JP2010028186A - Diversity receiver and diversity reception method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a diversity receiver which suppresses the generation of reception defects such as the break of video or sound signals during channel search. <P>SOLUTION: The diversity receiver instructs a switching part 18 to have the video and sound signals of a strong hierarchy be selected when starting the channel search. During the channel search, a plurality of reception systems are divided into two groups, one group of the reception systems is made to perform the channel search, and the other group of the reception systems is made to receive the video and sound signals. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a diversity receiver that receives a digital broadcast using a plurality of antennas in a moving body such as an automobile.

  In ISDB-T (Integrated Services Digital Broadcasting for Terrestrial), a transmission system for digital terrestrial broadcasting in Japan, the transmission bandwidth of one channel is divided into 13 segments, and each segment is combined to a maximum of three layers. Transmission can be performed. 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.

  By the way, in a digital broadcast receiving apparatus mounted on a moving body such as an automobile, the received electric field strength of broadcast radio waves varies greatly with movement due to the influence of multipath fading. For this reason, a digital broadcast receiver mounted on a mobile unit receives broadcast radio waves with a plurality of antennas, and performs diversity combining such as selective combining and maximum ratio combining of the received digital broadcast signals to perform digital broadcasting. A signal can be received stably. This makes it possible to receive high-quality weak-layer broadcasting without interruption even while moving.

  On the other hand, in a digital broadcast receiving apparatus mounted on a mobile body, a receivable channel changes according to the vehicle position. For this reason, when a program of a certain broadcast station is being watched and the reception area of this broadcast station is left, it becomes difficult to receive the program of the broadcast station that has been viewed. In order to solve this problem, for example, in Patent Document 1, during normal reception, a broadcast signal of an arbitrary channel is received by diversity using a plurality of antennas and a plurality of demodulation units, and a video / audio signal is output. At the time of searching, the plurality of antennas and the plurality of demodulation units are divided into two groups, and the broadcast signal of the arbitrary channel received at the time of the normal reception is divided using the antenna and the demodulation unit of one group. By receiving and outputting a video / audio signal and performing a channel search using the antenna and demodulator of the other group, it is possible to acquire channel information of a new broadcasting station.

JP 2005-184548 A

  However, in the above-described digital broadcast receiving apparatus, during normal reception, the influence of multipath fading can be reduced and the digital broadcast signal can be stably received by diversity using a plurality of antennas and a plurality of demodulation units. However, at the time of channel search, a plurality of antennas and a plurality of demodulation units are divided into two groups, so that the effect of diversity is reduced and digital broadcast signals cannot be stably received, and high-quality weak hierarchical broadcasting. There is a problem that reception failure such as interruption of the video / audio signal is likely to occur.

  The present invention has been devised in view of the above problems, and an object of the present invention is to provide a diversity receiver that can suppress the occurrence of reception failure such as interruption of video / audio signals during channel search. .

  In order to achieve the above object, the present invention receives a digital broadcast signal in which a video / audio signal of a program having the same content is transmitted through a first layer having high noise resistance and a second layer having low noise resistance by hierarchical transmission. Diversity receiving apparatus, 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 output from the diversity combining unit A decoding unit that decodes the first layer digital data and the second layer digital data from the data, the first layer video / audio signal output from the decoding unit, and the second layer, respectively. A switching unit that selects and outputs one of the video / audio signals of the hierarchy, and the digital signal output from the diversity combining unit A program information extraction unit for extracting channel information from the data, and at the time of channel search, the plurality of reception units are divided into two so that one performs channel search and the other receives the video / audio signal. And a control unit that instructs the switching unit to select the video / audio signal of the first layer.

  In addition, this is a diversity reception method for receiving digital broadcast signals transmitted on the first layer, in which video / audio signals of programs having the same content by layer transmission are strong in noise resistance, and in the second layer, which is weak in noise resistance. A reception step having a plurality of reception units for receiving, selecting and demodulating the digital broadcast signal, a diversity combining step for diversity combining the output signal of the reception step, and a 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, and the first layer video / audio signal output from the decoding step and the second layer digital data. A switching step of selecting and outputting either one of the video / audio signals; A program information extraction step for extracting channel information from the digital data output from the diversity combining step, and at the time of channel search, the plurality of receiving units are divided into two, one performs channel search, and the other Receives the video / audio signal, and the switching step selects the video / audio signal of the first layer.

  According to the present invention, it is possible to suppress reception failure such as interruption of video / audio signals when performing a channel search, and there is an effect that a user can receive a broadcast in a suitable state.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows a block diagram of the diversity receiver in the embodiment 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 notifies the user of information on receivable channels found by the 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.

  Hereinafter, an example of the operation of the diversity receiver will be described with reference to the flowchart of FIG.

  During normal reception, the control unit 21 instructs the channel selection units 11a to 11d to select a channel specified by the user and instructs the diversity combining unit 14 to demodulate the four reception systems 10a to 10d. Four diversity combining using signals 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, the video / audio signal of the weak hierarchy is selected, and when the reception status is degraded or greatly fluctuated, the video of the strong hierarchy is selected.・ Audio signals can be selected.

  For example, the control unit 21 starts the channel search when an operation for starting the channel search is performed by the user or when the reception state of the broadcast radio wave is deteriorated (S11).

  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.

  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.

  When the control unit 21 finds a receivable channel by channel search, the control unit 21 acquires channel information such as NIT, BIT, SDT, and EIT included in the TS signal of this channel from the program information extraction unit 20. (S15). Based on the acquired channel information, the control unit 21 can determine, for example, whether the current channel is a relay station or the same affiliated station, or create a channel list. .

  Thereafter, when the channel search is completed, the control unit 21 instructs the channel selection units 12a to 12d to select the same channel as that during normal reception, and instructs the diversity combining unit 14 to specify the four reception systems 10a. 4-diversity combining is performed using a demodulated signal of -10d (S16). Alternatively, if the channel search can find a relay station of the currently received channel or the same affiliated station, the control unit 21 instructs the channel selection units 12a to 12d to select these channels. May be.

  Finally, the control unit 21 instructs the switching unit 18 to cancel the selection of the video / audio signal of the higher hierarchy (S17).

  As described above, the diversity receiver of the present invention performs reception by 4-diversity combining using the demodulated signals from the four reception systems during normal reception, and two channels for two reception systems during channel search. Dividing into groups, the group of one receiving system receives the same channel as in normal reception, and the group of the other receiving system performs channel search to search for receivable channels. 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.

  In addition, although the diversity 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 diversity receiving apparatus divides into two receiving system groups at the time of channel search, and one receiving system group receives the same channel as at the normal receiving time, and the other receiving system group. Performs a channel search to obtain receivable channels. 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 embodiment of the diversity receiver by this invention. It is a flowchart which shows an example of operation | movement of the diversity receiver by 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・ Audio output unit 20... Program information extraction unit 21.

Claims (5)

A diversity receiver that receives a digital broadcast signal transmitted in a first layer in which video and audio signals of programs having the same content by noise transmission are strong in noise resistance and a second layer in which noise resistance is weak,
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;
At the time of channel search, the plurality of reception units are divided into two, one is subjected to channel search, the other is received the video / audio signal, and the switching unit is instructed to perform the first hierarchy A diversity receiving apparatus comprising: a control unit that selects a video / audio signal.   2. The diversity receiver according to claim 1, wherein the plurality of reception units are configured by four reception units, and during the channel search, two of the reception units perform channel search, and the remaining two reception units have the above-described channels. A diversity receiving apparatus characterized by receiving a video / audio signal.   2. The diversity receiver according to claim 1, wherein the plurality of reception units includes four reception units, and at the time of the channel search, one of the reception units performs channel search, and the remaining three reception units include the above-described reception units. A diversity receiving apparatus characterized by receiving a video / audio signal.   2. The diversity receiver according to claim 1, wherein the plurality of receiving units are configured by four receiving units, and during the channel search, three of the receiving units are caused to perform channel search, and the remaining one receiving unit is configured to perform the channel search. A diversity receiving apparatus characterized by receiving a video / audio signal. A diversity reception method for receiving a digital broadcast signal transmitted in a first layer in which video / audio signals of programs having the same content by noise transmission are strong in noise resistance and in a second layer weak in noise resistance,
Receiving step 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 extraction step for extracting channel information from the digital data output from the diversity combining step;
At the time 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 selects the video / audio signal of the first layer. Diversity receiving method characterized by:

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