JP2011049713A - Digital broadcast receiver - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem wherein the optimum combination at a receiving level after carrier synthesis is not achieved even if antennas having a high receiving level are selected among N antennas. <P>SOLUTION: This digital broadcast receiver is equipped with: a plurality of antennas; a plurality of demodulators; a demodulation signal selector for selectively outputting a plurality of demodulation signals to a first or second group; a first carrier synthesizer for performing carrier synthesis of the demodulation signals of the first group and outputting the resultant signal; a receiving state determination device for determining a receiving state of a digital signal by a synthesized demodulation signal outputted by the first carrier synthesizer; a decoder for decoding the synthesized demodulation signal outputted by the first carrier synthesizer and outputting the resultant signal; a second carrier synthesizer for performing carrier synthesis of the demodulation signals of the second group and outputting the resultant signal; and a search device for searching for a relay station by the synthesized demodulation signal outputted by the second carrier synthesizer, wherein the demodulation signal selector selects a plurality of demodulation signals in accordance with a determination result of the receiving state determination device. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a digital broadcast receiving apparatus, and more specifically, when a plurality of antennas and demodulators are provided, program viewing is performed with a minimum combination of antennas and demodulators, and relaying is performed with the remaining antennas and demodulators. The present invention relates to a digital broadcast receiving apparatus capable of performing a station search.

  Japan's terrestrial digital broadcasting will start in December 2003 in the three major metropolitan areas, and in order to increase the coverage of the coverage area for the analog TV broadcast on July 24, 2011, nationwide. A number of relay stations are installed sequentially.

  Mobile terrestrial digital broadcast receivers, such as one-seg broadcast receivers built into mobile phones and in-vehicle digital televisions, are equipped with multiple antennas and demodulators to improve reception performance. Along with this, a receiving station has been developed that switches the relay station appropriately.

  Further, there is a technique in which a plurality of antennas and demodulators are separately controlled for program viewing (receiving) and relay station search, and are controlled independently to receive and process different broadcast waves simultaneously (for example, Patent Documents). 1, see Patent Document 2).

JP 2007-60560 A JP 05-049884 A

  In the case of a mobile receiver having two antennas and a demodulator, the above conventional technique searches for another relay station using the other antenna and demodulator while receiving a program using the other antenna and demodulator. That's it. At that time, the antenna and demodulator with the higher reception level of the broadcast wave currently being viewed are selected for reception to continue viewing, and the antenna and demodulator with the lower reception level are selected for the relay station search. It is going to be used for. At present, in order to further improve the reception sensitivity, a product having four antennas and a demodulator has already been commercialized, and in that case, for reception to continue viewing the two antennas and the demodulator. The remaining two are used for searching. Similarly, it may be possible to select the two antennas and the demodulator whose reception level of the broadcast wave currently being viewed is higher for reception to continue viewing, but when performing carrier synthesis, There was a problem that it might not be an optimal choice.

  In addition, when two antennas are selected from four antennas, there are six combinations. In addition, when two antennas and a demodulator cannot receive enough images, there are many combinations of antenna selection methods, such as using three antennas and a demodulator for reception to continue viewing. There is a problem that it is not possible to determine a simple combination at high speed.

  Further, when receiving while moving, the optimal antenna selection method changes with movement, but there is no mechanism to follow it, and there is a problem that it is not possible to always select the optimal antenna.

  In order to solve the above-mentioned problems, the digital broadcast receiving apparatus according to the present invention receives demodulated signals from N antennas and combines carriers, and as a result, any combination uses the smallest number of antennas for broadcasting. It is equipped with a reception state determiner that can determine whether a sufficient reception level for viewing is obtained, and can appropriately review the antenna selection method based on information on the passage of time, travel distance, and traveling direction. is there.

  Further, the digital broadcast receiving apparatus according to the present invention is not the result of actual carrier synthesis, but actually calculates the reception level after carrier synthesis from the signal for each subcarrier frequency of each demodulator. A reception state estimator is provided for determining which combination can obtain a sufficient reception level for viewing with the least number of antennas without trying all combinations.

  According to the digital broadcast receiving apparatus of the present invention, the reception state determining unit selects a minimum number of antennas and demodulator combinations and performs the search function and the like with the remaining antennas. Not only when a certain amount of time has elapsed, but when a certain amount of time has passed, when a certain distance has been moved, or when the orientation of the receiver has changed, the optimal antenna combination is inspected again. There is an effect that it is possible to search for another relay station while making a selection and watching more stable television.

The block diagram which shows the structure of the digital broadcast receiver in Embodiment 1 of this invention. The figure explaining the processing content of the demodulated signal selector, the 1st carrier combiner, and the 2nd carrier combiner in Embodiment 1 of the present invention. The flowchart explaining the processing content of the reception state determination device in Embodiment 1 of this invention. The block diagram which shows the structure of the digital broadcast receiver in Embodiment 2 of this invention.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

(Embodiment 1)
FIG. 1 is a block diagram showing a configuration of a digital broadcast receiving apparatus according to Embodiment 1 of the present invention. Hereinafter, the configuration of the digital broadcast receiving apparatus will be described with reference to FIG.

  The digital broadcast receiving apparatus demodulates radio waves received by the first antenna 101, the second antenna 102, the Nth antenna 103 (N is an integer of 3 or more), and the first antenna 101 that receive digital broadcast radio waves. The first demodulator 104, the second demodulator 105 that demodulates the radio wave received by the second antenna 102, and the Nth demodulator 106 that demodulates the radio wave received by the Nth antenna 103 (N is 3 or more) ), The demodulated signal output from the first demodulator 104, the demodulated signal output from the second demodulator 105, and the demodulated signal output from the Nth demodulator 103 are input, A demodulated signal selector 107 that selects and outputs two groups; a first demodulated signal group selected by the demodulated signal selector 107; and a first carrier synthesizer that performs carrier synthesis; The demodulated signal synthesized by one carrier synthesizer 108 is inputted, the reception state judgment unit 109 for judging the reception state of the broadcast radio wave, and the demodulated signal synthesized by the first carrier synthesizer 108 are inputted, The decoder 110 that decodes the broadcast stream, decodes video and audio, and presents content such as subtitles and data broadcasts, etc., and inputs the second demodulated signal group selected by the demodulated signal selector 107, and performs carrier synthesis The second carrier synthesizer 111, the demodulated signal output from the second carrier synthesizer 111 is input, and the relay station searcher 112 that performs the relay station search and the reception state determination unit 109 have passed a certain period of time. The elapsed time measuring device 113 that notifies the movement, the movement distance measuring device 114 that notifies the reception state determination device 109 of the movement of a certain distance, and the current receiver And has direction is composed of a traveling direction measuring device 115 to notify that it has changed.

  The operation of Embodiment 1 of the present invention in the digital broadcast receiving apparatus having the above configuration will be described below.

  The first antenna 101 is an antenna for receiving a broadcast wave, and in the present invention, there is no particular designation of the format or the like. The same applies to the second antenna 102 and the Nth antenna 103. Further, the types of antennas from the antenna 1 to the antenna N and the attachment method may not be unified. The first demodulator 104 detects the radio wave received by the first antenna 101, divides it into OFDM subcarriers, and outputs it. The same applies to the second demodulator 105 and the Nth demodulator 106. The demodulated signal selector 107 inputs the signals for each subcarrier output from the first demodulator 104, the second demodulator 105, and the Nth demodulator 106, and outputs these signals for each demodulator by two. This switch outputs in groups. The demodulator signal to be sent to the first carrier synthesizer 108 or the second carrier synthesizer 111 is controlled according to an instruction from the reception state determination unit 109.

  Here, FIG. 2 explains processing contents of the demodulated signal selector 107, the first carrier combiner 108, and the second carrier combiner 111 in the first embodiment. In the case of Japanese terrestrial digital broadcasting, broadcast waves are modulated by the OFDM method, and one carrier frequency is composed of 5617 subcarriers. All of the graphs 201 to 206 in FIG. 2 schematically show reception states for each of 5617 subcarriers.

  For example, as in the case of FIG. 2, the reception level of each antenna is very good with antenna 1 and antenna 2 being 40, and the reception level of antenna 3 and antenna 4 is not so good with 30. . In the conventional example, the antenna 1 and the antenna 2 are selected from the reception level and used for reception in order to receive the radio wave of the broadcasting station currently being viewed, and the antenna 3 and the antenna 4 are searched to search for other relay stations. Was selected to be used for search to execute. However, the reception contents of the antenna 1 and the antenna 2 are the same for each subcarrier, so the reception level by carrier synthesis does not improve. However, each of the antenna 3 and the antenna 4 alone has a low reception level for each antenna. However, when viewed for each subcarrier, the antenna 3 and the antenna 4 are in a relationship that complement each other's unreceivable locations. It shows that the reception level may be better than when combining antenna 1 and antenna 2 for carrier synthesis.

  The reception state determiner 109 considers the above logic, and selects a combination of antennas that provides the best reception level after carrier synthesis, while sufficiently securing the reception level of the currently viewed broadcast wave, The remaining antenna can be used to receive another broadcast wave such as a relay station search.

  FIG. 3 is a flowchart for explaining a process in which the reception state determination unit 109 determines that it is optimal to input the number of N antennas to the first carrier combiner 108. is there.

  In step S301, it is determined whether or not the current broadcast can be received with only one of the N antennas. Here, there are N combinations of selecting one from N antennas, and the one having the best reception level is selected from N combinations. If there are N ways that can ensure a sufficient reception level for viewing (“Yes” in step S301), the process proceeds to step S304, and the determination is completed. If none of the N ways can ensure a sufficient reception level for viewing (“No” in step S301), the process proceeds to step S302.

  In step S302, two of the N antennas are selected and it is determined whether the current broadcast can be received. Here, there are Nx (N-1) / 2 combinations for selecting two antennas from N antennas, and the one having the best reception level is selected from the combinations. In addition, the index when selecting two is not based on the individual reception level for each antenna, but based on the reception level after carrier synthesis as described above.

  If there are Nx (N−1) / 2 types that can secure a reception level sufficient for viewing (“Yes” in step S302), the process proceeds to step S305, and the determination is completed. If none of the Nx (N−1) / 2 ways can ensure a sufficient reception level for viewing (“No” in step S302), the process proceeds to step 303.

  Similarly, the determination is made including the case where reception is not possible unless all N are used (steps S303 and S307). As a result, the minimum antenna necessary for viewing the current program is selected, and the other antennas can be used for processing of receiving other radio waves such as a relay station search.

The decoder 110 inputs the demodulated signal carrier-synthesized by the first carrier synthesizer 108, decodes video and audio, interprets subtitles and data broadcasts, and presents them.
The second carrier synthesizer 111 inputs a signal that has passed through an antenna demodulator not selected as an input to the first carrier synthesizer 108 and synthesizes the carrier. The content of the carrier synthesis process is the same as that of the first carrier synthesizer 108.

  The relay station search unit 112 searches for a relay station that transmits the same broadcast wave as the broadcast station being viewed by the first carrier combiner 108 based on the output from the second carrier combiner 111. It is. For this purpose, a physical channel different from the physical channel of the broadcast currently being viewed is sequentially checked, and the second carrier combiner among the first demodulator 104 to the N-th demodulator 106 is used. This is realized by selectively instructing only those input to 111.

  In this example, the antenna and demodulator not selected for reception are used for the purpose of relay station search, but other physical channels may be selected for purposes other than the relay station search. For example, a search for affiliated stations, acquisition and accumulation of program guide data of other stations, monitoring of emergency alert broadcasts at other stations, channel selection / viewing of other broadcast stations, and the like may be used.

  The elapsed time measuring unit 113 measures the elapsed time after the reception state determining unit 109 determines the combination of antenna selections. Since the radio wave conditions change depending on the surrounding conditions and the weather even if there is no movement of the place, it may be more optimal to review the antenna selection at regular intervals. The notification is sent to the reception state determiner 109 as a fixed time elapse notification.

  The moving distance measuring device 114 measures the moving distance after the combination of antenna selections is determined by the reception state determining unit 109. Since the radio wave condition changes with the movement of the place, it may be a more optimal combination to review the antenna selection every time a certain distance is moved. Therefore, the movement distance is measured, and the reception state determination unit 109 Notify as a fixed distance movement notification.

  The traveling direction measuring device 115 measures a change in the traveling direction after the combination of antenna selections is determined by the reception state determining unit 109. As the antenna changes its direction, the reception level changes greatly, so if it is a digital broadcast receiver installed in a vehicle, it is better to review the antenna selection when the direction of travel of the car changes. Therefore, a change in the traveling direction is notified to the reception state determiner 109 as a traveling direction change notification.

  In this way, the reception state determination unit 109 selects the minimum necessary antenna from the N antennas, and also receives a fixed time elapsed notification input from the elapsed time measurement unit 113 and input from the movement distance measurement unit 114. It is possible to always realize an optimal combination of antenna selections by performing a review so as to follow a change in the reception status such as a notification of a certain distance movement or a notification of a change in travel direction input from the travel direction measuring instrument 115. it can.

(Embodiment 2)
FIG. 4 is a block diagram showing the configuration of the digital broadcast receiving apparatus according to Embodiment 2 of the present invention. Hereinafter, the configuration of the digital broadcast receiving apparatus will be described with reference to FIG.

  The first antenna 401, the second antenna 402, and the Nth antenna 403 are the same as the first antenna 101, the second antenna 102, and the Nth antenna 103 of FIG. The first demodulator 404, the second demodulator 405, and the N-th demodulator 406 are the first demodulator 104, the second demodulator 105, and the N-th demodulator 106 in FIG. Is the same. The reception state estimator 407 receives all demodulator outputs from the first demodulator 404 to the N-th demodulator 406, calculates the reception level after carrier synthesis, and performs carrier synthesis for each antenna combination. The subsequent reception level is estimated, and the estimated reception level (estimated reception level) is output. The reception state determiner 408 determines the best combination of antennas from the estimated reception level output from the reception state estimator 407, and outputs the result.

  The demodulated signal selector 409 is the same as the demodulated signal selector 107 of FIG. The first carrier synthesizer 410 is the same as the first carrier synthesizer 108 of FIG. 1 of the first embodiment. The decoder 411 is the same as the decoder 110 of FIG. The second carrier synthesizer is the same as the second carrier synthesizer 111 of FIG. The relay station searcher 413 is the same as the relay station searcher 112 of FIG. 1 of the first embodiment. The time lapse measuring instrument 414 is the same as the time lapse measuring instrument 113 of FIG. The moving distance measuring device 415 is the same as the moving distance measuring device 114 of FIG. The traveling direction measuring instrument 416 is the same as the traveling direction measuring instrument 115 of FIG.

  Here, the operation of Embodiment 2 of the present invention in the digital broadcast receiving apparatus configured as described above will be described below.

  In reception state estimator 407, the demodulated signal for each subcarrier output from first demodulator 404 to Nth demodulator 406 is input, and each combination for each antenna is determined from the reception level for each subcarrier of each antenna. The reception level after the carrier synthesis at can be obtained by calculation. As a result, in the case of the first embodiment, the determination is made by actually measuring the reception level after carrier combination using the first carrier combiner 108, but in the second embodiment, each combination is actually This eliminates the need for carrier synthesis.

  As a result, the selection of the antenna can be determined at high speed, so that the followability can be improved while obtaining the same effect as in the first embodiment.

  The digital broadcast receiving apparatus of the present invention realizes the most optimal and efficient antenna selection method in a receiving apparatus having three or more antennas and can follow changes in the reception environment, so that stable viewing is possible. In this way, a digital broadcast receiving apparatus for a mobile unit that can use the radio waves of another broadcasting station such as a relay station search is realized.

101, 401 First antenna 102, 402 Second antenna 103, 403 Nth antenna 104, 404 First demodulator 105, 405 Second demodulator 106, 406 Nth demodulator 107, 409 Demodulated signal Selector 108, 410 First carrier combiner 109, 408 Reception status determiner 110, 411 Decoder 111, 412 Second carrier combiner 112, 413 Relay station searcher 113, 414 Elapsed time measuring instrument 114, 415 Movement Distance measuring instrument 115, 416 Traveling direction measuring instrument 407 Reception state estimator

Claims (4)

A plurality of antennas for receiving digital broadcast signals;
A plurality of demodulators for demodulating the received digital broadcast signal;
A demodulated signal selector for selecting and outputting the demodulated demodulated signals to the first group or the second group;
A first carrier synthesizer for carrier-combining and outputting the output demodulated signal of the first group;
A reception state determiner for determining a reception state of the received digital signal based on the combined demodulated signal output from the first carrier combiner;
A decoder that decodes the combined demodulated signal output from the first carrier combiner and outputs the decoded signal as a video signal and / or an audio signal;
A second carrier synthesizer for synthesizing and outputting the output demodulated signals of the second group;
A relay station searcher that searches for a relay station based on the combined demodulated signal output from the second carrier combiner;
The digital broadcast receiving apparatus, wherein the demodulated signal selector sorts a plurality of demodulated signals demodulated according to a determination result from the reception state determiner into the first group or the second group. An elapsed time measuring device that measures a certain time and outputs a certain time elapsed notification;
A travel distance meter that measures travel distance and outputs a fixed distance travel notification;
A travel direction measuring device that detects a change in the travel direction and outputs a travel direction change notification;
2. The reception state determination unit according to claim 1, wherein the reception state determination unit determines a reception state of the received digital signal based on at least the fixed time elapse notification, the fixed distance movement notification, or the traveling direction change notification. Digital broadcast receiver. A plurality of antennas for receiving digital broadcast signals;
A plurality of demodulators for demodulating the received digital broadcast signal;
A demodulated signal selector for selecting and outputting the demodulated demodulated signals to the first group or the second group;
A first carrier synthesizer for carrier-combining and outputting the output demodulated signal of the first group;
A decoder that decodes the combined demodulated signal output from the first carrier combiner and outputs the decoded signal as a video signal and / or an audio signal;
A second carrier synthesizer for synthesizing and outputting the output demodulated signals of the second group;
A relay station searcher that searches for a relay station based on the combined demodulated signal output from the second carrier combiner;
A reception state estimator for estimating a reception level after carrier synthesis for each combination of the plurality of antennas from reception levels of the plurality of demodulated signals input from the plurality of demodulators;
A reception state determiner that determines a combination of a plurality of the demodulated signals according to the estimated reception level,
The digital broadcast receiving apparatus, wherein the demodulated signal selector sorts a plurality of demodulated signals demodulated according to a determination result from the reception state determiner into the first group or the second group. An elapsed time measuring device that measures a certain time and outputs a certain time elapsed notification;
A travel distance meter that measures travel distance and outputs a fixed distance travel notification;
A travel direction measuring device that detects a change in the travel direction and outputs a travel direction change notification;
4. The digital signal according to claim 3, wherein the reception state determiner determines a combination of a plurality of the demodulated signals based on at least the fixed time progress notification, the fixed distance movement notification, or the traveling direction change notification. Broadcast receiving device.

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