JP6647990B2 - Digital broadcast receiver - Google Patents

Description

  The present invention relates to a digital broadcast receiving apparatus that is mounted on a vehicle or the like and receives digital broadcasts such as video and audio.

  Conventionally, a program is viewed by diversity reception using four tuners, and diversity reception using four tuners is canceled when the combined C / N value is 25 or more and radio wave quality is good. 2. Description of the Related Art There is known an in-vehicle broadcast receiving apparatus in which program viewing is continued by diversity reception using two tuner sections and search operation is performed in the background by diversity reception using the other two tuner sections ( For example, see Patent Document 1.)

JP 2012-2570011 A

  By the way, in the in-vehicle broadcast receiving apparatus disclosed in Patent Document 1, when the diversity reception using the four tuners is canceled, it is determined by the combined C / N value whether or not there is any obstacle to the program viewing thereafter. Therefore, if the reception state in each of the four tuners varies depending on the direction of arrival of radio waves and the polarization (horizontal / vertical) at the time of reception, the diversity reception using the four tuners is canceled. There has been a problem that the program viewing may be hindered. For example, it is assumed that the radio wave quality of one of the four tuners is particularly good, and the radio qualities of the other three tuners are not so large but the combined C / N value is 25 or more. In such a case, even after the diversity reception using the four tuners is canceled and the program viewing is continued using two of the three tuners having not so good radio wave quality, these two tuners may be used. If the combined C / N value of the unit is equal to or less than the C / N value at which the program can be viewed, the viewing of the program is hindered.

  SUMMARY OF THE INVENTION The present invention has been made in view of such a point, and an object of the present invention is to provide a digital broadcast receiving apparatus capable of continually viewing a program after canceling diversity reception.

  In order to solve the above-described problem, a digital broadcast receiving apparatus of the present invention has a plurality of tuners for receiving a broadcast signal input via each of a plurality of antennas, and a plurality of tuners corresponding to each of the plurality of tuners. A plurality of demodulation processing means for performing demodulation processing using a broadcast signal received by a corresponding tuner unit; and a synthesizing means for synthesizing all or a part of demodulated signals output from each of the plurality of demodulation processing means. A video / audio reproducing unit that reproduces video and audio corresponding to the received program based on the synthesized signal output from the synthesizing unit, and a demodulated signal output from each of the plurality of demodulation processing units by the synthesizing unit. When the units are combined, using the remaining demodulated signal, a background processing unit that performs another operation in parallel with the reproduction operation by the video / audio reproduction unit, Receiving means for detecting a reception state of a broadcast signal based on the signals before and after combining by the combining means, and combining obtained by combining all demodulated signals output from the plurality of demodulation processing means. The reception state detected based on the subsequent signal is better than the first determination criterion, and the reception state detected individually based on the demodulated signals output from each of the plurality of demodulation processing means. When the variation is smaller than the second determination criterion, the reproducing operation is performed by the video / audio reproducing unit based on the synthesized signal obtained by synthesizing a part of the plurality of demodulated signals by the synthesizing unit. Switching means for switching to perform another operation by the background processing means using

  It is confirmed that not only the reception state detected based on the signal obtained by combining the outputs of the plurality of demodulation processing means is good, but also that the reception state detected based on the output of each demodulation processing means has little variation. In this case, the reproduction operation of the program (video and audio) using all the demodulation processing means is switched to the reproduction of the program using a part of the demodulation processing means and the background operation using the remaining demodulation processing means. Therefore, it is possible to satisfactorily continue program viewing after switching.

  In addition, it is preferable that the above-described combining unit outputs a combined demodulated signal corresponding to diversity reception using all or a part of the demodulated signal output from each of the plurality of demodulation processing units. Thus, the reception quality of a program can be improved by using a plurality of tuners.

  Further, it is desirable that the above-mentioned reception state detecting means detects the reception state using the C / N value of the broadcast signal. By using the C / N value, the reception state of the broadcast signal can be reliably detected.

  Further, it is desirable that the above-mentioned variation in the reception state is represented by a standard deviation calculated using a plurality of C / N values corresponding to demodulated signals output from each of the plurality of demodulation processing units. By using the standard deviation, it is possible to reliably know the variation in the reception state of each tuner unit.

  Further, the above-mentioned plurality of demodulation processing means are divided into two groups, and one group whose reception state detected based on the combined signal is relatively good corresponds to the video / audio reproduction means. It is desirable that switching by the switching unit be performed so that the other group whose reception information is relatively poor corresponds to the background processing unit. As a result, it is possible to continue program viewing with as good a reception quality as possible even after switching.

Further, the above-mentioned switching means may be configured such that the reception state detected based on the combined signal obtained by combining all the demodulated signals output from the plurality of demodulation processing means is better than the first determination criterion. If the reception states detected based on the demodulated signals output from each of the plurality of demodulation processing units included in one group are both better than the third criterion, the determination regarding the variation is performed. It is desirable to perform the switching without any change. By confirming before switching that the program viewing can be continued with good reception quality even after switching, it is possible to omit the determination operation regarding the variation.

  It is preferable that the background processing unit performs at least one of a search for a relay station or an affiliated station and creation of an electronic program guide as other operations. This makes it possible to perform a search operation of a relay station or affiliated station and an operation of creating an electronic program guide while satisfactorily continuing to view programs.

It is a figure showing the composition of the digital terrestrial broadcasting receiver of one embodiment. 5 is a flowchart showing an operation procedure of the terrestrial digital broadcast receiver. FIG. 4 is an explanatory diagram illustrating a relationship between a C / N value and a switching operation. It is a flowchart which shows the operation | movement procedure of the modification of a digital terrestrial broadcasting receiver.

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

  FIG. 1 is a diagram illustrating a configuration of a terrestrial digital broadcast receiver according to one embodiment. As shown in FIG. 1, a terrestrial digital broadcast receiver 100 according to the present embodiment includes four tuners 10, 12, 14, 16, an OFDM (Orthogonal Frequency Division Multiplex) demodulator 20, an MPEG decoder 40, a digital-analog converter. (D / A) 42, a speaker 44, a display processing unit 46, a display device 48, a control unit 50, and an operation unit 60. This terrestrial digital broadcast receiver 100 is mounted on a vehicle.

  Each of the tuners 10, 12, 14, 16 transmits a broadcast signal of a reception frequency of a channel corresponding to a designated broadcast station to antennas 11, 13, 15, 17 provided in a one-to-one correspondence. Receive through.

  The OFDM demodulation unit 20 performs OFDM demodulation processing on a broadcast signal (IF signal) input from each of the four tuners 10 to 16 and outputs a TS (transport stream) signal. In the present embodiment, a combining diversity configuration is used in which the broadcast signals input from each of the four tuner units 10 to 16 are used, the phases of these broadcast signals are adjusted, and then combined and received. As the number increases, the C / N value can be improved.

  Therefore, the OFDM demodulation unit 20 includes four demodulation units 22, 24, 26, and 28 and a combining unit 30. The demodulation unit 22 performs an OFDM demodulation process on the broadcast signal output from the tuner unit 10. The demodulation unit 24 performs an OFDM demodulation process on the broadcast signal output from the tuner unit 12. The demodulation unit 26 performs an OFDM demodulation process on the broadcast signal output from the tuner unit 14. The demodulator 28 performs an OFDM demodulation process on the broadcast signal output from the tuner 16. The combining unit 30 combines and outputs demodulated signals output from all or some of the four demodulation units 22 to 28. Specifically, (1) a combining operation using the four demodulated signals output from each of the four demodulators 22 to 28 (the combined demodulated signal output by this combining operation is referred to as “combined output 1” (2) Combining operation using two demodulated signals output from each of the two demodulation units 22 and 24 (the combined demodulated signal output by this combining operation is referred to as “combined output 2”). And a combining operation using the two demodulated signals output from each of the two demodulating units 26 and 28 (the combined demodulated signal output by this combining operation is referred to as “combined output 3”). It is done selectively.

  The MPEG decoder 40 outputs the audio and the sound of the received program included in the TS signal (the TS signal corresponding to the composite output 1 or the TS signal corresponding to any one of the composite outputs 2 and 3) output from the OFDM demodulation unit 20. It decodes a video MPEG signal and outputs audio data and video data. Actually, the TS signal output from the OFDM demodulation unit 20 is input to the demultiplexer, and the audio and video MPEG signals corresponding to the program of one channel desired by the user are separated. However, such a program receiving operation itself is the same as the conventional method, and FIG. 1 shows only a schematic configuration.

  The digital-analog converter 42 converts audio data output from the MPEG decoder 40 into an analog audio signal, and outputs the analog audio signal from the speaker 44. The display processing unit 46 converts the video data output from the MPEG decoder 40 into a video signal in a format suitable for display (for example, NTSC format) and displays the video signal on the display device 48.

  The control unit 50 controls the entire program receiving operation of the terrestrial digital broadcast receiver 100, and receives a full-segment digital broadcast using the composite output 1 and the composite outputs 2 and 3 according to the reception state of the broadcast signal. Switching between full segment digital broadcast reception using one of them and background operation using one of the combined outputs 2 and 3 is performed. To this end, the control unit 50 includes a reception state detection unit 51, a standard deviation calculation unit 52, a switching control unit 53, a search processing unit 54, and an EPG creation unit 55.

The reception state detection unit 51 detects a C / N value as a reception state of the broadcast signal based on the signals before and after the combination by the combining unit 30. As a result, the following seven C / N values CN ₁ , CN ₂ , CN ₃ , CN ₄ , CN _D1 , CN _D2 , and CN _D3 are obtained.

CN ₁ : C / N value corresponding to the demodulated signal output from demodulation section 22;
CN ₂ : C / N value corresponding to the demodulated signal output from demodulation section 24,
CN ₃ : C / N value corresponding to the demodulated signal output from demodulation section 26,
CN ₄ : C / N value corresponding to the demodulated signal output from demodulation section 28,
CN _D1 : a C / N value corresponding to a combined output 1 obtained by combining four demodulated signals output from each of the four demodulation units 22 to 28;
CN _D2 : a C / N value corresponding to a combined output 2 obtained by combining two demodulated signals output from each of the two demodulation units 22 and 24,
CN _D3 : a C / N value corresponding to a combined output 3 obtained by combining two demodulated signals output from each of the two demodulation units 26 and 28.

The standard deviation calculation unit 52 standardizes the four C / N values CN ₁ , CN ₂ , CN ₃ , and CN ₄ corresponding to the demodulated signals output from the demodulation units 22 to 28 (CN (standard deviation)). Is calculated. Assuming that the average value of CN ₁ , CN ₂ , CN ₃ , and CN ₄ is CN _AV , CN (standard deviation) can be calculated using the following equation.

  The switching control unit 53 combines four demodulated signals output from each of the four demodulation units 22 to 28 during program viewing by diversity reception using the four tuners 10 to 16 (combination signal). The reception state detected based on the output 1) is better than the first determination criterion, and the reception state individually detected based on the demodulated signals output from each of the four demodulation units 22 to 28. When the variation in the state is smaller than the second determination criterion, the MPEG decoder 40 or the like is used based on a combined signal (combined output 2 or 3) obtained by combining a part of the four demodulated signals by the combining unit 30. Switch to the required configuration by sending a command to view the program and perform the background operation based on the combined signal (combined output 3 or 2) obtained by combining the rest of the four demodulated signals. That perform control (switching control).

Specifically, the switching control unit 53, C / N value CN _D1 detected based on the composite output 1 is not more 26 dB (the first criterion) above, CN (standard deviation) 3 dB (second The above-described switching control is performed when the value is less than the criterion.

  The search processing unit 54 sends a frequency switching instruction to the tuner units 10 and 12 (or the tuner units 14 and 16) subjected to the background operation by the switching control by the switching control unit 53 and is included in each channel. By examining the program contents, a search operation for detecting a relay station or affiliated station of another channel broadcasting another program having the same contents as the program being viewed by the user is performed.

  The EPG creating unit 55 sends a frequency switching instruction to the tuner units 10 and 12 (or the tuner units 14 and 16) subjected to the background operation by the switching control by the switching control unit 53, and the EPG creating unit 55 is included in each channel. By examining the program contents, an EPG (electronic program guide, electronic program guide) for receivable programs is created.

  The above-described four demodulation units 22, 24, 26, and 28 serve as a plurality of demodulation processing means, and the combining unit 30 serves as a combining means. An MPEG decoder 40, a digital-analog converter (D / A) 42, a speaker 44, a display process Unit 46 and display device 48 as video / audio playback means, search processing unit 54 and EPG creation unit 55 as background processing means, reception state detection unit 51 as reception state detection means, standard deviation calculation unit 52, switching control The units 53 correspond to the switching means, respectively.

  The terrestrial digital broadcast receiver 100 of the present embodiment has such a configuration, and its operation will be described next. For example, in the present embodiment, when a full-segment digital broadcast program is being viewed by diversity reception using the four tuners 10 (this reception format is referred to as “four-diver configuration”) and the reception state is good. Then, while continuing to watch a full-segment digital broadcast program by diversity reception (this reception format is referred to as a “two-diver configuration”) using the tuner units 10 and 12 as a part thereof, the remaining tuner units 14 and 16 It is assumed that the operation is switched to a background operation of full-segment digital broadcasting by a two-divers configuration using.

FIG. 2 is a flowchart showing an operation procedure of the terrestrial digital broadcast receiver 100. 4 while the program is being viewed by a diver configuration, the switching control unit 53, C / N value CN _D1 in 4 diver configuration detected by the reception state detecting section 51 determines whether or 26 dB (step 100). If C / N value CN _D1 is less than 26 dB, i.e., if the higher reception state can continue program viewing in 2 divers configuration not good is performed a negative determination, continuing this judgment is repeated.

Also, C / N value CN _D1 is affirmative determination is made in the determination of step 100 in the case of more than 26 dB. Next, the switching control unit 53 calculates four C / N values CN ₁ , CN ₂ , CN ₃ , which are calculated by the standard deviation calculation unit 52 and correspond to the demodulated signals output from each of the demodulation units 22 to 28. It is determined whether the standard deviation CN (standard deviation) of CN ₄ is less than 3 dB (step 102). When the standard deviation CN (standard deviation) is 3 dB or more, that is, the dispersion of four C / N values CN ₁ , CN ₂ , CN ₃ , CN ₄ corresponding to the demodulated signals output from each of the demodulation units 22 to 28. a negative determination is performed when a large, the determination operation for the C / N value CN _D1 is repeated back step 100.

When the standard deviation CN (standard deviation) is less than 3 dB, an affirmative determination is made in the determination of step 102. Then, switching control unit 53, C / N value CN _D2 in one of the two divers configuration corresponding to the tuner section 10 and 12 detected by the reception state detecting section 51, the other corresponding to the tuner unit 14, 16 determines whether C / N value CN _D3 or more at 2 diver configuration (step 104).

C / N value CN _D2 is affirmative determination is made in the case of more than C / N value CN _D3. Next, the switching control unit 53 sends a switching instruction to the OFDM demodulation unit 20, the MPEG decoder 40, the search processing unit 54, the EPG creation unit 55, and the like. Thereafter, in response to this switching instruction, one of the two diver configurations corresponding to the tuners 10 and 12 and the program viewing by the MPEG decoder 40 are performed (step 106), and the other two diver configuration corresponding to the tuners 14 and 16 is performed. A background operation is performed by the search processing unit 54 and the EPG creating unit 55 (Step 108).

On the other hand, C / N value CN _D2 is a negative determination is made in the determination of step 104 in the case of less than C / N value CN _D3. Next, the switching control unit 53 sends a switching instruction to the OFDM demodulation unit 20, the MPEG decoder 40, the search processing unit 54, the EPG creation unit 55, and the like. Thereafter, in response to the switching instruction, the other two diver configurations corresponding to the tuners 14 and 16 and the program viewing by the MPEG decoder 40 are performed (step 110), and the one two diver configuration corresponding to the tuners 10 and 12 is performed. A background operation is performed by the search processing unit 54 and the EPG creating unit 55 (step 112).

  FIG. 3 is an explanatory diagram showing the relationship between the C / N value and the switching operation. In FIG. 3, the vertical axis indicates the C / N value in the 4-diver configuration or the 2-diver configuration, and the standard deviation of the four C / N values corresponding to each demodulator. The horizontal axis indicates the elapsed time t. For example, it is assumed that the operation procedure shown in FIG. 2 is repeated at a repetition cycle of once per second.

In the example shown in FIG. 3, t = 5 for 4 divers configuration at the point (s) C / N value CN _D1 is greater than 26dB as switching determination value. Since the standard deviation CN (standard deviation) at this time exceeds 3 dB, the 4-diver configuration is maintained, and the switching to the 2-diver configuration is not performed. Therefore, it is possible to satisfactorily continue viewing the program.

On the other hand, when the value of CN (standard deviation) is large and the variation of the C / N value for each tuner unit (each demodulation unit) is large, switching to the two-diver configuration as in the related art is performed. As shown by the dotted line, the C / N value CN _D2 (or CN _D3 ) of the two-diver configuration may be lower than the C / N value at which the program can be viewed, and when the program viewing becomes difficult (t = 8), When switching to the 4-diver configuration again, the program being viewed may be temporarily interrupted, which is undesirable in maintaining good reception quality.

Thus, the terrestrial digital broadcast receiver 100 of the present embodiment, 4 reception state detected on the basis of the combined output CN _D1 obtained by the diver configuration not only good, yet each of demodulator 22 to 28 When it is confirmed that there is little variation in the reception state detected based on the output of the program, the program viewing using the 4-diver configuration is used to switch from the program viewing using the 2-diver configuration to the program viewing using the other 2-diver configuration. Since the operation can be switched to the background operation, it is possible to satisfactorily continue the program viewing after the switching. In particular, by detecting the reception state using the C / N value of the broadcast signal, the reception state of the broadcast signal can be reliably detected.

Also, a standard calculated using _four C / N values CN ₁ , CN ₂ , CN ₃ , and CN ₄ corresponding to demodulated signals output from each of the four demodulation units 22 to 28 as a variation in the reception state. By using the deviation, it is possible to reliably know the variation in the reception state of each of the tuners 10 to 16.

  In addition, the four demodulation units 22 to 28 are divided into two groups (one two-diver configuration and the other two-diver configuration), and a program is viewed in one group having a relatively good reception condition, and the other group is viewed. By performing the background operation, it is possible to continue program viewing with the best possible reception quality even after switching.

  Further, by providing the search processing unit 54 and the EPG creation unit 55, it is possible to perform a search operation of a relay station or an affiliated station or an operation of creating an electronic program guide while continually watching a program.

FIG. 4 is a flowchart showing an operation procedure of a modified example of the terrestrial digital broadcast receiver 100. 4 while the program is being viewed by a diver configuration, the switching control unit 53, C / N value CN _D1 in 4 diver configuration detected by the reception state detecting section 51 determines whether or 26 dB (step 200). If C / N value CN _D1 is less than 26 dB, i.e., if the higher reception state can continue program viewing in 2 divers configuration not good is performed a negative determination, continuing this judgment is repeated.

Also, C / N value CN _D1 is affirmative determination is made in the determination of step 100 in the case of more than 26 dB. Then, switching control unit 53, C / N value CN _D2 in one of the two divers configuration corresponding to the tuner section 10 and 12 detected by the reception state detecting section 51, the other corresponding to the tuner unit 14, 16 determines whether C / N value CN _D3 or more at 2 diver configuration (step 202).

C / N value CN _D2 is affirmative determination is made in the case of more than C / N value CN _D3. Next, the switching control unit 53 determines whether the C / N values CN ₁ and CN ₂ corresponding to the two tuner units 10 and 12 included in one of the two diver configurations are both 21 dB or more (step). 204).

If the C / N values CN ₁ and CN ₂ are both 21 dB or more, a positive determination is made. Next, the switching control unit 53 sends a switching instruction to the OFDM demodulation unit 20, the MPEG decoder 40, the search processing unit 54, the EPG creation unit 55, and the like. Thereafter, in response to the switching instruction, one of the two diver configurations corresponding to the tuners 10 and 12 and the program viewing by the MPEG decoder 40 are performed (step 206), and the other two diver configuration corresponding to the tuners 14 and 16 is performed. A background operation is performed by the search processing unit 54 and the EPG creating unit 55 (step 208).

If at least one of the C / N values CN ₁ and CN ₂ is less than 21 dB, a negative determination is made in the determination at step 204. Next, the switching control unit 53 calculates four C / N values CN ₁ , CN ₂ , CN ₃ , which are calculated by the standard deviation calculation unit 52 and correspond to the demodulated signals output from each of the demodulation units 22 to 28. It is determined whether the standard deviation CN (standard deviation) of CN ₄ is less than 3 dB (step 210). When the standard deviation CN (standard deviation) is 3 dB or more, that is, the dispersion of four C / N values CN ₁ , CN ₂ , CN ₃ , CN ₄ corresponding to the demodulated signals output from each of the demodulation units 22 to 28. a negative determination is performed when a large, the determination operation for the C / N value CN _D1 is repeated back step 200.

  If the standard deviation CN (standard deviation) is less than 3 dB, an affirmative determination is made in the determination of step 210. In this case, the process proceeds to step 206, where one of the two divers corresponding to the tuners 10 and 12 and program viewing by the MPEG decoder 40 (step 206), and the other two divers corresponding to the tuners 14 and 16 A background operation (step 208) is performed by the search processing unit 54 and the EPG creating unit 55.

Further, when the C / N value CN _D2 a negative determination in the determination of step 202 is less than C / N value CN _D3 is performed, the switching control unit 53, two tuners portions included in the other 2 divers configuration 14 Then, it is determined whether the C / N values CN ₃ and CN ₄ corresponding to the above are both 21 dB or more (step 212).

If the C / N values CN ₃ and CN ₄ are both 21 dB or more, an affirmative determination is made. Next, the switching control unit 53 sends a switching instruction to the OFDM demodulation unit 20, the MPEG decoder 40, the search processing unit 54, the EPG creation unit 55, and the like. Thereafter, in response to this switching instruction, the other two diver configurations corresponding to the tuners 14 and 16 and the program viewing by the MPEG decoder 40 are performed (step 214), and the one two diver configuration corresponding to the tuners 10 and 12 is performed. A background operation is performed by the search processing unit 54 and the EPG creating unit 55 (step 216).

If at least one of the C / N values CN ₃ and CN ₄ is less than 21 dB, a negative determination is made in the determination of step 212. Next, the switching control unit 53 calculates four C / N values CN ₁ , CN ₂ , CN ₃ , which are calculated by the standard deviation calculation unit 52 and correspond to the demodulated signals output from each of the demodulation units 22 to 28. It is determined whether the standard deviation CN (standard deviation) of CN ₄ is less than 3 dB (step 218). When the standard deviation CN (standard deviation) is 3 dB or more, that is, the dispersion of four C / N values CN ₁ , CN ₂ , CN ₃ , CN ₄ corresponding to the demodulated signals output from each of the demodulation units 22 to 28. a negative determination is performed when a large, the determination operation for the C / N value CN _D1 is repeated back step 200.

  If the standard deviation CN (standard deviation) is less than 3 dB, an affirmative determination is made in the determination at step 218. In this case, the process proceeds to step 214, where the other two divers corresponding to the tuners 14 and 16 and the program viewing / listening by the MPEG decoder 40 (step 214), and the other two divers corresponding to the tuners 10 and 12 A background operation (step 216) is performed by the search processing unit 54 and the EPG creating unit 55.

  In this way, by confirming before switching that the program viewing can be continued with good reception quality even after switching from the program viewing with the 4-diver configuration to the program viewing with the 2-diver configuration (steps 204 and 212). In addition, it is possible to omit the operation of determining the variation (steps 210 and 218).

  Note that the present invention is not limited to the above embodiment, and various modifications can be made within the scope of the present invention. For example, in the above-described embodiment, the reception state is detected using the C / N value, but other characteristic values may be used.

  In the above-described embodiment, the terrestrial digital broadcast receiver 100 having a 4-diver configuration has been described. However, the number of the tuner units 10 and the like may be other than four. In addition, switching from program viewing of full-segment digital broadcasting using the 4-diver configuration to program viewing of full-segment digital broadcasting using the 2-diver configuration and background operation of full-segment digital broadcasting using the 2-diver configuration was performed. The background operation may be switched to one-segment digital broadcasting.

  Further, in the above-described embodiment, the standard deviation is used to know the degree of variation in the reception state, but another index may be used. For example, a cumulative value of the deviation from the average value may be used.

  As described above, according to the present invention, not only is the reception state detected based on the signal obtained by combining the outputs of the plurality of demodulation processing units good, but also the detection is performed based on the output of each demodulation processing unit. When it is confirmed that there is little variation in the received state, the reproduction operation of the program (video and audio) using all the demodulation processing means is changed to the reproduction of the program using some demodulation processing means and the remaining Since the operation can be switched to the background operation using the demodulation processing means, it is possible to satisfactorily continue viewing the program after the switching.

Reference Signs List 100 terrestrial digital broadcast receiver 10, 12, 14, 16 Tuner unit 30 OFDM demodulation unit 40 MPEG decoder 42 Digital-analog converter (D / A)
44 speaker 46 display processing unit 48 display device 50 control unit 51 reception state detection unit 52 standard deviation calculation unit 53 switching control unit 54 search processing unit 55 EPG creation unit 60 operation unit

Claims (7)

A plurality of tuner units for receiving a broadcast signal input via each of the plurality of antennas,
A plurality of demodulation processing means provided corresponding to each of the plurality of tuner units, and performing demodulation processing using a broadcast signal received by the corresponding tuner unit,
Combining means for combining all or a part of the demodulated signal output from each of the plurality of demodulation processing means,
A video / audio reproducing unit that reproduces video and audio corresponding to the received program based on the synthesized signal output from the synthesizing unit,
When a part of the demodulated signals output from each of the plurality of demodulation processing units is synthesized by the synthesizing unit, the remaining demodulated signals are used to perform other operations in parallel with the reproduction operation by the video / audio reproduction unit. Background processing means for performing the operation of
A reception state detection unit that detects a reception state of a broadcast signal based on the signals before and after the combination by the combining unit,
A reception state detected based on a combined signal obtained by combining all of the demodulated signals output from the plurality of demodulation processing units is better than a first determination criterion, and When the variation in the reception state individually detected based on the demodulated signals output from each of the demodulation processing means is smaller than a second determination criterion, the combining means combines some of the plurality of demodulated signals. Switching means for performing a reproducing operation by the video / audio reproducing means based on the signal after the synthesis, and switching to perform another operation by the background processing means using the rest of the plurality of demodulated signals,
A digital broadcast receiving apparatus comprising:   2. The combining unit according to claim 1, wherein the combining unit outputs a combined demodulated signal corresponding to diversity reception using all or a part of the demodulated signals output from each of the plurality of demodulation processing units. 3. Digital broadcast receiver.   The digital broadcast receiving apparatus according to claim 1, wherein the reception state detection unit detects a reception state using a C / N value of a broadcast signal.   4. The method according to claim 3, wherein the variation in the reception state is represented by a standard deviation calculated using a plurality of C / N values corresponding to demodulated signals output from each of the plurality of demodulation processing units. The digital broadcast receiving device according to the above.   The plurality of demodulation processing units are divided into two groups, and one group whose reception state detected based on the combined signal is relatively good corresponds to the video / audio reproduction unit, The digital broadcasting according to any one of claims 1 to 4, wherein switching is performed by the switching unit so that the other group whose information is relatively poor corresponds to the background processing unit. Receiver. The switching unit is configured such that a reception state detected based on a combined signal obtained by combining all of the demodulated signals output from the plurality of demodulation processing units is better than the first determination criterion. And when the reception states detected based on the demodulated signals output from each of the plurality of demodulation processing units included in the one group are both better than a third criterion, The digital broadcast receiving apparatus according to claim 5, wherein the switching is performed without performing.   The said background processing means performs at least one operation of search of a relay station or an affiliated station, and creation of an electronic program guide as said other operation | movement, The said any one of Claims 1-6 characterized by the above-mentioned. Digital broadcast receiver.

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