving systems 10c, 10c, 10d) is possible to perform diversity combining using the two demodulated signals supplied (hereinafter referred to as 2-2 diversity combining). Furthermore, the diversity combining unit 14 performs diversity combining using three demodulated signals supplied from any three receiving systems (for example, the receiving systems 10a to 10c), and the remaining one receiving system (for example, the receiving system 10d). The demodulated signal supplied can be processed without diversity combining (hereinafter referred to as 3-1 diversity combining).

  When the diversity combining unit 14 performs four diversity combining, the four channel selecting units 12a to 12d select the same channel, and the diversity combining unit 14 outputs one demodulated signal, which is supplied to the error correcting unit 15a. The Also, when performing 2-2 diversity combining or 3-1 diversity combining, the four receiving systems are divided into two groups, so that each group selects a different channel and the diversity combining unit 14 Outputs two demodulated signals, which are supplied to error correction sections 15a and 15b, respectively.

  Note that any method may be used for diversity combining. 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 combining method is a combining method that selects only the signal of the antenna having the highest received power and does not use the signals of other antennas. The equal gain combining method is a method of combining signals with the same phase from each antenna. The maximum ratio combining method is a method of combining signals with the same phase from each antenna and further applying a weight proportional to the received power.

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

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

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

A GPS (Global Positioning System) receiving system 22 includes a GPS antenna unit 22a and a GPS receiving unit 22b. Here, a GPS signal is received, the current position of the vehicle is measured, position information based on latitude and longitude is extracted, and output to the control unit 21.
The reception area storage unit 23 stores electronic map information to which regional boundaries are added. One region may be one prefecture or a group of a plurality of prefectures. In FIG. 2, the example of the specific area of the electronic map information which the receiving area memory | storage part 23 hold | maintains is shown. Hereinafter, this electronic map information is referred to as a reception area map.

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

An arrow in FIG. 2 shows an example of a moving route of a vehicle equipped with the digital broadcast receiving device according to the first embodiment of the present invention.
Hereafter, as shown in FIG. 2, 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 border between the prefecture and Iwate Prefecture. 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 apparatus according to the first embodiment of the present invention.
The control unit 21 acquires vehicle position information supplied from the GPS receiving unit 22b. Then, the control unit 21 refers to the reception area map held by the reception area storage unit 23 to grasp where the current position is located on the reception area map.
When the vehicle is located at point A in FIG. 2, the channel selection units 12a to 12d are instructed to select a channel designated by the user, and the diversity combining unit 14 is instructed to provide four reception systems 10a to 10d. 4 diversity combining using the demodulated signal is performed (S10). The demodulated signal output from the diversity combining unit 14 is supplied to the error correction unit 15a to be subjected to error correction processing. Thereafter, the strong layer video / audio signal output from the strong layer decoding unit 16 is switched by the switching unit 18. Then, one of the video / audio signals in the weak hierarchy output from the weak hierarchy 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 video / audio signals in the strong hierarchy or the video / audio signals in the weak hierarchy 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 video / audio signal of a weak hierarchy is selected. When the reception status is unstable or greatly fluctuating, it is strong. Hierarchical video / audio signals can be selected.

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 a better reception state than the present, A channel search is started (proceeds to S12).
First, the control unit 21 instructs the switching unit 18 to select a high-level video / audio signal (S12). That is, the video / audio output unit 19 outputs a video / audio signal of a strong hierarchy.

Next, the control unit 21 instructs the diversity combining unit 14 to perform 2-2 diversity combining or 3-1 diversity combining (S13).
In the case of performing 2-2 diversity combining, the diversity combining unit 14 performs diversity combining using demodulated signals supplied from any two receiving systems (in this case, the receiving systems 10a and 10b), and after diversity combining Are supplied to the error correction unit 15a. The diversity combining unit 14 performs diversity combining using the demodulated signals supplied from the remaining two receiving systems (in this case, the receiving systems 10c and 10d), and the demodulated signal after diversity combining is error-corrected unit 15b. To supply.

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

Here, a channel search processing procedure will be described. For example, when the currently received channel is “NHK General / Akita”, the control unit 21 refers to the broadcast station database in the reception area storage unit 23 and reads “NHK General / Akita” at a broadcast station in Iwate Prefecture. The physical channels of the relay stations of “NHK General / Iwate”, which are broadcasting stations of the same series (series ID = 0), are searched in order. If a receivable channel is found and it is determined that the broadcasting stations are of the same series based on various program information (NIT, BIT, SDT, EIT, etc.) of this channel acquired by the program information extraction unit 20, The channel selection units 12a to 12d are instructed to select this channel. Alternatively, when “NHK General / Akita” is currently receivable, the control unit 21 holds the physical channels of the found broadcasting stations of the same series in the memory and cannot receive “NHK General / Akita”. In this case, the physical channel may be selected.
Also, if you search for the physical channel of the relay station of “NHK General / Iwate” and no broadcasting station of the same series is found, you can search for other physical channels that have not been searched yet, The physical channel of the relay station of “NHK General / Iwate” may be searched.

  As another channel search processing procedure, the control unit 21 searches all physical channels in order, or sequentially searches the physical channels of relay stations of each broadcasting station for all broadcasting stations broadcast in Iwate Prefecture. It is also possible to find a receivable broadcast station, create a list of broadcast stations receivable at the current position, and present it to the user.

  On the other hand, in the case of performing 3-1 diversity combining, the diversity combining unit 14 performs diversity combining using demodulated signals supplied from arbitrary three receiving systems (in this case, receiving systems 10a to 10c), and the rest The demodulated signal supplied from one receiving system (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 rather than performing the channel search stably, the control unit 21 instructs the diversity combining unit 14 to output the demodulated signal after diversity combining. The signal is supplied to the error correction unit 15a, and the demodulated signal of the reception 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 channel selection of the currently received channel, and also instructs the channel selection unit 12d to sequentially search channels to be searched by channel search. Select a station.

  In addition, the control unit 21 instructs the diversity combining unit 14 to give diversity combining when it is desired to place more importance on stable and reliable channel search than to stably receive the currently received channel. The later demodulated signal is supplied to the error correcting unit 15b, and the demodulated signal of the receiving system 10d is supplied to the error correcting unit 15a. Subsequently, the control unit 21 instructs the channel selection units 12a to 12c to sequentially select channels to be searched by channel search, and instructs the channel selection unit 12d to select a channel currently received. To continue.

Thereafter, when the channel search in S14 is completed, the control unit 21 instructs the diversity combining unit 14 to perform four diversity combining 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 higher hierarchy (S16).

  As described above, the digital broadcast receiving apparatus of the present invention performs reception by 4-diversity combining using the demodulated signals from the four receiving systems during normal reception. When the prefectural border is crossed, the four receiving systems are divided into two groups, one receiving system group receives the previously received channel, and the other receiving system group searches the channel. To search for a receivable channel. This makes it possible to receive a program even during channel search. By outputting a high-level video / audio signal that is highly resistant to noise before starting the channel search, it is possible to suppress the occurrence of reception failure such as the video / audio signal being interrupted during the channel search. A channel search can be performed at an appropriate timing, such as when crossing regional boundaries.

Embodiment 2 of the present invention will be described.
The block diagram of the digital broadcast receiving apparatus in the second embodiment is the same as the block diagram of the digital broadcast receiving apparatus in the first embodiment shown in FIG.

In the second embodiment, the reception area storage unit 23 stores electronic map information to which the boundary line of the broadcast reception area is added for each region. In FIG. 5, the example of the specific area of the electronic map information which the receiving area memory | storage part 23 hold | maintains is shown. Hereinafter, this electronic map information is referred to as a reception area map.
The reception area storage unit 23 holds the same data as the broadcasting station database of the digital broadcast receiving apparatus in the first embodiment shown in FIG.

FIG. 5 shows an example of a moving route of a vehicle equipped with a digital broadcast receiver according to the second embodiment of the present invention.
Hereinafter, as shown in FIG. 5, a vehicle equipped with a digital broadcast receiving device passes from point D in Akita Prefecture to point E entering the broadcast receiving area in Iwate Prefecture, point F out of the broadcast receiving area in Akita Prefecture, The process of the digital broadcast receiving apparatus when moving to point G in Iwate Prefecture will be described.

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

  When the vehicle is located at point D in FIG. 5, the channel selection units 12a to 12d are instructed to select a channel designated by the user, and the diversity combining unit 14 is instructed to provide four reception systems 10a to 10d. 4 diversity combining using the demodulated signal is performed (S10). The demodulated signal output from the diversity combining unit 14 is supplied to the error correction unit 15a to be subjected to error correction processing. Thereafter, the strong layer video / audio signal output from the strong layer decoding unit 16 is switched by the switching unit 18. Then, one of the video / audio signals in the weak hierarchy output from the weak hierarchy 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 video / audio signals in the strong hierarchy or the video / audio signals in the weak hierarchy 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 video / audio signal of a weak hierarchy is selected. When the reception status is unstable or greatly fluctuating, it is strong. Hierarchical video / audio signals can be selected.

  As shown in FIG. 5, when the control unit 21 detects that the vehicle has reached the point E and has entered the broadcast reception area in Iwate Prefecture (S18), there is a possibility that there is a channel with a better reception state than the present. Since there is, a channel search is started (proceeds to S12).

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

Next, the control unit 21 instructs the diversity combining unit 14 to perform 2-2 diversity combining or 3-1 diversity combining (S13).
In the case of performing 2-2 diversity combining, the diversity combining unit 14 performs diversity combining using demodulated signals supplied from any two receiving systems (in this case, the receiving systems 10a and 10b), and after diversity combining Are supplied to the error correction unit 15a. The diversity combining unit 14 performs diversity combining using the demodulated signals supplied from the remaining two receiving systems (in this case, the receiving systems 10c and 10d), and the demodulated signal after diversity combining is error-corrected unit 15b. To supply.

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

  Here, a channel search processing procedure will be described. For example, if the currently received channel is “NHK General / Akita”, first, the broadcast station database in the reception area storage unit 23 is referred to search for the physical channel of the relay station of “NHK General / Akita” Search for channels that can be received by “NHK Sogaku / Akita” other than the channel currently being received. Relay based on various channel program information (NIT, BIT, SDT, EIT, etc.) acquired by the program information extraction unit 20 with the reception status of the newly found channel being better than the currently received channel. If it is determined that the channel is a station, the channel selection units 10a to 10d are instructed to select the channel. Alternatively, when the currently received broadcast is receivable, the control unit 21 holds the physical channel of the found relay station in the memory, and this is the case when the currently received broadcast cannot be received. You may make it select a physical channel.

On the other hand, when the reception state of the currently received broadcast is better than the reception state of the found relay station, or when the relay station is not found, the control unit 21 again broadcasts the broadcast station in the reception area storage unit 23. With reference to the database, the physical channels of the relay stations of “NHK General / Iwate”, which is a broadcast station of the same series (sequence ID = 0) as “NHK General / Akita”, are sequentially searched in the broadcast station in Iwate Prefecture. If a receivable channel is found and it is determined that the broadcasting stations are of the same series based on various program information (NIT, BIT, SDT, EIT, etc.) of this channel acquired by the program information extraction unit 20, The channel selection units 10a to 10d are instructed to select this channel. Alternatively, if the currently received broadcast is receivable, the control unit 21 holds the physical channel of the found broadcast station of the same series in the memory, and the currently received broadcast cannot be received. In this case, the physical channel may be selected.
Also, if you search for the physical channel of the relay station of “NHK General / Iwate” and no broadcasting station of the same series is found, you can search for other physical channels that have not been searched yet, The physical channel of the relay station of “NHK General / Iwate” may be searched.

  As another channel search processing procedure, the control unit 21 sequentially searches all physical channels, or sequentially searches the physical channels of the relay stations of each broadcasting station for all broadcasting stations broadcast in Akita Prefecture and Iwate Prefecture. Thus, a receivable broadcast station may be found, a list of broadcast stations receivable at the current position may be created, and presented to the user.

  On the other hand, in the case of performing 3-1 diversity combining, the diversity combining unit 14 performs diversity combining using demodulated signals supplied from arbitrary three receiving systems (in this case, receiving systems 10a to 10c), and the rest The demodulated signal supplied from one receiving system (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 rather than performing the channel search stably, the control unit 21 instructs the diversity combining unit 14 to output the demodulated signal after diversity combining. The signal is supplied to the error correction unit 15a, and the demodulated signal of the reception 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 channel selection of the currently received channel, and also instructs the channel selection unit 12d to sequentially search channels to be searched by channel search. Select a station.

  In addition, the control unit 21 instructs the diversity combining unit 14 to give diversity combining when it is desired to place more importance on stable and reliable channel search than to stably receive the currently received channel. The later demodulated signal is supplied to the error correcting unit 15b, and the demodulated signal of the receiving system 10d is supplied to the error correcting unit 15a. Subsequently, the control unit 21 instructs the channel selection units 12a to 12c to sequentially select channels to be searched by channel search, and instructs the channel selection unit 12d to select a channel currently received. To continue.

Thereafter, when the channel search in S14 is completed, the control unit 21 instructs the diversity combining unit 14 to perform four diversity combining 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 higher hierarchy (S16).

  When the control unit 21 detects that the vehicle has reached the point F as shown in FIG. 5 and is out of the broadcast reception area in Akita Prefecture, the control unit 21 performs a 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 for the physical channel of the relay station of “NHK General / Akita” in the processing operation shown in FIG. .

  As described above, the digital broadcast receiving apparatus of the present invention performs reception by 4-diversity combining using the demodulated signals from the four receiving systems during normal reception. When the local broadcasting station reception area is exceeded, the four receiving systems are divided into two groups, one receiving system group receives the previously received channel, and the other receiving system group is Channel search is performed to search for receivable channels. This makes it possible to receive a program even during channel search. By outputting a high-level video / audio signal that is highly resistant to noise before the search is started, it is possible to suppress the occurrence of poor reception such as a video / audio signal being interrupted during a channel search. In addition, by performing a channel search when the local broadcast reception area is exceeded, compared to the first embodiment in which the channel search is performed when the local area is exceeded, the timing is actually set according to the reception environment. Channel search can be started.

  In addition, although the digital broadcast receiver in the embodiment of the present invention has shown the configuration example with four reception systems, the configuration with two, three, five or more reception systems is also possible. Even in such a case, the digital broadcast receiving apparatus divides into two reception system groups at the time of channel search, and one reception system group receives the same channel as during normal reception, and the other reception system has The group performs a channel search and obtains a receivable channel. By outputting a high-level video / audio signal that is highly resistant to noise before starting the channel search, it is possible to suppress the occurrence of reception failure such as the video / audio signal being interrupted during the channel search.

It is a block diagram which shows the structure of the digital broadcast receiver in Example 1 of this invention. 5 is an example of a reception area map held by a reception area storage unit 23 in the digital broadcast receiving apparatus according to the first embodiment of the present invention. 5 is an example of a broadcasting station database held by a reception area storage unit 23 in the digital broadcast receiving apparatus according to the first embodiment of the present invention. It is a flowchart which shows an example of operation | movement of the digital broadcast receiver in Example 1 of this invention. 7 is an example of a reception area map held by a reception area storage unit 23 in the digital broadcast receiving apparatus according to the second embodiment of the present invention. It is a flowchart which shows an example of operation | movement of the digital broadcast receiver in Example 2 of this invention.

Explanation of symbols

10a to 10d ... reception system 11a to 11d ... antenna part 12a to 12d ... channel selection part 13a to 13d ... demodulation part 14 ... ... diversity combining part 15a, 15b ... Error correction unit 16 ..... Strong layer decoding unit 17 ..... Weak layer decoding unit 18 ..... Switching unit 19 ..... Video・ Voice output unit 20 ・ ・ ・ ・ ・ ・ ・ ・ Program information extraction unit 21 ・ ・ ・ ・ ・ ・ ・ ・ Control unit 22 ・ ・ ・ ・ ・ ・ ・ ・ GPS reception system 21a ・ ・ ・ ・ ・ ・ GPS Antenna unit 22b... GPS receiving unit 23.

Claims (6)

A digital broadcast receiving apparatus that receives a digital broadcast signal transmitted in a first layer in which a video / audio signal is strong in noise resistance and a second layer in which noise resistance is weak by hierarchical transmission,
A plurality of reception units having a reception antenna, a channel selection unit, and a demodulation unit;
A diversity combining unit that combines the output signals of the plurality of receiving units with diversity;
A decoding unit for decoding the first layer digital data and the second layer digital data from the digital data output from the diversity combining unit;
A switching unit that selects and outputs one of the first layer video / audio signal and the second layer video / audio signal output from the decoding unit;
A program information extraction unit for extracting channel information from the digital data output from the diversity combining unit;
A position information acquisition unit for acquiring position information indicating a current position of the digital broadcast receiver;
A reception area storage unit for storing a channel list corresponding to the broadcast area;
When the current position of the digital broadcast receiving device indicated by the position information exceeds the broadcast area of the currently received channel stored in the reception area storage unit, a channel search is started. A plurality of receiving units are divided into two, one is subjected to channel search, the other is made to receive the video / audio signal, and the switching unit is instructed to input the first level video / audio signal A digital broadcast receiving apparatus comprising: a control unit that selects   2. The digital broadcast receiving apparatus according to claim 1, wherein the plurality of receiving units are configured by four receiving units, and during the channel search, two of the receiving units perform channel search, and the remaining two receiving units include A digital broadcast receiving apparatus for receiving the video / audio signal.   2. The digital broadcast receiving apparatus according to claim 1, wherein the plurality of receiving units include four receiving units, and during the channel search, one of the receiving units performs channel search, and the remaining three receiving units include A digital broadcast receiving apparatus for receiving the video / audio signal.   2. The digital broadcast receiving apparatus according to claim 1, wherein the plurality of receiving units are configured by four receiving units, and at the time of the channel search, three of the receiving units perform channel search, and the remaining one receiving unit includes A digital broadcast receiving apparatus for receiving the video / audio signal.   2. The digital broadcast receiving apparatus according to claim 1, wherein when the control unit detects that a broadcast area of a channel currently received from the position information acquisition unit has entered another broadcast area, the reception area A third step of referring to the physical channel of the relay station for a broadcasting station of the same series as the channel currently received in the broadcasting area at the current position from the storage unit and searching for these physical channels. A digital broadcast receiver. A diversity receiving method for receiving a digital broadcast signal transmitted in a first layer in which video / audio signals are highly resistant to noise by hierarchical transmission and a second layer that is weak in noise resistance,
A receiving step having a plurality of receiving units for receiving, selecting and demodulating the digital broadcast signal;
A diversity combining step of diversity combining the output signal of the receiving step;
A decoding step for decoding each of the first layer digital data and the second layer digital data from the digital data output from the diversity combining step;
A switching step of selecting and outputting one of the first layer video / audio signal and the second layer video / audio signal output from the decoding step;
A program information extracting step for extracting channel information from the digital data output from the diversity combining step;
A position information acquisition step of acquiring position information indicating a current position of the digital broadcast receiver;
A reception area storing step for storing a channel list corresponding to the broadcast area,
When the current position of the digital broadcast receiving device indicated in the position information step exceeds the broadcast area of the currently received channel stored in the reception area storage unit, a channel search is started. The plurality of receiving units are divided into two, one performs a channel search, the other receives the video / audio signal, and the switching step selects the video / audio signal of the first layer. Digital broadcast receiving method.

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