JP2009253613A - Broadcast receiver, and broadcast reception control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To properly switch a plurality of broadcasts in the same transmission channel corresponding to reception environment. <P>SOLUTION: A CNR indicating a reception state of broadcasting wave of the selected channel to be reproduced is detected by a channel decode unit 130. Further, a packet error regarding B-rank broadcasting of the channel is detected by a source decode unit 140. A switch determination part 212<SB>k</SB>determines switching between A-rank broadcasting and B-rank broadcasting for each threshold TH<SB>k</SB>in accordance with a comparison result of reception quality of the B-rank broadcasting calculated based on these detection results and each of thresholds TH<SB>k</SB>(k=1-3, V). According to the results of switching determination and B-rank packet error detection, a threshold calculation part 215 calculates a new threshold TH<SB>V</SB>so that a ratio of an appropriate period for selecting the B-rank broadcasting approaches a ratio of an actual period of selecting the B-rank broadcasting, and uses the value for switching control of the A-rank broadcasting and the B-rank broadcasting. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a broadcast receiving apparatus, a broadcast reception control method, a broadcast reception control program, and a recording medium on which the broadcast reception control program is recorded.

  In recent years, digitalization of broadcasting has been promoted, and terrestrial digital broadcasting, BS (Broadcasting Satellite) digital broadcasting, and CS (Communication Satellite) broadcasting have been put into practical use. Such digital broadcasting employs a transmission method called hierarchical transmission conforming to the ISDB-T (International Services Digital Broadcasting Terrestrial) standard.

  In such hierarchical transmission, one channel (transmission band) is divided into a plurality of regions (referred to as “segments”), broadcast signals are transmitted with different modulation methods for each segment, and different broadcasts are simultaneously transmitted on the same channel. It is a transmission system for broadcasting. For example, in the current terrestrial digital broadcasting, one channel is divided into 13 segments, one broadcast signal is modulated in one central segment, and the other 12 broadcast signals are transmitted in the remaining 12 segments. Modulation is performed, and simultaneous broadcasting (simultaneous broadcasting) for simultaneously broadcasting the same program is performed.

  By the way, a broadcast with a smaller number of segments in a simultaneous broadcast such as a broadcast using one segment (hereinafter also referred to as “1 segment broadcast”) (hereinafter also referred to as “A layer broadcast”) is a broadcast using 12 segments (hereinafter referred to as “A-layer broadcast”). Hereinafter, the playback image quality and playback sound quality are inferior to those of a broadcast with a larger number of segments in a simultaneous broadcast (hereinafter also referred to as “12-segment broadcasting”), but the error tolerance is higher. . Therefore, as a terrestrial digital broadcast broadcast receiving apparatus mounted on a moving body such as a vehicle, in order to cope with a change in the reception quality of broadcast waves accompanying the movement of the moving body, when the reception quality is low, broadcast of the A layer Has been proposed (see Patent Document 1: hereinafter referred to as “conventional example”).

JP 2005-223549 A

  In the above-described conventional technology, the A-layer broadcast and the B-layer broadcast are automatically switched, and one fixed threshold value is used for the switching. By the way, when switching between the A-layer broadcast and the B-layer broadcast, video and audio are not seamlessly connected, so it is assumed that there are users who prefer to switch between the hierarchical broadcasts as much as possible. On the other hand, it is assumed that there are users who want to continue to view the B-layer broadcast that has the best reproduction image quality and reproduction sound quality as much as possible.

  It has been difficult to realize such switching that can satisfy all users of various types of preferences with a single threshold value. In addition, the difference in the reception state of the broadcast wave due to the difference in the residential area for each user, and further the difference in the reception state of the broadcast wave due to the position change on the moving route when the broadcast receiving device is mounted on a moving body such as a vehicle Therefore, it is very difficult to realize with one threshold value.

  For this reason, there is a need for a technique that can automatically and appropriately switch between the A-layer broadcast and the B-layer broadcast according to a change in the reception state of the broadcast wave. Meeting this requirement is one of the problems to be solved by the present invention.

  The present invention has been made in view of the above circumstances, and provides a broadcast receiving apparatus and a broadcast reception control method capable of appropriately switching a plurality of broadcasts in the same transmission channel in response to changes in the reception environment. The purpose is to provide.

  According to the first aspect of the present invention, there are at least two or more broadcasts including a first broadcast having a higher error tolerance and a second broadcast having a lower error tolerance than the first broadcast in the same transmission channel. A broadcast receiving apparatus that receives a digital broadcast wave and plays back at least the first broadcast and the second broadcast, and detects an error in a demodulation result of the second broadcast. Based on a result of comparison between each of a plurality of different threshold values and the reception quality of the second broadcast obtained in consideration of the frequency of occurrence of the error detected by the error detection means Determination means for performing switching determination between the first broadcast and the second broadcast for each threshold value; based on a detection result by the error detection means and a determination result by the determination means; Determining means for determining a threshold value actually used for switching; switching means for switching between the first broadcast and the second broadcast based on the threshold value determined by the determining means and the reception quality of the second broadcast And a broadcast receiving apparatus.

  According to a tenth aspect of the present invention, there are at least two or more broadcasts including a first broadcast having a higher error tolerance and a second broadcast having a lower error tolerance than the first broadcast in the same transmission channel. A broadcast reception control method for receiving a digital broadcast wave and switching and reproducing at least the first broadcast and the second broadcast, and is different from a detection step of detecting an error in a demodulation result of the second broadcast; Based on a comparison result between each of the plurality of thresholds and the reception quality of the second broadcast obtained in consideration of the frequency of occurrence of the error detected in the detection step, the first broadcast for each of the plurality of thresholds And a determination step for determining switching between the second broadcast; and a threshold value actually used for the switching based on the detection result in the detection step and the determination result in the determination step A switching step of switching between the first broadcast and the second broadcast based on the threshold value determined in the determination step and the reception quality of the second broadcast. This is a broadcast reception control method.

  According to an eleventh aspect of the present invention, there is provided a broadcast reception control program that causes a calculation means to execute the broadcast reception control method according to the tenth aspect.

  A twelfth aspect of the invention is a recording medium in which the broadcast reception control program according to the eleventh aspect is recorded so as to be readable by a calculation means.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the following description and drawings, the same or equivalent elements are denoted by the same reference numerals, and redundant description is omitted.

[First Embodiment]
First, a first embodiment of the present invention will be described with reference to FIGS.

<Configuration>
FIG. 1 is a block diagram illustrating a schematic configuration of a broadcast receiving apparatus 100 according to the first embodiment. The broadcast receiving apparatus 100 is a broadcast receiving apparatus that receives an A-layer broadcast (1 segment broadcast) and a B-layer broadcast (12 segment broadcast) that are simultaneously broadcast in the terrestrial digital broadcast.

  As shown in FIG. 1, the broadcast receiving apparatus 100 includes an antenna 110, a tuner unit 120, a channel decoding unit 130 as a reception state detecting unit, a source decoding unit 140, and a selection unit 150. The broadcast receiving apparatus 100 includes a sound output unit 160, a display unit 170, and an operation input unit 180 as a part of the initial value setting means. Further, the broadcast receiving apparatus 100 includes a control unit 190.

  The antenna 110 receives a broadcast wave. The reception result by the antenna 110 is sent to the tuner unit 120.

  The tuner unit 120 converts the channel signal to be selected from the broadcast wave signal received by the antenna 110 into an intermediate frequency band signal in accordance with the channel selection command CSC supplied from the control unit 190. The tuner unit 120 having such a function includes an antenna input filter, a high frequency amplifier, a band pass filter (hereinafter also referred to as “RF filter”), a mixer (mixer), an intermediate frequency filter (hereinafter also referred to as “IF filter”), A local oscillation circuit and the like (both not shown) are provided.

  In the tuner unit 120, the signal from the antenna 110 passes through the antenna input filter, and after the low frequency component is removed, the signal is amplified by the high frequency amplifier. The signal thus amplified by the high frequency amplifier is extracted to a desired station generated by the local oscillation circuit in accordance with the channel selection command CSC from the control unit 190 in the mixer after a signal in a specific high frequency range is extracted by the RF filter. It is mixed with a local oscillation signal having a corresponding frequency. A signal in a predetermined intermediate frequency band is selected by the IF filter from the mixing result by the mixer. This selection result is converted from analog to digital and then sent to the channel decode unit 130 as a signal CSS.

  The channel selection command CSC is output from the control unit 190 in digital form, but is used in the local oscillation circuit after being converted from digital to analog.

  The channel decoding unit 130 demodulates the signal CSS from the tuner unit 120 (OFDM demodulation or the like) in accordance with the channel decoding control command CDC from the control unit 190, and then generates a data packet based on the demodulation result. The packet PKD generated in this way is sent to the source decoding unit 140. The packet PKD sent from the channel decoding unit 130 includes an A layer packet APK and a B layer packet BPK (see FIG. 2).

  Further, the channel decoding unit 130 detects a CNR (Carrier to Noise Ratio) value of the signal CSS. This detection result is sent to the control unit 190 as a detection value CNR.

  The source decode unit 140 receives the packet PKD from the channel decode unit 130. Then, the source decode unit 140 performs source decode processing in accordance with the source decode control command SDC from the control unit 190 to generate A layer data AAV which is audio data and video data corresponding to the A layer broadcast, and B layer broadcast B hierarchical data BAV, which is audio data and video data corresponding to As shown in FIG. 2, the source decoding unit 140 having such a function includes a packet separation unit 141 as an error detection unit and a layer processing unit 142.

  The packet separator 141 receives the packet PKD from the channel decode unit 130. Then, the packet separator 141 separates the packet PKD into an A layer packet APK and a B layer packet BPK. Thus, the separated layer packet APK and layer B packet BPK are sent to the layer processing unit 142.

  Further, the packet separator 141 detects an error in the B layer packet BPK. The error detected in this way is sent to the control unit 190 as a B layer packet error BPE.

  The layer processing unit 142 receives the layer A packet APK and the layer B packet BPK from the packet separation unit 141. Then, the hierarchy processing unit 142 generates the A hierarchy data AAV and the B hierarchy data BAV in accordance with the source decoding control command SDC by the control unit 190. The hierarchical processing unit 142 having such a function includes an A hierarchical processing unit 142A and a B hierarchical processing unit 142B.

  The A layer processing unit 142A receives the A layer packet APK from the packet separation unit 141. The A-layer processing unit 142A is an H.264 standard adopted for A-layer broadcasting (1-segment broadcasting) in terrestrial digital broadcasting. In accordance with the H.264 / AVC format, source decoding processing is performed to generate A layer data AAV. The A layer data AAV generated in this way is sent to the selection unit 150.

  The B layer processing unit 142B receives the B layer packet BPK from the packet separation unit 141. Then, the B layer processing unit 142B performs source decoding processing according to the MPEG2 method adopted for B layer broadcasting (12-segment broadcasting) in terrestrial digital broadcasting to generate B layer data BAV. The B layer data BAV thus generated is sent to the selection unit 150.

  Returning to FIG. 1, the selection unit 150 receives the A layer data AAV and the B layer data BAV from the source decoding unit 140. Then, the selection unit 150 selects either the A layer data AAV or the B layer data BAV in accordance with the switching command SWC from the control unit 190. The sound data in the hierarchical data selected by the selection unit 150 is sent to the sound output unit 160 as output sound data ADT. The video data in the hierarchical data selected by the selection unit 150 is sent to the display unit 170 as output video data VDT.

  The sound output unit 160 includes (i) a DA converter (Digital to Analog Converter) that converts the output audio data ADT received from the selection unit 150 into an analog signal, and (ii) an analog output from the DA converter. It comprises an amplifier that amplifies the signal, and (iii) a speaker that converts the amplified analog signal into sound. The sound output unit 160 reproduces the broadcast sound selected by the switching unit 150.

  The display unit 170 includes, for example, (i) a display device such as a liquid crystal panel, an organic EL (Electro Luminescence) panel, a PDP (Plasma Display Panel), and (ii) output video data VDT received from the selection unit 150. A display control circuit for displaying an image on the display device. The display unit 170 reproduces the broadcast video selected by the selection unit 150.

  The operation input unit 180 includes a key unit provided in the main body of the broadcast receiving device 100 and / or a remote input device including the key unit. Here, a touch panel provided in a display device of the display unit 170 can be used as the key part provided in the main body. In addition, it can replace with the structure which has a key part, or can also employ | adopt the structure input with a sound using a voice recognition technique in combination.

  When the user operates the operation input unit 180, it is possible to specify a channel selection channel and an initial threshold value for broadcast switching described later. The result of operation input to the operation input unit 180 is sent to the control unit 190 as operation input data IPD.

  The control unit 190 controls the operation of the broadcast receiving apparatus 100. As shown in FIG. 3, the control unit 190 having such a function includes a channel selection control unit 191 and a switching control unit 192.

  The channel selection control unit 191 receives the channel selection channel input to the operation input unit 180 as the operation input data IPD. Then, the channel selection control unit 191 generates a channel selection command CSC for selecting the specified channel according to the channel selection channel specification, and sends the channel selection command CSC to the tuner unit 120. As a result, a signal corresponding to the broadcast wave of the designated channel is extracted by the tuner unit 120 and supplied to the channel decoding unit 130 as the signal CSS.

The switching control unit 192 performs control to switch which of the A layer broadcast and the B layer broadcast is selected as a reproduction broadcast to the channel selected by the channel selection control unit 191. As shown in FIG. 4, the switching control unit 192 having such a function includes a reception quality information buffer 211 and switching determination units 212 ₁ , 212 ₂ , and 212 ₃ as part of the determination unit. In addition, the switching control unit 192 includes a switching determination unit 212 _V as part of the determination unit and the switching unit, and a threshold value calculation unit 215 as a part of the initial value setting unit and the determination unit.

  The reception quality information buffer 211 receives the detection value CNR from the channel decoding unit 130 and the B layer packet error BPE from the source decoding unit 140. The reception quality information buffer 211 temporarily stores the reception quality information.

Each of the switching determination units 212 _k (k = 1 to 3, V) periodically reads the detection value CNR and the B layer packet error BPE from the reception quality information buffer 211 as reception quality information RST. Then, the switching determination unit 212 _k comprehensively considers the detection value CNR and the occurrence frequency of the B layer packet error BPE, and calculates the reception quality at that time.

Subsequently, the switching determination unit 212 _k determines which one of the A layer broadcast and the B layer broadcast should be selected as a reproduction broadcast based on the threshold value TH _k stored therein and the calculated reception quality. . For example, when the A layer broadcast is selected, when the calculated reception quality reaches the reception quality to be switched to the B layer broadcast, the broadcast selection is switched so that the B layer broadcast is selected as a reproduction broadcast. Make a decision. Further, when the B layer broadcast is selected, when the calculated reception quality deteriorates to the reception quality to be switched to the A layer broadcast, the broadcast selection is switched so that the A layer broadcast is selected as the reproduction broadcast. Make a decision.

In the above determination, the threshold value TH _k is used. Note that the threshold value TH _k may be one fixed value, but in the first embodiment, the threshold value used for determination of switching from the A layer broadcast to the B layer broadcast and the B layer broadcast to the A layer A value different from the threshold value used for determination of switching to broadcasting is adopted.

Here, the threshold value TH _j (j = 1 to 3) is fixedly determined in advance. In the first embodiment, the threshold value TH ₁ is determined from the viewpoint of performing layer selection with an emphasis on A-layer broadcasting, and the threshold value TH ₃ is determined from the viewpoint of performing layer selection with an emphasis on B-layer broadcasting. ing. The threshold value TH ₂ is between the threshold value TH ₁ and the threshold value TH _3, and is determined from the viewpoint of performing hierarchical selection that is considered standard.

In addition, the threshold value TH _V is set by the threshold value calculation unit 215. A method for determining the threshold TH _V will be described later.

The determination result by the switching determination unit 212 _j (j = 1 to 3) is sent to the threshold value calculation unit 215 as the determination result SW _j . The determination result by the switching determination unit 212 _V is sent to the threshold value calculation unit 215 as the determination result SW _V and also sent to the selection unit 150 as the switching command SWC.

The threshold value calculation unit 215 periodically reads out the B layer packet error BPE from the reception quality information buffer 211 as the B layer error information BRT. Then, based on the occurrence frequency of the B layer packet error BPE, the threshold calculation unit 215 obtains a first ratio R _F that is a ratio of the period in which the B layer broadcast can be selected and reproduced satisfactorily.

Further, the threshold value calculation unit 215 receives the determination result SW _k from the switching determination unit 212 _k (k = 1 to 3, V). Then, the threshold value calculation unit 215 obtains in each case of adopting the threshold TH _k in the switching determination unit 212 _k, the second rate R _S B hierarchy broadcasting is the ratio to the total duration of the period being _selected, the _k.

The threshold calculation unit 215 compares the first ratio R _F thus obtained with the second ratio R _{S, k} . Then, the threshold calculation unit 215 performs a first determination based on the comparison result to determine whether or not there is a threshold that can be closer to the first ratio R _F than the current value of the threshold TH _V. For example, when the second ratio R _{S, j} (j = 1 to 3) is closer to the first ratio R _F than the second ratio R _{S, V} , the result of the first determination Will be positive.

If the result of the first determination is affirmative, the threshold value calculation unit 215 calculates a new threshold value TH _V so as to approach the threshold value that is considered optimal at that time. For example, if there is a second ratio R _{S, j} (j = 1 to 3) that is closer to the first ratio R _F than the second ratio R _{S, V} , the first of them is the first A new threshold value TH _V is calculated so as to approach the threshold value corresponding to the one close to 1 ratio R _F. Incidentally, in the first embodiment, a threshold value considered optimal at that time, the current value predetermined fraction only optimum close to possible threshold correction of the difference between the threshold TH _V, current threshold TH _V A new threshold TH _V is calculated by applying to the value.

On the other hand, if the result of the first determination is negative, the threshold calculation unit 215 determines whether or not the frequency of hierarchy switching exceeds the allowable value based on the determination result SW _V. I do. The second if the result of the determination is negative, the threshold value calculation unit 215 maintains the threshold value TH _V. On the other hand, when the result of the second determination is affirmative, the threshold value calculation unit 215 makes the first ratio R _F as close as possible based on the determination result SW _j (j = 1 to 3). Then, a new threshold value TH _V is calculated so as to approach the threshold value at which the hierarchy switching frequency can be within the allowable value.

When the new threshold value TH _V is calculated as described above, the threshold value calculation unit 215 sets the new threshold value TH _V in the switching determination unit 212 _V. In the first embodiment, the variable range of the threshold value TH _V is the range [TH _{1 to} TH ₃ ].

Further, the threshold calculation unit 215 receives the initial threshold value input to the operation input unit 180 as the operation input data IPD. Then, the threshold value calculation unit 215 sets the designated initial threshold value as the threshold value TH _V in the switching determination unit 212 _V. In the first embodiment, any _one of the threshold values TH ₁ , TH ₂ , TH ₃ can be designated as the initial threshold value.

Here, in the first embodiment, once the initial threshold value is designated, the initial threshold value is used until a new initial threshold value is designated. Further, when the once initial threshold specified is not performed also, the threshold TH ₂ is adapted to be used as an initial threshold.

<Operation>
Next, the operation of the broadcast receiving apparatus 100 of the first embodiment configured as described above will be described mainly focusing on the hierarchy switching process.

  As a premise, a user inputs a desired channel to the operation input unit 180, and the tuning control unit 191 in the control unit 190 issues a tuning command CSC corresponding to the desired station to the tuner unit 120. And Then, the CNR value of the broadcast wave of the desired channel is detected by the channel decoding unit 130, and the detection result CNR is sequentially sent to the switching control unit 192 in the control unit 190. Further, it is assumed that the source decode unit 140 performs a B layer packet error detection operation, and the B layer packet error BPE that is the detection result is sequentially sent to the switching control unit 192.

In the hierarchy switching process of the first embodiment, as shown in FIG. 5, first, an initial threshold value setting process is performed in step S11. In this initial threshold value setting process, the threshold value calculation unit 215 that has received the initial threshold value input to the operation input unit 180 sets the specified initial threshold value as the threshold value TH _V in the switching determination unit 212 _V. In the first embodiment, any _one of the threshold values TH ₁ , TH ₂ , TH ₃ can be designated as the initial threshold value.

Once the initial threshold value is specified, the initial threshold value is set as the threshold value TH _V in the switching determination unit 212 _V until new initial threshold value is specified in step S11. Further, when the initial threshold value has not been designated, the threshold value TH ₂ is set in the switching determination unit 212 _V.

Next, in step S12, a switching determination process is performed. In this switching determination process, each of the switching determination units 212 _k (k = 1 to 3, V) periodically uses the detection value CNR and the B layer packet error BPE as reception quality information RST from the reception quality information buffer 211. read out. Then, the switching determination unit 212 _k calculates the reception quality at that time based on the detection value CNR and the occurrence frequency of the B layer packet error BPE.

Subsequently, the switching determination unit 212 _k determines which one of the A layer broadcast and the B layer broadcast should be selected as a reproduction broadcast based on the threshold value TH _k stored therein and the calculated reception quality. . For example, when the A-layer broadcast is selected and the calculated reception quality reaches the reception quality to be switched to the B-layer broadcast, the broadcast selection is switched so that the B-layer broadcast is selected as a reproduction broadcast. Make a decision. In addition, when the layer B broadcast is selected and the calculated reception quality deteriorates to the reception quality to be switched to the layer A broadcast, the layer selection is switched so that the layer A broadcast is selected as a reproduction broadcast. Make a decision. The determination result by the switching determination unit 212 _k is sent to the threshold value calculation unit 215 as the determination result SW _k .

Next, in step S13, it is determined whether or not the current value of the threshold value TH _V needs to be corrected from the viewpoint of the ratio of the selection period of the B-layer broadcast to the entire period. For this determination, first, the threshold calculation unit 215 periodically reads out the B layer packet error BPE from the reception quality information buffer 211 as the B layer error information BRT. Subsequently, the threshold value calculation unit 215 obtains a first ratio R _F that is a ratio of the period during which the B layer broadcast can be selected and reproduced satisfactorily based on the occurrence frequency of the B layer packet error BPE.

On the other hand, the threshold value calculation unit 215 uses the threshold value TH _k in the switching determination unit 212 _k based on the determination result SW _k received from the switching determination unit 212 _k (k = 1 to 3, V). A second ratio R _{S, k} that is the ratio of the period in which the B-layer broadcast is selected to the entire period is _obtained .

Subsequently, the threshold value calculation unit 215 compares the first ratio R _F and the second ratio R _{S, k} . Then, the threshold calculation unit 215 performs a first determination based on the comparison result to determine whether or not there is a threshold that can be closer to the first ratio R _F than the current value of the threshold TH _V. For example, when the second ratio R _{S, j} (j = 1 to 3) is closer to the first ratio R _F than the second ratio R _{S, V} , the result of the first determination Will be positive.

If the first determination result is affirmative: (step S13 Y) immediately, in order to correct the threshold value TH _V, the process proceeds to step S15. On the other hand, if the first determination result is negative: (step S13 N), while maintaining the threshold value TH _V, the process proceeds to step S14.

In step S14, the threshold value calculation unit 215 performs a second determination based on the determination result SW _V to determine whether or not the hierarchy switching frequency exceeds an allowable value. If the second determination result is negative: (step S14 N), the threshold value calculation unit 215 determines to maintain the threshold TH _V, the process returns to the step S12.

On the other hand, if the second determination result is affirmative: It is determined (step S14 Y), the threshold value calculation unit 215 should be corrected threshold TH _V. Then, the process proceeds to step S15.

In step S15, a new threshold value TH _V is calculated and set. In this process, a new threshold value TH _V is calculated by a different method depending on whether the result of the first determination is affirmative or the result of the second determination is affirmative.

In the calculation process of the new threshold value TH _V when the result of the first determination is affirmative, the threshold value calculation unit 215 calculates the new threshold value TH _V so as to approach the threshold value that is considered to be optimal at that time. . For example, if there is a second ratio R _{S, j} (j = 1 to 3) that is closer to the first ratio R _F than the second ratio R _{S, V} , the first of them is the first A new threshold value TH _V is calculated so as to approach the threshold value corresponding to the one close to 1 ratio R _F. The threshold value calculation unit 215, a threshold value considered optimal at that time, the current value predetermined fraction only optimum close to possible threshold correction of the difference between the threshold TH _V, current value of the threshold TH _V To calculate a new threshold value TH _V. As a result, as in the case of PLL (Phase Lock Loop), the threshold value TH _V changes in the direction of convergence to the optimum threshold value.

On the other hand, in the calculation process of the new threshold value TH _V when the result of the second determination is affirmative, the threshold value calculation unit 215 determines the first ratio R based on the determination result SW _j (j = 1 to 3). _A new threshold value TH _V is calculated so as to be as close as possible to _F and close to a threshold value at which the frequency of layer switching can be within an allowable value.

As described above, a new threshold value TH _V is calculated. Then, the threshold calculation unit 215 sets a new threshold TH _V in the switching determination unit 212 _V. Then, the process returns to step S12.

Thereafter, it is repeated the processing up to the above step S12 to S15, while being corrected as required threshold TH _V, hierarchical switching processing between the A-layer broadcast and the B-layer broadcast using threshold TH _V is performed . Then, according to the result of the layer switching process, the A unit broadcast or the B layer broadcast is selected by the selection unit 150, and the sound and image of the selected layer broadcast are reproduced by the sound output unit 160 and the display unit 170.

As described above, in the first embodiment, the channel decoding unit 130 detects the CNR indicating the reception state of the broadcast wave of the channel selected to be reproduced. Further, the source decode unit 140 detects a B layer packet error which is an error in the demodulation result of the B layer broadcast of the channel selected to be reproduced. According to the comparison result between the reception quality of the B layer broadcast calculated based on these detection results and each of the threshold values TH _k (k = 1 to 3, V), the A layer broadcast and the B layer for each threshold TH _k. The switching determination unit 212 _k performs switching determination with hierarchical broadcasting. Then, considering the switching frequency, based on the result of the switching determination and the detection result of the error of the B layer packet, the threshold value calculation unit 215 compares the ratio of the period during which the B layer broadcast can be comfortably viewed and the actual A new threshold value TH _V is calculated so that the ratio of the period of switching to the B level approaches. Then, switching between the A layer broadcast and the B layer broadcast is controlled using the calculated new threshold value TH _V.

  Therefore, according to the first embodiment, it is possible to appropriately switch a plurality of broadcasts in the simultaneous broadcast in response to a change in the reception environment.

[Second Embodiment]
Next, a second embodiment of the present invention will be described mainly with reference to FIGS.

<Configuration>
The broadcast receiving apparatus according to the second embodiment is different from the broadcast receiving apparatus 100 according to the first embodiment described above only in that a switching control unit 193 having the configuration illustrated in FIG. 6 is provided instead of the switching control unit 192. Is different. Hereinafter, this difference will be mainly described.

As shown in FIG. 6, the switching control unit 193 is different from the switching control unit 192 (see FIG. 4) described above as (a) instead of the switching determination unit 212 _V as a part of the determination unit. The difference is that a switching determination unit 212 ₄ is provided, (b) a switching selection unit 213 as switching means is further provided, and (c) a threshold selection unit 216 is provided instead of the threshold calculation unit 215.

The switching determination unit 212 ₄ is different from the switching determination unit 212 _V described above in that a fixed threshold value TH ₄ is stored in the same manner as the switching determination units 212 _{1 to} 212 ₃ . . The threshold TH ₁ to TH ₄ are as it goes from the TH ₁ to TH _4, is adapted to perform hierarchical selection with an emphasis on selection of the B-layer broadcast.

Determination result SW ₄ by the switching determination unit 212 ₄ is sent to the switching selecting portion 213 and a threshold selector 216. Note that the determination results SW _{1 to} SW ₃ by the switching determination units 212 _{1 to} 212 ₃ are also sent to the switching selection unit 213 and the threshold selection unit 216.

The switching selection unit 213 receives the determination results SW _{1 to} SW ₄ from the switching determination units 212 _{1 to} 212 ₄ . Then, the switching selection unit 213 selects the determination results SW _{1 to} SW ₄ in accordance with the switching selection command STS from the threshold selection unit 216 and sends it to the selection unit 150 as the switching command SWC.

Similar to the threshold calculation unit 215 described above, the threshold selection unit 216 periodically reads out the B layer packet error BPE from the reception quality information buffer 211 as the B layer error information BRT. Then, the threshold selection unit 216 obtains a first ratio R _F that is a ratio of the period in which the B layer broadcast can be selected and reproduced satisfactorily based on the occurrence frequency of the B layer packet error BPE.

Similarly to the threshold calculation unit 215, the threshold selection unit 216 receives the determination result SW _k from the switching determination unit 212 _k (k = 1 to 4). The threshold selector 216 calculates in each case of adopting the threshold TH _k in the switching determination unit 212 _k, the second rate R _S B hierarchy broadcasting is the ratio to the total duration of the period being _selected, the _k.

The threshold selection unit 216 compares the first ratio R _F thus obtained with the second ratio R _{S, k} . Based on the comparison result, the threshold selection unit 216 sorts the thresholds TH ₁ to TH ₄ in an order in which the threshold value selection unit 216 can be closer to the first ratio R _F than the current threshold value actually used. Subsequently, the threshold selection unit 216 determines whether or not the switching frequency is equal to or less than the allowable value in the sort order.

Based on the result of this determination, the threshold selection unit 216 determines the threshold that can be closest to the first ratio R _F among the thresholds whose switching frequency is equal to or less than the allowable value as the threshold to be actually used. Then, the threshold selection unit 216 sends an optimal switching selection command indicating that _{one of} the determination results SW _{1 to} SW ₄ corresponding to the determined threshold to be selected to the switching selection unit 213 as the switching selection command STS.

Similarly to the threshold value calculation unit 215 described above, the threshold value selection unit 216 receives the initial threshold value input to the operation input unit 180 as the operation input data IPD. Then, the threshold selection unit 216 sends an initial switching selection command indicating that _{one of} the determination results SW _{1 to} SW ₄ corresponding to the designated initial threshold should be selected to the switching selection unit 213 as the switching selection command STS. In the second embodiment, any one of the threshold values TH ₁ , TH ₂ , TH ₃ , TH ₄ can be designated as the initial threshold value.

Here, in the second embodiment, as in the case of the first embodiment described above, once the initial threshold value is specified, the initial threshold value is used until a new initial threshold value is specified. It has become. Further, when the once initial threshold specified is not performed also, the threshold TH ₂ is adapted to be used as an initial threshold.

<Operation>
Next, the operation of the broadcast receiving apparatus of the second embodiment configured as described above will be described mainly focusing on the layer switching process.

  As a premise, as in the case of the first embodiment described above, a user inputs a desired channel to the operation input unit 180, and the channel selection control unit 191 in the control unit 190 selects a channel corresponding to the desired station. It is assumed that the command CSC is issued to the tuner unit 120. Then, the CNR value of the broadcast wave of the desired channel is detected by the channel decode unit 130, and the detection result CNR is sequentially sent to the switching control unit 192 in the control unit 190. Further, it is assumed that the source decode unit 140 performs a B layer packet error detection operation, and the B layer packet error BPE as the detection result is sequentially sent to the switching control unit 192.

In the hierarchy switching process of the second embodiment, as shown in FIG. 7, first, in step S21, an initial threshold setting process is performed. In the second embodiment, any one of the threshold values TH ₁ , TH ₂ , TH ₃ , TH ₄ can be designated as the initial threshold value.

In this initial threshold setting process, the threshold selection unit 216 that has received the initial threshold designation input to the operation input unit 180 should select _{one of} the determination results SW _{1 to} SW ₄ corresponding to the designated initial threshold. An initial switching selection command is sent to the switching selection unit 213 as a switching selection command STS. Once the initial threshold value is specified, the initial threshold value is used in step S21 until the initial threshold value is newly specified. If the initial threshold value has never been specified, the threshold value TH ₂ is used as the initial threshold value.

Next, in step S22, a switching determination process is performed. In this switching determination process, as in the first embodiment, each of the switching determination units 212 _k (k = 1 to 4) periodically receives the detected value CNR and the B layer packet error from the reception quality information buffer 211. BPE is read as reception quality information RST. Then, the switching determination unit 212 _k calculates the reception quality at that time based on the detection value CNR and the occurrence frequency of the B layer packet error BPE.

Subsequently, as in the case of the first embodiment, the switching determination unit 212 _k selects either the A layer broadcast or the B layer broadcast based on the threshold value TH _k stored therein and the calculated reception quality. It is determined whether or not to select the broadcast for reproduction. The determination result by the switching determination unit 212 _k is sent to the switching selection unit 213 and the threshold selection unit 216 as the determination result SW _k .

Next, in step S23, an optimal threshold value selection process is performed from the viewpoint of the ratio of the selection period of the B layer broadcast to the entire period and the switching frequency. In the optimum threshold selection process, first, the threshold selection unit 216 periodically reads out the B layer packet error BPE from the reception quality information buffer 211 as the B layer error information BRT. Then, the threshold selection unit 216 obtains a first ratio R _F that is a ratio of the period in which the B layer broadcast can be selected and reproduced satisfactorily based on the occurrence frequency of the B layer packet error BPE.

Subsequently, the threshold selection unit 216 receives the determination result SW _k from the switching determination unit 212 _k (k = 1 to 4). The threshold selector 216 calculates in each case of adopting the threshold TH _k in the switching determination unit 212 _k, the second rate R _S B hierarchy broadcasting is the ratio to the total duration of the period being _selected, the _k.

The threshold selection unit 216 compares the first ratio R _F thus obtained with the second ratio R _{S, k} . Based on the comparison result, the threshold selection unit 216 sorts the thresholds TH ₁ to TH ₄ in an order in which the threshold value selection unit 216 can be closer to the first ratio R _F than the current threshold value actually used. Subsequently, the threshold selection unit 216 determines whether or not the switching frequency is equal to or less than the allowable value in the sort order.

Based on the result of this determination, the threshold selection unit 216 determines the threshold that can be closest to the first ratio R _F among the thresholds whose switching frequency is equal to or less than the allowable value as the threshold to be actually used. Then, the threshold selection unit 216 sends an optimal switching selection command indicating that _{one of} the determination results SW _{1 to} SW ₄ corresponding to the determined threshold to be selected to the switching selection unit 213 as the switching selection command STS. Then, the process returns to step S22.

  Thereafter, the processes in steps S22 and S23 are repeated to determine the optimum threshold value, and the layer switching process between the A layer broadcast and the B layer broadcast using the determined threshold value is executed. Then, according to the result of the layer switching process, the A unit broadcast or the B layer broadcast is selected by the selection unit 150, and the sound and image of the selected layer broadcast are reproduced by the sound output unit 160 and the display unit 170.

As described above, in the second embodiment, the channel decoding unit 130 detects the CNR indicating the reception state of the broadcast wave of the channel selected to be reproduced. Further, the source decode unit 140 detects a B layer packet error which is an error in the demodulation result of the B layer broadcast of the channel selected to be reproduced. In accordance with the comparison result between the reception quality of the B layer broadcast calculated based on these detection results and each of the threshold values TH _k (k = 1 to 4), the A layer broadcast and the B layer broadcast for each threshold TH _k The switching determination unit 212 _k performs the switching determination. Then, based on the result of the switching determination and the detection result of the error of the B layer packet, taking into account the switching frequency, the threshold selection unit 216 can determine the ratio of the period during which the B layer broadcast can be comfortably viewed and the actual The optimum threshold value is determined from the threshold values TH _k (k = 1 to 4) so that the ratio of the period during which the layer B is switched to is closer. Then, switching between the A layer broadcast and the B layer broadcast is controlled using the determined threshold value.

  Therefore, according to the second embodiment, it is possible to appropriately switch a plurality of broadcasts in the simultaneous broadcast in response to a change in the reception environment.

[Modification of Embodiment]
The present invention is not limited to the above-described embodiment, and various modifications are possible.

  For example, in the first embodiment described above, the number of switching determination units that use a fixed threshold is three, but the number is not limited as long as it is a plurality. Moreover, in said 2nd Embodiment, although the number of the switching determination parts was four, if it is plurality, the number will not ask | require.

  In the first and second embodiments, the CNR is detected as the reception state of the broadcast wave of the desired channel. However, the electric field strength may be detected.

  In the first and second embodiments, the B layer packet error is detected and considered as the reception quality of the B layer broadcast. However, the bit error rate in the B layer data is detected and considered. It may be.

  In the first and second embodiments, the two-layer broadcasts of the A-layer broadcast and the B-layer broadcast are included in the same transmission channel. However, the number of layer broadcasts included in the same transmission channel is as follows. It may be 3 or more.

  In the first and second embodiments described above, the case of simultaneous broadcasting (simultaneous broadcasting) has been exemplified, but the present invention can be applied even when the broadcasting of a plurality of layers is not simultaneous broadcasting. Of course you can.

  Note that the control unit 190 in the above embodiment includes a central processing unit (CPU), a digital signal processor (DSP), a read only memory (ROM), and a random access memory (RAM). It is also possible to configure the computer as a computing means including the above, and execute the processing in the above-described embodiment on a computer prepared in advance. This program is recorded on a computer-readable recording medium such as a hard disk, CD-ROM, or DVD, and is read from the recording medium and executed by the computer. The program may be acquired in a form recorded on a portable recording medium such as a CD-ROM or DVD, or may be acquired in a form of delivery via a network such as the Internet. Also good.

It is a block diagram which shows roughly the structure of the broadcast receiver which concerns on 1st Embodiment of this invention. It is a block diagram which shows the structure of the source decoding unit of FIG. It is a block diagram which shows the structure of the control unit of FIG. It is a block diagram which shows the structure of the switching control part of FIG. It is a flowchart for demonstrating the hierarchy switching process in 1st Embodiment. It is a block diagram which shows the structure of the switching control part in the broadcast receiver which concerns on 2nd Embodiment of this invention. It is a flowchart for demonstrating the hierarchy switching process in 2nd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Broadcast receiving apparatus 130 ... Channel decoding unit (reception state detection means)
141 ... Packet separation unit (error detection means)
180 ... operation input unit (part of initial value setting means)
212 _{1 to} 212 ₃ ... Switching determination unit (part of determination means)
212 _V ... Switching determination unit (part of determination means, switching means)
212 ₄ ... Switching determination unit (part of determination means)
213... Switching selection unit (switching means)
215... Threshold value calculation unit (determining means, part of initial value setting means)
216... Threshold selection unit (decision means, part of initial value setting means)

Claims (12)

Receiving a digital broadcast wave in which at least two or more broadcasts including a first broadcast of a layer having a high error tolerance and a second broadcast of a layer having a lower error tolerance than the first broadcast exist in the same transmission channel; A broadcast receiving device for switching and reproducing the first broadcast and the second broadcast,
Error detection means for detecting an error in the demodulation result of the second broadcast;
Based on a comparison result between each of a plurality of different threshold values and the reception quality of the second broadcast obtained in consideration of the frequency of occurrence of the error detected by the error detection means, for each of the plurality of threshold values Determining means for determining switching between the first broadcast and the second broadcast;
Determining means for determining a threshold value actually used for the switching based on a detection result by the error detection means and a determination result by the determination means;
Switching means for switching between the first broadcast and the second broadcast based on the threshold value determined by the determination means and the reception quality of the second broadcast;
A broadcast receiving apparatus comprising: It further comprises reception state detection means for detecting the reception state of the broadcast wave,
The reception quality of the second broadcast is obtained by further considering the detection result by the reception state detection means,
The broadcast receiving apparatus according to claim 1.   The broadcast receiving apparatus according to claim 1, wherein the plurality of threshold values include the threshold value actually used.   The broadcast receiving apparatus according to claim 1, wherein the determining unit determines any one of the plurality of threshold values as the threshold value to be actually used.   The broadcast receiving apparatus according to claim 1, wherein the determination unit continuously changes the threshold value to be actually used.   The determination means includes a ratio of a period in which the reception quality of the second broadcast obtained based on a detection result by the error detection means is equal to or higher than a predetermined threshold, and a period during which the switching means is switched to the second broadcast. The broadcast receiving apparatus according to any one of claims 1 to 5, wherein the threshold value to be actually used is determined so as to be close to the ratio.   The broadcast receiving apparatus according to claim 6, wherein the determining unit determines the threshold to be actually used in consideration of a switching frequency in the switching determination of the determining unit.   The broadcast receiving apparatus according to claim 1, further comprising an initial setting unit that performs initial setting of the threshold to be actually used.   The broadcast according to any one of claims 1 to 8, wherein the determination unit determines the threshold to be actually used within a range from a minimum value to a maximum value of the plurality of threshold values. Receiver device. Receiving a digital broadcast wave in which at least two or more broadcasts including a first broadcast of a layer having a high error tolerance and a second broadcast of a layer having a lower error tolerance than the first broadcast exist in the same transmission channel; A broadcast reception control method for switching and reproducing the first broadcast and the second broadcast,
A detection step of detecting an error in a demodulation result of the second broadcast;
Based on a comparison result between each of a plurality of different threshold values and the reception quality of the second broadcast obtained in consideration of the frequency of occurrence of the error detected in the detection step, the first threshold value is set for each of the plurality of threshold values. A determination step of performing switching determination between one broadcast and the second broadcast;
A determination step for determining a threshold value actually used for the switching based on a detection result in the detection step and a determination result in the determination step;
A switching step of switching between the first broadcast and the second broadcast based on the threshold value determined in the determination step and the reception quality of the second broadcast;
A broadcast reception control method comprising:   A broadcast reception control program for causing a calculation means to execute the broadcast reception control method according to claim 10.   12. A recording medium in which the broadcast reception control program according to claim 11 is recorded so as to be readable by an arithmetic means.

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