JP2006222557A - Receiver - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a receiver capable of selecting layers in response to the reception state, even when digital broadcast data (modulation system or the like) differ by layers. <P>SOLUTION: The receiver 10 receives digital broadcast waves at least the modulation systems of which differ by each layer, a plurality of the layers being specified by dividing a prescribed frequency band into a plurality of layers. A program content discriminating section 20 discriminates whether the received signals of layers result from a simultaneous broadcast, indicating a broadcast program of the same content in the layers and outputs a program discrimination control signal, and a power comparison section 18 compares a reception state (reception power) by each layer and outputs a layer selection control signal, in response to the result of the comparison when the program discrimination control signal indicates the simultaneous broadcast. Further, a TS-Demux 21 selects among the layers, in response to the layer selection control signal. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a receiving apparatus that receives a digital broadcast wave, and more particularly to a receiving apparatus that is mounted on a mobile body and receives a terrestrial digital broadcast wave.

  Generally, in terrestrial digital broadcasting (ISDB-T), hierarchical transmission is allowed, and different modulation schemes, transmission rates, and error tolerances can be given to each layer (up to three layers). Here, a hierarchy means each group when a predetermined frequency bandwidth is divided into a plurality of groups and different information is assigned to each group. For example, a frequency band having a width of 5.7 MHz is divided into 13 segments, and one or a plurality of segments are divided as one layer.

  In such terrestrial digital broadcasting, the same broadcast content (broadcast program) may be transmitted in a plurality of layers, and a receiving device that receives a terrestrial digital broadcast wave has the most reception state in the plurality of layers. A good hierarchy is selected and received. For example, when the same broadcast content is broadcasted in a plurality of layers, there is one that compares the received power of pilot signals in each layer and selects the layer with the highest received power (for example, Patent Documents) 1).

  Here, a packet error rate after Reed-Solomon (RS) decoding, a bit error rate after Viterbi decoding, and a TMCC (Transmission and Multiplexing Configuration Control) amplitude value may be compared to select a layer with a good reception state. Has been done.

  On the other hand, a diversity reception method is known as a technique for preventing the deterioration of the reception state. For example, the received power value of the received signal is detected for each antenna series by the power detection circuit and received by the diversity selection circuit. An antenna selection diversity signal is output if the difference in power value between the antenna series is equal to or greater than a threshold value, and a signal combining diversity signal is output if the difference is not greater than the threshold value.

  The diversity switching circuit includes an antenna selection circuit that measures the signal quality of the received signal and outputs the received signal of the antenna that provides the best signal quality, and a signal combining circuit that combines the received signals, and the diversity switching circuit is an antenna selection diversity signal. When the signal is received, the output signal of the antenna selection circuit is selected, and when the signal synthesis diversity signal is received, the output signal of the signal synthesis circuit is selected (for example, see Patent Document 2).

  Furthermore, in order to perform decoding with a lower error rate when receiving a signal that has been coded and modulated using an arbitrary combination among a plurality of modulation methods and coding rates, the demodulated data is converted into modulation method information and coding rate. Some of them are quantized according to the level of quantization corresponding to the combination of information, so that even if the modulation method or coding rate is changed or switched, the digital signal always has stable error rate characteristics. There is one that decodes data (see, for example, Patent Document 3).

Japanese Patent Application Laid-Open No. 2003-304510 (pages 7 to 9, FIGS. 1 to 2) Japanese Unexamined Patent Publication No. 2003-244043 (pages 6 to 7, FIGS. 1 to 3) JP 2000-252841 A (pages 4 to 5, FIGS. 1 and 8)

  Since the conventional receiving apparatus is configured as described above, when the same broadcast content is transmitted in a plurality of layers, it is possible to receive a layer having a good reception state, but in each layer, the same digital broadcast If the data is transmitted and the digital broadcast data differs from layer to layer even though the broadcast contents are the same, the layer cannot be selected according to the reception state. For example, if the video modulation method and / or compression method is different for each layer (that is, if the digital broadcast data is different), there is a problem that the layer cannot be selected according to the reception state.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a receiving apparatus capable of selecting a layer according to a reception state even if digital broadcast data differs from layer to layer. To do.

  The receiving apparatus according to the present invention receives a digital broadcast wave in which a predetermined frequency bandwidth is divided into a plurality of layers and a plurality of layers are defined, and at least a modulation method is different for each layer. The receiving apparatus determines whether or not the broadcast program having the same content is transmitted in these layers and outputs a program determination control signal, and includes a plurality of program determination control signals. And a hierarchy selection means for selecting one of the hierarchies according to the reception state of each hierarchy when the broadcast program having the same content is transmitted in the hierarchy. is there.

  According to the present invention, when receiving digital broadcast waves having at least different modulation methods for each layer, it is configured to select one of the layers according to the reception state of each layer for simulcast. Even if the digital broadcast data (for example, the modulation method) is different, the hierarchy can be selected according to the reception state.

Embodiment 1 FIG.
First, a terrestrial digital broadcast wave received by a receiving apparatus according to Embodiment 1 of the present invention will be described with reference to FIG. In terrestrial digital broadcasting, one digital broadcasting wave is transmitted from one broadcasting station (not shown), and this digital broadcasting wave is called a transport stream (TS). One TS includes at least one broadcast service, and a service identification number (TS_ID) is assigned to each broadcast service.

  In terrestrial digital broadcasting, for example, an OFDM (Orthogonal Frequency Division Multiplexing) system to which a so-called guard interval is added is used, and a digital video signal (video stream), a digital audio signal (audio stream), and service information are used for TS. (Service Information: SI information) is included, and this SI information includes, for example, data indicating TS_ID, transmission channel (three-digit number), broadcast station name, program information, broadcast area, and the like. (For example, the broadcast target area is determined by the area identifier included in Service_id in the service list descriptor included in NIT (Network Information_id) in SI information).

  Transmission data by terrestrial digital broadcasting (ISDB-T system) is, for example, a group of data (hereinafter referred to as a segment) including a plurality of TSPs (Transport Stream Packets) defined by MPEG-2 (Moving Picture Experts Group phase 2). ) And is subjected to transmission path coding defined in advance, and a pilot signal is added to each segment to form an OFDM segment. Then, a total of 13 OFDM segments are subjected to IFFT (Inverse Fast Fourier Transform) and are collectively converted into OFDM transmission signals. That is, the bandwidth of about 5.7 MHz per channel is divided into 13 segments.

  As shown in FIGS. 1A and 1B, 13 segments are transmitted in one layer (A layer), and 13 segments are transmitted in a plurality of layers (as shown in FIGS. 1C and 1D). In the illustrated example, there are cases where transmission is performed in three layers (A layer to C layer), and parameters such as a carrier modulation scheme, an inner code coding rate, and a time interleave length may be set for each layer. it can. Further, as shown in FIG. 1 (d), for one segment (for example, a segment located in the center) SG1 among the 13 segments, a part of the television signal is received when frequency interleaving is performed in the segment. Can be (partial reception).

  Here, in the terrestrial digital broadcasting, 12 segments excluding the central one segment and the central one segment are transmitted in a simulcast format, and the 12 segments are transmitted by the 64QAM (Quadrature Amplitude Modulation) method, and the remaining one segment ( The center segment) is transmitted by a QPSK (Quadri-Phase Shift Keying) method.

  FIG. 2 is a block diagram showing a configuration of the receiving apparatus according to Embodiment 1 of the present invention. The illustrated receiving apparatus 10 receives the above-described OFDM transmission signal via an antenna 11, and the OFDM transmission signal is received by a tuner unit 12. Downconverted to IF (intermediate frequency) signal. The IF signal is converted into a digital signal by an analog / digital (A / D) converter unit (ADC) 13. Next, the digital signal is decomposed into a plurality of signals having different frequency bands by an FFT (Fast Fourier Transform) unit 14, and transmission path distortion of these signals is corrected by a pilot demodulating unit 15.

  The signals corresponding to the carriers thus obtained are frequency deinterleaved by the frequency deinterleaver 16 and then time deinterleaved by the time deinterleaver 17. That is, the data is rearranged and given to the power comparison unit 18. The output of the FFT unit 14 is given to the TMCC demodulator 19, and the TMCC demodulator 19 provides information on each segment (for example, information indicating partial reception, modulation scheme, convolutional coding rate, and number of segments: hereinafter simply segment information). (Referred to as “hierarchical information”) is generated and provided to the power comparison unit (power comparison means) 18.

  The power comparison unit 18 receives a program determination control signal generated by a program content determination unit (program content determination means) 20 to be described later, and broadcast program content of each segment (hierarchy) is simulcast (in accordance with the program determination control signal). If it is determined that the broadcast is the same broadcast), a layer selection control signal for selecting a segment (hierarchy) in a good reception state according to the power status of the pilot carrier in consideration of the segment information is output. This hierarchy selection control signal is given from the power comparison unit 18 to the TS-Demux (TS-separation unit) 21. Then, the TS-Demux (reproduction selection means) 21 performs video and audio reproduction selection according to the hierarchy selection control signal as described later, and the video and audio signal decoded by the video and audio decoding unit 25 are received. Each is supplied to a monitor and a speaker (both not shown).

  By the way, each segment (hierarchy) is given from the power comparison unit 18 to the layer division unit 22, and each layer (layer) in the layer division unit 22 depends on the modulation scheme and the inner coding scheme (convolution coding scheme) for each segment (layer). Are demodulated and Viterbi-decoded (first to third demodulation and Viterbi decoding 22a to 22c: The first to third demodulation and Viterbi decoding 22a to 22c are, for example, layers A to C shown in FIG. C demodulation and Viterbi decoding). The Viterbi-decoded data of each segment (hierarchy) is arranged in the TS reproduction unit 23 according to the transmission order, and the outer code decoding unit 24 performs error correction processing according to the RS (Reed Solomon) code, and then TS -Given to Demux21.

  As shown in FIG. 2, the TS-Demux 21 includes a PSI / SI data acquisition unit 21a, each segment (hierarchy) data identification unit 21b, a video and audio reproduction selection unit 21c, and a PSI / SI data acquisition unit 21a. Then, the SI data is acquired from the output of the outer code decoding unit 24, and the SDT and EIT data in the SI data are given to the program content determination unit 20 and, as will be described later, the PMT information is assigned to each segment (hierarchy) data identification unit. 21b.

  The program content determination unit 20 determines the program content according to SDT and EIT, and provides a program determination control signal to the power comparison unit 18. That is, the program content determination unit 20 generates and compares the program name and program content for each segment (hierarchy), and provides the power comparison unit 18 with a program determination control signal indicating whether or not it is simulcast. Become.

  On the other hand, each segment (hierarchy) identifying unit 21b identifies each segment (hierarchy) according to the PWT information (PSI) and provides the segment identification result to the video and audio reproduction selecting unit 21c. The video and audio reproduction selection unit 21c determines which segment (hierarchy) data is adopted as the video and audio reproduction data in accordance with the hierarchy selection control signal output from the power comparison unit 18, and the segment identification result described above. The desired segment (hierarchy) signal is selected from the output of the outer code decoding unit 24 using the packet IDs (PID) of the video and audio data of the segment (hierarchy) identified by the video and audio decoding unit 25. To give. Then, the video and audio decoding unit 25 decodes the segment (hierarchy) signal and outputs a video signal and an audio signal.

  Here, with reference to FIG. 3, generation of a hierarchy selection signal in the power comparison unit 18 will be described. The power comparison unit 18 includes first to third delay units 18a to 18c and a power calculation and comparison unit 18d. The output signal from the time deinterleaving unit 17 shown in FIG. That is, it is given to the first to third delay units 18a to 18c for each of the hierarchies A to C. In other words, the signal of the segment (hierarchy) A is given to the first delay unit 18a, and the signal of the segment (hierarchy) B is given to the second delay unit 18b. Further, the signal of the segment (hierarchy) C is given to the first delay unit 18c.

  The first to third delay units 18a to 18c have different transmission delay amounts, delay the signals of the segments (hierarchies) A to C, and align the timings of the signals of the segments (hierarchies) A to C. The delay difference between segments (hierarchies) is corrected. The power calculation and comparison unit 18d first determines whether or not the program content of each segment (hierarchy) is simulcast according to the program content control signal given from the program content determination unit 20, and determines that it is simulcast. The signals of segments (hierarchies) A to C, which are simulcasts, are input. Here, the outputs of the first to third delay units 18a to 18c are assumed to be simulcast.

  The power calculation and comparison unit 18d first calculates the square (that is, power) of the pilot carrier waveform amplitude in each signal of the segments (hierarchies) A to C. As described above, the segment information of each segment (hierarchy) is sent from the TMCC demodulator 19 to the power calculation and comparison unit 18d, and is received according to the modulation scheme and convolution coding rate information in each segment (hierarchy). Obtaining the sensitivity, the power calculation and comparison unit 18d compares the received power between segments (hierarchies) in consideration of the reception sensitivity. Then, the power calculation and comparison unit 18d determines the segment (hierarchy) having the best reception state among the segments (hierarchy) A to C, and outputs the layer selection control signal to the video and audio reproduction selection unit 21c.

  Subsequently, the TS-DEMUX 21 will be described with reference to FIG. TS data is given from the outer code decoding unit 24 to the PSI / SI acquisition unit 21a and the video and audio reproduction selection unit 21c, and the PSI / SI acquisition unit 21a converts the PMT information in the PSI / SI data in the TS data into each segment. The data is output to the (hierarchy) data identification unit 21b.

  Each segment (hierarchy) data identification unit 21b recognizes the PID of video and audio data of each segment (hierarchy) based on the PMT information, and gives the recognition result to the video and audio reproduction selection unit 21c. In the video and audio reproduction selection unit 21c, a PID corresponding to a desired segment (hierarchy) is selected based on the hierarchy selection control signal, and the video and audio data corresponding to the selected PID is sent to the video and audio decoding unit 25. Output.

  Further, the program content determination unit 20 will be described with reference to FIG. As described above, SDT and EIT data are given from the PSI / SI data acquisition unit 21a to the program content determination unit 20, and the program content determination unit 20 assigns Service_id assigned to each segment (hierarchy) (or each program). In response to the contents of the program name and content of each segment (according to the contents of the program name and the segment of the extended event descriptor) according to the Service_type and Service_name in the service descriptor (Service Descriptor) in the SDT and the Short Event Descriptor and Extended Event Descriptor in each EIT In comparison, it is determined whether or not it is simultaneous broadcasting, and a program determination control signal as a determination result is output to the power comparison unit 18.

Next, the operation will be described.
Referring to FIG. 2, one segment reception (partial reception) is now performed in layer A. In layer A, the modulation method is QPSK, the coding rate is 1/2, and the video compression method is H.264. H.264, audio channel is 2ch, layer B is modulation method is 64QAM, coding rate is 3/4, video compression method is MPEG2, audio channel is 5.1ch, layer A and B are layered transmission Suppose that it is done.

  In the tuner unit 12 to the time deinterleaving unit 17 shown in FIG. 2, the same processing is performed for both the layers A and B as described above, and the reception sensitivity of the layer A is higher than the reception sensitivity of the layer B by the TMCC demodulation unit 19. Is also recognized to be about 15 dB lower. In the power comparison unit 18, when it is determined by the program determination control signal given from the program content determination unit 20 that the layers A and B are simultaneous broadcasts, the reception sensitivity of the layer A is approximately 15 dB lower than the reception sensitivity of the layer B In consideration of this, the power comparison between the hierarchy A and the hierarchy B is performed. For example, even when the power of the layer B is lower than the reception sensitivity and the power of the layer A is 10 dB lower than the power of the layer B, if the reception power of the layer A is higher than the reception sensitivity, the power comparison unit 18 A hierarchy selection control signal for instructing selection is output.

  Here, when the modulation method is QPSK and the coding rate is 1/2 according to the provisions of the ARIB standard, the required C / N (carrier-to-noise ratio) = 4.9 dB, and the modulation method Is 64QAM and the coding rate is 3/4, the required C / N (carrier-to-noise ratio) = 20.1 dB. As a result, the reception sensitivity difference between layers A and B is about 15 dB.

  In the layer division unit 22 to the outer code decoding unit 24, the same processing is performed for both the layers A and B as described above, and TS data is given from the outer code decoding unit 24 to the PSI / SI data acquisition unit 21a. The PSI / SI data acquisition unit 21a acquires PMT (PSI) information, SDT and EIT data, gives the PMT information to each segment (hierarchy) data identification unit 21b, and gives the SDT and EIT data to the program content determination unit 20. .

  Each segment (hierarchy) data identifying unit 21b identifies the PIDs of the video and audio data of the hierarchies A and B from the PMT information, and gives the identification result to the video and audio reproduction selecting unit 21c. Then, the video and audio reproduction selection unit 21c converts the video data and audio data of the hierarchy A from the TS data according to the video PID and audio PID of the hierarchy A by the hierarchy selection control signal given from the power comparison unit 18. Extract. These video data and audio data are given to the video and audio decoding unit 25.

  On the other hand, the program content determination unit 20 stores the Service_type and Service_name of the hierarchies A and B from the SDT data (here, mainly the service type and service name are stored), and the Event_name_char and Text_char of the hierarchies A and B from the EIT data. (Here, mainly the program name and program descriptor are stored). Then, the program content determination unit 20 compares the program information relating to the layers A and B to determine whether the broadcast is a simulcast, and sends a program determination control signal indicating whether the broadcast is a simulcast or not to the power comparison unit 18. Output to. Then, as described above, the power comparison unit 18 provides the hierarchy selection control signal to the video and audio reproduction selection unit 21c, and the video and audio reproduction selection unit 21c performs hierarchy selection according to the hierarchy selection control signal.

  In this way, if either layer A or B is selectively received, for example, layer A can be received even in an environment where the radio wave condition is severe in the mobile body, so that the video quality and audio Although the number of channels is inferior, it is possible to avoid a state in which video and audio are interrupted. That is, even if the digital broadcast data differs for each layer, the layer can be selected according to the reception state.

  In the above example, segment information (information such as modulation scheme and convolutional coding rate) is supplied from the TMCC demodulator 19 to the power comparator 18, and the power comparator 18 outputs the segment information when outputting the layer selection control signal. Although it is considered, a delay profile may be further considered. For example, as shown in FIG. 6, the output of the pilot demodulating unit 15 is given to a delay profile unit (delay profile detecting means) 26, and the delay profile obtained by the delay profile unit 26 (the delay profile is a digital broadcast having a desired wave). (The relative intensity and delay time of the wave and the interference wave) may be provided to the power comparison unit 18 (in FIG. 6, the same reference numerals are used for the same components as those shown in FIG. 2). Attached).

  Here, one segment reception (partial reception) is performed in layer A. In layer A, the modulation method is QPSK, the coding rate is 1/2, and the video compression method is H.264. H.264, audio channel is 2ch, layer B is modulation method is 64QAM, coding rate is 3/4, video compression method is MPEG2, audio channel is 5.1ch, and layer A and B are hierarchical transmission As described above, even when the power of layer B is lower than the reception sensitivity and the power of layer A is 10 dB lower than the power of layer B, the reception power of layer A is lower than the reception sensitivity. If it is high, the power comparison unit 18 selects the hierarchy A. At this time, the delay profile unit 26 considers the D / U ratio when the arrival time difference between the desired wave and the disturbing wave exceeds the guard interval length. (See FIG. 7).

  For example, even if the power of layer B is equal to or higher than the reception sensitivity, a layer selection control signal for instructing selection of layer A is output when the D / U ratio is 5 dB or more and 20 dB or less. Here, according to the provisions of the ARIB standard, when the modulation method is QPSK and the coding rate is 1/2, the required C / N (carrier-to-noise ratio) = 4.9 dB, and the modulation method is 64QAM. When the coding rate is 3/4, the D / U ratio is calculated according to the required C / N (carrier-to-noise ratio) = 20.1 dB.

  In this way, if the hierarchy selection is performed in consideration of the delay profile, the hierarchy can be selected with high accuracy according to the reception state even if the digital broadcast data differs for each hierarchy.

  Further, as shown in FIG. 8, a GPS position information detection unit (position detection means) 27 may be provided separately, and the position information obtained by the GPS position information detection unit 27 may be provided to the power comparison unit 18 ( In FIG. 8, the same components as those shown in FIG. 2 are denoted by the same reference numerals).

  Referring to FIG. 8, as described above, even when the power of layer B is lower than the reception sensitivity and the power of layer A is 10 dB lower than the power of layer B, the reception power of layer A is higher than the reception sensitivity. The power comparison unit 18 selects the hierarchy A. At this time, the GPS position information detection unit 27 obtains the position information of the moving object according to the GPS signal received via the antenna 27a. Then, the GPS position information detection unit 27 determines in which area on the map the moving body is located according to the position information and the map data. For example, it is determined whether the moving body is located in a large city area, a small and medium city area, or a suburban area.

  For example, if the GPS position information detection unit 27 determines that the moving body is located in a large city, the power comparison unit 18 instructs the selection of the hierarchy B even if the reception power of the hierarchy B is equal to or higher than the reception sensitivity. Stops output of the selection control signal. That is, in a large urban area, the reception state often deteriorates due to a building group or the like, so that reception of the layer B is avoided.

  Although not shown, the position information obtained by the GPS position information detection unit 27 and the received power of each of the hierarchies A and B at the position are stored in the memory in association with each other, and the mobile object receives the terrestrial digital broadcast. In this case, the memory may be searched according to the position information obtained by the GPS position information detection unit 27, the received power of each of the hierarchies A and B may be obtained, and the hierarchies may be switched according to the result. That is, if the received power of each of the hierarchies A and B corresponding to the position of the moving body is stored while the moving body is traveling, the hierarchy switching control can be performed according to the position of the moving body.

  By the way, in order to reduce the uncomfortable feeling when switching from the hierarchy A to the hierarchy B or from the hierarchy B to the hierarchy A, as shown in FIG. 9A, when performing the switching control from the hierarchy A to the hierarchy B, As shown in FIG. 9B, hierarchy switching is performed with a delay of time (chattering) t1. Then, as shown in FIG. 9A, when switching control from the hierarchy B to the hierarchy A is performed, the switching control is performed with a delay of time t2, as shown in FIG. 9B. Here, time t1> time t2.

  If the switching timing is adjusted in this way, that is, if the switching time has hysteresis, since time t1> time t2, it is possible to reduce a sense of incongruity when switching from the hierarchy A to the hierarchy B. That is, at the time of layer switching, the layer selection signal is output with the switching timing delayed by a time defined according to the segment information related to the layer after switching. In the above-described first embodiment, the power comparison unit 18 and the TS-Demux 21 collectively function as a hierarchy selection unit.

  As described above, according to the first embodiment, when at least the modulation schemes are different between the plurality of hierarchies A and B, if the hierarchies A and B are simulcasts, depending on the reception state of each of the hierarchies A and B Thus, since one of the hierarchies A and B is selected, it is possible to reduce the frequency at which video and audio are interrupted in the middle.

  According to the first embodiment, the hierarchy selection control signal is generated in consideration of the segment information (hierarchy information), the delay profile, and the moving body position information, so that the hierarchy switching can be performed with high accuracy. effective.

  According to the first embodiment, since the hierarchy selection signal is output after being delayed by a time defined according to the hierarchy information related to the hierarchy after switching, the sense of incongruity at the time of hierarchy switching is provided. There is an effect that can be reduced.

It is a figure which shows the format of the terrestrial digital broadcast received with the receiver by Embodiment 1 of this invention, (a) is an example in which one hierarchy was comprised by 13 segments, (b) is three 13 segments. Examples divided into layers, (c) and (d) are diagrams showing examples of transmission spectra. It is a block diagram which shows the 1st example of a structure of the receiver by Embodiment 1 of this invention. It is a block diagram for demonstrating operation | movement of the electric power comparison part shown in FIG. FIG. 3 is a block diagram for explaining an operation of TS-Demux shown in FIG. 2. It is a block diagram for demonstrating operation | movement of the program content determination part shown in FIG. It is a block diagram which shows the 2nd example of a structure of the receiver by Embodiment 1 of this invention. FIG. 8 is a diagram illustrating a state in which the arrival time difference between a desired wave and an interfering wave exceeds a guard interval length in the delay profile detected by the delay profile detection unit illustrated in FIG. 7. It is a block diagram which shows the 3rd example of a structure of the receiver by Embodiment 1 of this invention. It is a figure for demonstrating the time control (chattering control) at the time of switching between hierarchy, (a) is a timing diagram when not performing time control, (b) is a timing diagram when performing time control. It is.

Explanation of symbols

10 Receiver, 11 Antenna, 12 Tuner, 13 Analog / Digital Converter (ADC), 14 FFT (Fast Fourier Transform), 15 Pilot Demodulator, 16 Frequency Deinterleaver, 17 Time Deinterleaver, 18 Power Comparison Unit, 19 TMCC demodulation unit, 20 program content determination unit, 21 TS-Demux (TS-separation unit), 22 layer division unit, 22a to 22c demodulation and Viterbi decoding, 23 TS playback unit, 24 outer code decoding unit, 25 video And a voice decoding unit, 26 delay profile unit, 27 GPS position information detection unit.

Claims (7)

In a receiving device that receives a digital broadcast wave in which a predetermined frequency bandwidth is divided into a plurality of layers and a plurality of layers are defined, and at least the modulation method is different for each layer,
A program content determination means for determining whether the broadcast program of the same content is transmitted in the hierarchy and outputting a program determination control signal;
Hierarchy selection means for selecting one of the hierarchies according to the reception state for each of the hierarchies when the program determination control signal indicates that the broadcast program having the same content is transmitted in the plural hierarchies A receiving apparatus comprising: The hierarchy selection means is a power comparison means for obtaining received power for each hierarchy and comparing these received powers and outputting a hierarchy selection control signal according to the comparison result;
2. The receiving apparatus according to claim 1, further comprising reproduction selection means for selecting a hierarchy indicated by the hierarchy selection control signal and reproducing and outputting a signal transmitted in the hierarchy. Hierarchical information acquisition means for obtaining information relating to a hierarchy including at least a modulation scheme for each hierarchy as hierarchical information,
3. The receiving apparatus according to claim 2, wherein the power comparison means generates a hierarchy selection control signal in consideration of the hierarchy information. A delay profile detection means for detecting a delay profile indicating a relative intensity and a delay time between the digital broadcast wave and the interference wave as a desired wave;
4. The receiving apparatus according to claim 2, wherein the power comparison means generates a hierarchy selection control signal in consideration of the delay profile.   The power comparison means determines a power ratio between the desired wave and the disturbing wave when the difference in arrival time between the desired wave and the disturbing wave exceeds the guide interval length in the delay profile, and considers the determination result to determine the hierarchical selection control signal. The receiving apparatus according to claim 4, wherein the receiver is generated. Having position detecting means for detecting the current location of the moving body to obtain position information;
The power comparison means generates the hierarchy selection control signal based on the surrounding environment indicated on the map corresponding to the position information. The receiving device according to item. 4. The receiving apparatus according to claim 3, wherein the power comparing means outputs the hierarchy selection signal after delaying by a time specified according to the hierarchy information relating to the hierarchy after switching when switching the hierarchy. .

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