JP2009225099A - Digital broadcast receiver - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a digital broadcast receiver, can shorten the time period starting from the change in broadcasting channel to the start of video and audio output. <P>SOLUTION: The digital broadcast receiver 10 receives digital broadcast of an OFDM system, and is provided with: a pilot detection part 2 which detects a position of a pilot signal from a received signal S1 from prior to the establishment of OFDM frame synchronization; a demodulation part 3 which demodulates the received signal S1, based on the position of the pilot signal detected by the pilot detection part 2 from before the establishment of the OFDM frame synchronization; a synchronization establishment part 7, which establishes the OFDM frame synchronization of the received signal S1; and a deinterleaving part 4, which performs deinterleave processing to a signal S3 demodulated by the demodulation part 3 from before the establishment of the OFDM frame synchronization. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a digital broadcast receiving apparatus that receives an OFDM digital broadcast.

  In Japanese terrestrial digital broadcasting ISDB-T (Service Integrated Terrestrial Digital Broadcasting), a plurality of groups of data of a transport stream (hereinafter referred to as TS) defined by the MPEG-2 system is used as a data segment, and the data segment A plurality of OFDM segments each having a pilot signal and a TMCC (Transmission and Multiplexing Configuration Control) signal added thereto are combined to form an OFDM symbol and an OFDM frame for transmission.

  The receiving apparatus demodulates the received signal, establishes the synchronization of the OFDM frame using the synchronization signal in the TMCC signal, separates the TMCC signal and TS from the OFDM frame, and performs TS based on the TMCC information in the decoded TMCC signal. Play the packet. That is, the reproduction of the TS packet is not started until the synchronization of the OFDM frame is established. Therefore, when the broadcast channel is changed, there is a problem that it takes time from the change to the reproduction of the TS packet.

  Patent Document 1 proposes a method for early decoding of control information included in a TMCC signal.

  Patent Document 2 discloses a method for early establishment of synchronization of an OFDM frame and reproduction of a TS packet.

JP 2001-111515 A JP 2002-84255 A

  As described above, the conventional receiving apparatus reproduces the TS packet after establishing synchronization of the OFDM frame. Therefore, there is a problem that it takes time from the change of the broadcast channel to the reproduction of the TS packet.

  Specifically, the OFDM frame synchronization signal is transmitted only once at the beginning of the OFDM frame. The synchronization establishment of the OFDM frame is usually performed by continuously detecting the OFDM frame synchronization signal a plurality of times (for example, twice). For this reason, in order to establish synchronization of the OFDM frame, it is necessary to receive at least one OFDM frame. Actually, since the reception start is not necessarily the beginning of the OFDM frame, at least two OFDM frames must be received before the synchronization of the OFDM frame is established.

  One OFDM frame of terrestrial digital broadcasting is about 231 msec, which is a MODE3 transmission system currently being broadcast. If two OFDM frames are required until the synchronization of the OFDM frame is established, it is about 462 msec.

  In the method of Patent Document 1, the TMCC signal can be decoded before the synchronization of the OFDM frame is established, and the reproduction of the TS packet can be started before the synchronization of the OFDM frame is established.

  Also, in the method of Patent Document 1, before OFDM frame synchronization is established, every time a divided TMCC packet is received, a method of searching the beginning of the OFDM frame while shifting the order of each received divided TMCC packet is presented. Yes. By using this method, it is possible to accurately know in which OFDM symbol position in the OFDM frame the received divided TMCC packet is located before establishing the OFDM frame synchronization.

  In the method of Patent Document 2, TS packets can be reproduced at 0th symbol, 51st symbol, 102nd symbol, and 153th symbol in one OFDM frame in MODE3 of digital terrestrial broadcasting. When combined with the method of Patent Document 1, OFDM frame synchronization can be established and TS packet reproduction can be started at any of the 0th, 51st, 102nd, and 153th symbols.

  However, in digital terrestrial broadcasting, a time interleaving method that is convolutional interleaving is adopted, and in the receiving apparatus, time deinterleaving processing is performed between demodulation processing and TS reproduction processing. In this time deinterleaving process, time of about 1 OFDM frame is required. Therefore, even if the methods of Patent Documents 1 and 2 are used, a maximum of about 3 frames are required from the time when the broadcast channel is changed until the TS packet is reproduced. Reception of the OFDM frame is required.

  The present invention has been made to solve the above-described problems, and provides a digital broadcast receiving apparatus that can shorten the time from the change of a broadcast channel to the reproduction of a TS packet (and thus the start of video / audio output). With the goal.

  In order to solve the above-mentioned problem, a first form of the present invention is a digital broadcast receiving apparatus that receives an OFDM digital broadcast, and detects the position of a pilot signal from the received signal before the establishment of OFDM frame synchronization. A pilot detector, a demodulator that demodulates the received signal based on the position of the pilot signal detected by the pilot detector before the establishment of OFDM frame synchronization, and a demodulator that demodulates the received signal before the establishment of OFDM frame synchronization. And a deinterleaving unit that performs a deinterleaving process on the received signal.

  According to the first aspect of the present invention, since the deinterleaving process is performed before the OFDM frame synchronization is established, the deinterleaving process is performed at a point earlier than the conventional case (when the deinterleaving process is performed after the OFDM frame synchronization is established). As a result, the time from the change of the broadcast channel to the start of video / audio output can be shortened compared to the conventional case.

Embodiment 1 FIG.
A digital broadcast receiving apparatus 10 according to this embodiment receives an OFDM digital broadcast. As shown in FIG. 1, an FFT unit 1, a pilot detection unit 2, a demodulation unit 3, and a deinterleave unit 4, TS reproduction unit 5, error correction unit 6, synchronization establishment unit 7, TMCC decoding unit 8, and TMCC initial unit 9.

  For example, as shown in FIG. 2, an OFDM transmission signal includes a TS for video signal and audio signal, a pilot signal of CP (Continual Pilot) and SP (Scattered Pilot), a TMCC signal, and an AC1 (Auxiliary Chanel1). And an additional information signal of AC2. This transmission signal is orthogonal frequency division multiplexed (OFDM) using a plurality of carriers, and time-divided in units of OFDM symbols to form one OFDM frame with a plurality of OFDM symbols.

  2 is a data segment of OFDM symbol number i and carrier number j, and TS data is arranged in each Sij.

  The FFT unit 1 performs a fast Fourier transform (FFT) process on the received OFDM modulated signal (received signal) S1 of each broadcast channel. Note that the carrier and the clock are regenerated from the received OFDM modulated signal by a separate circuit (not shown).

  The pilot detection unit 2 detects the position of a pilot signal (for example, SP) from the signal S2 processed by the FFT unit 1. Since the pilot signal is inserted in the signal S2 at a constant carrier interval, the position of the pilot signal can be easily detected by checking the correlation of the signal S2. For example, in the case of SP, as shown in FIG. 2, each OFDM symbol is inserted at an interval of 12 carriers, and the arrangement of the insertion differs depending on the OFDM symbol number. There are three.

Pattern 0: 0, 12, 24 ... Carrier pattern 1: 3, 15, 27 ... Carrier pattern 2: 6, 18, 30 ... Carrier pattern 3: 9, 21, 33 ... Carrier SP is Since the power value is high, if the power values of the carriers of the above patterns 0 to 3 are multiplied and summed in the symbol, the product sum result of the pattern in which the pilot signal is actually arranged is Compared, the value protrudes greatly. Using this, the position of the SP is detected. Specifically, the carrier power value is calculated at the carrier positions shown in the patterns 0 to 3, and the calculated power value is summed for one symbol period for each pattern. When the reception of one symbol is completed, the value of the product-sum result of each of the four patterns is compared, and it is detected which pattern has the maximum power value, that is, which pattern has the pilot signal To do.

  Conventionally, the position of the pilot signal is detected after the synchronization of the OFDM frame is established and the arrangement of the pilot signal is determined. In this embodiment, as described above, based on the correlation of the signal S2. Thus, it is performed before the synchronization of the OFDM frame is established.

  Based on the pilot signal arrangement information T1 detected by the pilot detection unit 2 and the TMCC information U1 from the TMCC initial unit 9 or the TMCC information U2 from the TMCC decoding unit 8, the demodulation unit 3 performs processing in the FFT unit 1. The demodulated signal S2 is demodulated.

  More specifically, the demodulator 3 performs the above-described demodulation processing based on the TMCC information U1 from the TMCC initial unit 9 during the period until the TMCC information U2 is extracted from the signal S2 by the TMCC decoder 8 as described later. When the TMCC information U2 is extracted from the signal S2 by the TMCC decoding unit 8, the above demodulation processing is performed based on the TMCC information U2 from the TMCC decoding unit 8.

  Based on the TMCC information U1 from the TMCC initial unit 9 or the TMCC information U2 from the TMCC decoding unit 8, and the frame synchronization signal V1 and the frame synchronization establishment signal V2 from the synchronization establishing unit 7, the deinterleaving unit 4 Deinterleaving processing (for example, frequency deinterleaving processing and time deinterleaving processing) is performed on the signal S2 processed in (1).

  On the transmission side, interleaving processing (for example, time interleaving processing and frequency interleaving processing) for ensuring mobile reception performance and multipath resistance is performed. A convolutional interleaving process is employed for the time interleaving process. For example, in the case of the MODE 3 transmission method, the interleave length can be set to any value of 0, 1, 2, and 4. On the receiving side (deinterleaving unit 4), processing for returning the interleaving processing performed on the transmitting side is performed.

  More specifically, the deinterleaving unit 4 receives a period from the TMCC initial unit 9 until TMCC information U2 is extracted from the signal S2 by the TMCC decoding unit 8 as described later (that is, before OFDM frame synchronization is established). When the above deinterleaving process is performed based on the TMCC information U1 and the TMCC information U2 is extracted from the signal S2 by the TMCC decoding unit 8 (that is, after the synchronization of the OFDM frame is established), the TMCC information U2 from the TMCC decoding unit 8 Based on the above, the deinterleaving process is performed. When the frame synchronization establishment signal V2 from the synchronization establishment unit 7 is input, the deinterleaving unit 4 outputs the signal S4 subjected to the deinterleaving process to the TS reproduction unit S5.

  In the deinterleaving unit 4, a delay based on the interleaving length occurs from the input of the signal S3 from the demodulation unit 3 to the output of the signal S4 after the deinterleaving process. The interleaving length determines the capacity of the delay line in the time deinterleaving process, and the time until the signal S4 is output through this delay line is the delay time in the time deinterleaving process. For example, this delay time is as follows when the interleave length is 0, 1, 2, 3, 4 in the MODE 3 transmission method.

When MODE3 and interleave length are 0 Delay time = none When MODE3 and interleave length are 1 Delay time = 96 * OFDM symbol When MODE3 and interleave length are 2 Delay time = 96 * 2 * OFDM symbol = 192 * OFDM symbol MODE3 When the interleaving length is 4, delay time = 96 * 4 * OFDM symbol = 384 * OFDM symbol In the broadcast that is actually used, MODE3 and interleaving length = 2, so that a delay of 192 * OFDM symbol = about 218 msec Will occur.

  In this embodiment, since the deinterleaving unit 4 performs the deinterleaving process before the synchronization of the OFDM frame is established, the signal S4 corresponding to the above delay time is accumulated at the time when the synchronization of the OFDM frame is established. The By this accumulation, the signal S4 can be output to the TS reproduction unit 5 immediately after the OFDM frame synchronization is established, and the TS reproduction unit 5 can immediately reproduce the TS packet.

  The TS reproducing unit 5 reproduces (assembles) a TS packet from the signal S4 processed by the deinterleaving unit 5 based on TMCC information U2 described later from the TMCC decoding unit 8 and a frame synchronization signal V1 from the synchronization establishing unit 7. )

  The error correction unit 6 performs error correction processing for each TS packet on the TS packet S5 reproduced by the TS reproduction unit 6, and outputs a TS packet having no error as a TS packet S6 without error as a result of the processing. To do. The error-free TS packet S6 is reproduced as an audio image by a subsequent processing unit.

  The synchronization establishing unit 7 detects the frame synchronization signal V1 from the signal S2 processed in the FFT process 1, and outputs the frame synchronization signal V1 to the units 3, 4, 5, and 6. When the synchronization establishment unit 7 establishes the synchronization of the OFDM frame based on the detected frame synchronization signal, the synchronization establishment unit 7 outputs a frame synchronization establishment signal V2 to the deinterleaving unit 4.

  The TMCC decoding unit 8 separates the TMCC signal from the signal S2 processed in the FFT processing 1 based on the frame synchronization signal V1 detected by the synchronization establishing unit 7, demodulates and decodes the TMCC signal, and outputs the TMCC information U2. To extract.

  The TMCC initial unit 9 stores the TMCC information U2 extracted by the TMCC decoding unit 8 at the time of selecting each broadcast channel, and when the same broadcast channel is selected again, the TMCC decoding unit 8 uses the signal S2 from the signal S2. During the period until the TMCC information U1 is extracted, the TMCC information U2 of the same broadcast channel is output as TMCC information U1 to the units 3 and 4 from the stored TMCC information U2.

  Next, the operation of the digital broadcast receiving apparatus 10 will be described.

  When the received signal S1 is subjected to FFT processing in the FFT unit 1, the processed signal S2 is output to the pilot detecting unit 2, the synchronization establishing unit 7, and the TMCC decoding unit 8.

  The pilot detection unit 3 detects the position of the pilot signal based on the correlation of the signal S2 from the signal S2 from the FFT unit 1 before establishing the synchronization of the OFDM frame, and information on the position of the pilot signal together with the signal S2. T1 is output to the demodulator 3. In parallel with this, TMCC information U2 is output from the TMCC initial unit 9 to the demodulating unit 3 and the deinterleaving unit 4.

  Then, in the demodulator 3, the pilot signal position information T 1 from the pilot detector 2 and the TMCC information U 1 from the TMCC initial unit 9 with respect to the signal S 2 from the pilot detector 2 before the synchronization of the OFDM frame is established. Based on this, a demodulation process is performed, and the processed signal S3 is output to the deinterleave unit 3. In the deinterleaving unit 3, before the synchronization of the OFDM frame is established, the signal S3 from the demodulation unit 3 is deinterleaved based on the TMCC information U1 from the TMCC initial unit 9, and the signal S4 after the processing is accumulated. Is done.

  On the other hand, in the synchronization establishing unit 7, the frame synchronization signal V1 is detected from the signal S2 from the FFT unit 1, and when the frame synchronization signal V1 is detected, the frame synchronization signal V1 is converted into each unit 4, 5, 6, 8 Is output. Further, when the frame synchronization is established, the synchronization establishment unit 7 outputs a frame synchronization establishment signal V2 to the units 4 and 8.

  On the other hand, the TMCC decoding unit 8 separates the TMCC signal from the signal S2 from the FFT unit 1 based on the frame synchronization signal V1 and the frame synchronization establishment signal V2 from the synchronization establishment unit 7, and the TMCC signal is demodulated and decoded. TMCC information U2 is extracted from the TMCC signal, and the TMCC information U2 is output to each of the units 3, 4, 5, 6 and 9.

  When the TMCC information U2 from the TMCC decoding unit 8 is input, the TMCC initial unit 9 stores the TMCC information U2. In addition, when the TMCC information U2 from the TMCC decoding unit 8 is input, the demodulation unit 3 performs demodulation processing based on the TMCC information U2 from the TMCC decoding unit 8 instead of the TMCC information U1 from the TMCC initial unit 9. To continue. In addition, when the TMCC information U2 from the TMCC decoding unit 8 is input, the deinterleaving unit 4 replaces the TMCC information U1 from the TMCC initial unit 9 with the TMCC information U2 from the TMCC decoding unit 8 based on the TMCC information U2. Continue interleaving.

  In the deinterleaving unit 4, when the frame synchronization establishment signal V 2 from the synchronization establishment unit 7 is input, the deinterleaved signal S 4 is output to the TS reproduction unit 5.

  In the TS reproduction unit 5, the TS is separated from the signal S4 from the deinterleaving unit 4 based on the TMCC information U2 from the TMCC decoding unit 8 and the frame synchronization signal V1 from the synchronization establishment unit 7, and the TS packet S5 is reproduced. The TS packet S5 is output to the error correction unit 6. Then, the error correction unit 6 performs error correction processing on the TS packet S5, and the error correction unit 6 outputs an error-free TS packet S6. Then, the TS packet S6 is played back as an audio video by a processing unit at a later stage.

  As described above, in the digital broadcast receiving apparatus 10, the pilot detection unit 2 detects the position of the pilot signal from the signal S2 before the synchronization of the OFDM frame is established based on the correlation of the signal S2. Then, the respective processes of the demodulator 3 and the deinterleave unit 4 are sequentially started before the establishment of the OFDM frame synchronization, and the processing of the TS reproduction unit 5 is started simultaneously with the establishment of the OFDM frame synchronization. As a result, after the broadcast channel is changed, TS packet playback in the TS playback unit 5 is started earlier than before (therefore, an audio image is output earlier than before).

  In this embodiment, for example, as shown in FIG. 3, since the reproduction of the TS packet in the TS reproducing unit 4 is started simultaneously with the establishment of the synchronization of the OFDM frame, an error from the start of the detection of the frame synchronization signal in the synchronization establishing unit 7 The period until the start of output of error-free TS packets in the correction unit 6 is 1 OFDM frame at the shortest, and 2 OFDM frames at the longest.

  On the other hand, in the prior art, after the OFDM frame synchronization is established, the processes of the pilot detection unit 2, the demodulation unit 3, the deinterleaving unit 4, the TS reproduction unit 5, and the error correction unit 6 are started in order. 4, the period from the start of detection of the frame synchronization signal at the synchronization establishment unit 7 to the start of output of the TS packet without error from the error correction unit 6 is about 2 OFDM frames at the shortest, and about 3 OFDM frames at the longest. It becomes.

  Therefore, in this embodiment, the period from the detection start of the frame synchronization signal in the synchronization establishment unit 7 to the start of the output of the TS packet without error in the error correction unit 6 (according to the broadcast channel) is therefore higher than in the prior art. It can be seen that the time from the time of change to the start of audio-video output is shortened.

  According to the digital broadcast receiving apparatus 10 configured as described above, the deinterleaving unit 4 performs the deinterleaving process before the OFDM frame synchronization is established, so in the conventional case (when the deinterleaving process is performed after the OFDM frame synchronization is established). The deinterleaving process can be completed at an earlier point in time, so that the time from the change of the broadcast channel to the start of video / audio output can be shortened compared to the conventional case.

  Further, when the OFDM frame synchronization is established by the synchronization establishment unit 7, the deinterleaving unit 4 outputs the signal S4 that has been subjected to the deinterleaving process. The time from the change of the broadcast channel to the start of video / audio output can be shortened compared to the conventional case.

  In addition, in this embodiment, as in Patent Document 2, in the case of the MODE 3 transmission method, the synchronization position of the OFDM frame is set not only at the position of the 0th symbol but also at the 51st, 102nd, and 153rd symbols, If the initial value of the randomizer of the error correction unit 6 is changed, the time until the output of the TS packet S6 from the error correction unit 7 can be further shortened.

Embodiment 2. FIG.
A digital broadcast receiving apparatus 10B (FIG. 5) according to this embodiment is a modification of the first embodiment. Only the parts different from the first embodiment will be described below.

  In this embodiment, the deinterleaving unit 4 outputs the deinterleaved signal S4 promptly without waiting for the establishment of OFDM frame synchronization.

  According to the method defined in the digital terrestrial broadcasting standard, the derandomizer in the error correction unit 6 is initialized for each OFDM frame header. Also, TS packet playback (hereinafter referred to as TS playback) in the TS playback unit 5 is initialized for each OFDM frame header. For this reason, unless the synchronization of the OFDM frame is established, the TS reproduction process in the TS reproduction unit 5 and the error correction process in the error correction unit 6 are not correctly performed. Therefore, normally, the signal S4 is not output from the deinterleaving unit 4 until the synchronization of the OFDM frame is established as in the first embodiment.

  In this embodiment, since the signal S4 is output from the deinterleave unit 4 before the OFDM frame synchronization is established, the position of the OFDM frame header cannot be specified (that is, the OFDM frame synchronization cannot be established). Therefore, initialization of TS reproduction of the TS reproduction unit 5 and initialization of the derandomizer in the error correction unit 6 cannot be performed correctly.

  In order to solve this, the error correction unit 6 initializes a derandomizer for each OFDM symbol header and performs error correction processing until the OFDM frame synchronization is established. The deinterleaving unit 4 specifies the position of the OFDM frame header of the output signal S4 based on the error correction processing result of the error correction unit 6, and based on the position of the specified OFDM frame header, the TS reproduction unit 5 The error correction unit 6 performs initialization.

  More specifically, when the signal S4 is output from the deinterleaving unit 4 before the establishment of OFDM synchronization, the TS reproduction unit 4 synchronizes each OFMD symbol header of the signal S4 and initializes TS reproduction based on the synchronization. The TS packet S5 is reproduced from the signal S4.

  Then, when the signal S5 is output from the TS reproduction unit 5 before the OFDM synchronization is established, the error correction unit 6 performs synchronization for each OFMD symbol header of the signal S5 and initializes the derandomizer based on the synchronization, Error correction processing is performed on the signal S5 for each TS packet. Then, as shown in FIG. 5, the error correction unit 6 outputs the error correction processing result (presence / absence of error) 6A to the deinterleave unit 4, and if there is no error as a result of the error correction processing, there is no error. The TS packet S6 is output.

  The deinterleaving unit 4 specifies the position of the OFDM frame header of the output signal S4 based on the error correction result 6A from the error correction unit 6. That is, when the error correction processing result 6A corresponding to the output OFDM symbol has no error, the deinterleaving unit 4 specifies the header of the output OFDM symbol as an OFDM frame header (that is, the output OFDM symbol) The OFDM symbol header for each OFDM frame interval is specified as the OFDM frame header with reference to the symbol).

  When the deinterleaving unit 4 specifies the position of the OFDM frame header of the output signal S4, the position of the specified OFDM frame header in the deinterleaved signal S4 (that is, using the output OFDM symbol as a reference) Information indicating that it is the header of the OFDM frame (hereinafter referred to as OFDM frame header information) is added to the position of the OFDM symbol header for each OFDM frame interval), and signal S4 is output to TS reproduction section 5.

  On the other hand, when the error correction result 6A corresponding to the output OFDM symbol has an error, the deinterleaving unit 4 determines that the header of the output OFDM symbol is not an OFDM frame header.

  Then, the TS reproducing unit 5 detects the OFDM frame header information for the signal S4 from the deinterleave unit 4, and until the OFDM frame header information is detected from the signal S4, as described above. Synchronization is performed for each OFMD symbol header of the signal S4, and the reproduction of the TS packet is initialized based on the synchronization. When the OFDM frame header information is detected from the signal S4, the OFDM frame header information is detected thereafter. Synchronization is performed only at the position, and reproduction of the TS packet is initialized based on the synchronization, and the TS packet S5 is reproduced from the signal S4 as described above.

  When the TS reproducing unit 5 detects the OFDM frame header information, the TS reproducing unit 5 adds the OFDM frame header information to the position of the OFDM frame header of the signal S5 and outputs the signal S5.

  Then, the error correction unit 6 detects the OFDM frame header information for the signal S5 from the TS reproduction unit 5, and until the OFDM frame header information is detected from the signal S5, as described above. Synchronization is performed for each OFMD symbol header of the signal S5, and the derandomizer is initialized based on the synchronization. When the OFDM frame header information is detected from the signal S5, only the position where the OFDM frame header information is detected thereafter. Synchronize with and initialize the derandomizer based on the synchronization. Then, as described above, error correction processing is performed on the signal S5 for each TS packet, and the processing result 6A is output to the deinterleaving unit 4.

  After the OFDM frame synchronization is established by the synchronization establishment unit 7, the TS reproduction unit 5 and the error correction unit 6 are synchronized on the basis of the frame synchronization signal from the synchronization establishment unit 7, and TS reproduction processing and error are respectively performed. Correction processing may be performed.

  In this embodiment, since TS reproduction in the TS reproduction unit 4 is started before the synchronization of the OFDM frame is established, the error correction unit 6 starts from the detection of the frame synchronization signal in the synchronization establishment unit 7 as shown in FIG. The period until the start of error-free TS output is shorter than in the case of Embodiment 1, and it does not take 1 OFDM frame at the shortest and takes 2 OFDM frames at the longest.

  According to the digital broadcast receiving apparatus 10B configured as described above, the TS reproduction unit 5 synchronizes the signal S4 from the deinterleaving unit 4 for each OFDM symbol header of the signal S4, and based on the synchronization, the TS The error correction unit 6 synchronizes the TS packet S5 from the TS reproduction unit 5 for each OFDM symbol header of the TS packet S5, and performs error correction processing based on the synchronization. Then, the deinterleaving unit 4 specifies the position of the OFDM frame header of the output signal S4 based on the result 6A of the error correction processing of the error correction unit 6. When the deinterleaving unit 4 specifies the position of the OFDM frame header, the TS playback unit 5 changes the synchronization for each OFDM symbol header from the synchronization for each specified OFDM frame header, and performs TS playback based on the changed synchronization. The error correction unit 6 also changes from synchronization for each OFDM symbol header to synchronization for the specified OFDM frame header, and performs error correction processing based on the changed synchronization. Therefore, the TS reproduction process of the TS reproduction unit 5 and the error correction process of the error correction unit 6 are performed without using the synchronization signal from the synchronization establishment unit 7 (therefore, before the establishment of the OFDM frame synchronization by the synchronization establishment unit 7). As a result, the time from the change of the broadcast channel to the start of video / audio output can be further shortened compared to the conventional case.

  Further, when the deinterleave unit 4 identifies the position of the OFDM frame header of the output signal S4, the deinterleave unit 4 adds OFDM frame header information to the position of the identified OFDM frame header in the deinterleaved signal S4, and after the processing The TS reproduction unit 5 detects the OFDM frame header information for the signal S4 from the deinterleaving unit 4 and synchronizes at the position where the OFDM frame header information is detected. It is possible to make the unit 5 appropriately take the OFDM frame synchronization.

  Further, the TS reproducing unit 5 adds OFDM frame header information to the position of the OFDM frame header specified by the deinterleave unit 4 in the reproduced TS packet S5, and outputs the reproduced TS packet S5, and the error correcting unit 6 Detects the OFDM frame header information from the TS packet from the TS reproduction unit 5 and synchronizes at the position where the OFDM frame header information is detected, so that the error correction unit 6 can appropriately synchronize the OFDM frame. I can do things.

1 is a schematic configuration diagram of a digital broadcast receiving device 10 according to Embodiment 1. FIG. It is a figure explaining an example of a structure of a transmission signal. FIG. 10 is a diagram for explaining the time from the start of detection of frame synchronization at the synchronization establishment unit 7 to the output of an error-free TS packet from the error correction unit 6 in the case of the first embodiment. It is a figure explaining the time from the detection start of the frame synchronization in a synchronous establishment part in the conventional case to the TS packet without an error being output from an error correction part. FIG. 5 is a schematic configuration diagram of a digital broadcast receiving device 10B according to Embodiment 2. FIG. 10 is a diagram for explaining the time from the start of detection of frame synchronization at the synchronization establishment unit 7 to the output of an error-free TS packet from the error correction unit 6 in the case of the second embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 FFT part, 2 Pilot detection part, 3 Demodulation part, 4 Deinterleaving part, 5 TS reproduction | regeneration part, 6 Error correction part, 6A Information of the result of an error correction process, 7 Synchronization establishment part, 8 TMCC decoding part, 9 TMCC initial stage Unit, 10, 10B digital broadcast receiver, S1 received signal, signal processed by S2 FFT unit, signal processed by S3 demodulator, signal processed by S4 deinterleave unit 4, reproduced by S5 TS playback unit 5 TS packet, S6 error-free TS packet, T1 pilot signal position information, TMCC information stored in the U1 TMCC initial part, U2 TMCC information, V1 frame synchronization signal, V2 frame synchronization establishment signal.

Claims (5)

A digital broadcast receiver for receiving an OFDM digital broadcast,
A pilot detector that detects the position of the pilot signal from the received signal before the OFDM frame synchronization is established;
A demodulator that demodulates the received signal based on the position of the pilot signal detected by the pilot detector before establishing OFDM frame synchronization;
A deinterleaving unit that performs a deinterleaving process on the signal demodulated by the demodulating unit before establishing the OFDM frame synchronization;
A digital broadcast receiving apparatus comprising: A synchronization establishing unit for establishing OFDM frame synchronization of the received signal;
The digital broadcast receiving apparatus according to claim 1, wherein the deinterleaving unit outputs a signal obtained by performing the deinterleaving process when OFDM frame synchronization is established by the synchronization establishing unit. A TS reproduction unit that synchronizes the signal output from the deinterleave unit for each OFDM symbol header of the signal, and reproduces a TS packet from the signal based on the synchronization;
The TS packet output from the TS reproduction unit is further synchronized with each OFDM symbol header of the TS packet, and further includes an error correction unit that performs error correction processing on the TS packet based on the synchronization,
The deinterleaving unit specifies the position of the OFDM frame header of the output signal based on the error correction processing result of the error correction unit,
When the deinterleaving unit specifies the position of the OFDM frame header, the TS playback unit changes from synchronization for each OFDM symbol header to synchronization for each specified OFDM frame header, and the above TS based on the changed synchronization. Play the packet,
When the deinterleaving unit specifies the position of the OFDM frame header, the error correction unit changes the synchronization for each OFDM symbol header from the synchronization for each OFDM symbol header, and the TS described above based on the changed synchronization. The digital broadcast receiving apparatus according to claim 1, wherein packet error correction processing is performed. When the position of the OFDM frame header of the output signal is specified, the deinterleave unit adds the OFDM frame header information to the position of the specified OFDM frame header in the deinterleaved signal, and outputs the signal.
The TS reproduction unit detects the OFDM frame header information with respect to a signal from the deinterleave unit, and synchronizes at a position where the OFDM frame header information is detected. Digital broadcast receiver. The TS reproduction unit adds OFDM frame header information to the position of the OFDM frame header specified by the deinterleave unit in the reproduced TS packet, and outputs the reproduced TS packet.
5. The error correction unit detects the OFDM frame header information for a TS packet from the TS reproduction unit, and synchronizes at a position where the OFDM frame header information is detected. Digital broadcast receiver.

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