JP4215420B2 - Digital broadcast receiver - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a digital broadcast receiver, and more particularly to a terrestrial digital broadcast receiver that receives a signal modulated by an orthogonal frequency division multiplexing (OFDM) transmission method.
[0002]
[Prior art]
In recent years, an orthogonal frequency division multiplexing (OFDM) system has been proposed as a system excellent in high-quality transmission and frequency efficiency improvement in a system for transmitting video signals or audio signals. OFDM (Orthogonal Frequency Division Multiplexing) is an orthogonal frequency division multiplexing scheme, that is, a multiplexing scheme in which each carrier wave is orthogonalized and digitally modulated for each carrier wave. In the terrestrial digital broadcasting scheduled to start broadcasting from 2003, this OFDM method is adopted.
[0003]
For example, digital terrestrial television broadcasting based on the standard ARIB STD-B31 of the Japan Radio Industry Association (hereinafter referred to as “ARIB”) divides the transmission band of one channel into 13 bands (OFDM segments). The OFDM segment is a basic band (1/13 of the TV channel band) signal of a transmission signal obtained by adding a control signal carrier to a data carrier.
[0004]
In the transmission band of one channel divided into 13 segments, transmission parameters and information to be transmitted can be set for each segment.
[0005]
For this reason, it is possible to broadcast a high-definition television broadcast on one channel, or to broadcast various services such as a plurality of standard television broadcasts and data broadcasts on one channel.
[0006]
Also, by setting the transmission parameters of some segments to be strong against interference, it is possible to provide services suitable for reception by mobile objects such as automobiles and reception of mobile terminals in addition to reception at home. .
[0007]
On the other hand, in the terrestrial digital audio broadcasting defined in the standard ARIB STD-B29 etc., there are two broadcastings, one segment method using one OFDM segment having the same structure as that of digital television broadcasting and three segment method using three OFDM segments. Form is planned.
[0008]
FIG. 8 is a diagram showing a segment structure of a one-segment audio broadcasting.
Referring to FIG. 8, the one-segment audio broadcasting is scheduled to transmit voice and data to a receiver using one OFDM segment having a bandwidth of about 429 kHz. The data includes, for example, characters, still images, simple moving images, and the like.
[0009]
FIG. 9 is a diagram showing a segment structure of a three-segment audio broadcasting.
Referring to FIG. 9, the three-segment audio broadcasting is scheduled to transmit voice and data to a receiver using three OFDM segments having a bandwidth of about 429 kHz. The data includes, for example, characters, still images, simple moving images, and the like. Three-segment audio broadcasting can transmit higher-quality images and higher-quality images than the one-segment audio broadcasting.
[0010]
The three-segment audio broadcasting uses three segments as shown in FIG. 9, but the central segment can be received by a one-segment receiver. Thus, receiving a part of the three segments is called partial reception. A segment that is partially received is referred to as a partially received segment.
[0011]
In order to receive a 3-segment broadcast signal, it is first necessary to determine whether the input signal is a 1-segment signal or a 3-segment signal. Therefore, the receiver receives only the partial reception segment and demodulates a transmission and multiplexing configuration control (TMCC) signal transmitted in the partial reception segment. In addition to the synchronization word and various transmission parameters, the TMCC signal includes identification information indicating whether the broadcast is in the 1-segment format or the 3-segment format.
[0012]
FIG. 10 is a block diagram showing a configuration of a front end block 500 of a conventional terrestrial digital broadcast receiver.
[0013]
Referring to FIG. 10, a high frequency signal input (RF signal input) input from an antenna (not shown) is input to tuner unit 504. The tuner unit 504 down-converts the RF signal to an intermediate frequency (IF frequency), extracts a desired frequency with an IF filter, and further performs frequency conversion to convert the IF frequency signal into a baseband signal.
[0014]
The baseband signal is input to the A / D conversion unit 506. In the A / D conversion unit 506, the baseband signal is converted from an analog signal to a digital signal.
[0015]
The output of the A / D conversion unit 506 is given to the synchronization processing unit 508. The synchronization processing unit 508 is a Hilbert transform unit 532 that performs Hilbert transform, a delay circuit 534 that performs delay processing, and a processing unit 536 that performs narrowband automatic frequency tuning (AFT), clock recovery, and symbol synchronization processing. Including. The processing unit 536 includes a real axis (hereinafter referred to as “I axis”) component signal (in-phase detection axis signal) and an imaginary axis (hereinafter referred to as “Q axis”) component signal (orthogonal detection axis signal). Is output. The in-phase detection axis signal and the quadrature detection axis signal are provided to a fast Fourier transform unit (hereinafter referred to as “FFT unit”) 510.
[0016]
The FFT unit 510 performs fast Fourier transform on the input signal to convert time axis data into frequency axis data. The output of the FFT unit 510 is given to the broadband AFT unit 512. Broadband AFT section 512 adjusts the frequency deviation in units of carrier intervals in each broadcasting form by performing pattern matching of a large number of pilot signals arranged at arrangement positions defined in a predetermined standard in the data.
[0017]
When the frequency shift in the carrier interval unit is adjusted, the frame synchronization / TMCC decoding unit 514 decodes a TMCC (Transmission and Multiplexing Configuration Control) signal by 1 bit per symbol. The TMCC signal includes a synchronization word and various transmission parameters.
[0018]
When a TMCC signal for one frame is decoded, a frame head position is determined by detecting a synchronization word, and frame synchronization is achieved. Thereafter, error correction of the TMCC signal is performed, and the demodulation unit 518 performs DQPSK (Differential Quadrature Phase Shift Keying), 16QAM (Quadrature Amplitude Modulation), 64 QAM, QPSK (Quadrature Phase Shift Keying) based on various transmission parameters included in the TMCC signal. ) Is determined and demodulated. The output of demodulator 518 is applied to post-processor 522 that performs deinterleaving and error correction.
[0019]
The post-processing unit 522 includes a frequency deinterleaving unit 542, a time deinterleaving unit 544, a demapping unit 546, a bit deinterleaving unit 548, a multiple frame configuration unit 550, a Viterbi decoding unit 552, and a byte deinterleaving unit. 554, an energy diffusion unit 556, and an RS decoding unit 558.
[0020]
The frequency deinterleaving unit 542 performs processing to restore the frequency interleaving performed to compensate for the loss of a signal of a specific frequency due to radio wave reflection or the like. The output of the frequency deinterleave unit 542 is given to the time deinterleave unit 544. The time deinterleaving unit 544 performs processing for restoring the time interleaving performed for pair fading and the like.
[0021]
The I-axis component signal and Q-axis component signal subjected to time deinterleaving are processed by a demapping unit 546 in 6 bits (in the case of QPSK), 12 bits (in the case of 16QAM) or 18 bits (in the case of 64QAM). Each is converted to a signal.
[0022]
In the signal converted by the demapping unit 546, the bit interleaving performed for the purpose of increasing error resilience is canceled by the bit deinterleaving unit 548, and then the convolution performed by the Viterbi decoding unit 552 on the transmission side Error correction is performed using the code.
[0023]
Similarly to bit interleaving, the signal subjected to Viterbi decoding is subjected to energy spread processing after byte interleaving performed for the purpose of increasing error resilience is canceled in the byte deinterleaving unit 554, and Reed-Solomon decoding (hereinafter referred to as Reed-Solomon decoding) The RS decoding unit 558 performs “RS decoding”. The RS decoding unit 558 outputs the transport stream TS that has been error-corrected.
[0024]
In the transport stream TS, a compressed signal is expanded in an MPEG decoding unit (not shown), and converted into an analog video or analog audio via a digital / analog conversion unit (not shown).
[0025]
In the receiver as shown in FIG. 10, the tuner unit 504, the synchronization processing unit 508, the FFT unit 510, and the broadband AFT are internally switched between when receiving a 1-segment broadcast and when receiving a 3-segment broadcast. It is normal.
[0026]
For example, in the tuner unit 504, when the received signal is a one-segment signal, the built-in IF filter pass bandwidth is set to one segment width, and when the received signal is a three-segment signal, the built-in IF filter pass bandwidth is set. The width is 3 segments. In this case, when the signal is a one-segment signal, if the pass band width of the IF filter remains wide, signal deterioration due to interference between adjacent channels is expected, so this signal deterioration is avoided.
[0027]
Further, for example, in the FFT unit, switching is performed according to the number of segments of the received signal so as to perform calculation for the number of points corresponding to the number of received segments.
[0028]
[Problems to be solved by the invention]
Considering a receiver that can receive both the 1-segment broadcast and the 3-segment broadcast, it is expected that a certain amount of time will be required until the 3-segment broadcast can be normally received.
[0029]
FIG. 11 is a diagram illustrating the signal processing when the three-segment audio broadcast is received by the front end block 500 of FIG. In FIG. 11, from the tuner unit 504 to the frame synchronization / TMCC decoding unit 514 in FIG. 10 is represented as “branch 1”, and from the frequency deinterleave unit 542 to the RS decoding unit 558 is represented as “post-processing”.
[0030]
Referring to FIGS. 10 and 11, in period T1, first, in order to perform partial reception, the signal of the reception channel is converted into a baseband signal with the bandwidth of the SAW filter built in tuner unit 504 as one segment. The In the period T2, the baseband signal output from the tuner unit 504 is converted from an analog signal to a digital signal.
[0031]
Subsequently, pre-synchronization processing for one segment, FFT processing for one segment, and broadband AFT processing for one segment are performed in periods T3, T4, and T5, respectively. Then, in the period T6, when the frame synchronization for one segment is taken and the TMCC signal is decoded, it can be seen that the signal received according to the content of the decoded TMCC signal is for three-segment broadcasting.
[0032]
As described above, in the periods T1 to T6, one segment is partially received and the TMCC signal is decoded. If the received signal is a one-segment broadcast, the processed data can be transmitted to the post-processing unit as it is, but the process can proceed, but if the received signal is a three-segment broadcast, Since only the partial reception of the data necessary for reception has reached the frame synchronization / TMCC decoding unit 514, normal reception cannot be performed even if the process proceeds.
[0033]
Therefore, when the TMCC signal is decoded in period T6 and it is determined that the received signal is for three-segment broadcasting, the tuner unit 504, the synchronization processing unit 508, the FFT unit 510, and the broadband AFT are configured to receive the three-segment broadcasting. Internal processing is switched.
[0034]
In a period T7, the signal of the reception channel is converted into a baseband signal with the bandwidth of the SAW filter built in the tuner unit 504 as three segments. In the period T8, the baseband signal output from the tuner unit 504 is converted from an analog signal to a digital signal.
[0035]
Subsequently, in periods T9, T10, and T11, pre-synchronization processing for three segments, FFT processing for three segments, and broadband AFT processing for three segments are performed, respectively. Then, in the period T12, frame synchronization for one segment is established, and when the TMCC signal is decoded, differential demodulation or synchronous demodulation is performed in the period T13. Then, after the period T14, the branch 1 receives the three-segment broadcast normally. After the period T14, various deinterleaving and various error corrections for 3 segments are performed in the post-processing unit.
[0036]
As described above, a digital broadcast receiver that receives a digital audio broadcast can receive a certain amount of information when receiving a three-segment broadcast as compared to when receiving a one-segment broadcast. There is a problem that it takes time.
[0037]
By the way, terrestrial digital audio broadcasting is required to be capable of stable mobile reception and miniaturization of a receiver, in addition to a request for data transmission such as high-quality audio broadcasting and still images.
[0038]
Conventionally, a technique called diversity reception is used for reception in a mobile unit, and it is expected that diversity reception is also used in a digital broadcast receiver mounted on a mobile unit such as an automobile.
[0039]
FIG. 12 is a first block diagram showing a configuration of a front end block of a terrestrial digital broadcast receiver to which diversity reception is applied.
[0040]
Referring to FIG. 12, this front-end block includes a diversity unit 520 that combines or selects outputs according to the degree of reception of branch BR1, branch BR2, and branches BR1 and BR2, and outputs of diversity unit 520. And a post-processing unit 522 that performs various deinterleaving processes and error correction processes. For example, when the moving body is an automobile, the branch BR1 is connected to an antenna installed outside the vehicle, and the branch BR2 is connected to an antenna embedded in a window glass inside the vehicle.
[0041]
The branch BR1 converts a RF signal from a first antenna (not shown) into an intermediate frequency (IF) signal, limits the band, and further converts the signal into a baseband signal. The output of the tuner unit 504a is converted from an analog signal. A / D conversion unit 506a for converting into a digital signal, a synchronization processing unit 508a that receives the output of the A / D conversion unit 506a and performs symbol synchronization, clock synchronization, and narrowband automatic frequency tuning (AFT) processing, and synchronization processing FFT unit 510a that performs fast Fourier transform according to the output of unit 508a. In the FFT unit 510a, the time axis data is converted into frequency axis data.
[0042]
The branch BR1 further includes a broadband automatic frequency tuning (AFT) unit 512a that receives a signal converted into frequency axis data, detects a pilot signal, performs pattern matching, and adjusts a frequency shift in units of carrier intervals, and a broadband AFT unit The frame synchronization / TMCC decoding unit 514a decodes the TMCC signal in accordance with the output of 512a, performs frame synchronization, and corrects the error of the TMCC signal, and synchronizes based on the TMCC signal decoded by the frame synchronization / TMCC decoding unit 514a. A synchronous differential switching control signal generating unit 516a that generates a differential switching signal, and a demodulating unit 518a that performs either synchronous demodulation or differential demodulation according to the output of the synchronous differential switching control signal generating unit 516a. Including.
[0043]
The branch BR2 converts an RF signal from a second antenna (not shown) into an intermediate frequency (IF) signal, limits the band, and further converts the signal into a baseband signal. The output of the tuner unit 504b is converted from an analog signal. A / D conversion unit 506b for converting to a digital signal, a synchronization processing unit 508b that receives the output of the A / D conversion unit 506b and performs processing of symbol synchronization, clock synchronization, and narrowband automatic frequency tuning (AFT), and synchronization processing FFT unit 510b that performs fast Fourier transform in accordance with the output of unit 508b. In the FFT unit 510b, the time axis data is converted into frequency axis data.
[0044]
The branch BR2 further includes a broadband automatic frequency tuning (AFT) unit 512b that receives a signal converted into frequency axis data, detects a pilot signal, performs pattern matching, and adjusts a frequency shift in units of carrier intervals, and a broadband AFT unit A frame synchronization / TMCC decoding unit 514b that decodes the TMCC signal in accordance with the output of 512b and performs frame synchronization, and a synchronization difference that creates a synchronous differential switching signal based on the TMCC signal decoded by the frame synchronization / TMCC decoding unit 514b A dynamic switching control signal creation unit 516b and a demodulation unit 518b that performs either synchronous demodulation or differential demodulation in accordance with the output of the synchronous differential switching control signal creation unit 516b.
[0045]
Since the post-processing unit 522 has the same configuration as that included in the front end block 500 described with reference to FIG. 10, the description thereof will not be repeated.
[0046]
FIG. 13 is a second block diagram illustrating a configuration of a front end block of a terrestrial digital broadcast receiver to which diversity reception is applied.
[0047]
Referring to FIG. 13, this front end block further includes a post-processing unit 522a in branch BR1 in place of post-processing unit 522 that receives the output of diversity unit 520 in the configuration of the front-end block shown in FIG. 12 differs from the case of FIG. 12 in that the branch BR2 further includes a post-processing unit 522b. Diversity unit 520 then outputs transport stream TS.
[0048]
As shown in FIGS. 12 and 13, when diversity reception is performed, how far the two reception functions are provided is a trade-off between circuit scale and performance. For this reason, if the diversity part is present in the rear part of the process as shown in FIG. 13, the performance is expected to be improved as compared with the case of FIG.
[0049]
It is an object of the present invention to provide a digital broadcast receiving apparatus in which, when performing diversity reception, the time required for normal reception is reduced when receiving a three-segment broadcast.
[0050]
[Means for Solving the Problems]
According to the present invention, there is provided a digital broadcast receiver capable of receiving a plurality of broadcast forms of digital broadcasts each using a plurality of broadcast waves each modulated by an orthogonal frequency division multiplex transmission system and having a different bandwidth per channel. The first and second branches, each of the first and second branches receiving a high-frequency signal and performing band limitation according to the type of broadcasting form, and the output of the tuner section as a digital signal A pre-signal processing unit that performs conversion and fast Fourier transform, and a post-signal processing unit that receives the output of the front signal processing unit and performs frame synchronization, and extracts the type of broadcast form from the output of the front signal processing unit, At the start of reception, the first branch is instructed to perform signal processing suitable for the first broadcast mode, the second branch is instructed to perform signal processing suitable for the second broadcast mode, and after reception starts, When the broadcast type of the received broadcast is extracted by the post-signal processing unit of any one of the second branches, the first and second signals are processed so as to perform signal processing suitable for the extracted type of broadcast. A control unit that instructs the branch, and a diversity unit that receives the output of the first and second branches and outputs a signal according to the degree of reception of each of the first and second branches. Prepare.
[0051]
Preferably, the type of broadcast form further includes identification information indicating whether the broadcast is a one-segment format of digital audio broadcast or a three-segment format of digital audio broadcast.
[0052]
More preferably, the previous signal processing unit includes an FFT unit that changes the FFT size according to the identification information instructed from the control unit and performs fast Fourier transform.
[0053]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same reference numerals indicate the same or corresponding parts.
[0054]
FIG. 1 is a block diagram showing a front end block of a digital broadcast receiving apparatus according to the present invention.
[0055]
Referring to FIG. 1, a digital broadcast receiving apparatus according to the present invention includes a CPU 12 that performs switching control of the entire apparatus in accordance with an instruction signal including a type of broadcast form of audio broadcasting and channel tuning information from a user, Depending on the output, RF signals are received from first and second antennas (not shown) to limit the band, convert analog signals to digital signals, various synchronizations, fast Fourier transforms, and transmission and multiplexing configuration control (TMCC) signals. Branches 1 and 2 that perform decoding and various demodulations, a TMCC signal determination unit 14 that receives TMCC signals decoded from branches 1 and 2 and determines whether to receive one segment or three segments, and demodulation of branches 1 and 2 In response to the received signal, the output of branch 1 and the output of branch 2 are combined according to the degree of reception, or The diversity unit 16 that selects the output of the signal, the deinterleave unit 18 that receives the output of the diversity unit 16, and the error correction process that receives the output of the deinterleave unit 18 and outputs the transport stream TS Error correction unit 20.
[0056]
The branch 1 receives the RF signal from the first antenna and performs a bandwidth limitation on the tuner unit 4a. The branch unit 1 receives the output signal of the tuner unit 4a and converts the analog signal into a digital signal and performs various synchronizations and synchronization. Unit 6a, FFT unit 8a that receives the output of A / D and synchronization unit 6a and performs fast Fourier transform, and processing unit that receives the output of FFT unit 8a and performs wideband AFT, frame synchronization, TMCC decoding, and various demodulation processes 10a.
[0057]
The branch 2 receives a RF signal from the second antenna and performs a band limitation on the tuner unit 4b, receives an output signal from the tuner unit 4b, converts an analog signal into a digital signal, and performs various synchronizations and synchronization. Unit 6b, FFT unit 8b that receives the output of A / D and synchronization unit 6b and performs fast Fourier transform, and processing unit that receives the output of FFT unit 8b and performs wideband AFT, frame synchronization, TMCC decoding, and various demodulation processes 10b.
[0058]
The detailed configuration of deinterleave unit 18 and error correction unit 20 is the same as that of post-processing unit 522 described with reference to FIG. 10, and therefore description thereof will not be repeated.
[0059]
FIG. 2 is a flowchart for explaining the control of the CPU 12 in FIG.
[0060]
Referring to FIG. 1 and FIG. 2, since there are only two types of 1-segment broadcasting and 3-segment broadcasting in terrestrial digital audio broadcasting, initial settings suitable for this situation are performed in step S1. That is, branch 1 is set to receive 1 segment broadcast, and branch 2 is set to receive 3 segment broadcast.
[0061]
Subsequently, in step S2, the received signal waits until the processing of the tuner, A / D and various types of synchronization, FFT, wideband AFT, frame synchronization and TMCC decoding is completed in both branches.
[0062]
Then, when the received signal is a one-segment broadcast, an accurate TMCC signal can be obtained from the processing unit 10a of the branch 1 that has been set for receiving one segment. At this time, an accurate TMCC signal cannot be obtained from the processing unit 10b of the branch 2 that has been set to receive three segments. Therefore, the TMCC signal determination unit 14 notifies the CPU 12 that the received signal is a one-segment signal.
[0063]
On the other hand, when the received signal is a three-segment broadcast, an accurate TMCC signal can be obtained from the processing unit 10b of the branch 2 that is set for receiving the three segments. In addition, since the processing unit 10a of the branch 1 set for receiving one segment performs partial reception, an accurate TMCC signal can also be obtained. Then, the TMCC signal determination unit 14 receives TMCC signals from both branches and notifies the CPU 12 that the received signal is a three-segment signal.
[0064]
Subsequently, in step S3, the CPU 12 determines whether or not the content of the TMCC indicates a one segment signal. If the contents of the TMCC indicate that it is a one-segment signal, the process proceeds to step S4, and the branch 2 that has been set to the three-segment reception operation in the initial setting is reset to the one-segment reception operation. Then, the reception setting for both branches is completed.
[0065]
On the other hand, if it is determined in step S3 that the contents of the TMCC indicate a 3-segment signal, the process proceeds to step S5, and branch 1 that has been set to the 1-segment reception operation in the initial setting is changed to 3 segments. Set to receive operation again. Then, the reception setting for both branches is completed.
[0066]
FIG. 3 is a diagram illustrating a state where the TMCC signal is decoded and the reception setting by the CPU 12 for both branches is completed.
[0067]
Referring to FIG. 3, the reception signal is a 3-segment signal, and the information is included in the TMCC signal, and the state where the CPU has completed setting the 3-segment reception operation for both branches 1 and 2 is shown.
[0068]
4 is a view showing both branches of the front end block of FIG. 1 in some detail.
[0069]
Referring to FIG. 4, branch 1 receives an RF signal from a first antenna (not shown) to limit the band, and receives an output signal from tuner 4a to convert an analog signal into a digital signal. A / D conversion unit 6a1 that performs various synchronizations, a synchronization unit 6a2 that receives a digital signal output from the A / D conversion unit 6a1 and performs a pre-synchronization process, and an FFT that performs a fast Fourier transform upon receiving the output of the synchronization unit 6a2 Unit 8a, a wideband AFT unit 10a1 that receives the output of FFT unit 8a and adjusts the frequency shift in units of carrier intervals, and a frame that receives the output of wideband AFT unit 10a1 and performs frame synchronization processing and decoding of the TMCC signal Various demodulation processes are performed in response to the outputs of the synchronization & TMCC decoding unit 10a2 and the frame synchronization & TMCC decoding unit 10a2. And a control unit 10a3.
[0070]
The branch 2 receives a RF signal from a second antenna (not shown) to limit the bandwidth, and receives an output signal from the tuner 4b to convert an analog signal into a digital signal and perform various synchronizations. A conversion unit 6b1, a synchronization unit 6b2 that receives a digital signal output from the A / D conversion unit 6b1, and performs a pre-synchronization process; an FFT unit 8b that receives an output from the synchronization unit 6b2 and performs a fast Fourier transform; and an FFT unit 8b A wideband AFT unit 10b1 that adjusts the frequency deviation in units of carrier intervals in response to the output of the frame, a frame synchronization & TMCC decoding unit 10b2 that receives the output of the wideband AFT unit 10b1, performs frame synchronization processing and decodes the TMCC signal, A demodulator 10b3 that receives the output of the frame synchronization & TMCC decoder 10b2 and performs various demodulation processes; Including.
[0071]
The configuration other than the branches 1 and 2 is the same as that in FIG. 1 and the description will not be repeated.
[0072]
In the branches 1 and 2, the CPU 12 controls the operation switching for receiving one segment and receiving three segments. For example, in the tuner units 4a and 4b, the CPU 12 sets the pass band of the built-in surface acoustic wave filter (SAW filter) to one segment or three segments. Further, the FFT units 8a and 8b are set by the CPU 12 so that the FFT size is for one segment or three segments.
[0073]
FIG. 5 is a flowchart for explaining the flow of data in each branch at the time of diversity reception.
[0074]
With reference to FIG. 4 and FIG. 5, the data flow of branch 1 will be described first in section A. In the initial state, as described with reference to FIG. 2, the branch 1 is set to the one-segment reception operation.
[0075]
In step S11, the tuner unit 4a sets the pass band of the SAW filter to one segment, and performs detection processing. Subsequently, in step S12, the output of the tuner unit 4a is A / D converted by the A / D conversion unit 6a1, and the A / D converted signal is subjected to pre-synchronization processing for one segment by the synchronization unit 6a2 in step S13. The
[0076]
Subsequently, in step S14, the signal that has undergone the pre-synchronization process is subjected to fast Fourier transform in the FFT unit 8a with the FFT size for one segment. Then, the output of the FFT unit 8a is subjected to frequency shift adjustment processing in units of carrier intervals for one segment by the broadband AFT unit 10a1 in step S15. When the frequency shift is adjusted, in step S16, a frame synchronization process and a TMCC decoding process for one segment are performed by the frame synchronization & TMCC decoding unit 10a2.
[0077]
Subsequently, in step S17, it is determined whether the content of the decoded TMCC signal indicates that the received signal is a 1-segment signal or whether the received signal is a 3-segment signal.
[0078]
If it is determined in step S17 that the received signal is a one-segment signal, the branch 1 setting remains in the one-segment operation, and the process proceeds to step S18 where various demodulations for one segment are performed.
[0079]
On the other hand, if it is determined in step S17 that the received signal is a three-segment signal, the setting of branch 1 is changed to a three-segment operation, and the process proceeds to step S19 and the reception process is performed again from the beginning.
[0080]
In step S19, the setting of the pass band of the SAW filter of the tuner unit 4a is changed to 3 segments, and detection processing is performed. Subsequently, in step S20, the output of the tuner unit 4a is A / D converted by the A / D conversion unit 6a1, and the A / D converted signal is subjected to pre-synchronization processing for three segments by the synchronization unit 6a2 in step S21. The
[0081]
Subsequently, in step S22, the signal that has undergone the pre-synchronization process is fast Fourier transformed at the FFT unit 8a with the FFT size for three segments. In step S23, the output of the FFT unit 8a is subjected to frequency shift adjustment processing in units of carrier intervals for three segments by the broadband AFT unit 10a1. When the frequency shift is adjusted, in step S24, frame synchronization processing and TMCC decoding processing for three segments are performed by the frame synchronization & TMCC decoding unit 10a2. In subsequent step S25, various demodulations for three segments are performed.
[0082]
Next, the data flow of branch 2 shown in part B will be described. In the initial state, as described in FIG. 2, the branch 2 is set to the 3-segment reception operation.
[0083]
In step S61, the tuner unit 4b sets the pass band of the SAW filter to 3 segments, and performs detection processing. Subsequently, in step S62, the output of the tuner unit 4b is A / D converted by the A / D conversion unit 6b1, and the A / D converted signal is subjected to pre-synchronization processing for three segments by the synchronization unit 6b2 in step S63. The
[0084]
Subsequently, in step S64, the signal that has undergone the pre-synchronization process is fast Fourier transformed at the FFT unit 8b with the FFT size for three segments. Then, the output of the FFT unit 8b is subjected to frequency shift adjustment processing in units of carrier intervals for three segments by the broadband AFT unit 10b1 in step S65. When the frequency shift is adjusted, in step S66, frame synchronization processing and TMCC decoding processing for three segments are performed by the frame synchronization & TMCC decoding unit 10b2.
[0085]
Subsequently, in step S67, it is determined whether the content of the decoded TMCC signal indicates that the received signal is a one-segment signal or whether the received signal is a three-segment signal.
[0086]
If it is determined in step S67 that the received signal is a 3-segment signal, the branch 2 setting remains in the 3-segment operation, and the process proceeds to step S68 to perform various demodulations for 3 segments.
[0087]
On the other hand, when the received signal is a one-segment signal in step S67, the TMCC decoding result does not become a normal value. As a result, the setting of branch 2 is changed to the one-segment operation, and the process proceeds to step S69 again from the beginning. Reception processing is performed.
[0088]
In step S69, the passband of the SAW filter of the tuner unit 4b is changed to one segment, and detection processing is performed. Subsequently, in step S70, the output of the tuner unit 4b is A / D converted by the A / D conversion unit 6b1, and the A / D converted signal is subjected to pre-synchronization processing for one segment by the synchronization unit 6b2 in step S71. The
[0089]
Subsequently, in step S72, the signal that has undergone the pre-synchronization process is subjected to fast Fourier transform at the FFT unit 8b with the FFT size for one segment. In step S73, the output of the FFT unit 8b is subjected to frequency shift adjustment processing in units of carrier intervals for one segment by the broadband AFT unit 10b1. When the frequency shift is adjusted, in step S74, frame synchronization processing and TMCC decoding processing for one segment are performed by the frame synchronization & TMCC decoding unit 10b2. In subsequent step S75, various demodulations for one segment are performed.
[0090]
Branches 1 and 2 are set by the processing of the A and B portions, and the demodulated result is subjected to diversity reception processing in step S76. Then, various deinterleaves for one or three segments indicated by the TMCC signal are performed (step S77), and then various error corrections are performed and a transport stream TS is output (step S78).
[0091]
FIG. 6 is a diagram for explaining an operation according to the flow of FIG. 5 when one segment signal is received.
[0092]
Referring to FIG. 6, in the initial setting, branch 1 is set to a 1-segment reception operation, and branch 2 is set to a 3-segment reception operation.
[0093]
In the period T1 to T7, each process of the tuner, A / D conversion, pre-synchronization, FFT, wideband AFT, frame synchronization, and various demodulation for one segment is performed in the branch 1 set to the one-segment operation. In parallel with this, each of the tuner, A / D conversion, pre-synchronization, FFT, wideband AFT, and frame synchronization processing is performed in the branch 2 set to the three-segment operation in the period T1 to T6.
[0094]
As a result of the TMCC decoding in the period T6, it is found that the received signal is a one-segment signal, so that the branch 2 is set to the one-segment operation. In the period T7 to T13, the tuner 2, A / D conversion, pre-synchronization, FFT, wideband AFT, frame synchronization, and various demodulation processes for one segment are performed in the branch 2 set to the one-segment operation.
[0095]
On the other hand, the branch 1 that has been performing a normal reception operation can directly use the result of the reception operation. Accordingly, the diversity unit selects the output of the branch 1 and outputs it to the post-processing unit during the periods T8 to T13. The post-processing unit performs various deinterleaving for one segment in the period T9, performs various error corrections in the period T10, and outputs the transport stream TS based on the output result of the branch 1 in the periods T11 to T16.
[0096]
In the period T14, since the branch 2 has also received the one-segment signal normally, the diversity unit synthesizes the output of the branch 1 and the output of the branch 2 according to the goodness of reception of the branches 1 and 2, or Is selected and transmitted to the post-processing section. Then, the post-processing unit outputs the transport stream TS using the output of the diversity unit.
[0097]
FIG. 7 is a diagram for explaining an operation according to the flow of FIG. 5 when a 3-segment signal is received.
[0098]
Referring to FIG. 7, in the initial setting, branch 1 is set to a 1-segment reception operation, and branch 2 is set to a 3-segment reception operation.
[0099]
In the period T1 to T6, each process of tuner, A / D conversion, pre-synchronization, FFT, broadband AFT, and frame synchronization is performed in the branch 1 set to the one-segment operation. In parallel with this, in the period T1 to T7, the tuner 2, A / D conversion, pre-synchronization, FFT, wideband AFT, frame synchronization, and various demodulation processes for three segments are performed in the branch 2 set to the three-segment operation. Is done.
[0100]
As a result of the TMCC decoding in the period T6, it is found that the received signal is a 3-segment signal, so that the branch 1 is set to the 3-segment operation. In the period T7 to T13, each process of tuner, A / D conversion, pre-synchronization, FFT, wideband AFT, frame synchronization, and various demodulation for three segments is performed in the branch 1 set to the three-segment operation.
[0101]
On the other hand, the branch 2 that has been performing a normal reception operation can directly utilize the result of the reception operation. Therefore, the diversity unit selects the output of the branch 2 and outputs it to the post-processing unit during the periods T8 to T13. In the post-processing unit, various deinterleaving for three segments is performed in the period T9, various errors are corrected in the period T10, and the transport stream TS based on the output result of the branch 2 is output in the periods T11 to T16.
[0102]
In the period T14, the branch 1 also receives the 3-segment signal normally, so the diversity unit combines the output of the branch 1 and the output of the branch 2 according to the goodness of reception of the branches 1 and 2, or Is selected and sent to the post-processing unit. Then, the post-processing unit outputs the transport stream TS using the output of the diversity unit.
[0103]
During periods T11 to T16, there may be cases where the best state due to diversity reception is not achieved, but reception of three-segment audio broadcasting can be started early. Of course, when the branch 2 is in a better reception state than the branch 1, the best reception can be performed after the period T11. After period T17, even in the case where branch 1 is in a better reception state than branch 2, reception in the best state is possible due to diversity reception.
[0104]
Compared to the case of the digital broadcast receiving apparatus that does not perform diversity reception in FIG. 11, the digital broadcast receiving apparatus of the present invention can shorten the time required to normally receive the three-segment broadcast as shown in FIG. it can.
[0105]
In the embodiment of the present specification, the case of performing typical diversity reception having two branches has been described, but the number of branches may be two or more. For example, if there are more than two broadcast modes, if a plurality of branches of the number of broadcast modes are provided and the initial setting of the plurality of branches is set to reception operations of different broadcast modes, it is necessary for normal reception in the same way. Time can be shortened.
[0106]
The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.
[0107]
【The invention's effect】
According to the present invention, in the terrestrial digital audio broadcasting receiver, diversity reception technology is used, and one branch is set to receive one segment and the other branch is set to receive three segments before TMCC decoding. To do.
[0108]
After TMCC decoding, it is determined whether 1-segment broadcasting or 3-segment broadcasting is performed. Thereafter, normal diversity reception is performed in accordance with the broadcasting form in which both branches are identified. In this way, it is possible to quickly receive a three-segment broadcast of a terrestrial digital audio broadcast.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a front end block of a digital broadcast receiving apparatus of the present invention.
FIG. 2 is a flowchart for explaining control of a CPU 12 in FIG.
FIG. 3 is a diagram illustrating a state in which a TMCC signal is decoded and reception setting by a CPU 12 for both branches is completed.
FIG. 4 is a view showing both branches of the front end block of FIG. 1 in some detail.
FIG. 5 is a flowchart for explaining the flow of data in each branch at the time of diversity reception.
6 is a diagram for explaining an operation according to the flow of FIG. 5 when a one-segment signal is received.
7 is a diagram for explaining an operation according to the flow of FIG. 5 when a 3-segment signal is received.
FIG. 8 is a diagram showing a segment structure of a one-segment audio broadcasting.
FIG. 9 is a diagram showing a segment structure of a three-segment audio broadcasting.
FIG. 10 is a block diagram showing a configuration of a front end block 500 of a conventional terrestrial digital broadcast receiver.
FIG. 11 is a diagram illustrating signal processing when the front-end block 500 of FIG. 10 receives a three-segment audio broadcast, with time on the horizontal axis.
FIG. 12 is a first block diagram showing a configuration of a front end block of a terrestrial digital broadcast receiver to which diversity reception is applied.
FIG. 13 is a second block diagram showing a configuration of a front end block of a terrestrial digital broadcast receiver to which diversity reception is applied.
[Explanation of symbols]
1, 2 branch, 4a, 4b tuner, 6a, 6b A / D and synchronization unit, 6a1, 6b1 A / D conversion unit, 6a2, 6b2 synchronization unit, 8a, 8b FFT unit, 10a, 10b processing unit, 10a1, 10b1 Wideband AFT unit, 10a2, 10b2 frame synchronization & TMCC decoding unit, 10a3, 10b3 demodulation unit, 14 TMCC signal determination unit, 16 diversity unit, 18 deinterleave unit, 20 error correction unit.

Claims (3)

A digital broadcast receiving apparatus that divides a transmission band of one channel into a plurality of segments and receives a broadcast in a broadcast form including the divided one or more segments ,
Comprising first and second branches;
The first and second branches are
A tuner unit that receives a high-frequency signal and performs band limitation according to the broadcast mode ;
A pre-signal processing unit for converting the output of the tuner unit into a digital signal and performing a fast Fourier transform;
Receiving the output of the previous signal processing unit to perform frame synchronization, and including a post signal processing unit that extracts the broadcast form from the output of the previous signal processing unit,
At the start of reception, the first branch is instructed to perform signal processing suitable for the first broadcasting form, the second branch is instructed to perform signal processing suitable for the second broadcasting form, after receiving the start the first, when the broadcast scheme received is extracted in any of the post-signal processing section of the second branch, extracted the first to perform a signal processing suitable for the broadcast mode, A control unit for instructing the second branch;
After being instructed to perform signal processing suitable for the broadcasting form extracted by the control unit, the output signals output from the post signal processing units of the first and second branches are combined or selected. A digital broadcast receiver including a diversity unit for outputting . The first broadcasting form is a digital audio broadcasting in a one-segment format,
The second broadcasting form is a three-segment digital audio broadcasting,
  The digital broadcast receiving apparatus according to claim 1, wherein a broadcast form is extracted based on a TMCC signal decoded by the post signal processing unit. The digital broadcast receiving apparatus according to claim 2, wherein the pre-signal processing unit includes an FFT unit that performs fast Fourier transform by changing an FFT size according to the extracted broadcast form .

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