JP2007158492A - Terrestrial digital television receiver - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mobile terrestrial digital television receiver that solves a problem of disabling reception of a terrestrial digital television broadcast when a reception electric field strength is lowered and an error correction capability limit is exceeded in the case that a user moves while viewing the mobile terrestrial digital television receiver. <P>SOLUTION: The mobile terrestrial digital television receiver includes: a mobile phone network communication means 101 for making communication with a mobile phone network; a terrestrial digital TV reception means 102 for receiving a terrestrial digital television broadcast; a communication signal delay means 603 and a received signal delay means 604 for applying delay processing to the respective signals; and a video switching means 105 and an audio switching means 106 for switching the respective signals, and the mobile terrestrial digital television receiver always monitors an error occurrence level in the reception of the terrestrial digital television, uses the mobile phone network to connect with an IP network just before the reception electric field strength is lowered and the error correction limit is reached and can seamlessly view the terrestrial digital television broadcast even when the reception electric field strength is lowered by receiving IP retransmission contents to switch video and audio outputs. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a terrestrial digital television receiver capable of receiving and viewing digital terrestrial television broadcasts.

  In recent years, various types of television broadcasting have been shifting to digital broadcasting having the advantages of high image quality, multi-channels, and high added value through data broadcasting. As for terrestrial television broadcasting, this broadcasting started in 2003 in the three major areas and is now being developed nationwide. This terrestrial digital television broadcast is characterized in that it can be satisfactorily received by a mobile terminal or a portable terminal, and the viewable area is gradually expanding. In addition, the terrestrial digital television reception function for mobile terminals is currently under development by mobile phone operators and terminal manufacturers, and is expected to be realized in recent years.

  When a conventional analog television broadcast receiver moves while receiving, the reception state changes each time due to a change in the reception radio wave condition due to a change in the reception environment, and the viewing screen is disturbed accordingly. Was. That is, when the radio wave condition gradually deteriorates due to the movement of the receiving terminal, the quality of the viewing screen also gradually deteriorates, making viewing difficult.

  The reception quality characteristic at this time is shown in FIG. The graph shown as analog TV reception in this figure shows the characteristics of reception quality when the received electric field strength changes when receiving terrestrial analog television broadcast. This graph means that the reception quality deteriorates in proportion to a decrease in the received electric field strength when the received electric field strength falls below a certain level in terrestrial analog television reception.

  On the other hand, as for the reception characteristics of terrestrial digital television broadcasting, as shown in the digital TV reception graph of FIG. 2, the reception quality is almost constant even when the reception electric field strength is considerably weakened. This is because an error that appears as noise on the screen can be eliminated by correcting an error that occurs when the received electric field strength drops due to the error correction capability unique to digital processing. However, when the decrease in the received electric field strength exceeds the limit of the error correction capability, the reception quality level is abruptly deteriorated and the reception quality level is deteriorated as compared with the reception of terrestrial analog television.

  An example of the prior art as a countermeasure when such a reception state of television broadcasting deteriorates will be described with reference to the drawings.

  FIG. 7 is a block diagram of the first prior art. A received radio wave from the antenna 710 is divided into two by a distributor 711 and supplied to an analog TV receiver 701 and a digital TV receiver 702. The video signal and the audio signal output from both receivers are switched to one by the video switch 704 and the audio switch 703 and are reproduced as video and audio by the display 708 and the speaker 707, respectively. This changeover switch is changed over by a changeover control unit 706.

  Normally, when a television program received by the digital TV receiver 702 is viewed and the reception state of the digital TV receiver 702 becomes poor, packet errors from the digital demodulator increase. When the error value becomes larger than a preset value, the switching control unit 706 switches the audio switch 703 and the video switch 704 to the analog TV side so that the TV program received by the analog TV receiver 701 can be viewed. . At this time, it is necessary to set in the channel setting unit of the analog TV receiver 701 a program (simultaneous broadcast program) having the same content as the TV program being viewed on the digital TV receiver 702. Therefore, EPG (electronic program) information from the digital TV receiver 702 is input to the channel setting unit 705, an analog TV channel of the same program as the digital TV broadcast is searched from the analog TV program information of the EPG, and the analog TV receiver 701 is searched. The information is output.

  With the configuration as described above, it is possible to automatically switch the reception content to analog broadcast reception when the reception state of the digital broadcast deteriorates (see, for example, Patent Document 1).

  On the other hand, FIG. 8 is a block configuration diagram of the second prior art, in which a television broadcast wave received by an antenna 822 is demodulated by a tuner / demodulator 811 and finally displayed on a television receiver display 817. Unit 801 and the cellular phone communication signal received by antenna 849 are received by the wireless transmission / reception circuit unit, and information on the area where the terminal exists is stored in base station data storage means 839, area code conversion means 840, converted data acquisition means 848, etc. It is comprised from the mobile telephone part 803 acquired by these.

  With the above configuration, even if it is difficult to view a TV station by moving while watching a TV program and it becomes difficult to view, the area information obtained from the base station when the last call was made with a mobile phone By selecting a channel of the same affiliated station based on this, continuous viewing of the same program is possible even while moving (see, for example, Patent Document 2).

  FIG. 9 is a block diagram of the third prior art, in which a television broadcast wave from the broadcasting station 910 is received by the complementary viewing service server 920, and contents for complementary viewing service are created and stored. When viewing is difficult for some reason while viewing the TV broadcast on the mobile terminal 950, the content for the complementary viewing service is transmitted from the mobile terminal 950 to the complementary viewing service server 920 via the wireless base station 940 and the telephone public network 930. Send a delivery request. The supplemental viewing service server 920 that has received the distribution request transmits the requested supplemental viewing service content to the portable terminal 950 via the telephone public network 930 and the wireless base station 940.

With the configuration described above, even if it becomes difficult to view TV, it is possible to view the contents of the program that follows the scene that has become unviewable by acquiring and playing back the content for complementary viewing service. (For example, refer to Patent Document 3).
JP 2000-332632 A JP 2004-153399 A JP 2004-349932 A

  However, the configuration according to the related art as described above has the following problems.

  First, in the first prior art, when the digital broadcast cannot be viewed, the program can be viewed by switching to the analog broadcast. However, if the radio wave condition is so bad that the digital broadcast cannot be viewed, Similarly, broadcasts often have poor radio wave conditions, and even when switched to analog broadcasting, reception quality that can withstand viewing may not be obtained.

  Also, in the second conventional technique, if the digital broadcast program being viewed cannot be viewed because the reception state has deteriorated, even if radio waves from other transmitting stations can be received, In this case, it is difficult to continue viewing even if the channel is switched to another channel. Also, depending on the region, there may be cases where programs of the same broadcaster series are not transmitted on a plurality of channels, and in this case, viewing cannot be continued by switching the reception channel.

  Also, in the third conventional technology, if there is no supplementary viewing content providing service business as described above, it is impossible to continue viewing using this technology, and even if there is a similar service, Since viewing is not possible during downloading, it is difficult to continue viewing in real time. The content data provided is limited to either a high-speed playback file that thins out the screen of the video stream to catch up with real-time television broadcasting, or a digest file that summarizes only important scenes, so the entire program content is completely Can not watch. In order to shorten the download time, it is necessary to reduce the content capacity. For this purpose, however, the conversion bit rate for video compression and expansion must be reduced, resulting in degradation of the quality of the reproduced image. Become.

  Even in such a case, the present invention is intended to enable continuous television broadcast program viewing.

  In order to solve the above-mentioned problems, a terrestrial digital television receiver according to the present invention performs communication between a terrestrial digital TV receiving means for receiving radio waves of terrestrial digital television broadcasting and a mobile phone communication network, thereby performing voice communication and Mobile phone network communication means for performing IP connection to the Internet, video switching means for switching and outputting one of the video signal demodulated by the terrestrial digital TV receiving means and the video signal demodulated by the mobile phone network communication means, From the audio switching means for switching and outputting one of the audio signal demodulated by the terrestrial digital TV receiving means and the audio signal demodulated by the mobile phone network communication means, and the terrestrial digital TV receiving means or the mobile phone network communication means Control means for issuing an instruction to switch between video display and audio output based on the information of the video, and a video display device for displaying the video signal on a display medium And an audio reproduction means for reproducing an audio signal, wherein video and audio are reproduced by appropriately switching between the reception signal from the terrestrial digital TV reception means and the communication signal from the mobile phone network communication means. Is.

  According to the terrestrial digital television receiver of the present invention, even when viewing of a terrestrial digital television broadcast program on a portable terminal becomes difficult due to a deterioration in radio wave condition, the same program as that of the terrestrial digital television broadcast is displayed. Using IP retransmission, it is possible to seamlessly switch from viewing a program through terrestrial digital television reception to viewing through a communication over an IP network.

  Hereinafter, an example of an embodiment of a terrestrial digital television receiver according to the present invention will be described with reference to the drawings.

(Embodiment 1)
FIG. 1 is a block diagram showing a configuration of a terrestrial digital television receiver according to Embodiment 1 of the present invention. Hereinafter, in the first embodiment, the configuration and operation of the present invention will be specifically described.

  In FIG. 1, a mobile phone network communication means 101 performs a voice call by communicating with a mobile phone operator device 114. In addition, it connects to the IP network 115 via the cellular phone carrier device 114, acquires IP retransmission data of terrestrial digital television broadcasting, and outputs it in the form of video and audio signals after performing demodulation processing. To do.

  This data communication function is also used to acquire EPG data (iEPG) on the Internet. Further, the current position is measured using the GPS antenna 112, and the information is output to the control means 109.

  The terrestrial digital TV receiving means 102 receives the terrestrial digital television broadcast radio wave transmitted from the terrestrial digital television broadcast station 113 using the receiving antenna 111, performs the demodulation process, and then outputs the video signal and the audio signal. Output in format. The reception status is constantly monitored and the information is output.

  The video switching unit 105 switches between the video signal from the cellular phone network communication unit 101 and the video signal from the terrestrial digital TV receiving unit 102 using the switching control signal from the control unit 109, and outputs either one. The voice switching means 106 switches between the voice signal from the cellular phone network communication means 101 and the voice signal from the terrestrial digital TV receiving means 102 using the switching control signal from the control means 109, and outputs either one.

  The video display means 107 displays the video signal from the video switching means 105 on a display panel or the like equipped in the mobile terminal. The sound reproduction means 108 outputs the sound signal from the sound switching means 106 as an audible sound using an output device such as a speaker.

  The control unit 109 controls the switching contents of the video switching unit 105 and the audio switching unit 106 based on the reception state information from the terrestrial digital TV receiving unit 102, and outputs a switching control signal. Before switching, the mobile phone network communication means 101 outputs a request for connection to the television broadcasting station 113 via the IP network 115, a request for receiving IP retransmission data, and a request for demodulating received data.

  The operation of the terrestrial digital television receiver configured as described above will be described.

  The terrestrial digital television broadcasting radio wave from the terrestrial digital television broadcasting station 113 is received by the terrestrial digital TV receiving means 102 via the receiving antenna 111, the video display means 107 displays the video, and the audio reproduction means 108 plays the audio. When a digital terrestrial television broadcast program is being viewed by performing the above-described reproduction, good television reception is possible if the received electric field intensity representing the strength of the television broadcast radio wave is sufficiently strong. However, when the received electric field strength deteriorates, the reception state deteriorates with the conventional analog television receiver, and the quality of video and audio to be reproduced deteriorates.

  However, digital terrestrial television receivers can maintain the best reception quality as shown in Fig. 2 by correcting errors that occur due to the deterioration of the reception status by the error correction capability through digital signal processing. It is. When the amount of error exceeds the limit of the error correction capability, the terrestrial digital television receiver cannot receive television.

  Therefore, as shown in FIG. 5, when the received electric field strength gradually decreases due to a change in the viewing position or the like and reaches the level indicated by S1, the control means 109 uses the mobile phone network communication means 101 to Mobile phone network communication with the device 114 is performed, and the IP network network 115 is connected. Thereby, connection and data communication with various servers existing on the IP network are possible.

  A digital terrestrial television broadcasting station 113 is connected to the IP network 115. Digital terrestrial television broadcasting retransmits its contents to the IP network from the viewpoint of fusion of broadcasting and communication. In the present invention, each television broadcaster implements this IP retransmission service. Assumes that.

  The mobile phone network communication means 101 connects to the mobile phone network and the IP network to connect to this television broadcaster, and prepares to receive the same content as the program content of the currently received terrestrial digital television broadcast. Start and start receiving content. When the received electric field strength further decreases and reaches the level of S2 in FIG. 5, which is just before the error correction capability limit, the control means 109 displays the contents of the received digital terrestrial television broadcast for the currently viewed video and audio. In order to switch from IP to the content of IP reception, a switching signal is output to the video switching means 105 and the audio switching means 106, and the video and audio are switched to the content received from the IP receiving side, that is, the cellular phone network communication means 101.

  As a result, when the received electric field intensity reaches the level of S2, the video display means 107 and the audio reproduction means 108 are switched from the contents of the digital terrestrial television broadcast reception to the contents of the IP reception. Even after the output is switched, the terrestrial digital TV receiving means 102 continues to receive the terrestrial digital television broadcast. However, if the received electric field strength further decreases and exceeds the level of S3, that is, the error correction capability limit, the terrestrial digital TV receiving means. The terrestrial digital television broadcast reception at 102 becomes impossible. Still, the terrestrial digital TV receiving means 102 continues to receive terrestrial digital television broadcast radio waves.

  In this way, by preparing, starting, and switching IP reception with different thresholds S1 and S2, the reception state is predicted to be deteriorated, and reception switching without interruption is performed. it can.

  Next, there is a case where the received electric field strength recovers as the viewing position changes. However, when the received electric field strength gradually increases and exceeds the level of S2, all errors generated can be corrected by the error correction function. Digital television broadcasts can be received and viewed satisfactorily. Therefore, the control unit 109 outputs a switching signal to the video switching unit 105 and the audio switching unit 106 in order to switch the video and audio currently being viewed from the content of the IP reception to the content of the digital terrestrial television broadcast reception. The sound is switched to the content received from the terrestrial digital television broadcast receiving side, that is, the terrestrial digital TV receiving means 102.

  As a result, when the received electric field intensity increases and reaches the level of S2, the video display means 107 and the audio reproduction means 108 switch from the IP reception program content to the terrestrial digital television broadcast reception program content. Thereafter, when the received electric field strength further increases and reaches the level of S4, the received electric field strength is necessary and sufficient for receiving the terrestrial digital television broadcast. Exit.

  The terrestrial digital television receiver of the present invention can retransmit IP using the mobile phone network by the above configuration and operation even when reception of terrestrial digital television broadcast becomes difficult due to poor reception. By using the service, it is possible to provide a digital terrestrial television receiver that can perform uninterrupted television viewing.

  In the present invention, a decoding error is used as an error for determination that occurs when the received electric field strength is low. Digital television broadcasts including digital terrestrial television broadcasts are broadcast after the amount of data is compressed by encoding video, audio, data, etc. using a digital compression / decompression algorithm called MPEG. In the receiver, the compressed data is decoded by a decoder called a decoder and returned to the original data, and then used for the television reception process. If the received electric field strength is low, the electric field strength of the television broadcast radio wave obtained from the antenna is low, and the received radio wave is mixed with noise as a whole. If the decoding process described above is performed using this, the decoding process is not performed correctly due to the influence of noise components, and a decoding error occurs. In the present embodiment, as shown in FIG. 3, the switching timing can be more appropriately determined by indirectly determining the strength of the received electric field strength using this decoding error.

  In addition to the decoding error, the received electric field strength can be determined using the received C / N ratio. The reception C / N ratio indicates the ratio of the signal strength (Carrier) to the total noise power (Noise) from the antenna. If the value is large, good reception is possible. In this embodiment, as shown in FIG. 4, it is possible to indirectly determine the strength of the received electric field strength using this received C / N ratio.

  Alternatively, using the GPS position information from the mobile phone network communication means 101, the control means 109 can output a switching signal for switching between video and audio signals. In such a case, it is possible to predict that the terrestrial digital television broadcast cannot be received by storing the receivable area information of the broadcast station that is received in advance and comparing it with the GPS position information in a timely manner. IP reception is started when a certain threshold is exceeded with respect to the boundary of the responsible area that can be received, and switching from digital terrestrial television broadcasting to IP reception is performed when the boundary of the responsible area that can be received is exceeded. . Naturally, in the reverse case, the IP reception is switched to the terrestrial digital television broadcast reception.

(Embodiment 2)
Hereinafter, in the second embodiment, the configuration and operation of the present invention will be specifically described. The configuration according to this embodiment is shown in FIG. 6, and in this embodiment, the same components as those in Embodiment 1 are denoted by the same reference numerals, and the description thereof will be omitted as appropriate.

  As described in the first embodiment, it is possible to switch between terrestrial digital television broadcast reception and IP retransmission reception in accordance with the strength of the received electric field intensity, and output video and audio, thereby enabling continuous television viewing. However, when the signal transmission timings of the terrestrial digital television broadcast reception and the IP retransmission reception do not match, the temporal phases of the two may be different. If the video and audio are switched in such a state, the video and audio are not continuously switched, and the video and audio may be disturbed at the moment of switching, leading to a reduction in reception quality.

  Therefore, in the second embodiment, as shown in FIG. 6, a communication signal delay unit 603 is provided between the mobile phone network communication unit 101 and the terrestrial digital TV reception unit 102, and the video switching unit 105 and the audio switching unit 106. Received signal delay means 604 is provided.

  The communication signal delay means 603 delays the video signal and audio signal from the mobile phone network communication means 101 by the time instructed by the control means 609 and outputs them. The reception signal delay means 604 delays the video signal and audio signal from the terrestrial digital TV reception means 102 by the time instructed by the control means 609 and outputs them.

  The control unit 609 outputs a delay request to the communication signal delay unit 603 and the reception signal delay unit 604 in addition to the functions described in the first embodiment.

  Communication signals and reception signals output from the cellular phone network communication means 101 and the terrestrial digital TV reception means 102 are in a signal format used in a general television receiver, and therefore are aligned when displayed on the screen. The horizontal sync signal and the vertical sync signal are used as the reference.

  Therefore, the control unit 609 extracts the components of the horizontal synchronization signal and the vertical synchronization signal from the signals obtained from the mobile phone network communication unit 101 and the terrestrial digital TV reception unit 102, and compares the phases of the respective synchronization signals, Determine which signal is delayed and how much.

  Then, in order to delay the signal that precedes in time and adjust the phase to the signal that is delayed, a delay command and delay information are sent to the delay means of the signal that precedes in time. Output. Upon receiving this instruction, the delay means performs a specified amount of time delay processing on the communication signal or the received signal. The signals output from the communication signal delay means 603 and the reception signal delay means 604 are signals having the same time phase.

  Since other configurations, functions, and operations are the same as those in the first embodiment, description thereof is omitted here.

  The terrestrial digital television receiver of the present invention configured as described above uses the delay means to match the phases of both signals, so that even if the video switching means and the audio switching means are used for switching, It is possible to provide a terrestrial digital television receiver capable of more seamless switching with less disturbing sound.

  In this embodiment, in order to detect the temporal phase difference between the communication signal from the cellular phone network communication means 101 and the reception signal from the terrestrial digital TV receiving means 102, the components of the horizontal synchronization signal and the vertical synchronization signal are detected. However, this is a temporal phase difference using PCR (Program Clock Reference) included in the terrestrial digital television broadcast signal and time stamp information included in the IP retransmission signal or similar time information. Even if this is detected, the same effect can be obtained.

  The terrestrial digital television receiver of the present invention receives the IP retransmission content using the communication means of the cellular phone network even when reception of the terrestrial digital television broadcast becomes difficult due to the deterioration of the reception state. The present invention relates to a terrestrial digital television receiver capable of seamless viewing.

1 is a block diagram showing a configuration of a terrestrial digital television receiver according to Embodiment 1 of the present invention. The graph which shows the relationship between the reception electric field strength which concerns on embodiment of this invention, and reception quality The graph which shows the relationship between the decoding error which concerns on embodiment of this invention, and reception quality The graph which shows the relationship between reception C / N ratio and reception quality which concerns on embodiment of this invention The figure which shows the received electric field strength and each receiving process which concern on embodiment of this invention FIG. 2 is a block diagram showing a configuration of a terrestrial digital television receiver according to Embodiment 2 of the present invention. The block diagram which shows the structure which concerns on a 1st prior art The block diagram which shows the structure which concerns on a 2nd prior art The block diagram which shows the structure which concerns on a 3rd prior art

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Mobile phone network communication means 102 Digital terrestrial TV receiving means 105 Video switching means 106 Audio switching means 107 Video display means 108 Audio reproduction means 109 Control means 110 Communication antenna 111 Reception antenna 112 GPS antenna 113 Terrestrial digital television broadcasting station 114 Mobile Telephone carrier device 115 IP network 603 Communication signal delay means 604 Received signal delay means 609 Control means

Claims (7)

Digital terrestrial TV receiving means for receiving radio waves of digital terrestrial television broadcasting, mobile telephone network communication means for performing voice communication and IP connection to the Internet by communicating with a mobile telephone communication network, and receiving the terrestrial digital TV Video switching means for switching and outputting one of the video signal demodulated by the means and the video signal demodulated by the mobile phone network communication means; the audio signal demodulated by the terrestrial digital TV receiving means; and the mobile phone network communication means Audio switching means for switching and outputting one of the demodulated audio signals, and control means for issuing a video display and audio output switching instruction based on information from the terrestrial digital TV receiving means or the mobile phone network communication means; A video display means for displaying the video signal on a display medium; and an audio playback means for playing back the audio signal. Terrestrial digital television receiver, characterized in that for reproducing video and audio switches the communication signal from the received signal and the mobile phone network communication means from the means appropriate. 2. The control unit according to claim 1, wherein the control unit outputs a switching signal for switching between a video signal and an audio signal by using a rate of occurrence of a decoding error when demodulating a digital signal from the terrestrial digital TV receiving unit. Terrestrial digital television receiver. 2. The terrestrial digital television according to claim 1, wherein the control means outputs a switching signal for switching a video signal and an audio signal using a reception C / N ratio from the terrestrial digital TV receiving means. Receiving machine. 2. The digital terrestrial television receiver according to claim 1, wherein the control means outputs a switching signal for switching video and audio signals using GPS position information from the mobile phone network communication means. The control means predicts in advance that the state of terrestrial digital television broadcast reception will deteriorate using information from the terrestrial digital TV receiving means or the mobile phone network communication means, and from the mobile phone network communication means. 2. The digital terrestrial television receiver according to claim 1, wherein preparation for communication is started in advance before switching to a signal. 6. The terrestrial digital television receiver according to claim 1, wherein the control means further includes a phase difference between a reception signal from the terrestrial digital TV reception means and a communication signal from the mobile phone network communication means. A delay control amount is calculated and a delay command is issued; in addition, a received signal delay means for delaying a received signal from the terrestrial digital TV receiving means; and a communication for delaying a communication signal from the mobile phone network communication means A digital terrestrial television receiver comprising signal delay means. The control means detects a time phase difference between the received signal from the terrestrial digital TV receiving means and the communication signal from the mobile phone network communication means, and delays the received signal so that both signals have the same phase. 7. The terrestrial digital television receiver according to claim 6, wherein a delay control signal is output to each of the means and the communication signal delay means.

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