JP2002217864A - Digital signal receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To precisely decode demodulation information in a digital signal receiver for receiving a digital signal, for transmission data and demodulation information of the transmission data are included in one and the same data string. SOLUTION: One symbol includes a plurality of unit sections according the mode. In the respective unit sections corresponding to one and the same symbol, same demodulation information is transmitted repeatedly. Demodulation information is extracted independently and decoded for the respective unit sections. A decoding result having the highest reliability is selected from a plurality of decoding results corresponding to the same symbol, and it is treated as the decoding result corresponding to the symbol. Thus, demodulation information is decoded precisely and a digital signal can normally be received, even if a transmission line characteristic is disturbed in some sections.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital signal receiving apparatus, and more particularly, to a digital signal receiving apparatus suitable for receiving terrestrial digital television broadcasting (hereinafter, also simply referred to as "terrestrial digital broadcasting"). Related to the device.

[0002]

2. Description of the Related Art In recent years, digital television broadcasting, which replaces conventional analog television broadcasting, has been introduced for the purpose of achieving higher image quality, more channels, higher functions, and higher quality.

In digital terrestrial broadcasting in Japan, orthogonal frequency division multiplexing (OFDM) has been decided to be adopted as a transmission system.

[0004] OFDM is called a multi-carrier system, and is characterized in that thousands of carriers are set up in a transmission band, and data is allocated to each carrier for broadcasting. For this reason, even if it is partially damaged, it can be covered by another carrier wave, and has an advantage that it is strong against ghosts which are a problem in terrestrial waves. For this reason, there are expectations for new applications such as mobile communication.

FIGS. 8 and 9 are first and second views for explaining the structure of a data signal used for digital terrestrial broadcasting.

Referring to FIG. 8, one OFDM frame period (hereinafter, also simply referred to as "one frame period"), which is a basic unit of a data signal used for digital terrestrial broadcasting, is composed of symbols # 0 to # 203. , And 204 OFDM symbols (hereinafter simply referred to as “symbols”) transmitted in series on the time axis.

Referring to FIG. 9, each symbol is a data signal D corresponding to transmission data obtained by encoding a normal audio signal or video signal, each signal being assigned to a different frequency.
S, a null signal NS corresponding to dummy data, and a pilot signal PS.

[0008] Pilot signal PS includes information related to the data structure and demodulation of transmission data, and has a higher level than data signal DS and null signal NS. According to the terrestrial digital broadcasting standard, the pilot signal PS includes a transmission and multiplexing configuration (TMCC).
uration Control) signal,
A signal for transmitting demodulation information necessary for the demodulation operation of the receiving device, such as transmission parameters of each OFDM segment, is included. The encoded demodulated information is transmitted by the TMCC signal. Hereinafter, the demodulated information transmitted by the TMCC signal is also referred to as “TMCC information”.

[0009] The arrangement position of the TMCC signal in each symbol is determined in advance according to the standard. Therefore, knowing the arrangement position of the TMCC signal in each symbol with reference to the position of the start pulse STP indicating the start position of the data in one symbol generated based on the signal transmitted in synchronization with the data Can be. Each symbol includes a predetermined number of TMCC signals determined in accordance with the mode and the type of segment described later.

[0010] In each symbol, 1-bit data indicating TMCC information is transmitted. That is, the 13 TMCC signals included in one symbol are:
All transmit the same signal level ("1" or "0"), and the receiving apparatus extracts a TMCC signal every time each symbol is received, and extracts the TM included in the symbol.
The operation of obtaining one bit of the CC information is executed.

As described above, each symbol includes a plurality of signals arranged in a predetermined frequency band. As described above, since one frame is formed by these 204 symbols input in time series, 204 bits of TMCC information can be obtained by receiving one frame. .

Further, in a data standard according to terrestrial digital broadcasting, the number of carriers to be used can be switched between three modes. Specifically, three types of mode 1, mode 2 and mode 3 are set. In mode 2, the number of carriers twice as large as in mode 1 is used. In mode 3, the number of carriers twice as large as in mode 2 is used. Data transmission is performed.

FIG. 10 is a conceptual diagram for explaining the data structure of each symbol according to each mode.

Referring to FIG. 10A, mode 1 corresponds to the minimum number of carriers mode, and the number of carriers is set to 2k. One OFDM symbol is one unit section F
Contains 0. The pilot signal PS including the TMCC signal and the data signal DS are included in the unit section. Null signal NS
And signals corresponding to the guard interval are included outside the unit section in each OFDM symbol.

Referring to FIG. 10B, in mode 2, the number of carriers is set to 4k, and one OFDM symbol includes unit sections F0 and F1. Therefore, in mode 2, twice the number of carriers as in mode 1 is used.

Referring to FIG. 10C, data transmission is performed in mode 3 using twice the number of carriers in mode 2. Specifically, one OFDM symbol includes unit sections F0 to F3.

Each of the unit sections F0 to F3 includes the same number of carriers. However, since the used frequency band is the same even when the mode is different, the frequency bandwidth corresponding to each unit section changes according to the mode. That is, the interval (frequency domain) between the carriers changes according to the mode. Further, since data transmission is performed in synchronization with a clock of a constant frequency that does not depend on the mode, the transmission time per one OFDM symbol becomes longer as the mode number increases.

As described above, as the mode number increases, the number of carriers in one symbol increases, and accordingly, the number of TMCC signals included in each OFDM symbol also increases. However, the point that 1-bit TMCC information is transmitted by a plurality of TMCC signals included in one OFDM symbol is the same even when the mode is changed.

Therefore, the arrangement pattern of the TMCC signal in the terrestrial digital broadcasting mode 2 and mode 3 is a repetition of the arrangement pattern in mode 1 corresponding to the minimum carrier number mode. That is, in the unit section F1 in the mode 2, the TMCC signal transmitting the same signal level as that of the unit section F0 is output from the unit section F1.
It is arranged like 0.

Similarly, the unit sections F1 to F1 in mode 3
Also in F3, TMCC signals for transmitting the same signal level as in unit section F0 are repeatedly arranged in the same manner as in unit section F0.

That is, in the mode 2, the unit section F
0 from the TMCC signal transmitted using both
One bit of the MCC information is decoded and extracted, and in mode 3, the TMCC transmitted using the unit sections F0 to F3 is decoded.
One bit of TMCC information is decoded and extracted from the signal.

In an ideal transmission state, the same OF
The decoding result of each TMCC signal included in the DM symbol is
It is aligned to either “1” or “0”. Therefore, in each symbol, by executing majority processing between the decoding results of the plurality of TMCC signals, the 1-bit TMC corresponding to the symbol is executed.
C information can be determined.

[0023]

However, when transmission channel characteristics are temporally disturbed due to fading or the like,
If the transmission path characteristics are greatly disturbed in frequency due to the influence of multipath or the like, there is a possibility that TMCC information cannot be correctly obtained in accordance with the section where the transmission path characteristics are disturbed.

In particular, transmission path characteristics are disturbed in a relatively wide frequency range, and TMCC
If the signal level of the signal cannot be transmitted correctly, the result of majority processing in the symbol may be different from one bit of TMCC information that should be transmitted.

In such a case, TMCC information, that is, information necessary for the demodulation operation cannot be obtained on the receiving device side, and there is a possibility that terrestrial digital broadcasting cannot be normally received.

The present invention has been made to solve such a problem, and an object of the present invention is to provide demodulation information of transmission data between transmission data typified by terrestrial digital broadcast data. It is an object of the present invention to provide a configuration of a digital signal receiving device capable of extracting the demodulated information with high accuracy in receiving a digital signal into which a signal is inserted.

[0027]

According to one aspect of the present invention, there is provided a digital signal receiving a digital data sequence including transmission data and a demodulation information signal obtained by encoding demodulation information necessary for demodulating the transmission data. A demodulation unit for extracting and demodulating a demodulation information signal inserted based on a predetermined pattern for transmitting unit information constituting demodulation information for each predetermined section of a digital data sequence. When,
A demodulation information processing unit for obtaining demodulation information based on demodulation data from the demodulation unit. In each of the N (N: natural number) unit sections forming the same predetermined section,
The same demodulated information signal is transmitted repeatedly. The demodulation information processing unit receives the demodulation data from the demodulation unit and the detection result of the counter unit for detecting the boundary between the unit section and the predetermined section, and responds to each unit information independently for each unit section. A first decoding processing unit for generating a decoding result to be performed, and one of the most reliable ones selected from N decoding results output from the first decoding processing unit and corresponding to the same predetermined section. And a second decoding processing unit for performing the decoding.

Preferably, each unit information corresponds to 1-bit data constituting demodulated information, and in each unit section,
A predetermined number of demodulated information signals are inserted. The first decoding processing unit executes majority processing based on an integrated value of a predetermined number of demodulated data corresponding to a unit section.

Preferably, the digital data sequence is a signal conforming to the standard of terrestrial digital broadcasting.
Each unit section is defined corresponding to each OFDM symbol, and has the same number of carriers as the number of carriers included in the predetermined section in the minimum carrier number mode.

[0030]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a schematic block diagram showing a main part of the configuration of a digital television receiver 1 shown as a typical example of a digital signal receiver according to the present invention.

Referring to FIG. 1, in digital television receiver 1, RF signal received from an antenna (not shown) is provided.
The signal is tuned by tuners 6a and 6b and applied to demodulation units 100a and 100b, respectively.

The demodulated signals from the demodulation units 100a and 100b are supplied to a transport stream decoder (hereinafter, referred to as a transport stream decoder).
8a and 8b, respectively, and to a MPEG decoding unit 10 via a changeover switch 9. That is, baseband signals are extracted from the selected channels from TS decoders 8a and 8b.

The MPEG decoding unit 10 receives the data stream supplied from the changeover switch 9 and uses a random access memory (RAM) 15 as a buffer for temporarily storing data, thereby converting the data into a video signal and an audio signal. Convert.

Here, as described above, two systems, that is, a system from the tuner 6a to the TS decoder 8a and a system from the tuner 6b to the TS decoder 8b are provided. By providing such a plurality of systems, it is possible to receive independent channels in parallel. For example, when a mode for displaying a 4-channel multi-screen is provided, four systems are provided.

In the following, tuners 6a and 6b are collectively referred to simply as tuner 6, demodulators 100a and 100b are collectively referred to simply as demodulator 100, and TS decoders 8a and 8b are collectively referred to as TS decoder 8, respectively. It shall be.

The digital television receiver 1 further includes TS decoders 8a and 8b via a data bus BS1.
And a processing unit 44 for performing predetermined processing on data stored in the built-in storage device 48 via the data bus BS1 and outputting the processed data via the data bus BS1. And a ROM 40 for recording a program used for the arithmetic processing of the arithmetic processing unit 44
And a RAM 42 for providing a memory area for the operation of the arithmetic processing unit 44, and a high-speed digital interface 46 for inputting and outputting data between the data bus BS1 and the outside. Although not particularly limited, as the internal storage device 48 and the ROM 40, for example, it is possible to use a flash memory capable of electrically writing and reading data.

The data after the arithmetic processing unit 44 has processed the data stored in the internal storage device 48 in accordance with the instruction given from the outside is synthesized from the on-screen display (On Screen Display) processing unit 30. To the vessel 61.

The combiner 61 combines the output from the MPEG decoding unit 10 and the output from the on-screen display processing unit 30, and supplies the combined output to the video output terminal 64.
The output from the video output terminal 64 is provided to the display unit 4 and displayed.

The digital broadcast receiving apparatus 1 further receives, on the basis of the data stored in the built-in storage device 48, data obtained as a result of processing by the arithmetic processing section 44, and provides a sound effect for the video output on the display section. Receiving the data processed by the arithmetic processing unit 44 based on the data stored in the built-in storage device 48 and the like, and generating an audio signal. A PCM decoder 22 provided to the synthesizer 61 is provided.

The synthesizer 60 outputs the output from the MPEG decoding unit 10, the additional sound generator 65 and the PCM decoder 2.
2 and outputs the synthesized result to the audio output terminal 62. The audio signal provided to the audio output terminal 62 is output from the audio output unit 2 as an audio signal.

The digital broadcast receiving apparatus 1 may be provided with a modem 50 for exchanging data with an external device and an IC card interface 52 for receiving information from an IC card, if necessary. Good.

Via the high-speed digital interface 46, for example, an external storage device 80 such as an HDD for a home server, and a remote controller (or keyboard or the like) 82 as an external input device are connected to the data bus BS1.

The digital broadcast receiving apparatus 1 has a structure integrated with a display section 4 for receiving a video output and displaying it on a display and an audio output section 2 such as a speaker for receiving an audio output signal and outputting the audio. Is also good.

FIG. 2 is a block diagram showing the configuration of the demodulation unit 100. Referring to FIG. 2, demodulation section 100 converts the signal down-converted by tuner 6 into an analog signal.
An A / D converter 102 that converts digital data into a digital signal; and an A / D converter 102 that corresponds to I-axis data.
A Hilbert transform unit 104 for generating a D-axis data by phase-shifting the digital signal from
A symbol synchronization unit 106 that receives I-axis data and Q-axis data output from the D conversion unit 102 and the Hilbert conversion unit 104 and executes synchronization adjustment for each symbol.

The delay section 105 delays the digital signal from the A / D conversion section 102 by a processing time required for the generation of Q-axis data in the Hilbert conversion section 104, and transmits it to the symbol synchronization section 106 as I-axis data. . Thereby, the timing is adjusted between the I-axis data and the Q-axis data input to the symbol synchronization section 106, and the I-axis data and the Q-axis data generated based on the same digital signal are output at the same timing. , To the symbol synchronization section 106.

In the symbol synchronization section 106, a narrow band AFC (Auto Freq) for adjusting the frequency within the carrier interval.
quency control), and synchronization of clock signals is achieved.

The demodulation section 100 further receives the digital data synchronized for each symbol in the symbol synchronization section 106, and executes a fast Fourier transform (FFT) process for converting the time domain into a frequency domain signal. FFT unit 108 for converting the FF into the frequency domain.
A wideband AFC section 110 for adjusting a frequency shift in units of a carrier interval with respect to an output signal from the T section 108 is included.

The demodulation unit 100 converts the signal into the frequency domain.
Further, upon receiving a digital data string including I-axis data and Q-axis data subjected to synchronization processing, frequency adjustment, and the like, TM
A TMCC decoding unit 150 for extracting a CC signal; a detection unit 112 for executing detection such as differential detection or synchronous detection on a digital data sequence; and time interleaving and frequency interleaving performed on the transmission side. Deinterleaving section 114 for performing frequency deinterleaving and time deinterleaving for canceling
And an error correction unit 116 for decoding the error correction coding performed on the transmission side.

The detection process by the detector 112, the deinterleave process by the deinterleaver 114, and the error correction process by the error corrector 116 are performed by the TMCC decoder 150.
Modulation method included in the TMCC information obtained by
This is performed based on demodulation information such as an interleave length and an error coding rate. The digital data string processed by the error correction unit 116 from the detection unit 112 is transmitted to the TS decoder 8 as transport stream data (TS data).

FIG. 3 is a block diagram illustrating the configuration of TMCC decoding section 150. Referring to FIG. 3, TMCC decoding section 150 includes a wideband AFC (Auto Frequency Control).
l) Digital data string (digital data Di,
Dq), mode signal MDS and start pulse STP
In response to this, extraction of the TMCC signal included in the data sequence and synchronization timing adjustment for each frame are executed.

The TMCC decoder 150 counts the count data CNT1 for counting 1404 cycles corresponding to the number of carriers included in one unit section described with reference to FIG. 10 based on the start pulse STP and the mode signal MDS.
And a counting unit 152 for generating CNT2 for counting the number of unit sections.

FIG. 4 is a diagram for explaining the operation of the counter unit 152. Referring to FIG. 4A, count data CNT1 indicates a count-up operation from an initial value 0 to a full count value 1403 corresponding to the number of carriers 1404 in each of unit sections F0 to F3 shown in FIG. It starts in response to the start pulse STP. When the count value CNT1 reaches the full count value 1403, the counter 152 returns the count value CNT1 to the initial value 0.

Therefore, for example, in mode 3, the count data CNT1 reaches the full count value four times in one OFDM symbol.

Each time the count data CNT1 reaches the full count value 1403, the count data CNT2 is counted up from the initial value 0 by one. The full count value of the count data CNT2 differs depending on the mode. In mode 3, since four unit sections are included, the initial value is “0” and the full count value is “3”.
As a result, the count-up operation of the count data CNT2 is performed.

Referring to FIG. 4B, in mode 2, since the number of unit sections included is two, the initial value is set to "0", the full count value is set to "1", and count data CNT2 is counted. An up operation is performed.

Referring to FIG. 4C, in mode 1, count data CNT2 is both 0 in the initial value and the full count value, and count data CNT2 is not updated. This is because in mode 1, one unit section is included.

As described above, the boundary between each unit section and each symbol can be detected based on the count data CNT1 and CNT2.

As described above, in each of the unit sections F0 and F1 in mode 2, a TMCC signal indicating the same signal level (“0” or “1”) is included based on the same arrangement pattern. Have been. Similarly, in mode 3, in each of the unit sections F0 to F3, a TMCC signal indicating the same signal level is included based on the same arrangement pattern.

Referring again to FIG. 3, demodulation section 150 extracts the TMCC signal from the digital data sequence,
It includes a DBPSK demodulation unit 154 for performing K demodulation (Differential Binary Phase Shift Keying).

The position of the TMCC signal in the data string according to the standard can be specified by the counting operation in the counter section 152. Therefore, DBPSK demodulation section 154 extracts a TMCC signal from the digital data sequence based on count signal CNT1.

FIG. 5 is a conceptual diagram illustrating a demodulation method of DBPSK demodulation. DBPSK modulation is a discrete phase modulation based on a differential system.

Referring to FIG. 5, DBPSK demodulation section 154
Performs phase comparison between TMCC signals at the same position in each symbol between symbols, and outputs demodulated data based on the phase comparison result. In FIG. 5, the n-th n symbols (n: an integer from 0 to 202) and the next (n
+1) Comparison of the TMCC signal with the symbol is shown. Note that the DBP is also applied to the 203rd symbol during the 0th symbol in the next frame period.
SK demodulation is performed.

As shown in FIG. 5A, when the TMCC signal has the same phase between n symbols and (n + 1) symbols, "0" is obtained as demodulated data. Conversely, as shown in FIG. 5B, if the phase of the TMCC signal is opposite between n symbols and (n + 1) symbols, “1” is obtained as demodulated data.

FIG. 6 is a block diagram illustrating the configuration of TMCC processing section 160. Referring to FIG. 6, TMCC processing section 160 receives demodulated data from DBPSK demodulation section 154 and count data CNT1 and CNT2,
Majority decision processing unit 1 that executes majority decision processing for each unit section
62, a majority processing result comparison unit 164 for comparing the majority processing result for each unit section from the majority processing unit 162 within the same symbol to select the most reliable majority result, and a majority processing result. A majority decision processing determining unit 166 for determining the majority decision result selected by the comparing unit 164;

As described above, since a plurality of TMCC signals included in the same symbol are intended to transmit the same signal level, ideally, one OFC signal is transmitted.
Demodulated data from the DBPSK demodulation section 154 corresponding to DM symbols are all unified to “0” or “1”.

Therefore, under an ideal transmission state, the majority decision result TFD corresponding to the integrated value of the demodulated data in each unit section indicates that the number of predetermined TMCC signals included in one unit section is M ( M: a natural number), it is either “0” or “M”.

The value of M differs depending on the type of segment. In particular, the arrangement position of the TMCC signal differs depending on the segment format (differential or synchronous).
It is included in the arrangement of the C signal. Therefore, when applying the present invention, only the arrangement of the TMCC signal in accordance with the synchronous segment system needs to be considered. Since M = 13 in the arrangement pattern of the synchronous segment system, the case where M = 13 is described in the following description.

By executing such a majority decision process, the majority decision result TFD is set to "0" or "13" even when a TMCC signal cannot be transmitted correctly in a part of the frequency range within each unit section. Is determined to be closer to any one of
It can be estimated whether 1-bit data transmitted by the CC signal is “0” or “1”.

The majority decision processing unit 162 is configured to count one unit section corresponding to one unit section based on count data CNT2 for counting the number of unit sections in one OFDM symbol.
Majority decision processing result T based on 3 (M) TMCC signals
Output FD. That is, the majority decision processing result TFD is
This is 4-bit data for indicating an integer from 0 to 13 (M).

The majority processing result comparison unit 164 selects the most reliable one of the same symbols among the majority processing results obtained for each unit section.

That is, in the mode 1, the majority processing result comparison unit 164 compares the majority processing result TFD from the majority processing unit 162 with the selected majority processing result TSD.
In the mode 2, the two majority processing results TFD respectively corresponding to the unit sections F0 and F1 are compared, and a more reliable one is selected and output as the majority processing result TSD. Similarly, in the mode 3, the majority processing result comparison unit 164 performs three comparison processes, and among the majority processing results TFD corresponding to each of the four unit sections F0 to F3, the most reliable one. A high majority processing result is selected and output as a majority processing result TSD.

Here, the majority decision processing result TFD is
The closer to “0” or “13”, the higher the reliability. That is, when the majority processing result TFD is in the range of 0 to 6, it indicates that the signal level transmitted by the TMCC signal is "0".
The smaller the value of D, the higher the reliability.

On the contrary, the majority decision processing result TFD is 7-13
Indicates that the signal level transmitted by the TMCC signal is "1", but it is determined that the larger the value of the majority decision processing result TFD, the higher the reliability.

The majority decision processing unit 166 determines the majority decision result TS selected by the majority decision result comparison unit 164.
D, and a TMCC bit T indicating 1-bit data transmitted by the TMCC signal in the symbol.
MB is set to either “0” or “1”.

Specifically, the majority decision processing result TSD is 0 to
6, the TMCC bit TMB is:
It is set to “0”. Conversely, if the majority decision processing result TSD is in the range of 7 to 13, the TMCC bit TMB
Is set to “1”.

Referring again to FIG. 3, TMCC decoding section 15
0 further includes a synchronization word detection unit 156 for receiving a TMCC bit TMB obtained by the TMCC processing unit 160 and detecting a synchronization word.

Synchronization word detection section 156 outputs 1 of the TMCC bit TMB output by TMCC processing section 160.
It has a register 157 for storing 6 bits.
The register 157 has a FIFO method (First In First Ou).
At t), the TMCC bit TMB is stored. That is, when a new TMCC bit TMB is input, the register 1
The oldest TMCC bit TMB stored in 57 is deleted.

The synchronization word detection section 156
The frame head position is detected by comparing the 16-bit TMCC bits stored in 7 with a predetermined 16-bit synchronization word pattern for each symbol. Specifically, the synchronization word detection unit 156 activates the frame start trigger FTG when the data stored in the register 157 matches the synchronization word pattern.
At the same time, frame head detection protection is also performed.

According to the terrestrial digital broadcasting standard, a predetermined 16-bit synchronization word pattern is inverted and set for each frame. For example, the synchronization word pattern in the m-th frame (m: natural number) is "11
00101000010001 ", the synchronization word pattern in the (m + 1) th frame is
It is set to “0011010111101110”.
Therefore, by utilizing this property, the synchronization word pattern can be detected, and the detection of the frame head position and the protection of the frame head detection can be executed.

Since the symbol number can be determined from the frame start position detected in this way, various demodulations and a majority decision process in the frequency direction within the same symbol are performed, so that various symbols can be obtained in the same manner as the synchronous word detection. TMCC
Information can be obtained.

TMC extracted by TMCC processing section 160
The C information TSB is sequentially transmitted to the error correction decoding unit 158.

In each frame, the 0th to 203rd frames
The TMCC information TSB included in the twentieth to 203rd symbols of the twelfth symbol has been subjected to error correction coding. The error correction decoding unit 158 operates based on the frame start trigger FTG, performs error correction decoding performed on the TMCC information TSB corresponding to the twentieth and subsequent symbols, and is inserted into the transmission data and transmitted. Extract TMCC information.

The timing adjustment section 170 includes a completely decoded TMCC information, a digital data string including I-axis data Di and Q-axis data Dq from the wideband AFC section,
In response to the start pulse STP and the frame pulse generated by the synchronization word detection unit 156, the timing between these data is adjusted, and the next block, that is, FIG.
Is output to the detection unit 112.

Referring again to FIG. 6, TMCC processing section 16
From 0, the majority processing result TSD (4 bits) selected by the majority processing result comparison unit 164 and the T generated by the majority processing determination unit 166 based on the majority processing result TSD.
Either one of the MCC bits TMB is the TMCC information T
It is sent to the error correction unit 158 as SB.

By performing error correction using the majority decision processing result TSD, it is possible to improve the error correction capability while requiring a circuit scale of 4 bits.
Information can be decoded more accurately. On the other hand, the TMCC bit T
By performing error correction using the MB, the circuit scale of the error correction unit 158 can be reduced.

In the standard according to the terrestrial digital broadcasting, information on the segment format (differential or synchronous) is also included in the TMCC information.
Before decoding the CC signal, it is impossible to know the segment format of the currently received data. However, as described above, the arrangement of the TMCC signal of the synchronous segment is included in the arrangement of the TMCC signal of the differential segment system. The form of may be applied.

Referring again to FIG. 4, in mode 1 in which the number of carriers is 2k, TMCC signal extraction is performed using the TMCC signal included in unit section F0. However, in mode 2 and mode 3 in which the number of carriers is 4k and 8k, one OFDM symbol includes a plurality of unit sections. Here, it is assumed that, in mode 3, the transmission path characteristics are extremely disturbed in terms of time or frequency.

FIG. 7 is a conceptual diagram for explaining the disturbance of the transmission path characteristics. Referring to FIG. 7, if there is a frequency range in which transmission path characteristics are disturbed in the same symbol, it becomes difficult to extract desired TMCC information in the section. Therefore, if majority processing is performed over one OFDM symbol, the majority processing result is:
It could be wrong. As a result, T
It is also conceivable that the MCC information cannot be accurately extracted, which may hinder the subsequent demodulation operation.

Further, as shown in FIG. 7, there is a possibility that the frequency range in which the transmission path characteristic is disturbed fluctuates with time.

Therefore, in the present invention, TMC
Mode 2 or mode 3 using the periodicity of the C signal
In, the majority decision process is executed independently for each unit section, and a highly reliable one is selected from the majority decision results in each unit section.

By executing such a majority decision process, in mode 2 and mode 3, if the transmission path characteristics are good in any of the plurality of unit sections, the TM
CC information can be correctly decoded. In other words,
In a mode such as mode 2 or mode 3 including a plurality of unit sections in which TMCC signals are inserted in the same pattern, even if the transmission path characteristics are extremely disturbed in some unit sections, the TMCC information is decoded well. be able to.

As a result, a digital signal can be received more accurately in response to the temporal or frequency disturbance of the transmission path characteristics.

Further, since a circuit for executing the majority decision processing may be provided in a scale corresponding to one unit section, the scale of the hardware circuit can be reduced.

In the present embodiment, reception of digital terrestrial broadcasting has been described as a representative, but application of the present invention is not limited to this. That is, the present invention has a configuration in which transmission data and demodulation information necessary for demodulation of transmission data are included in the same data sequence, and the demodulation information is periodically inserted for each unit section of the data sequence. It can be widely applied to digital signal reception.

The embodiments disclosed this time are to be considered in all respects as illustrative and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

[0097]

A digital signal receiving apparatus according to the present invention independently generates a decoding result of a demodulated information signal for each unit section in a predetermined section of a digital data string formed by a plurality of unit sections, and outputs the same predetermined Demodulation information is generated by employing a highly reliable decoding result from the decoding results corresponding to the section. As a result, even when the transmission path characteristics are disturbed corresponding to a part of the unit section, the demodulation information can be correctly decoded and the digital signal can be normally received.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram showing a main part extracted from a configuration of a digital broadcast receiving apparatus 1 shown as a representative example of a digital signal receiving apparatus according to the present invention.

FIG. 2 is a block diagram showing a configuration of a demodulation unit shown in FIG.

FIG. 3 is a block diagram illustrating a configuration of a TMCC decoding unit illustrated in FIG.

FIG. 4 is a diagram for explaining an operation of the counter unit shown in FIG. 3;

FIG. 5 is a conceptual diagram illustrating a demodulation method of DBPSK demodulation.

FIG. 6 is a block diagram illustrating a configuration of a TMCC processing unit illustrated in FIG. 3;

FIG. 7 is a conceptual diagram for explaining disturbance of transmission path characteristics.

FIG. 8 is a first diagram illustrating a structure of a data signal used for digital terrestrial broadcasting.

FIG. 9 is a second diagram illustrating the structure of a data signal used for digital terrestrial broadcasting.

FIG. 10 is a conceptual diagram illustrating a data structure of each symbol corresponding to each of a plurality of modes in digital terrestrial broadcasting.

[Explanation of symbols]

100, 100a, 100b demodulator, 150 TMC
C decoding section, 152 counter section, 154 DBPSK demodulation section, 156 synchronization word detection section, 158 error correction section, 160 TMCC processing section, 162 majority decision processing section,
164 majority processing result comparison section, 166 majority processing determination section, 170 timing adjustment section, F0 to F3 unit section, STP start pulse, CNT1, CNT2 count data, MDS mode signal.

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[Procedure amendment]

[Submission Date] January 15, 2002 (2002.1.1
5)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claim 5

[Correction method] Change

[Correction contents]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0029

[Correction method] Change

[Correction contents]

Preferably, the digital data sequence is a signal conforming to the standard of terrestrial digital broadcasting.
Each unit section is defined corresponding to each OFDM symbol, and one unit section is one unit section in the minimum carrier number mode.
In other modes, multiple unit sections are included.
No.

Claims (5)

[Claims] 1. A digital signal receiving apparatus for receiving a digital signal in which transmission data and a demodulation information signal obtained by encoding demodulation information necessary for demodulating the transmission data are included in the same data sequence, A demodulation unit for extracting and demodulating the demodulation information signal inserted based on a predetermined pattern for transmitting unit information constituting the demodulation information for each predetermined section of the data sequence; A demodulation information processing unit for obtaining the demodulation information based on the demodulated data from the unit. In each of N (N: natural number) unit sections forming the same predetermined section, the same A demodulation information signal is repeatedly transmitted, the demodulation information processing section includes a counter section for detecting a boundary between the unit section and the predetermined section, a demodulation data from the demodulation section and the A first decoding processing unit for generating a decoding result corresponding to each of the unit information independently for each of the unit sections in response to a detection result of the counter unit, and output from the first decoding processing unit. , A second decoding processing unit for selecting one with the highest reliability from the N decoding results corresponding to the same predetermined section,
Digital signal receiver. 2. The first decoding processing unit, wherein each of the unit information corresponds to 1-bit data constituting the demodulated information, and a predetermined number of the demodulated information signals are inserted in each of the unit sections. The digital signal receiving device according to claim 1, wherein a majority process is performed based on an integrated value of the predetermined number of the demodulated data corresponding to the unit section. 3. The demodulation information has been subjected to error correction coding, and the digital signal receiving apparatus receives the decoding result selected by the second decoding processing unit, and performs error correction decoding on the decoding result. The digital signal receiving device according to claim 2, further comprising an error correction decoding unit that decodes the demodulated information. 4. The third decoding processing unit that determines the 1-bit data corresponding to each of the predetermined sections based on the decoding result selected by the second decoding processing unit. The demodulation information further includes an error correction encoding, and the digital signal receiving apparatus receives the 1-bit data determined by the third decoding processing unit, and performs error correction decoding on the received 1-bit data. The digital signal receiving device according to claim 2, further comprising an error correction decoding unit that decodes the demodulated information. 5. The digital signal according to a standard for terrestrial digital broadcasting, wherein each of the predetermined sections is determined corresponding to each OFDM symbol, and each of the unit sections corresponds to the predetermined section in the minimum carrier number mode. The digital signal receiving device according to claim 1, wherein the digital signal receiving device has the same number of carriers as the number of carriers included.