JP3550124B2 - Digital broadcast receiver - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a digital broadcast receiving apparatus for receiving a digital broadcast transmission signal adopting a digital modulation method of transmitting digital information of a transmission signal as a baseband signal subjected to phase shift keying modulation.
[0002]
[Prior art]
FIG. 20 shows a CS that conforms to the “CS (Communications Satellite) Digital Broadcasting Receiver Standard (ARIB STD-B1 1.1 version)” defined by the Association of Radio Industries and Businesses (ARIB: Association of Industries and Businesses). FIG. 2 is a block diagram illustrating a part of a configuration of a digital broadcast transmitting apparatus.
[0003]
In CS digital broadcasting, a concatenated code in which error correction is double-combined is employed in order to further enhance the error correction capability of a transmission signal. Among the concatenated codes, a Reed-Solomon code is used as an outer code, and a convolutional code is used as an inner code. Then, QPSK (Quadrature Phase Shift Keying) is adopted as a modulation method of the transmission signal.
[0004]
20 includes a P / S (Parallel to Serial) converter 1 for converting byte data P0 to P7 (each of which is 1-bit data) to which an outer code has been added into serial data E, and serial data. A convolutional encoder 2 for inner-coding E, a puncture encoder 3 for thinning out the data amounts of the convolved data X and Y, and an in-phase signal I ( Hereafter, a mapper 4 is provided which converts the data into a quadrature-phase signal Q (hereinafter, referred to as Q data) and maps it to a symbol point in the QPSK phase diagram.
[0005]
The transmission signal is provided with an outer code by a Reed-Solomon encoder (not shown), and then transmitted through a P / S converter 1, a convolutional encoder 2, a puncture encoder 3, and a mapper 4 to form a modulator (not shown). And transmitted as a broadcast signal.
[0006]
FIG. 21 is a block diagram showing a part of the configuration of a receiving device for CS digital broadcasting. 21 includes a digital demodulator 5, a phase converter 6, an inner code decoder 7, a TS (Transport Stream) header detector 8, and an outer code decoder 9. FIG. 22 is a phase diagram of QPSK.
[0007]
In the receiving device of FIG. 21, signal processing reverse to that performed by the transmitting device of FIG. 20 is sequentially performed. That is, the digital demodulator 5 receives the QPSK-modulated signal, reproduces and demodulates the carrier and clock, converts the signal to the original baseband signal (I data, Q data), and performs transmission path distortion correction and the like. . Then, when the phase angles of the input I data and Q data are not correctly positioned in the QPSK phase diagram, the phase converter 6 changes the phase angles of the I data and Q data in the phase diagram. The inner code decoder 7 performs Viterbi decoding on the convolved signal while correcting the error (hereinafter, the inner code decoder 7 is referred to as a Viterbi decoder).
[0008]
The transmission data format of CS digital broadcasting is defined by ISO / IEC13818-1, and a total of 204 bytes obtained by adding a packet of 188 bytes plus 16 bytes of outer code data for error correction (parity data of Reed-Solomon code). It is a transport stream (TS) in units. At the beginning of the TS, a TS header (1 byte data indicating the beginning of the TS, which is defined as 00001111 = 47 hex data and determined by the above standard) is located as a predetermined synchronization signal for distinguishing one packet.
[0009]
The TS header detector 8 monitors the output data of the Viterbi decoder 7 at a cycle of 204 bytes in order to detect the TS header inserted in the data decoded by the Viterbi decoder 7. The outer code decoder 9 detects and corrects errors in the received signal based on the Reed-Solomon code (hereinafter, the outer code decoder 9 is referred to as a Reed-Solomon decoder). Then, the data after the error correction is transmitted to a display unit (not shown) such as a CRT.
[0010]
The Reed-Solomon decoder 9 generates a binary decoded error signal RS_ERR indicating whether or not the error correction has been normally performed. When there is an error in the decoded data equal to or more than a predetermined value, such as when the reception condition is not good, the decoding error signal RS_ERR is activated and used for re-reception and the like.
[0011]
Now, unlike the case of BS digital broadcasting, etc., the transmission signal of CS digital broadcasting has an absolute phase at the time of demodulation (a phase to be a reference in a QPSK phase diagram, for example, a phase at a point (0, 0)). Is not inserted. Therefore, when the QPSK-modulated transmission signal is demodulated by the digital demodulator 5, it is necessary to determine the absolute phase of the received signal.
[0012]
In the transmitting apparatus, for example, as shown in the QPSK phase diagram of FIG. 22, when the data C1 and C2 are both 0, the coordinate A where the I data takes the numerical value I1 and the Q data takes the numerical value Q1 is assigned. Similarly, when the data C1 and C2 are both 1, the coordinate C where the I data takes the numerical value -I1 and the Q data takes the numerical value -Q1, and when the data C1 is 1 and C2 is 0, the I data is the numerical value. When the data C1 is 0 and the data C1 is 1, the coordinates B are assigned to the I data and the Q data to take the numerical value -Q1, respectively.
[0013]
However, in the digital demodulator 5 of the receiving device, whether the absolute phase 0 ° of the demodulated data is located at the coordinate A in the phase diagram of FIG. 22 or at any of the other coordinates B, C, and D , Can not be identified. That is, although the digital demodulator 5 can demodulate I data and Q data, four types of data of 0 °, + 90 °, + 180 °, and + 270 ° are demodulated assuming that any one of the coordinates A to D is 0 °. It is not possible to identify whether it has been done.
[0014]
For example, it is assumed that bit data P0 and P1 of byte data P0 to P7 are mapped to coordinates B (0, 1) and coordinates A (0, 0), respectively, in the transmitting device. In this case, assuming that the digital demodulator 5 of the receiving apparatus demodulates at a phase angle of + 90 °, the received I data and Q data are coordinates C (1, 1) and coordinates B (0, 1), respectively. Will be demodulated. When demodulation is performed with a phase angle of + 180 °, coordinate A (0, 0) becomes coordinate C (1, 1) and coordinate B (0, 1) becomes coordinate D (1, 0). . In these cases, of course, correct decoding cannot be performed. In order for correct decoding to be performed, there is no phase angle shift between the transmission side and the reception side, and the received I data and Q data correspond to the coordinates B (0, 1) in the same manner as mapped in the transmission device. It needs to be demodulated to coordinates A (0,0).
[0015]
Thus, the TS header detector 8 and the phase converter 6 cooperate to determine the absolute phase of the received signal.
[0016]
First, the phase converter 6 sends the I data and Q data received by the digital demodulator 5 to the Viterbi decoder 7 without changing their phase angles. The Viterbi decoder 7 restores the convolved data C2 and C1 based on the QPSK phase diagram from the received I data and Q data, and performs Viterbi decoding from the data C2 and C1.
[0017]
By the way, in the data decoded by the Viterbi decoder 7, a TS header is inserted in units of 204 bytes. Therefore, when there is no deviation in the phase angle between the transmission signal and the reception signal (when the phase angle is a deviation of 0 °), the TS header detector 8 can detect a TS header that is 47 hex data in a cycle of 204 bytes. That is, when the TS header detector 8 can detect 47 hex data several times, it can be determined that there is no shift in the phase angle between the transmission signal and the reception signal.
[0018]
On the other hand, if the phase angle of the received signal demodulated by the digital demodulator 5 is shifted by + 180 ° from the phase angle of the transmitted signal, the received data C2 and C1 are all inverted as compared with the transmitted signal data. Will be. In this case, all the decoded data from the Viterbi decoder 7 must be inverted, and the TS header detector 8 detects the TS header as 47 hex data as 10111000 = B8 hex data.
[0019]
That is, when the TS header detector 8 detects B8 hex data, which is inverted data of the TS header, in a cycle of 204 bytes, it can be determined that the digital demodulator 5 is receiving the transmission signal with a phase angle of + 180 °. Therefore, the TS header detector 8 feeds this information back to the phase converter 6 as a phase conversion signal PS. That is, the delay of the phases of the I data and Q data from the digital demodulator 5 by 180 ° is transmitted to the phase converter 6 as the phase conversion signal PS.
[0020]
The phase converter 6 receives the phase conversion signal PS and converts the I data and Q data from the digital demodulator 5 to -180 degrees. That is, they are converted into inverted data of Ic = I (-I1 as a numerical value) and inverted data of Qc = Q (-Q1 as a numerical value). Then, the input signal is newly input to the Viterbi decoder 7.
[0021]
Thus, the input signal to the Viterbi decoder 7 is corrected to a phase angle shift of 0 °.
[0022]
When the phase angle of the received signal at the time of demodulation is shifted from the phase angle of the transmitted signal by + 90 ° or + 270 °, the signal is not a simple signal change as in the case of the + 180 ° shift, so that the Viterbi decoder 7 cannot decode normally. (Because convolution is also performed, it is a completely different signal). Therefore, at this time, the TS header detector 8 cannot detect the TS header signal.
[0023]
If the TS header cannot be detected, the TS header detector 8 determines that the current state is either the phase angle shift of + 90 ° or + 270 °, and performs phase conversion so as to bring about a change in the current phase. The feedback to the unit 6 is provided. That is, first, the signal PS is transmitted to the phase converter 6 to delay the phases of the I data and Q data from the digital demodulator 5 by 90 ° as the signal PS.
[0024]
The phase converter 6 receives the signal PS and converts the I data and Q data from the digital demodulator 5 into -90 degrees. That is, they are converted into inverted data of Ic = Q (-Q1 as a numerical value) and Qc = I data (I1 as a numerical value). Then, the input signal is newly input to the Viterbi decoder 7. Then, the TS header is again detected by the TS header detector 8 using the converted data.
[0025]
If the data is demodulated with a phase angle shift of + 270 °, the data input to the Viterbi decoder 7 in the first -90 ° conversion becomes the same as the data in the case of a + 180 ° shift. Therefore, the TS header detector 8 detects the B8 hex data, which is the inverted data of the TS header, at a cycle of 204 bytes.
[0026]
Therefore, after this, the TS header detector 8 transmits the signal PS to the phase converter 6 so as to delay the phases of the I data and Q data by 180 °, and the phase converter 6 performs -180 ° conversion, thereby The input signal to the decoder 7 is corrected to a phase angle shift of 0 °.
[0027]
Similarly, even when demodulation is performed at a phase angle of + 90 °, the input signal to the Viterbi decoder 7 is corrected to a phase angle of 0 ° by performing −90 ° conversion by the phase converter 6. You.
[0028]
[Problems to be solved by the invention]
In the conventional CS digital broadcasting, since the modulation method is only QPSK, the angle to be corrected by the phase converter 6 is 90 ° or a multiple thereof, and all phase angles can be handled.
[0029]
On the other hand, in the Digital Satellite News Gathering (hereinafter referred to as DSNG) standard of the DVB (Digital Video Broadcasting) standard: EN301 201 v1.1.1, the modulation method is QPSK, 8PSK (8 Phase Shift Keying). Three types, 16 QAM (16 Quadrature Amplitude Modulation), are adopted.
[0030]
Further, in each modulation scheme adopted in the DSNG standard, various variations are set for the coding rate. The combination (hereinafter referred to as a transmission mode) has a coding rate of 1/2, 2/3, 3/4, 5/6, 7/8 for QPSK, a coding rate of 2/3, 5/6 for 8PSK, In 8/9 and 16QAM, they are 3/4 and 7/8.
[0031]
In any of the transmission modes, a plurality of packets each having 204 bytes are included as one unit, and each packet is still a transport stream signal to which a Reed-Solomon code is added as an outer code. Each packet in the transport stream signal includes a TS header of 47 hex data = 0100000111.
[0032]
In each transmission mode, at least some bytes of the transport stream signal are convolutionally encoded one by one at a predetermined period, but the periods of the bytes to be convolutionally encoded are different.
[0033]
For example, when the coding rate is 5/6 in the 8PSK modulation system, the first byte is convolved, but the second to fifth bytes are not convolved. After the sixth byte is convolved, the next byte from the seventh byte to the tenth byte is not convolved (hereinafter, the same repetition).
[0034]
On the other hand, when the coding rate is 2/3 in the 8PSK modulation method, the first byte is convolved, but the second and third bytes are not convolved. After the fourth byte is convolved, the next fourth and fifth bytes are not convolved (hereinafter, the same repetition).
[0035]
FIG. 23 is a phase diagram of 8PSK / coding rate 2/3, FIG. 24 is a phase diagram of 8PSK / coding rate 5/6, 8/9, and FIG. 25 is 16QAM / coding rate 3/4. It is a phase diagram of 7/8.
[0036]
Various transmission modes are adopted in the DSNG standard in order to change the quality of a transmission signal according to a reception situation. For example, when the reception condition is good, 16QAM, which can transmit a large amount of information with one symbol in the phase diagram, can be adopted as the modulation method. Conversely, when the reception condition is bad, noise can be reduced. QPSK, which is strong against, can be adopted for the modulation method.
[0037]
FIG. 26 shows a part of the configuration of a CS digital broadcast transmitting apparatus conforming to the DSNG standard.
[0038]
The transmitting apparatus in FIG. 26 includes a P / S converter 1, a convolutional encoder 2, a puncture encoder 3, and a mapper 4, similarly to the transmitting apparatus in FIG. In addition to these, the transmitting apparatus of FIG. 26 further includes a P / P (Parallel to Parallel) converter 11 and a symbol sequencer 12.
[0039]
The byte data P0 to P7 to which the outer code has been added are converted by the P / P converter 11 in units of bytes into parallel data Ep for convolutional encoding or non-convolutional non-convolutional encoding. Is allocated to one of the parallel data NE.
[0040]
The convolutional parallel data Ep is converted into serial data Es by the P / S converter 1 and is internally encoded by the convolutional encoder 2. Then, the data amounts of the convolved data X and Y are thinned out by the puncture encoder 3, and the thinned data C 1 and C 2 are input to the symbol sequencer 12.
[0041]
On the other hand, the non-convolution parallel data NE is directly input to the symbol sequencer 12.
[0042]
Then, in the symbol sequencer 12, the convolved data C (that is, one or both of the data C1 and C2) and the non-convolved data U (that is, a part or all of the non-convolution parallel data NE) are appropriately transmitted. Are output to the mapper 4.
[0043]
The mapper 4 converts the data C and U into I data and Q data and maps them to symbol points in any of the phase diagrams in FIGS. 22 to 25 according to the transmission mode.
[0044]
The various transmission modes of the DSNG standard are characterized by the operation of the P / P converter 11 described above, and the contents are described in P / P conversion showing the relationship between the input byte data and the output destination in FIG. It is as shown in the table. 27. That is, in FIG. 27, each byte data (corresponding to byte data P0 to P7 in FIG. 26, and the subscript of each data indicates the number of bit digits, and A (Oldest), B, D, F, G, H, and L) are the data E to be convolutionally encoded or the data NE not to be convolutionally encoded. ing.
[0045]
For example, when the coding rate is 5/6 in the 8PSK modulation method, the first byte (A0 to A7) of the byte data after the outer code input to the P / P converter 11 is distributed to the convolution data E1. Then, the next four bytes (B0 to B7, D0 to D7, F0 to F7, G0 to G7) are allocated to the non-convolution data NE1, NE2, NE3, and NE4, respectively.
[0046]
By the way, since the TS header is inserted every 204 bytes as described above, in the case of 8PSK and a coding rate of 5/6, after the TS header which is the first byte is convolved, The incoming TS header will not be folded. This is because 204 is not divisible by 5, and the 205th byte where the next TS header exists is allocated to the non-convolutional data NE4.
[0047]
From this, when the TS header is first convolved with the convolution data E1, the next TS header is convolved with the 204 × 5 + 1 = 1021th byte TS header, and the other 205th byte TS header. The header, the TS header of 204 × 2 + 1 = 409 bytes, the TS header of 204 × 3 + 1 = 613 bytes, and the TS header of 204 × 4 + 1 bytes = 817 bytes are not convoluted (however, Considering only the data to be convolved among all data (that is, only the data amount of 1/5), the interval from the TS header of the first convolutional data E1 to the TS header to be convolved next is 204 bytes. Has become.)
[0048]
Therefore, in the conventional CS digital broadcasting, the TS header is always convolved at a cycle of 204 bytes. On the other hand, in DSNG, since such various transmission modes exist, some TS headers may not be convolved. It has become.
[0049]
Of course, when the convolved data is compared with the non-convolved data, the convolved data is inner-coded (that is, error-correction-coded) on the transmitting apparatus side. The receiving device has a higher ability to correct and decode the data than the data that is not embedded. For this reason, in the conventional CS digital broadcasting, TS header detection for phase detection has been performed on the convolved data.
[0050]
In the case of the DSNG standard, the conventional CS digital broadcast receiver shown in FIG. 21 cannot be used as it is. If the TS header detector 8 simply monitors the output data of the Viterbi decoder 7 at a fixed cycle of 204 bytes, in the case of the above-mentioned 8PSK / coding rate 5/6, the TS header detector 8 This is because a TS header that cannot be inserted cannot be detected separately.
[0051]
According to this DSNG standard, in the case of 8PSK, the possible phase angle deviation between the transmitting side and the receiving side is 0 °, + 45 °, + 90 °, + 135 °, + 180 °, + 225 °, + 270 °, + 315 °. And in the case of QPSK and 16QAM, the phase angle shifts are 0 °, + 90 °, + 180 °, and + 270 ° in 90 ° steps.
[0052]
As described above, not only the cycle of TS header detection but also the phase angle correction amount differs depending on the selected transmission mode, so that the conventional CS digital broadcast receiving apparatus shown in FIG. 21 cannot be used as it is. . This is because if the phase converter 6 performs only the -180 ° conversion or the -90 ° conversion, it cannot cope with, for example, 8PSK in 45 ° steps.
[0053]
Therefore, an object of the present invention is to provide a digital broadcast receiving apparatus capable of correctly correcting a phase in accordance with various modulation schemes and coding rates specified in the DSNG standard.
[0054]
[Means for Solving the Problems]
The invention according to claim 1 is a digital broadcast receiving apparatus for receiving a digital modulation transmission signal of a digital modulation system for transmitting digital information of a transmission signal as a baseband signal subjected to phase shift keying modulation, wherein the digital broadcast transmission signal is The includes a plurality of types of digital broadcast transmission signals different in at least one of the modulation scheme and the coding rate, each of the plurality of types of digital broadcast transmission signals, includes a plurality of packets of a predetermined number of bytes as one unit, Each packet is a transport stream signal with an outer code, and each packet in the transport stream signal includes a synchronization signal as predetermined 1-byte data for distinguishing one packet. Of the transport stream signals in any of the digital broadcast transmission signals of At least some of the bytes are inner-coded one by one at a predetermined period, and among the plurality of types of the digital broadcast transmission signal, the predetermined period of the inner-coded bytes is different from each other. A digital demodulator capable of recognizing the plurality of types of digital broadcast transmission signals and demodulating the digital broadcast transmission signals to the baseband signal; and a transport stream signal based on the demodulated baseband signal. An inner code decoder that decodes at least some of the bytes that are inner-coded as inner-coded decoded data, and outputs data that is not inner-coded as non-inner-coded decoded data; Encoded data and non-inner encoded decoded data are outer-coded based on the outer code and decoded, and the decoded data has an error of a predetermined value or more. When the outer code decoder that outputs a decoding error signal, the synchronization signal is detected from the at least some bytes decoded in the inner code decoder, and upon detection, the digital demodulator recognizes the synchronization signal. A first synchronization signal detector that changes a detection cycle of the synchronization signal in accordance with the predetermined cycle of inner coding based on the modulation scheme, and the modulation scheme recognized by the digital demodulator; 1, a detection result of the synchronization signal detector, and a phase detector that detects a deviation of a phase angle of the baseband signal from an absolute phase on a transmission side based on a decoding error signal from the outer code decoder; A phase converter that converts a phase of the baseband signal at a different phase angle for each of the plurality of types of digital broadcast transmission signals based on a detection result of a phase detector. Digital broadcast receiving apparatus.
[0055]
According to a second aspect of the present invention, in the digital broadcast receiving apparatus according to the first aspect, the synchronization signal is data having a specific bit arrangement, and the first synchronization signal detector includes the synchronization signal. A digital broadcast receiving apparatus which, even when a specific bit array cannot be detected when detecting a signal, detects a synchronization signal when a predetermined array, which is a part of the specific bit array, can be detected.
[0056]
The invention according to claim 3 is the digital broadcast receiving device according to claim 1, wherein the phase converter converts the baseband signal demodulated by the digital demodulator into a signal before phase shift keying modulation. A digital broadcast receiving apparatus that restores a transmission signal and changes digital information of the restored transmission signal to convert the phase of the baseband signal.
[0057]
According to a fourth aspect of the present invention, in the digital broadcast receiving apparatus according to the first aspect, the synchronization signal is detected from the non-inner coded decoded data output from the inner code decoder. The apparatus further includes a second synchronization signal detector that changes a detection cycle of the synchronization signal in accordance with the predetermined cycle of inner encoding based on the modulation scheme recognized by the digital demodulator; The detector recognizes the modulation scheme recognized by the digital demodulator, the detection result of the first synchronization signal detector, and the decoding error signal from the outer code decoder, instead of the decoding error signal from the outer code decoder. The baseband signal from the absolute phase based on the detected modulation scheme, the detection result of the first synchronization signal detector, and the detection result of the second synchronization signal detector. A digital broadcast receiving device for detecting a deviation of the phase angle of.
[0058]
According to a fifth aspect of the present invention, in the digital broadcast receiving apparatus according to the fourth aspect, the synchronization signal detected from the non-inner coded decoded data is shifted from the baseband signal by a specific phase angle. Is present, it is transformed into another predetermined one-byte data based on a predetermined conversion rule corresponding to each of the plurality of types of digital broadcast transmission signals to become a modified synchronization signal, and the second synchronization signal detection is performed. The detector performs not only the detection of the synchronization signal but also the detection of the modified synchronization signal, and the phase detector determines the phase of the baseband signal from the absolute phase based on the detection result of the modified synchronization signal. This is a digital broadcast receiving device that detects a shift in angle.
[0059]
The invention according to claim 6 is the digital broadcast receiving device according to claim 4, wherein the digital demodulator calculates a C / N of a received digital broadcast transmission signal, and the phase detector includes: A combination of the modulation scheme recognized by the digital demodulator, the detection result of the first synchronization signal detector, and a decoding error signal from the outer code decoder, or the modulation recognized by the digital demodulator A deviation of the phase angle of the baseband signal from the absolute phase based on any one of a combination of a detection result of the first synchronization signal detector and a detection result of the second synchronization signal detector. And a digital broadcast receiving apparatus further comprising a first switch for detecting one of the two combinations in accordance with the C / N calculation result. That.
[0060]
The invention according to claim 7 is the digital broadcast receiving apparatus according to claim 4, wherein the inner code decoder outputs the input data, and outputs the inner coded decoded data and the non-inner coded decoding. Compare the data, calculate the bit error rate from the difference between the two, the phase detector, the modulation scheme recognized by the digital demodulator, the detection result of the first synchronization signal detector, and, A combination of the decoding error signals from the outer code decoder, or the modulation scheme recognized by the digital demodulator, the detection result of the first synchronization signal detector, and the combination of the second synchronization signal detector Detecting a deviation of the phase angle of the baseband signal from the absolute phase based on one of the combinations of the detection results; It is further provided a digital broadcast receiver a second switch for selecting in accordance with a calculation result of Rareito.
[0061]
The invention according to claim 8 is the digital broadcast receiving apparatus according to claim 1, wherein the plurality of types of digital broadcast transmission signals have a plurality of types of modulation cycles in which the inner encoding cycle of the byte exists. A memory that contains a broadcast transmission signal and stores the at least some bytes continuously and sequentially in the inner code decoder; and a byte of the synchronization signal among the bytes stored in the memory. And the synchronization signal sandwiched between any one of the plurality of types of the inner encoding periods and the synchronization signal based on the information of the plurality of types of the inner encoding periods. And a selecting unit for selecting whether or not one of the synchronization signal detectors should detect the digital broadcast signal.
[0062]
According to a ninth aspect of the present invention, there is provided the digital broadcast receiving apparatus according to the first aspect, wherein the plurality of types of digital broadcast transmission signals have a plurality of types of internal encoding cycles of bytes. A broadcast transmission signal is included, and the inner-coded bytes are further subjected to puncture encoding using any of a plurality of puncture patterns, and the plurality of bytes are used in the puncture encoding. Which of the puncture patterns is used is predetermined according to the type of the period of the inner encoding, and the inner code decoder converts the punctured encoded bytes into the plurality of punctured patterns. After performing puncture decoding using any of the patterns, inner code decoding is performed, and in the puncture decoding, any of the plurality of puncture patterns is used. Detecting whether the byte has been used for the byte, based on the information of the used puncture pattern and the information of the plurality of types of the inner encoding period, which of the plurality of types of the inner encoding period And a puncture pattern detector for selecting whether the first synchronization signal detector should detect a synchronization signal sandwiched between the first and second synchronization signal detectors.
[0063]
BEST MODE FOR CARRYING OUT THE INVENTION
<Embodiment 1>
The present embodiment detects a variable period TS header detector that changes the detection period of a TS header as a synchronization signal in accordance with the period of convolutional encoding, and detects a deviation of a phase angle of a baseband signal from an absolute phase. Digital broadcast reception provided with a variable phase detector and a variable phase converter for converting the phase of a baseband signal in a phase diagram at a different phase angle for each digital broadcast transmission signal having various modulation schemes and coding rates Device. As a result, even when the digital broadcast transmission signal includes a plurality of types of digital broadcast transmission signals (such as QPSK, 8PSK, and 16QAM) as in the DSNG standard, it is possible to cope with each modulation scheme and coding rate. Thus, a digital broadcast receiving apparatus capable of correctly performing phase correction can be realized.
[0064]
FIG. 1 is a block diagram of a digital broadcast receiving apparatus according to the present embodiment. In FIG. 1, those having the same reference numerals as the functional blocks of the conventional digital broadcast receiving apparatus shown in FIG. 21 perform the same operation.
[0065]
The digital demodulator 5 that demodulates the digital broadcast transmission signal into I data and Q data as baseband signals can recognize which of the modulation modes QPSK, 8PSK and 16QAM among the transmission modes (encoding). I can't recognize the rate).
[0066]
For the recognition of the modulation method, for example, a receiver (not shown) for each modulation method is provided in the digital demodulator 5, and a detector (FIG. 1) for detecting which of the receivers has received the transmission signal is provided. (Not shown)). It should be noted that a selector (not shown) for selecting the output of the receiver for each modulation scheme and a control unit (not shown) for controlling the selection of the selector are provided. If the selection of the selector is controlled by the selector, the reception signal of each receiver is output as I data and Q data. The information on the modulation scheme recognized by the detector is output as a modulation scheme signal MR.
[0067]
The Viterbi decoder 7 decodes, as convolutional decoded data, a byte convolved on the transmitting device side of the received digital broadcast transmission signal based on the I data and Q data demodulated by the digital demodulator 5. , And outputs unconvolved data as non-convolutional decoded data.
[0068]
The Reed-Solomon decoder 9 outer-codes and decodes the convolutionally decoded data and the non-convolutionally decoded data, and activates and outputs a decoded error signal RS-ERR when an error exists in the decoded data beyond a predetermined value. .
[0069]
Reference numeral 19 denotes a delay unit for time adjustment, reference numeral 20 denotes a variable phase converter, reference numeral 21 denotes a variable period TS header detector, and reference numeral 22 denotes a variable phase detector.
[0070]
The variable period TS header detector 21 is a TS header detector provided in place of the TS header detector 8 of the conventional digital broadcast receiving apparatus shown in FIG. The TS header is detected from the embedded decoded data. The modulation scheme signal MR is input to the variable cycle TS header detector 21. When the TS header is detected, based on the modulation scheme recognized by the digital demodulator 5, the TS header is associated with the byte cycle of the convolution. Change the detection cycle.
[0071]
Further, the variable phase detector 22 performs each transmission based on the detection result of the variable period TS header detector 21, the modulation scheme signal MR from the digital demodulator 5, and the decoded error signal RS-ERR from the Reed-Solomon decoder 9. A phase angle deviation of the baseband signal from an absolute phase in the mode phase diagram (for example, the position of (C2, C1) = (0, 0) in QPSK) is detected.
[0072]
The variable phase converter 20 is a means for converting the phase of a received signal provided in place of the phase converter 6 of the conventional digital broadcast receiving apparatus shown in FIG. Based on this, the phase of the baseband signal in the phase diagram is converted at a different phase angle for each transmission mode. Specifically, the variable phase converter 20 receives the I data and Q data from the digital demodulator 5 and the phase conversion signal PS of the variable phase detector 22, and performs phase conversion at a different phase angle for each transmission mode. Generate Ic data and Qc data. Then, the generated Ic data and Qc data are input to the Viterbi decoder 7.
[0073]
The delay unit 19 converts the non-convolutional decoded data output from the Viterbi decoder 7 from the variable phase detector 22 in consideration of the signal processing time in the variable period TS header detector 21 and the variable phase detector 22. It is provided for input to the Reed-Solomon decoder 9 at the same time as the output convolutional decoded data.
[0074]
Next, the operation will be described. For example, as can be seen from the P / P conversion table in FIG. 27, the transmission data of the modulation scheme 16QAM and the coding rate 3/4 shown in the phase diagram of FIG. (= 204 bytes × １ ／) (204 bytes is the period from the first TS header being folded until the next TS header is folded, and 1/3 is the number of bytes to be folded and the bytes not to be folded. The ratio of the number of folded bytes to the sum))). This means that the TS header is always folded. This is because a TS header that is divisible by 3 and that comes in a cycle of 204 bytes is always allocated to (E1).
[0075]
In this case, the variable-period TS header detector 21 only needs to set a 68-byte period as the period of TS header detection. This is because the convolutionally decoded data is input to the variable period TS header detector 21 and the non-convolutionally decoded data is not input, so that the reception data of 68 bytes to be convolved may be monitored. Then, the TS header can be detected at the most appropriate cycle.
[0076]
Similarly, from the P / P conversion table in FIG. 27, the TS header detection cycle in the QPSK modulation scheme is 204 bytes, and when the coding rate is 2/3 in the 8PSK modulation scheme, the TS header detection cycle is 102 bytes (= 204 bytes × 1/2 (204 bytes is the period from the first TS header being folded until the next TS header is folded, and 1/2 is folded for the sum of bytes to be folded and bytes not to be folded When the coding rate is 5/6 in the 8PSK modulation method, the TS header detection period is 204 bytes (= 1020 bytes × １ ／/ 5 (1020 bytes are obtained after the TS header is first convolved, The period until the TS header is folded, 1/5 is the ratio of the number of bytes to be folded to the sum of the bytes to be folded and the bytes not to be folded)), the coding rate 8 in the 8PSK modulation scheme. At the time of / 9, the TS header detection cycle is 51 bytes (= 204 bytes × １ ／) (204 bytes is the cycle from the first TS header being folded until the next TS header is folded. The ratio of the number of convolved bytes to the sum of convolved and non-convolved bytes)), when the coding rate is 7/8 in the 16QAM modulation scheme, the TS header detection period is 612 bytes (= 204 × 7 bytes × 3). / 7 (204 × 7 bytes are the period from the first TS header being folded until the next TS header is folded (A, F, and H in FIG. 27 need to be distinguished). / 7 may be set as the ratio of the number of bytes to be folded to the sum of bytes to be folded and bytes not to be folded)), respectively. Then, in any of the transmission modes, the TS header can be detected at the most appropriate cycle.
[0077]
The cycle of the TS header detection is appropriately changed by the variable cycle TS header detector 21 according to the transmission mode of the signal received. Since the modulation system is recognized by the digital demodulator 5, if the variable period TS header detector 21 obtains the modulation system signal MR, the modulation system is known in advance in the variable period TS header detector 21. Therefore, the variable-period TS header detector 21 has only to try the TS header detection for the variation of the coding rate set for each modulation scheme. For example, when it is known that the PSK is 8PSK, since the coding rate is 2/3, 5/6, and 8/9, the TS header detection cycle is set to 51 bytes, 102 bytes, or 204 bytes, and sequentially. What is necessary is just to perform TS header detection.
[0078]
By the way, the variable phase converter 20 performs the phase conversion in units of 90 ° phase angle on the baseband signal at the time of 16QAM modulation and QPSK modulation, and performs the phase conversion of 45 ° phase unit at the time of 8PSK modulation. Perform on signals. That is, the phase of the baseband signal is converted at a different phase angle for each transmission mode.
[0079]
For example, in the modulation scheme 16QAM and coding rate 3/4, when the TS header (= 47 hex data) is detected in the variable period TS header detector 21, the deviation of the phase angle of the baseband signal from the absolute phase is 0 °. Can be determined. When the inverted TS header (= B8 hex data) is detected, the phase angle shift is + 180 °, and when the TS header is not detected, the phase angle shift is determined to be + 90 ° or + 270 °.
[0080]
Therefore, when the TS header is not detected, the variable phase converter 20 corrects the phase angle of the baseband signal by -90 degrees. Then, if the variable period TS header detector 21 subsequently detects the TS header, it can be determined that the deviation of the phase angle of the baseband signal has changed from + 90 ° to 0 °. Therefore, the phase conversion may be completed at this point.
[0081]
On the other hand, when the inverted TS header is detected by the variable period TS header detector 21 after the −90 ° correction, it can be determined that the deviation of the phase angle of the baseband signal has changed from 270 ° to 180 °. Therefore, the variable phase converter 20 converts the phase angle of the baseband signal again to −180 °, and thereafter, the TS header is detected by the variable period TS header detector 21 (that is, the phase angle shift becomes 0 °). After that, the phase correction may be terminated.
[0082]
In the case of 8PSK and coding rate 2/3, when the TS header is detected by the variable period TS header detector 21, it can be determined that the phase angle shift is either 0 ° or + 180 °. However, it is not possible to specify which one. This is because, as can be seen from FIG. 23, the symbols facing each other at 180 ° with the origin as a symmetrical point have the same value combination (for example, both 0 ° and 180 °) of the convolutionally coded pattern (C2, C1). (0, 0)), the variable period TS header detector 21 that performs TS header detection based on only the convolutional decoded data without using the non-convolutional decoded data sets the current symbol to 2 This is because it cannot be specified which of the two symbols.
[0083]
Also, at 8PSK and a coding rate of 2/3, when data of (C2, C1) = (0, 0) is subjected to a phase conversion of + 90 °, (C2, C1) = (1, 1) and convolution is performed. All of the inserted data will be inverted, and the phase detector will detect the inverted TS header.
[0084]
Therefore, similarly, when the inverted TS header is detected by the variable-period TS header detector 21, it can be determined that the phase angle shift is either + 90 ° or + 270 °, but it is not possible to specify which one is. . When the TS header is not detected, it can be determined that the phase angle shift is any of + 45 °, + 135 °, or + 225 °.
[0085]
On the other hand, in the case of 8PSK and the coding rate of 5/6 or 8/9, when detecting the TS header, it can be determined that the phase angle shift is any of 0 °, + 90 °, + 180 °, and + 270 °. However, it is not possible to specify which one. It should be noted that, as can be seen from the phase diagram of FIG. 24, each of the symbols arranged at 90 ° intervals is a convolutionally encoded pattern (C1) that is narrowed down to the above-mentioned four phase angle shift values. This is because they have the same value (0 or 1).
[0086]
At 8PSK / coding rate 5/6 or 8/9, the convolved data is only one bit of C1. When the phase shifts by 45 °, the polarity of the convolution data C1 is inverted and an inverted TS header is detected.
[0087]
Therefore, when the inverted TS header is detected in the case of 8PSK and the coding rate is 5/6 or 8/9, it is determined that the phase angle shift is any of + 45 °, + 135 °, + 225 °, and + 315 °. it can. However, it is not possible to specify which one.
[0088]
If the phase angle shift cannot be specified as in the 8PSK modulation method, it is necessary to specify the phase angle shift by adding further conditions. Therefore, in order to further determine the phase angle shift, the decoding error signal RS-ERR of the Reed-Solomon decoder 9 is used.
[0089]
For example, from the phase diagram of 8PSK and the coding rate of 5/6 in FIG. 24, it is either 0 ° or + 180 ° that the convolved data satisfies (C2, C1) = (0, 0). At this time, unconvoluted data U1 is 0 at 0 ° and 1 at + 180 °. This means that, for example, when the phase angle shift is + 180 °, the convolved data (C2, C1) is decoded normally, but the unconvolved data (U1) is not decoded normally. means. Therefore, the error correction of the Reed-Solomon decoder 9, which corrects all data regardless of the presence or absence of convolution, can be normally performed only when the phase angle shift is 0 °, and cannot be normally performed when the phase angle shift is 180 °. become.
[0090]
The Reed-Solomon decoder 9 performs the reverse operation (inverse conversion) of the conversion operation of the P / P converter 11 in the transmission device of FIG. 26 on the convolution decoded data and the non-convolution decoded data, Reproduce the original byte data sequence. Then, error correction is performed on the reproduced byte data, and a decoded error signal RS-ERR is output as to whether the error correction has been normally performed. This decoding error signal RS-ERR is input to the variable phase detector 22.
[0091]
For example, at 8PSK and a coding rate of 2/3, it was not possible to specify whether the phase angle shift was 0 ° or + 180 ° when the TS header was detected. However, the variable phase detector 22 generates the decoded error signal RS-ERR Accordingly, it is possible to further specify the phase angle shift that the phase angle shift is 0 ° when error correction is normally performed without error and that the phase angle shift is + 180 ° when error correction is not performed.
[0092]
That is, the variable phase detector 22 determines the transmission mode based on the modulation scheme signal MR from the digital demodulator 5, the detection result of the variable period TS header detector 21, and the decoded error signal RS-ERR from the Reed-Solomon decoder 9. The deviation of the phase angle of the baseband signal from the absolute phase at is detected. Then, the variable phase converter 20 converts the phase of the baseband signal in the phase diagram at a different phase angle for each transmission mode based on the detection result (phase conversion signal PS) of the variable phase detector 22.
[0093]
According to the digital broadcast receiving apparatus of the present embodiment, the variable-period TS header detector 21 changes the detection period of the TS header in accordance with the convolved TS header period, and the variable-phase detector 22 The phase shift of the baseband signal from the phase is detected, and the variable phase converter 20 converts the phase of the baseband signal in the phase diagram at a different phase angle for each transmission mode.
[0094]
Therefore, even when the digital broadcast transmission signal includes a plurality of types of digital broadcast transmission signals (QPSK, 8PSK, 16QAM, etc.) as in the DSNG standard, the digital broadcast transmission signal must be compatible with each modulation scheme and coding rate. A digital broadcast receiving apparatus that can correctly correct the phase can be realized.
[0095]
FIG. 2 is a diagram showing an example of a method of calculating phase conversion in the variable phase converter 20, and FIG. 3 performs -45 ° conversion of the phase conversion to obtain Qc data after phase conversion of -45. 1 shows an example of a converter.
[0096]
As shown in FIG. 2, for example, in the case where Qc data is obtained after phase conversion by performing -45 ° conversion, the value of I data is subtracted from the value of Q data as input data of the variable phase converter 20, and the result is obtained. May be multiplied by √2 and divided by 2 (see the phase diagrams in FIGS. 22 to 25).
[0097]
In order to obtain Qc data after phase conversion by performing -90 ° conversion, I data as input data may be inverted (inv (A) means inverting digital value A). That is, the numerical value of the Qc data is -I. When Qc data after phase conversion is obtained by performing -180 ° conversion, Q data as input data may be inverted. When Qc data after phase conversion is obtained by performing -270 ° conversion, I data as input data may be obtained. Data may be used as Qc data. When obtaining Ic data after the phase conversion, the calculation as shown in FIG. 2 may be performed.
[0098]
The −45 ° converter CV1 in FIG. 3 includes an adder AD1, a multiplier MP1, and a 1-bit shifter SH1 as a divider for the numerical value 2. The I data and the Q data are input to the adder AD1, and the numerical value of the I data is subtracted from the numerical value of the Q data. Then, the calculation result of the adder AD1 is sent to the multiplier MP1, where it is multiplied by √2. Then, the calculation result of the multiplier MP1 is sent to the one-bit shifter SH1, and is shifted in a direction in which the bit is reduced by one digit. As a result, division by the numerical value 2 can be performed. Therefore, the −45 ° converter CV1 in FIG. 3 implements the −45 ° conversion method in FIG. 2 and obtains Qc data after phase conversion.
[0099]
FIG. 4 is a diagram illustrating a configuration example of a converter that generates Qc data among the converters that form the variable phase converter 20. The Qc data generation variable phase converter 20a includes switches SW1 to SW4 each having an output connected to one input terminal of the next stage, control means CT1 for switching the switches, -45 °, -90 °, It is provided with converters CV1 to CV4 having respective phase angles of -180 ° and -270 °.
[0100]
Among them, the -45 ° converter CV1 is, for example, the converter of FIG. 3, and the -90 ° converter CV2 and the -180 ° converter CV3 are both inverters (not shown). In the case of Qc data, it is sufficient to output I data in the -270 ° conversion, so the -270 ° converter CV4 may be omitted. For example, a buffer for delaying a signal for time adjustment may be replaced with a -270 ° converter CV4. May be used.
[0101]
The Q data is input to one input terminal of the switch SW1, to the -45 degree converter CV1 and the -180 degree converter CV3. The I data is input to the -45 degree converter CV1, -90 degree converter CV2, and -270 degree converter CV4. The output of the −45 ° converter CV1 is connected to the other input terminal of the switch SW1, the output of the −90 ° converter CV2 is connected to the other input terminal of the switch SW2, and the output of the −180 ° converter CV3 is connected to the other input terminal of the switch SW3. , -270 ° converter CV4 is input to the other input terminal of switch SW4. Then, the output of the switch SW4 becomes Qc data. It should be noted that information on the detected phase angle shift (phase conversion signal PS) is input to the control means CT1, and controls the switching of the switches SW1 to SW4.
[0102]
For example, when the phase angle shift information is 0 °, the input Q data may be output as it is, and the control means CT1 may set the switches SW1 to SW4 as shown in FIG. On the other hand, for example, when the information of the phase angle shift is + 45 °, the switch SW1 may be switched from the state of FIG. 4 so that the output of the −45 ° converter CV1 is output as Qc data. The same applies to other phase angle shifts.
[0103]
It should be noted that the converter that generates Ic data among the converters that constitute the variable phase converter 20 can be configured only by modifying the Qc data generation variable phase converter 20a in FIG. That is, as the -45 ° converter CV1, a converter in which I data and Q data are added in the adder AD1 in the converter of FIG. 3 is adopted, and as the −90 ° converter CV2, Q data is output. An inverter for inverting and outputting I data may be used as a -180 ° converter, and an inverter for inverting and outputting Q data may be used as a -270 ° converter.
[0104]
Note that the variable phase converter 20b shown in FIG. 5, for example, may be used for the variable phase converter 20 without using both the Qc data generation variable phase converter 20a and the Ic data generation variable phase converter as described above. Is also good.
[0105]
The variable phase converter 20b of FIG. 5 includes an angle conversion read-only memory RM1, an adder AD2, and an inverse angle conversion read-only memory RM2.
[0106]
The angle conversion read-only memory RM1 stores a conversion table covering the phase values corresponding to the respective values of the I data and the Q data. The value is output. Then, the value of the detected phase angle shift (phase conversion signal PS) is subtracted from the output phase value in the adder AD2. The output of the adder AD2 is input to the inverse angle conversion read only memory RM2.
[0107]
The inverse angle conversion read-only memory RM2 stores a conversion table covering Qc data and Ic data values corresponding to the phase value calculated by the adder AD2. Then, the values of the corresponding Qc data and Ic data are output.
[0108]
Further, the variable phase detector 22 can be easily formed by using a selector or a decoder. The information of the modulation method signal MR from the digital demodulator 5, the detection result of the variable period TS header detector 21, and the decoding error signal RS-ERR are input, and the variable phase detector 22 May transmit a phase conversion signal PS specifying an appropriate phase conversion amount to the variable phase converter 20.
[0109]
<Embodiment 2>
The present embodiment is a modification of the digital broadcast receiving apparatus according to Embodiment 1, and detects the entire bit array of 47 hex data or B8 hex data when detecting a TS header instead of the variable period TS header detector 21. Even if it is not possible, if a selected bit, that is, a part of the bit array, can be detected, the TS header is detected as being detected. By doing so, phase correction can be performed even for a digital broadcast transmission signal under a low C / N environment.
[0110]
In the digital broadcast receiving apparatus according to the first embodiment, variable-period TS header detector 21 detects a TS header when all of TS header data (47 hex data: 01000111) or inverted TS header data (B8 hex data: 10111000) match. Was determined.
[0111]
However, when the digital broadcast transmission signal is under a low C / N environment, the TS header may not be able to be received as complete 8-bit data due to noise. In this embodiment, in such a case, even if the TS header cannot be completely detected, if a part of the bit array is detected, that is, if the specified number of bits in 8 bits matches, In addition, it is assumed that the TS header has been detected, thereby facilitating signal detection.
[0112]
FIG. 6 is a block diagram of the digital broadcast receiving apparatus according to the present embodiment. In FIG. 6, elements having the same functions as those of the digital broadcast receiving apparatus according to Embodiment 1 are denoted by the same reference numerals. Among them, reference numeral 18 denotes a selected bit number matching variable period TS header phase detector. The other configuration is the same as that of the digital broadcast receiving apparatus according to the first embodiment, and a description thereof will not be repeated.
[0113]
Next, the operation will be described. The variable-period TS header detector 21 according to the first embodiment detects TS header data (normal data “01000111”: 47 hex or inverted data “10111000”: B8 hex) and repeats it several times in a specified period. When it is detected, it is determined that the TS header has been detected.
[0114]
The Reed-Solomon decoder 9 at the subsequent stage starts the Reed-Solomon decoding only after receiving the determination result of the variable period TS header detector 21 (for the first time after detecting the TS header). This is because at the start of Reed-Solomon decoding, it is meaningless to perform error correction again at a later stage unless at least the Viterbi decoder 7 has correctly corrected the error and decoded the data.
[0115]
In other words, if the TS header has not been detected, it means that the Viterbi decoder 7 has not been able to decode normally, so that in order to start Reed-Solomon decoding, it is essential that the TS header be detected.
[0116]
In the first embodiment, the TS header is detected when all the 8 bits of the TS header data have been detected. However, when the reception state is poor and the C / N of the transmission path is poor, the reception is performed. Data reliability is reduced. Therefore, even if the TS header is Viterbi-decoded and error-corrected, the data may be erroneous, and the possibility that the variable-period TS header detector 21 cannot detect all 8 bits of the TS header increases.
[0117]
On the other hand, if it is possible to change the detection so that it is possible to detect any specified number of bits without desiring to detect all 8 bits of the TS header data, the C / N of the received data is bad, although there is a possibility of an error. At times, the TS header can be detected.
[0118]
For example, if the detection and discrimination can be performed by matching only a part of arbitrary 6 bits of the 8 bits of the TS data, the detection of the TS header becomes easy, and the Reed-Solomon decoder 9 at the subsequent stage starts error correction, The phase angle shift can be detected by the variable phase detector 22.
[0119]
As described above, it is determined that the TS header has been detected when the specified number of bits match, that is, when a predetermined arrangement that is a part of the TS header can be detected, it is determined that the TS header has been detected. As a result, even if the received data has low reliability under a low C / N environment, the phase angle shift can be detected and the phase correction can be performed.
[0120]
<Embodiment 3>
This embodiment is a modification of the digital broadcast receiving apparatus according to the second embodiment. Instead of the variable phase converter 20, the baseband signal demodulated by the digital demodulator 5 before the phase shift keying mapping is performed. A second variable phase converter that restores a convolution transmission signal and a non-convolution transmission signal and changes the phase of a baseband signal by changing digital information of the restored transmission signal is employed. Since a baseband signal is generally composed of multiple bits (for example, 8 bits), when converting the phase of the baseband signal, a circuit for converting a numerical value of multiple bits is required. In the case where the digital information of the transmission signal is changed, an inverter for changing the binary value may be adopted, and the circuit scale can be reduced.
[0121]
In the digital broadcast receiving apparatus according to the second embodiment, the phase angle shift is corrected by changing the values of the I data and Q data, which are the baseband signals demodulated by the digital demodulator 5.
[0122]
In the present embodiment, instead of changing the values of I data and Q data as baseband signals, convolutional data and non-convolutional data restored from I data and Q data (data C , U), the phase of the baseband signal is corrected.
[0123]
FIG. 7 is a block diagram of the digital broadcast receiving apparatus according to the present embodiment. In FIG. 7, elements having the same functions as those of the digital broadcast receiving apparatus according to the second embodiment are denoted by the same reference numerals. Reference numeral 23 is a second variable phase converter. The other configuration is the same as that of the digital broadcast receiving apparatus according to the second embodiment, and a description thereof will not be repeated.
[0124]
Next, the operation will be described. For example, in the transmission mode of the modulation scheme 8PSK and the coding rate 2/3, the TS header detector 18 with the selected bit number matching variable period detects the TS header, but the decoding error signal RS-ERR is activated and an error occurs. It is assumed that the variable phase detector 22 determines that the correction has not been performed normally. At this time, it can be determined that the I data and Q data demodulated by the digital demodulator 5 have a phase difference of + 180 °.
[0125]
In the digital broadcast receiving apparatus according to the second embodiment, Qc = inverted Q and Ic = inverted I are converted by variable phase converter 20, and Qc data and Ic data are input to Viterbi decoder 7 at the subsequent stage. Then, in the Viterbi decoder 7, (C2, C1) which is the restored data of the convolved transmission signal and (U1) which is the restored data of the unconvolved transmission signal are obtained from the phase diagram of FIG. Error correction was performed above.
[0126]
On the other hand, in the digital broadcast receiving apparatus according to the present embodiment, the second variable phase converter 23 first converts the I data and Q data from the digital demodulator 5 into a phase diagram of FIG. To restore the convolutional data (C2, C1) and the non-convolutional data (U1). Then, by changing the digital information at the stage of the restored data (C2, C1) and (U1), the phase of the baseband signal is converted as a result.
[0127]
That is, the bit contents of the restored data (C2, C1) and (U1) are converted based on the detection result of the variable phase detector 22. For example, when it is determined that the deviation of the phase angle is + 180 ° in the case of 8PSK and the coding rate is 2/3, it is known that the convolution data (C2, C1) is correct. The second variable phase converter 23 outputs (C2, C1) calculated from the above as it is. On the other hand, since the non-convolution data (U1) is inverted, U1 calculated from the phase diagram is inverted and output.
[0128]
This inversion can be easily performed by providing an inverter or the like in the second variable phase converter 23 because it only inverts the 1-bit data U1.
[0129]
As described above, in the present embodiment, data C and U as transmission signals before mapping are restored from I data and Q data as baseband signals demodulated by digital demodulator 5 and the restored convolutional data And changing the digital information at the stage of non-convolutional data to convert the phase of the baseband signal. Therefore, when a phase of a baseband signal (I data, Q data) composed of multiple bits is converted, a circuit for converting a numerical value of multiple bits is required. , U can be changed by using an inverter for changing the binary information, and the circuit scale can be reduced.
[0130]
FIG. 8 is a diagram showing a configuration example of the second variable phase converter 23. As shown in FIG. 8, second variable phase converter 23 receives Q data and I data, and calculates convolutional data decoder DC1 and non-convolutional data decoder which respectively calculate data C and U as transmission signals before mapping. DC2 is provided. The second variable phase converter 23 further includes a switch SW5 that selects either the output of the convolutional data decoder DC1 or the output obtained by inverting the output via the inverter IV1 and outputs the output as convolutional data. , A switch SW6 for selecting either the output of the non-convolutional data decoder DC2 or the output obtained by inverting the output via the inverter IV2 and outputting the selected non-convolutional data, and a switch SW6 for detecting the deviation of the detected phase angle. Control means CT2 for controlling the switches SW5 and SW6 based on the value (phase conversion signal PS).
[0131]
As described above, since the second variable phase converter 23 does not use a multiplier or a memory, the circuit scale can be reduced as compared with the phase conversion circuits of FIGS.
[0132]
<Embodiment 4>
This embodiment is a modification of the digital broadcast receiving apparatus according to Embodiment 1, and includes a variable period non-convolutional TS header detector that detects a TS header also from non-convolutional decoded data output from Viterbi decoder 7. Digital broadcast reception in which the deviation amount of the phase angle is specified using the detection result of the variable period non-convolutional TS header detector instead of the decoding error signal RS-ERR from the Reed-Solomon decoder 9 Device. Since it takes some time for the decoding error signal RS-ERR to be output from the Reed-Solomon decoder 9, the TS header is detected from the non-convolutional decoded data, and based on the detection result, the baseband from the absolute phase is determined. It is faster to detect a shift in the phase angle of the signal. Therefore, the phase can be corrected quickly.
[0133]
FIG. 9 is a block diagram of the digital broadcast receiving apparatus according to the present embodiment. In FIG. 9, elements having the same functions as those of the digital broadcast receiving apparatus according to Embodiment 1 are denoted by the same reference numerals. Reference numeral 24 denotes a variable period non-convolutional TS header detector. The other configuration is the same as that of the digital broadcast receiving apparatus according to the first embodiment, and a description thereof will not be repeated.
[0134]
In the present embodiment, the phase error is not specified by using the decoding error signal RS-ERR of the Reed-Solomon decoder 9 in the variable phase detector 22, but the non-convolution is used instead of the decoding error signal RS-ERR. A phase angle can be specified using a TS header detected from decoded data.
[0135]
The variable-period non-convolutional TS header detector 24 detects the TS header from the non-convolutional decoded data output from the Viterbi decoder 7 in the same manner as the variable-period TS header detector 21. 5, the detection period of the TS header is changed corresponding to the byte period of convolution.
[0136]
Next, the operation will be described. For example, with 8PSK and coding rate 5/6, there are cases where the TS header is folded and cases where the TS header is not folded. In the first embodiment, only the convoluted TS header is detected, and the deviation of the phase angle is specified based on the detection result and the decoding error signal RS-ERR.
[0137]
Here, in order for the Reed-Solomon decoder 9 to output the decoding error signal RS-ERR, after the variable period TS header detector 21 detects the convolutional TS header, the Reed-Solomon decoder 9 outputs It is necessary to make a correction, and as a result, to determine whether the error correction has been successfully performed or not.
[0138]
Generally, the error correction of the outer code by the Reed-Solomon decoder 9 uses a memory, so that it takes time until the error-corrected data and the decoded error signal RS-ERR are output. Therefore, the variable phase detector 22 is in a state of waiting for a job until the decoding error signal RS-ERR is output.
[0139]
The variable-period non-convolutional TS header detector 24 according to the present embodiment detects the convolutional TS header after the variable-period TS header detector 21 detects a TS header or detects an inverted TS header. Is detected. Then, the detection result is transmitted to the variable phase detector 22. The variable phase detector 22 determines the absolute phase based on the modulation scheme recognized by the digital demodulator 5, the detection result of the variable period TS header detector 21, and the detection result of the variable period non-convolutional TS header detector 24. Of the baseband signal from the baseband signal is detected.
[0140]
For example, in the case of 8PSK and coding rate 5/6, even if the variable period TS header detector 21 detects the TS header, there are four kinds of phase angle shifts of 0 °, + 90 °, + 180 °, and + 270 °. , It is not possible to identify which one.
[0141]
Here, focusing on the data (U2, U1, C1) = (0, 0, 0) when the phase shift of the received signal is 0 ° from the phase diagram of FIG. (0,1,0), (1,0,0) at a phase angle shift of + 180 ° and (1,1,0) at a phase angle shift of + 270 °, The convolutional data U2 and U1 will not be the same data as in the case where the phase angle shift is 0 °.
[0142]
Therefore, when the TS header of the non-convolutional data can be detected by the variable period non-convolutional TS header detector 24, the variable phase detector 22 can determine that the phase angle shift is 0 °. Therefore, at that time, the variable period non-convolutional TS header detector 24 notifies the variable phase detector 22 of the detection result, whereby the phase correction can be immediately terminated.
[0143]
On the other hand, when the TS header cannot be detected, the variable phase detector 22 can determine that the phase angle shift is other than 0 °. ° Convert. Then, the variable period non-convolutional TS header detector 24 verifies whether the TS header can be detected again.
[0144]
If the TS header cannot be detected at this stage, the variable phase converter 20 further performs -90 ° conversion in the same manner until the variable period non-convolutional TS header detector 24 can detect the TS header. (In this case, phase conversion is performed up to three times).
[0145]
As described above, since the TS header of the non-convolution data can also be detected, the modulation scheme and the coding rate having both the case where the TS header is convolved and the case where the TS header is not convolved are used. In the transmission mode, the phase angle shift can be specified based on the detection result of the TS header of the non-convolutional data before the decoding error signal RS-ERR is output, so that the phase can be corrected quickly.
[0146]
In the case of non-convolutional data, resistance to noise in a transmission path is weaker than that of convolutional data. Therefore, when a digital broadcast transmission signal is received under a low C / N environment, the possibility that the TS header of non-convolutional data can be correctly detected is low. In this case, even if it takes time, it is better to use the decoding error signal RS-ERR to reliably specify the phase angle shift.
[0147]
Therefore, it can be said that the digital broadcast receiving apparatus according to the present embodiment is suitable for a case where a digital broadcast transmission signal can be satisfactorily received under a relatively high C / N environment.
[0148]
<Embodiment 5>
The present embodiment is a modification of the digital broadcast receiving apparatus according to Embodiment 4, in which a second variable cycle non-convolutional TS header detector is provided instead of variable cycle non-convolutional TS header detector 24. Digital broadcast receiving device. In the second variable-period non-convolutional TS header detector, not only 47 hex data but also a signal of another predetermined 1-byte data obtained by transforming 47 hex data based on a predetermined conversion rule corresponding to each transmission mode is used. And a deviation of the phase angle of the baseband signal from the absolute phase is detected based on the detection result. As a result, the deviation of the phase angle of the baseband signal from the absolute phase can be specified earlier, and the phase correction can be performed more quickly.
[0149]
FIG. 10 is a block diagram of the digital broadcast receiving apparatus according to the present embodiment. In FIG. 10, elements having the same functions as those of the digital broadcast receiving apparatus according to Embodiment 4 are denoted by the same reference numerals. Reference numeral 25 is a second variable-period non-convolutional TS header detector. The other configuration is the same as that of the digital broadcast receiving apparatus according to the fourth embodiment, and a description thereof will not be repeated.
[0150]
Next, the operation will be described. In the fourth embodiment, the TS header detection of non-convolutional data is determined by detecting whether or not “01000111”, which is 47 hex data, is detected. Therefore, at 8PSK and a coding rate of 5/6, even if a TS header is detected in non-convolutional data, it is necessary to re-correct the phase up to three times.
[0151]
In the present embodiment, the second variable-period non-convolutional TS header detector 25 detects not only 47hex data of 01000111 but also a known pattern in which the data is deformed. Then, when the pattern can be detected in the designated cycle, the detection result is used for specifying the phase angle shift in the variable phase detector 22.
[0152]
For example, when the TS header is detected by the variable-period TS header detector 21 (TS header detection or inverted TS header detection) in the transmission mode of 8PSK / coding rate 5/6, 0 °, + 90 °, + 180 ° , + 270 ° in phase angle.
[0153]
FIGS. 11 to 13 show data (U2, U1, C1) when the phase diagram of FIG. 24 is shifted by + 90 °, + 180 °, and + 270 °, respectively. Focusing on the case where the phase angle shift is + 180 ° in FIG. 12, the non-convolution data (U2c, U1c) is (U2c, U1) = (a, b) in FIG. , U1c) = (reverse a, forward b). For example, (U2, U1, C1) = (0, 0, 0) in FIG. 24 is (U2, U1, C1) = (1, 0, 0) in FIG.
[0154]
On the other hand, as can be seen from FIGS. 11 and 13, there is no such a conversion rule when the phase angle is shifted by + 90 ° or + 270 °.
[0155]
Therefore, in the case of the transmission mode of 8PSK and coding rate 5/6, if there is a shift of + 180 ° phase angle, (U2c, U1c) = (inversion a, normal rotation b) according to this transmission mode. Based on the conversion rule, it is considered that the TS header is transformed into another predetermined 1-byte data to become a modified TS header.
[0156]
Specifically, when there is a + 180 ° phase angle shift, the TS header (“01000111”) of the non-convolutional data is reproduced as either “11101101” or “00010010” data. In the case of the transmission mode of 8PSK and coding rate 5/6, (U2c, U1c) is the adjacent bit data of the transmission signal that is not convolved, and thus the TS header (“01000111”) is divided into two bits. This is because one of the cases becomes “11101101” or “00010010” which is inverted.
[0157]
Therefore, if either of these two patterns can be detected consecutively for the specified period, the phase angle shift can be determined to be 180 °. In the case of 8PSK and the coding rate of 5/6, the number of phase corrections can be determined. Can be made up to twice. If the phase angle is shifted by 180 °, it can be detected at once, and if the phase is shifted by 90 ° or 270 °, once the -90 ° conversion is performed, the phase angle is shifted by either 180 ° or 0 ° , The detection becomes possible, and if the second correction is performed, the phase correction ends.
[0158]
According to the digital broadcast receiving apparatus according to the present embodiment, the second variable-period non-convolutional TS header detector 25 detects not only the TS header but also the baseband signal has a specific phase angle shift. In this case, a modified TS header modified to another predetermined 1-byte data is also detected, and the variable phase detector 22 detects the deviation of the phase angle of the baseband signal from the absolute phase based on the detection result of the modified TS header. Is detected. Therefore, the deviation of the phase angle of the baseband signal from the absolute phase can be specified earlier, and the phase can be corrected more quickly.
[0159]
<Embodiment 6>
This embodiment is a modification of the digital broadcast receiving apparatus according to Embodiment 5, in which variable phase detector 22 detects modulation scheme signal MR, detection result of variable period TS header detector 21, and decoding error signal. Based on either the combination of the RS-ERR or the combination of the modulation scheme signal MR, the detection result of the variable period TS header detector 21, and the detection result of the second variable period non-convolutional TS header detector 25, The digital broadcast receiving apparatus further includes a switch for selecting whether to detect a deviation of the phase angle of the baseband signal from the absolute phase in accordance with the calculation result of the C / N in the digital demodulator 5.
[0160]
As a result, the deviation of the phase angle of the baseband signal from the absolute phase can be detected by an optimal method suitable for the C / N of the received digital broadcast transmission signal. That is, in the case of low C / N, the switch selects a combination including the decoding error signal RS-ERR from the Reed-Solomon decoder 9 so that reliable phase correction can be performed. On the other hand, in the case of high C / N, , The switch selects a combination including the detection result of the second variable-period non-convolutional TS header detector 25 so that quick phase correction can be performed.
[0161]
FIG. 14 is a block diagram of the digital broadcast receiving apparatus according to the present embodiment. In FIG. 14, elements having the same functions as those of the digital broadcast receiving apparatus according to the fifth embodiment are denoted by the same reference numerals. The code 26 indicates the detection result of the second variable-period non-convolutional TS header detector 25 or the decoding error signal RS-ERR from the Reed-Solomon decoder 9 according to the C / N of the reception status. Is a switch for transmitting to the variable phase detector 22.
[0162]
Further, in the present embodiment, digital demodulator 5 calculates the C / N of the digital broadcast transmission signal and outputs it as C / N signal CN. Generally, the C / N of the received data can be easily calculated in the demodulation process inside the digital demodulator 5, and a known calculation circuit may be added. The other configuration is the same as that of the digital broadcast receiving apparatus according to the fifth embodiment, and a description thereof will not be repeated.
[0163]
Next, the operation will be described. Since the non-convolutional decoded data is not error-correction-coded data like the convolutional decoded data, the non-convolutional decoded data output from the Viterbi decoder 7 is erroneous due to an external factor such as reception C / N. Probability is high. Therefore, when the reception C / N is poor, there is a high possibility that the second variable-period non-convolutional TS header detector 25 cannot detect the header, and cannot be used for the determination of the phase angle by the variable phase detector 22.
[0164]
On the other hand, the decoding error signal RS-ERR of the Reed-Solomon decoder 9 determines whether or not the error was successfully corrected as a result of performing error correction on both the convolutional decoded data and the non-convolutional decoded data. Since it is a signal, there is a high possibility that correct contents can be output even when the reception C / N is poor.
[0165]
Therefore, when it is desired to perform the phase correction as quickly as possible in a state where the reception C / N is good, the switch 26 determines the detection result of the variable period non-convolutional TS header detector 25 according to the value of the C / N signal CN. 22, the variable phase detector 22 generates a signal based on the combination of the modulation scheme signal MR, the detection result of the variable period TS header detector 21, and the detection result of the second variable period non-convolutional TS header detector 25. The deviation of the phase angle of the baseband signal from the absolute phase may be detected.
[0166]
On the other hand, when the reception C / N is poor, the switch 26 supplies the decoding error signal RS-ERR to the variable phase detector 22 according to the value of the C / N signal CN so that the phase correction can be reliably performed. Based on a combination of the modulation scheme signal MR, the detection result of the variable period TS header detector 21, and the decoding error signal RS-ERR, the detector 22 can detect the deviation of the phase angle of the baseband signal from the absolute phase. What should I do?
[0167]
That is, the switch 26 determines whether the variable phase detector 22 has a combination of the modulation scheme signal MR, the detection result of the variable cycle TS header detector 21 and the decoding error signal RS-ERR, or the modulation scheme signal MR and the variable cycle TS Which of the combination of the detection result of the header detector 21 and the detection result of the second variable period non-convolutional TS header detector 25 detects the deviation of the phase angle of the baseband signal from the absolute phase Is selected according to the calculation result of the C / N signal CN.
[0168]
As described above, to specify the detected phase angle, it is possible to switch between using the TS header detection result of the non-convolutional decoded data and using the decoding error signal RS-ERR depending on the reception C / N. Therefore, the detected phase angle can be specified by an optimum method suitable for the reception C / N. As a result, quick phase correction or reliable phase correction can be performed according to reception conditions from low C / N to high C / N.
[0169]
That is, when the C / N is low, the switch 26 selects a combination including the decoding error signal RS-ERR so that the phase can be surely corrected. The combination including the detection result of the variable-period non-convolutional TS header detector 25 is selected so that quick phase correction can be performed.
[0170]
<Embodiment 7>
This embodiment is a modification of the digital broadcast receiving apparatus according to Embodiment 5, in which variable phase detector 22 detects modulation scheme signal MR, detection result of variable period TS header detector 21, and decoding error signal. Based on either the combination of the RS-ERR or the combination of the modulation scheme signal MR, the detection result of the variable-period TS header detector 21, and the detection result of the second variable-period non-convolutional TS header detector 25, The digital broadcast receiving apparatus further includes a second switch for selecting whether to detect a deviation of the phase angle of the baseband signal from the absolute phase in accordance with the calculation result of the bit error rate in the Viterbi decoder 7.
[0171]
As a result, the deviation of the phase angle of the baseband signal from the absolute phase can be detected by an optimal method suitable for the bit error rate reflecting the C / N of the received digital broadcast transmission signal. That is, in the case of the high bit error rate, the second switch selects a combination including the decoded error signal RS-ERR from the Reed-Solomon decoder 9 so that the phase can be surely corrected. In the case of (2), the second switch selects a combination including the detection result of the second variable-period non-convolutional TS header detector 25 so that quick phase correction can be performed.
[0172]
In the sixth embodiment, according to the C / N of the received data, the switch 26 determines which of the detection result of the second variable-period non-convolutional TS header detector 25 or the decoding error signal RS-ERR is detected. I had to choose to use it to identify the corner.
[0173]
In the present embodiment, the bit error rate is calculated in the Viterbi decoder 7 instead of calculating the C / N of the received data in the digital demodulator 5, and based on the bit error rate, the second switch , The second variable-period non-convolutional TS header detector 25 or the decoded error signal RS-ERR from the Reed-Solomon decoder 9 is transmitted to the variable phase detector 22.
[0174]
FIG. 15 is a block diagram of the digital broadcast receiving apparatus according to the present embodiment. In FIG. 15, elements having the same functions as those of the digital broadcast receiving apparatus according to Embodiment 5 are denoted by the same reference numerals. Among them, reference numeral 27 denotes a bit error calculated by the Viterbi decoder 7 using either the detection result of the second variable-period non-convolutional TS header detector 25 or the decoded error signal RS-ERR from the Reed-Solomon decoder 9. This is a switch for transmitting to the variable phase detector 22 according to the rate. The other configuration is the same as that of the digital broadcast receiving apparatus according to the fifth embodiment, and a description thereof will not be repeated.
[0175]
Next, the operation will be described. In general, the C / N of the received data can be calculated in a demodulation process inside the digital demodulator 5, but an additional circuit for calculation is required. When the C / N of the received data is bad, the bit error rate of the demodulated data (I, Q data) input from the digital demodulator is large (up to 0.5). When the C / N is good, the bit error rate is also large. Since this value becomes small (the minimum value is "0" without error), this information is used as a substitute for the reception C / N.
[0176]
The Viterbi decoder 7 calculates a numerical value corresponding to the bit error rate of the input data by comparing the data after error correction (both non-convolution data and convolution data) with the data input to the Viterbi decoder 7. it can. Since the bit error rate information is also used when verifying the decoding operation of the Viterbi decoder 7, it is usually provided as a function of the Viterbi decoder 7. Therefore, if the bit error rate information is used to control the operation of the second switch 27 depending on whether or not the value exceeds a predetermined value, the case where the switch 26 is controlled using the reception C / N The same operation can be realized.
[0177]
That is, receiving the bit error rate information BER calculated by the Viterbi decoder 7, the second switch 27 sets the variable phase detector 22 to the modulation method signal MR and the variable period TS header detector 21 according to the calculation result. And the combination of the decoding error signal RS-ERR or the modulation scheme signal MR, the detection result of the variable-period TS header detector 21 and the detection of the second variable-period non-convolutional TS header detector 25 Based on which combination of the results, a choice is made as to whether a phase angle deviation of the baseband signal from the absolute phase is detected.
[0178]
As described above, in order to specify the detected phase angle, the TS header detection result of the non-convolutional decoded data is used or the decoding error signal RS-ERR is used according to the bit error rate information BER calculated by the Viterbi decoder 7. The detection phase angle can be specified by an optimal method suitable for the value of the bit error rate reflecting the reception C / N. As a result, quick phase correction or reliable phase correction can be performed according to reception conditions from low C / N to high C / N.
[0179]
That is, in the case of the high bit error rate, the second switch 27 selects a combination including the decoding error signal RS-ERR so that the phase can be surely corrected. The second switch 27 can select a combination including the detection result of the second variable-period non-convolutional TS header detector 25 to enable quick phase correction. In addition, since the Viterbi decoder 7 generally calculates the bit error rate, an additional circuit for calculating the C / N in the digital demodulator 5 is not required as compared with the sixth embodiment. There are advantages.
[0180]
<Embodiment 8>
The present embodiment is a modification of the digital broadcast receiving apparatus according to Embodiment 1, and includes a continuous TS header memory that stores the convolutionally decoded data decoded by the Viterbi decoder 7 continuously and sequentially, Based on the information of the cycle in which the TS header byte appears among the bytes stored in the header memory and the information of the plural types of convolution periods, the TS sandwiched between any one of the plural types of convolution periods And a TS header selection unit for selecting whether the variable period TS header detector should detect the header. As a result, there are a plurality of types of convolution periods such as 16QAM / coding rate 7/8 (for 16QAM / coding rate 7/8, the convolution period has an interval of 3 bytes, 2 bytes, and 2 bytes). Even in the case of the modulation method, it is possible to detect a TS header having a phase at which data decoded by the Viterbi decoder becomes normal byte data, and correct phase correction can be performed.
[0181]
In the present embodiment, even when there are several possible arrangements of the TS header in the convolutional data, the TS header is accurately detected, and the detection phase angle is specified from the detection result and the decoding error signal RS-ERR. And phase correction.
[0182]
FIG. 16 is a block diagram of the digital broadcast receiving apparatus according to the present embodiment. In FIG. 16, elements having the same functions as those of the digital broadcast receiving apparatus according to Embodiment 1 are denoted by the same reference numerals. Reference numeral 28 denotes a continuous TS header memory for successively and sequentially storing the convolutionally decoded data decoded by the Viterbi decoder 7, and reference numeral 29 denotes a TS of the bytes stored in the continuous TS header memory 28. A TS header selection unit for selecting which arrangement of TS headers in the byte data should be detected by the variable-period TS header detector 21 based on information on a period in which the header byte appears and information on a plurality of types of convolution periods. is there. The other configuration is the same as that of the digital broadcast receiving apparatus according to the first embodiment, and a description thereof will not be repeated.
[0183]
Next, the operation will be described. In all of the DSNG transmission modes except 16QAM and a coding rate of 7/8, the TS header to be convolved is arranged only in "A" according to the P / P conversion table of FIG. By detecting the TS header arranged in the above, the phase for the inverse P / P conversion can be determined.
[0184]
However, in the case of 16QAM and a coding rate of 7/8, as shown in the P / P conversion table of FIG. 27, the TS header is convoluted with “A”, “F”, and “H” in the table. There are three types of patterns. For this reason, even if the TS header can be detected, it is not possible to identify the phase for performing the inverse P / P conversion unless it is determined which of the three types of the TS header is used. Therefore, the original byte data string cannot be reproduced. That is, in the first embodiment, since the "A" pattern can be detected only with a probability of 1/3, normal error correction can be performed only with a probability of 1/3.
[0185]
Assuming that the first TS header is convolved with “A”, the first TS header of the next TS packet is convolved with “F”, that is, the 3 × 204 byte + 1 = 613th byte, and “H” Is the first TS header of the 6 TS packet, that is, the 5 × 204 byte + 1 = 11021 byte TS header.
[0186]
Considering the number of data arranged only in the convolution data, if the TS header to be folded into “A” is the first byte, the TS header to be folded into “F” is the 263th byte, and the TS header is folded into “H”. The TS header to be inserted is the 438th byte. Based on the TS header arranged in “A”, the interval between the TS headers is FA = 262 bytes, HF = 175 bytes, and the next AH = 175 bytes, next F-next A = 262,...
[0187]
The continuous TS header memory 28 is used to continuously store the folded TS header and some byte data therebetween. In the above example, the convolutional TS header repeats the cycle of “A”, “F”, and “H” (262 + 175 + 175 = 612 byte cycle), and since the respective intervals are different, at least 3 TS headers (612 bytes) are repeated. I do.
[0188]
Then, the TS header selecting unit 29 selects “A” by recognizing the difference in the interval between the TS headers from the byte data repeatedly stored in the continuous TS header memory 28. That is, the TS header selection unit 29 obtains information on the period in which the TS header bytes appear (that the TS header appears in a period of 262 bytes, 175 bytes, or 175 bytes) obtained from the continuous TS header memory 28 and a plurality of types of tatami mats. Based on the information of the convolution period (in 16QAM, coding rate 7/8, the convolution period has an interval of 3 bytes, 2 bytes, and 2 bytes) and any one of a plurality of types of convolution periods The variable-period TS header detector 21 selects whether a TS header (“A”, “F”, or “H” TS header) sandwiched between the two should be detected.
[0189]
Since the selected TS header is repeated at a cycle of 612 bytes, the variable-period TS header detector 21 detects the TS header an arbitrary number of times in this cycle (612 bytes), and detects the detection result at the subsequent variable phase detection. Output to the container 22. The variable phase detector 22 specifies the phase by this, and the variable phase converter 20 corrects the phase. In accordance with the timing of the TS header selected by the TS header selecting unit 29, the Reed-Solomon decoder 9 normally performs inverse P / P conversion, and performs error correction using the reproduced byte data sequence.
[0190]
As described above, the convolved TS header and the byte data therebetween are continuously stored, and the TS of the phase at which the convolutional decoded data by the Viterbi decoder 7 can be reproduced into normal byte data due to the difference in the interval between the TS headers. By allowing the header to be selected and detected, even if there are several patterns of TS headers in the convolutional data, the TS header of the specified pattern can be reliably detected. Therefore, correct phase correction can always be performed, and normal error correction can be performed.
[0191]
<Embodiment 9>
This embodiment is a modification of the digital broadcast receiving apparatus according to the second embodiment, and is a modulation scheme in which a plurality of convolution periods exist, such as 16QAM and a coding rate of 7/8, as in the eighth embodiment. Even in the case of the system, the digital broadcast receiving apparatus is capable of detecting a TS header having a phase at which decoded data by a Viterbi decoder becomes normal byte data and performing correct phase correction.
[0192]
In the present embodiment, in the puncture decoding, which of a plurality of puncture patterns is used for each byte is detected, and information on the used puncture pattern and information on a plurality of types of convolution periods are used. The puncture pattern detector further includes a puncture pattern detector for selecting whether the TS header sandwiched between any of the plurality of types of convolution periods should be detected based on the variable-period TS header detector. As a result, the puncture pattern of the TS header is detected, and it is possible to determine from which of the plurality of types of convolution periods the detected TS header is a TS header sandwiched between which.
[0193]
In the eighth embodiment, when there are several possible arrangements of TS headers in convolutional data, the convolved TS headers are continuously stored, and decoding by the Viterbi decoder is performed depending on the difference in the interval between the TS headers. A TS header having a phase at which data can be reproduced into normal byte data is selected and detected.
[0194]
In the present embodiment, when a TS header convolved with a predetermined period is detected, a puncture period of the detected TS header is also detected at the same time, and a normal TS header position is detected from the puncture period. .
[0195]
FIG. 17 is a block diagram of a digital broadcast receiving apparatus according to the present embodiment. In FIG. 17, elements having the same functions as those of the digital broadcast receiving apparatus according to the second embodiment are denoted by the same reference numerals. The code 30 detects which of a plurality of puncture patterns is used for each byte data in the puncture decoding, and converts the information of the used puncture pattern and the information of a plurality of types of convolution periods into information. The puncture pattern detector selects a TS header sandwiched between any one of a plurality of types of convolution cycles and a selection bit number matching variable cycle TS header detector 18 based on the TS header. The other configuration is the same as that of the digital broadcast receiving apparatus according to the second embodiment, and a description thereof will not be repeated.
[0196]
Next, the operation will be described. In the transmitting apparatus of FIG. 26, the data convolved by the puncture encoder 3 is thinned out at a certain cycle. The puncturing coding of 16QAM and the coding rate of 7/8 adopts the 3/4 coding as shown in FIG. 18, and the convolutional encoder 2 and the puncture encoder 3 input 3 bits to the input. The data is thinned out according to a certain pattern so that the output becomes 4 bits.
[0197]
For example, the “A7” data is output both (X and Y) according to the puncture pattern X, Y = (○, ○) (hereinafter, referred to as puncture pattern 1), and the “A6” data is output as the puncture pattern X, Y = (○,-) (hereinafter referred to as puncture pattern 2), the Y data is thinned out, and only X data is output. The “A5” data is punctured pattern X, Y = (−, ○) (hereinafter punctured pattern 3). Puncturing coding so that X data is thinned out and only Y data is output.
[0198]
Each byte data of 16QAM and coding rate 7/8 arranged by the P / P conversion table of FIG. 27 is divided into bits by the puncture encoder 3 and the symbol sequencer 12 as shown in FIG. Symbol-mapped, digitally modulated, and transmitted. As shown in FIG. 19, the puncture pattern 1 is used for the most significant bit A7 in "A", whereas the puncture pattern 3 is used for the most significant bit F7 in "F". ing. Although not shown, the puncture pattern 2 is used for the most significant bit H7 at "H". As described above, which of the plurality of puncture patterns is used in the puncture coding is determined in advance in accordance with each of the data “A”, “F”, and “H”, and Different depending on the type.
[0199]
On the demodulation side, the I data and Q data demodulated by the digital demodulator 5 are used to map the I data and Q data to a phase diagram in the Viterbi decoder 7 to obtain convolution data. Then, the Viterbi decoder 7 performs error correction after returning the obtained convolutional data to the original signal using the same pattern as the puncture pattern at the time of puncturing encoding on the transmission side.
[0200]
At this time, there are three types of puncture-coded patterns on the transmitting side: puncture pattern 1 (use both X and Y), 2 (use only X), and 3 (use only Y). When the puncture decoding is performed, the same pattern is used to return. For example, when the received convolutional data is (Xa7, Ya7), the pattern 1 is always used (Xa7, Ya7), and when the received convolutional data is (Xa6, Ya5), the patterns 2 and 3 are used. (Xa6,-) and (-, Ya5). By finding out the combination of the pattern and the data in this way, it is possible to return to the same data as the transmitting side.
[0201]
Although the data decimated on the transmitting side cannot be recovered (data indicated by "-"), the data can be normally restored even if there is no data decimated by the error correction capability of the Viterbi decoder 7. Error correction and decoding are possible.
[0202]
In the transmission mode in which puncture encoding has been performed, the receiving side first searches for the relationship between the puncture pattern and the received data in the Viterbi decoder 7 in order to perform puncture decoding. When the relationship between the puncture pattern and the received data can be detected, the Viterbi decoder 7 reproduces the error-corrected convolutional data, and the TS header detector 18 can detect the TS header with the selected bit number matching variable period TS header detector 18.
[0203]
The selected bit number matching variable cycle TS header detector 18 detects a TS header with a cycle of 612 bytes.
[0204]
Here, at 16QAM / coding rate 7/8, A7 of “A” of P / P conversion is punctured by puncture pattern 1 and F7 of “F” is “H” by puncture pattern 3 H7 is encoded by the puncture pattern 2. Therefore, when the combination of the puncture pattern and the byte data is established and the TS header is detected, for example, if the detected TS header is "A", the head of the The puncture pattern is always 1, puncture pattern 3 for "F", and puncture pattern 2 for "H".
[0205]
Therefore, the puncture pattern detector 30 detects the first puncture pattern of the TS header detected by the selected bit number matching variable period TS header detector 18. The puncture pattern detector 30 is provided with information of a plurality of types of convolution periods (“A”, “F”, “H” information), and each puncture pattern and “A”, “F” , "H" are stored. Then, the detected puncture pattern information is fed back to the selected bit number matching variable period TS header detector 18, and any of the TS headers “A”, “F”, and “H” is selected bit number matching variable. The periodic TS header detector 18 indicates whether to detect. Thereby, the selected bit number matching variable period TS header detector 18 can determine which TS header of “A”, “F”, or “H” should be detected.
[0206]
For example, if the detected puncture pattern is 2, it can be understood that the currently detected TS header has been folded into “H”. Then, the convoluted TS header following the TS header detected by the selected-bit-number-matching variable-period TS header detector 18 is determined to be “A”. The period TS header detector 18 may set the detection period so as to detect the next TS header.
[0207]
This makes it possible to accurately detect, for example, a TS header folded into “A”. By detecting the TS header convolved with “A”, the Reed-Solomon decoder 9 performs inverse P / P conversion of the decoded data (convolution data and non-convolution data) to reproduce a byte data string, Corrects the error and can decode the data normally.
[0208]
As described above, since the puncture pattern of the detected TS header is detected and it is possible to determine the pattern of the detected TS header and the convolved TS data having the detected TS header. Even in the case of a modulation method in which a plurality of types of convolution periods exist, such as an encoding rate of 7/8, a TS header having a phase at which data decoded by a Viterbi decoder becomes normal byte data can be detected, and correct phase correction can be performed. Can be performed.
[0209]
Further, since a storage element such as a memory is not used unlike the eighth embodiment, there is an advantage that a required TS header pattern can be accurately detected with a small number of additional circuits, and correct phase correction can be quickly performed.
[0210]
【The invention's effect】
According to the first aspect of the present invention, the first synchronization signal detector changes the detection period of the synchronization signal in accordance with the period of the inner encoding, and the phase detector detects the phase of the baseband signal from the absolute phase. The angle shift is detected, and the phase converter converts the phase of the baseband signal at a different phase angle for each of a plurality of types of digital broadcast transmission signals. Therefore, even when the digital broadcast transmission signal includes a plurality of types of digital broadcast transmission signals (QPSK, 8PSK, 16QAM, etc.) as in the DSNG standard, the digital broadcast transmission signal must be compatible with each modulation scheme and coding rate. A digital broadcast receiving apparatus that can correctly correct the phase can be realized.
[0211]
According to the second aspect of the present invention, even if the first synchronization signal detector cannot detect all the specific bit arrays when detecting the synchronization signal, the first synchronization signal detector can detect a predetermined array as a part thereof. In this case, it is considered that a synchronization signal has been detected. Therefore, phase correction can be performed even for a digital broadcast transmission signal under a low C / N environment.
[0212]
According to the third aspect of the present invention, the phase converter restores the transmission signal before the phase shift keying modulation from the baseband signal demodulated by the digital demodulator, and changes the digital information of the restored transmission signal. Thus, the phase of the baseband signal is converted. Since a baseband signal is generally composed of multiple bits (for example, 8 bits), when converting the phase of the baseband signal, a circuit for converting a numerical value of multiple bits is required. When digital information of a transmission signal before keying modulation is changed, an inverter for changing the binary value may be adopted, and the circuit scale can be reduced.
[0213]
According to the fourth aspect of the present invention, the phase detector replaces the modulation method recognized by the digital demodulator, the detection result of the first synchronization signal detector, and the decoding error signal from the outer code decoder. The phase angle of the baseband signal from the absolute phase based on the modulation scheme recognized by the digital demodulator, the detection result of the first synchronization signal detector, and the detection result of the second synchronization signal detector. Detect the shift. Since it takes some time for the decoding error signal to be output from the outer code decoder, a synchronization signal is detected from the non-inner coded decoded data, and based on this detection result, the baseband signal from the absolute phase is detected. It is faster to detect a phase angle shift. Therefore, when the bytes to be encoded and the bytes not to be encoded are mixed in the digital broadcast transmission signal, the phase can be corrected quickly.
[0214]
According to the fifth aspect of the present invention, the second synchronization signal detector detects not only the synchronization signal but also another predetermined 1-byte data when the baseband signal has a specific phase angle shift. The phase detector also detects a deviation of the phase angle of the baseband signal from the absolute phase based on the detection result of the modified synchronization signal. Therefore, the deviation of the phase angle of the baseband signal from the absolute phase can be specified earlier, and the phase can be corrected more quickly.
[0215]
According to the invention described in claim 6, the phase detector is a combination of the modulation scheme recognized by the digital demodulator, the detection result of the first synchronization signal detector, and the decoding error signal from the outer code decoder. Or a combination of the modulation scheme recognized by the digital demodulator, the detection result of the first synchronization signal detector, and the detection result of the second synchronization signal detector. It further includes a first switch for selecting whether to detect a shift in the phase angle of the signal according to the calculation result of C / N in the digital demodulator. Therefore, the deviation of the phase angle of the baseband signal from the absolute phase can be detected by an optimal method suitable for the C / N of the received digital broadcast transmission signal. That is, in the case of low C / N, the first switch selects a combination including the decoding error signal from the outer code decoder so that the phase can be surely corrected. On the other hand, in the case of high C / N, , The first switch selects a combination including the detection result of the second synchronization signal detector so that quick phase correction can be performed.
[0216]
According to the invention described in claim 7, the phase detector is a combination of the modulation scheme recognized by the digital demodulator, the detection result of the first synchronization signal detector, and the decoding error signal from the outer code decoder. Or a combination of the modulation scheme recognized by the digital demodulator, the detection result of the first synchronization signal detector, and the detection result of the second synchronization signal detector. It further includes a second switch for selecting whether to detect a shift in the phase angle of the signal in accordance with the result of calculating the bit error rate in the inner code decoder. Therefore, the deviation of the phase angle of the baseband signal from the absolute phase can be detected by an optimal method that matches the value of the bit error rate reflecting the C / N of the received digital broadcast transmission signal. That is, in the case of the high bit error rate, the second switch selects a combination including the decoding error signal from the outer code decoder so that the phase can be surely corrected. On the other hand, in the case of the low bit error rate, , The second switch selects a combination including the detection result of the second synchronization signal detector, so that quick phase correction can be performed. Also, since the inner code decoder generally calculates the bit error rate, there is an advantage that an additional circuit for calculating C / N in the digital demodulator is not required as compared with the case of claim 6. There is.
[0219]
According to the eighth aspect of the present invention, a memory for continuously and sequentially storing at least some bytes decoded by the inner code decoder, and a byte of a synchronization signal among the bytes stored in the memory appear. On the basis of the information on the cycles and the information on the cycles of the plurality of types of inner coding, the first sync signal detector detects the synchronization signal sandwiched between any one of the cycles of the plurality of types of inner coding. A selection unit for selecting whether to detect. Therefore, even in the case of a modulation method in which a plurality of types of inner encoding periods exist, a synchronization signal having a phase at which data decoded by the inner code decoder becomes normal byte data can be detected, and correct phase correction can be performed.
[0218]
According to the ninth aspect of the present invention, in the puncture decoding, which of the plurality of puncture patterns is used for each byte is detected, and information on the used puncture pattern and a plurality of types of inner coding are detected. A puncture pattern detector for selecting which of the plurality of types of inner coding periods should be detected by the first synchronization signal detector based on the information on the period of Further prepare. As a result, a puncture pattern of the synchronization signal is detected, and it is possible to determine which of the plurality of types of the inner coding periods the synchronization signal is detected by the value thereof. . Therefore, even in the case of a modulation method in which a plurality of types of inner encoding periods exist, a synchronization signal having a phase at which data decoded by the inner code decoder becomes normal byte data can be detected, and correct phase correction can be performed. In addition, compared with the case of claim 8, there is an advantage that a necessary synchronization signal can be accurately detected with a small number of additional circuits because no memory is used.
[Brief description of the drawings]
FIG. 1 is a diagram showing a digital broadcast receiving apparatus according to a first embodiment.
FIG. 2 is a diagram illustrating an example of a method of calculating phase conversion in the variable phase converter 20 of the digital broadcast receiving apparatus according to the first embodiment.
FIG. 3 is a diagram illustrating an example of a −45 ° converter that obtains Qc data after phase conversion in the variable phase converter 20 of the digital broadcast receiving apparatus according to the first embodiment.
FIG. 4 is a diagram showing a Qc data generation variable phase converter included in the variable phase converter 20 in the digital broadcast receiving apparatus according to the first embodiment.
FIG. 5 is a diagram showing another configuration example of the variable phase converter 20 in the digital broadcast receiving apparatus according to the first embodiment.
FIG. 6 is a diagram illustrating a digital broadcast receiving apparatus according to a second embodiment.
FIG. 7 is a diagram showing a digital broadcast receiving apparatus according to a third embodiment.
FIG. 8 is a diagram showing a configuration example of a second variable phase converter 23 in the digital broadcast receiving apparatus according to the third embodiment.
FIG. 9 is a diagram showing a digital broadcast receiving apparatus according to a fourth embodiment.
FIG. 10 is a diagram showing a digital broadcast receiving apparatus according to a fifth embodiment.
FIG. 11 is a diagram showing data (U2, U1, C1) when the phase diagram of 8PSK and coding rate 5/6, 8/9 is shifted by a phase angle + 90 °.
FIG. 12 is a diagram showing data (U2, U1, C1) when the phase diagram of 8PSK and coding rate 5/6, 8/9 is shifted by a phase angle of + 180 °.
FIG. 13 is a diagram showing data (U2, U1, C1) when the phase diagram of 8PSK and coding rate 5/6, 8/9 is shifted by a phase angle + 270 °.
FIG. 14 is a diagram showing a digital broadcast receiving device according to a sixth embodiment.
FIG. 15 is a diagram showing a digital broadcast receiving apparatus according to a seventh embodiment.
FIG. 16 is a diagram showing a digital broadcast receiving device according to an eighth embodiment.
FIG. 17 is a diagram showing a digital broadcast receiving device according to a ninth embodiment.
FIG. 18 is a diagram illustrating puncturing encoding of 16QAM and an encoding rate of 7/8.
FIG. 19 is a diagram illustrating bit division in puncture coding of each byte data of 16QAM and a coding rate of 7/8.
FIG. 20 is a block diagram illustrating a part of the configuration of a CS digital broadcast transmitting apparatus.
FIG. 21 is a block diagram showing a conventional CS digital broadcast receiving device.
FIG. 22 is a phase diagram of QPSK.
FIG. 23 is a phase diagram of 8PSK (coding rate 2/3).
FIG. 24 is a phase diagram of 8PSK (coding rates 5/6, 8/9).
FIG. 25 is a phase diagram of 16QAM (coding rate 3/4, 7/8).
FIG. 26 is a block diagram illustrating a part of a configuration of a transmission device of the DSNG standard.
FIG. 27 is a diagram showing a P / P conversion relation table between input byte data and output data of each modulation scheme.
[Explanation of symbols]
Reference Signs List 5 digital demodulator, 7 inner code decoder (Viterbi decoder), 9 outer code decoder (Reed-Solomon decoder), 18 selected bit number matching variable period TS header detector, 19 delay unit, 20, 23 variable phase converter , 21 variable-period TS header detector, 22 variable-phase detector, 24, 25 variable-period non-convolutional TS header detector, 26, 27 switch, 28 continuous TS header memory, 29 TS header selector, 30 puncture pattern detection vessel.

Claims (9)

A digital broadcast receiving apparatus for receiving a digital broadcast transmission signal of a digital modulation method of transmitting digital information of a transmission signal as a baseband signal subjected to phase shift keying modulation,
The digital broadcast transmission signal includes a plurality of types of digital broadcast transmission signals different in at least one of the modulation scheme and the coding rate,
Each of the plurality of types of digital broadcast transmission signals includes a plurality of packets each having a predetermined number of bytes as one unit,
Each packet is a transport stream signal with an outer code,
Each packet in the transport stream signal includes a synchronization signal as predetermined 1-byte data for distinguishing one packet,
In any of the plurality of types of digital broadcast transmission signals, at least some bytes of the transport stream signal are inner-coded one by one at a predetermined cycle,
Among the plurality of types of the digital broadcast transmission signal, the predetermined period of the byte to be encoded is different,
A digital demodulator capable of receiving the plurality of types of digital broadcast transmission signals while recognizing the modulation scheme, and demodulating the digital broadcast transmission signals into the baseband signal;
Based on the demodulated baseband signal, the transport stream signal decodes at least some of the inner-coded bytes as inner-coded decoded data, and non-inner-coded data is non-inner. An inner code decoder that outputs as encoded / decoded data,
An outer code decoder that decodes the inner coded decoded data and the non-inner coded decoded data by outer coding based on the outer code, and outputs a decoded error signal when an error exists in the decoded data over a predetermined value. When,
Detecting the synchronization signal from the at least some bytes decoded by the inner code decoder, and upon detection, based on the modulation scheme recognized by the digital demodulator, the predetermined period of the inner coding. A first synchronization signal detector that changes a detection cycle of the synchronization signal in accordance with
Based on the modulation scheme recognized by the digital demodulator, the detection result of the first synchronization signal detector, and a decoding error signal from the outer code decoder, the baseband signal from the absolute phase on the transmission side A phase detector for detecting a phase angle shift of
A phase converter that converts the phase of the baseband signal at a different phase angle for each of the plurality of types of digital broadcast transmission signals based on a detection result of the phase detector. The digital broadcast receiving device according to claim 1,
The synchronization signal is data having a specific bit arrangement,
The first synchronizing signal detector detects the synchronizing signal when a predetermined sequence, which is a part thereof, can be detected even if the specific bit sequence cannot be entirely detected when detecting the synchronizing signal. Digital broadcast receiving device considered as. The digital broadcast receiving device according to claim 1,
The phase converter restores the transmission signal before phase shift keying modulation from the baseband signal demodulated by the digital demodulator,
A digital broadcast receiving apparatus that converts the phase of the baseband signal by changing digital information of the restored transmission signal. The digital broadcast receiving device according to claim 1,
Detecting the synchronization signal from the non-inner coded decoded data output from the inner code decoder, upon detection, based on the modulation scheme recognized by the digital demodulator, the predetermined of the inner coding A second synchronization signal detector that changes a detection cycle of the synchronization signal in accordance with a cycle;
The phase detector detects the modulation scheme recognized by the digital demodulator, the detection result of the first synchronization signal detector, and the decoding error signal from the outer code decoder; Based on the modulation method, the detection result of the first synchronization signal detector, and the detection result of the second synchronization signal detector, the phase angle of the baseband signal from the absolute phase Digital broadcast receiving device that detects deviation. The digital broadcast receiving device according to claim 4,
The synchronization signal detected from the non-inner coded decoded data has a predetermined conversion rule according to each of the plurality of types of digital broadcast transmission signals when a specific phase angle shift exists in the baseband signal. , And is transformed into another predetermined 1-byte data to be a transformed synchronization signal,
The second synchronization signal detector performs not only detection of the synchronization signal but also detection of the modified synchronization signal,
The digital broadcast receiving device, wherein the phase detector detects a deviation of a phase angle of the baseband signal from the absolute phase based on a detection result of the modified synchronization signal. The digital broadcast receiving device according to claim 4,
The digital demodulator calculates a C / N of the received digital broadcast transmission signal,
The phase detector is a combination of the modulation scheme recognized by the digital demodulator, a detection result of the first synchronization signal detector, and a decoding error signal from the outer code decoder, or the digital demodulator. The base from the absolute phase based on any of a combination of the modulation scheme recognized by the modulator, the detection result of the first synchronization signal detector, and the detection result of the second synchronization signal detector. Detect the shift of the phase angle of the band signal,
A digital broadcast receiving apparatus further comprising a first switch for selecting one of the two combinations in accordance with the C / N calculation result. The digital broadcast receiving device according to claim 4,
The inner code decoder compares the input data with the output inner coded decoded data and non-inner coded decoded data to be output, and calculates a bit error rate from the difference between the two.
The phase detector is a combination of the modulation scheme recognized by the digital demodulator, a detection result of the first synchronization signal detector, and a decoding error signal from the outer code decoder, or the digital demodulator. The base from the absolute phase based on any of a combination of the modulation scheme recognized by the modulator, the detection result of the first synchronization signal detector, and the detection result of the second synchronization signal detector. Detect the shift of the phase angle of the band signal,
A digital broadcast receiving apparatus further comprising a second switch that selects one of the two combinations in accordance with the calculation result of the bit error rate. The digital broadcast receiving device according to claim 1,
The plurality of types of digital broadcast transmission signals include a digital broadcast transmission signal of a modulation system in which a plurality of types of periods of byte inner encoding are present,
A memory for sequentially and sequentially storing the at least some bytes decoded in the inner code decoder;
Based on the information on the cycle in which the byte of the synchronization signal appears among the bytes stored in the memory, and the information on the plurality of types of the inner encoding cycles, one of the plurality of types of the inner encoding cycles is used. And a selection unit for selecting whether the first synchronization signal detector should detect a synchronization signal sandwiched between the digital broadcast reception device and the first synchronization signal detector. The digital broadcast receiving device according to claim 1,
The plurality of types of digital broadcast transmission signals include a digital broadcast transmission signal of a modulation system in which a plurality of types of periods of byte inner encoding are present,
The inner-coded bytes are further punctured using any of a plurality of puncture patterns,
Which of the plurality of puncture patterns is used in the puncture encoding is determined in advance in accordance with the type of the cycle of the inner encoding,
The inner code decoder performs puncture decoding on the punctured encoded bytes using any of the plurality of puncture patterns, and performs inner code decoding.
Detecting which of the plurality of puncture patterns is used for each byte in the puncture decoding, based on information on the puncture pattern used and information on the period of the plurality of types of inner coding. And a puncture pattern detector for selecting whether the first synchronization signal detector should detect a synchronization signal sandwiched between any one of the plurality of types of the inner encoding periods. Receiver.

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