JP3427348B2 - Digital broadcast receiver - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
The present invention relates to a digital broadcast receiver for receiving digital broadcast such as italic audio broadcasting, and more particularly to a digital broadcast receiver capable of detecting an abnormality in demodulation and / or decoding processing.

[0002]

2. Description of the Related Art In a DAB receiver, a transmission frame has a front side FIC (Fast Information Cha).
nnel: High-speed information channel) and MSC (M
ain Service Channel) and demodulates and decodes FIC and MSC.

[0003]

In the conventional DAB receiver, the error rate (Bit E) of each of the FIC and the MSC is increased.
Even if the error rate (bit error rate) is detected, the deterioration of the error occurrence rate is merely judged to be the deterioration of the broadcast wave reception environment.

An object of the present invention is to provide a digital broadcast receiver capable of accurately detecting demodulation and / or decoding process abnormality.

[0005]

According to the digital broadcast receiver (10) of the present invention, a digital broadcast transmitted by a transmission frame having a plurality of sections of different coding systems is received. Then, in the digital broadcast receiver (10), at least decoding is performed for each section, error checking is performed for each section, the error occurrence rate for each section is checked, and the error occurrence rate for each section is checked. When it is determined that the classified level ranges are not related to each other, it is determined that the demodulation and / or decoding process is abnormal.

The digital broadcast receiver 10 includes not only a digital radio broadcast receiver such as a DAB car radio 10 but also a digital television broadcast receiver.
Since each division of the transmission frame has a different coding method, an error correction bit is usually attached to each division, and the presence or absence and / or the number of error bits in each division and the error occurrence rate can be detected by the error correction bit. .

The number of sections included in the transmission frame and having different coding methods is not limited to two, and may be three or more. In DAB as an example of digital radio broadcasting,
The section included in the transmission frame and having a different coding method is F
IC and MSC, two in total.

The error rate may be the error rate of one segment or the average value of the error rates of the same segment in a predetermined number of transmission frames. "At least decoding is performed for each section" means that (a) demodulation may be performed for each section.
(B) The purpose is that demodulation may be performed collectively without distinguishing the sections.

The level range in which the error rate is classified is
For example, the level range of the error rate may be a total of two levels of good and bad, or a total of 3 levels of good, medium and bad.
It may be a level range of individual items, or may be further classified. When the level ranges in which the error occurrence rates of the respective sections are classified have no mutual relevance, the level ranges in which the error occurrence rates of the respective sections are classified are, for example, (a): And (b) there is at least one level range between the level ranges to be compared. More specifically, in (a), for example, if the level range of the error rate is two levels, good and bad, the level range of the error rate of a certain section is good, and The level range of the segment error rate is when it is bad. In (b), for example, assuming that the level range of the error rate is good, medium, and bad, the level range of the error rate of a certain section is good, and the error rate of the other section is good. If the level range of is medium, there is not one level range between them, so it cannot be said that there is no mutual relationship between the level ranges to be compared, but the error rate of a certain segment If the level range of is good and the level range of the error rate of the other categories is bad, there is one level range between them, so there is a mutual relationship between the compared level ranges. You can say no.

Since the error occurrence rate for each section is based on the transmission frame of the digital broadcast received in the same broadcast wave reception environment, the digital broadcast receiver
If there is no abnormality in the operation of (10), it should be within the same level range. Nevertheless, if there is no mutual relationship between the level ranges in which the error occurrence rates for each category are classified, a factor other than the broadcast wave reception environment, that is, an abnormality in demodulation and / or decoding processing, may occur. You can judge that

In this way, when it is determined that the level ranges in which the error occurrence rates of the respective categories are classified are not related to each other, the cause is something other than the broadcasting radio wave reception environment, that is, the digital broadcasting receiver (10). Assuming that the demodulation and / or decoding process is abnormal, the demodulation and / or decoding process of the digital broadcast receiver (10) can be accurately detected.

According to the digital broadcast receiver (10) of the present invention, when it is determined that there is an abnormality in the demodulation and / or decoding processing, the processing for coping with the abnormality in the demodulation and / or decoding processing is performed. Has become.

The processing for coping with the abnormality in the demodulation and / or decoding processing includes, for example, notification to the user to that effect. By knowing the abnormality in the demodulation and / or decoding process of the digital broadcast receiver (10), the user can perform an appropriate process such as repair.

According to the digital broadcast receiver (10) of the present invention, the processing for coping with the abnormality in the demodulation and / or decoding processing means that at least the section having a higher error rate is
This is a process of re-implementing demodulation and decoding.

"At least a process of demodulating and decoding a section having a larger error rate" is a process in which the level ranges in which the error rate of each section is classified are mutually related. If it is determined that there is no (a)
In addition to the process of re-performing demodulation and decoding only on the section with the higher error rate, (b) not only the section with the higher error rate, but also all the sections including the section with the lower error rate Process of re-implementing demodulation and decoding of
(C) For demodulation, all the sections are re-executed, but for decoding, only the section with the higher error rate is re-executed, and the re-execution for the section with the lower error rate is omitted. It is intended to include. In particular, although the decoding is performed for each section, the demodulation is the processing of (c) when not all the sections but all the sections are collectively performed.

Although the demodulation and decoding processor has not failed, due to an accidental timing error or the like,
Processing may be disturbed. When it is determined that the demodulation and / or decoding process is abnormal, at least the demodulation and decoding process is accidentally performed by re-implementing the demodulation and decoding for the segment classified into the level range having the larger error occurrence rate. If it is abnormal, the correct demodulated and decoded data for the segment can be obtained.

According to the digital broadcast receiver (10) of the present invention, when the classification having the larger error occurrence rate is related to the voice service component, the processing for coping with the abnormality in the demodulation and / or decoding processing can be performed. , Audio output suspension from the audio output means is included.

When the classification classified into the level range having the larger error occurrence rate is related to the service component of the voice, the voice based on such abnormal decoded data is directly output from the voice output means such as the speaker or the earphone. Issuing,
It causes noise. Therefore, noise can be prevented by operating the mute.

According to the digital broadcast receiver (10) of the present invention, the transmission frame has two sections of different coding systems, one of which is an interleaved section and the other of which is a non-interleaved section. .

For example, in DAB, the FIC and MSC constituting one section of the transmission frame are non-interleaved and interleaved sections, respectively. The non-interleaved segment and the interleaved segment are usually demodulated and decoded separately, and the error rate of each segment can be obtained to accurately detect the demodulation and decoding anomalies.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows the structure of a DAB transmission frame. Transmission frame (Transnisio
n frame) is a synchronization channel and FIC in order from the front.
(Fast Information Channel
l: First Information Channel) and M
It has an SC (Main Service Channel). FIC and MS
C is non-interleaved and interleaved, respectively. The FIC further includes a plurality of FIBs (Fast
Information Block), MS
C is a plurality of CIFs (Common Inter
The left frame). The specifications of DAB are determined from mode 1 to mode 4, and the duration of a transmission frame and the number of FIBs and CIFs in one transmission frame are different for each mode. For example, in mode 1, the time for one transmission frame is 9
The number of FIBs and CIFs in one transmission frame of 6 ms is 12 and 4, respectively.

FIG. 2 is a system configuration diagram of the DAB car radio 10. The DAB car radio 10 includes a signal processing unit 11,
And a user interface unit 20. In the signal processing unit 11, the DAB system microcomputer 12 has a memory 13
With multiple ensembles (each ensemble is a DQP
Transmitted by radio broadcasting waves modulated by SK-OFDM, one ensemble has a bandwidth of about 1.5 MHz.
And usually includes 6 broadcast programs. ), One ensemble is designated, and designation information is sent to the RF block 14. The RF block 14 is an RF (Radi) of the ensemble designated by the DAB system microcomputer 12.
o Frequency) and sends it to the demodulation block 15. In the demodulation block 15, the RF from the RF block 14
The signal is demodulated as DAB data, and the channel decoding block 16 performs error correction on the demodulated signal from the demodulation block 15 while detecting the number of error bits between the FIC and the MSC of each transmission frame. DA
The B system microcomputer 12 generates an MSC decoded signal corresponding to the designated channel. From the channel decoding block 16 to the DAB system microcomputer 12, the error bit number detected by the channel decoding block 16 and the FIC decoded signal generated by the channel decoding block 16 are sent, and D
Information related to which sub-channel of the MSC the currently selected service component is included in is sent from the AB system microcomputer 12 to the channel decoding block 16, and the channel decoding block 16 relates to the corresponding sub-channel. The decoded audio data is sent to the audio decoding block 24. The audio decoding block 24 decompresses the audio data (audio data compressed by MPEG) input from the channel decoding block 16 and sends it to the left and right speakers, and the audio heard by the user is played from the left and right speakers. The DAB control microcomputer 21 of the user interface unit 20 includes a memory 22, and the DAB control microcomputer 21 of the signal processing unit 11
B Exchanges data with the system microcomputer 12. DA
The B control microcomputer 21 uses the key as the instruction from the user.
While being input via 23, predetermined data is output to the display unit 24 to display information and inform the user.

FIG. 3 is a flowchart of the demodulation / decoding processing program. In S30, F for each transmission frame
The number of error bits of IC and MSC is detected. This detection is performed in the channel decoding block 16, and the DAB system microcomputer 12 can know it from the input information from the channel decoding block 16. In S31, the BER (Bit) is set for each FIC and MSC in a predetermined number of transmission frames.
The average values Af and Am of the Error Rate (bit error rate) are calculated. In S32, it is determined whether or not Af and Am are related. If the determination is YES, the program is terminated, and if NO, the process proceeds to S33. A
“F and Am are related to each other” means that Af and Am have almost the same value, and that Af and Am are not related to each other, Af and Am are classified into both. This is the case when there is a considerable gap in the level range. Demodulation block
When the processing in 15 and the channel decoding block 16 is normal, Af and Am are determined by the broadcast wave reception environment. For example, the broadcast wave reception environment is classified into three situations, that is, good, medium, and bad, and Af and Am also correspond to them, that is, good (example: Af, Am ≦ 1.0 ⁻³ ), medium (example : 1.0 ^-3 <A
f, Am <1.0 ⁻¹ ) and bad (eg Af, Am ≧ 1.
It is divided into three level ranges of 0 ^-1 ). When the processing in the demodulation block 15 and the channel decoding block 16 is normal, Af and Am indicate that the broadcast wave reception environment is good,
Corresponding to medium and evil, the level ranges of good, medium, and evil are the same as each other. On the other hand, when the processing in the demodulation block 15 and the channel decoding block 16 is abnormal, one of Af and Am is in the good level range, but the other is in the bad level range. For example, there is a considerable gap between the level ranges of both parties. In S33, MS
It is detected whether the demodulation / decoding of C is abnormal or the demodulation / decoding of FIC is abnormal, that is, whether the level range of Am is bad but the level range of Am is bad,
Or, even if the Am level range is good, it is detected whether the Af level range is bad, and if it is determined to be the former, the process proceeds to S34. If it is determined to be the latter, S3 is performed.
Go to 5. In steps S34 and S35, MSC and FIC abnormality countermeasure processing is performed, respectively. The MSC abnormality countermeasure processing in S34 is, for example, after the audio output from the audio output means such as a speaker is stopped (= mute),
If the MSC is demodulated and decoded again, and the BER of the MSC after the re-execution is the same as the level range of Af,
Release the mute and BER of MSC after re-execution
Again, the mute is continued even if the level range has a considerable difference from the level range of Af. FIC
The abnormality countermeasure process is, for example, that the FIC is demodulated and decoded again, and the BER of the FIC after the re-execution is Am.
FI after the re-execution if it is the same as the level range of
C is used, and the BER of the MSC after re-execution is Am
If it is a level range having a considerable difference from the level range of FIC, the FIC data is abnormal and the use is suspended.

Depending on the DAB radio, FIC and MSC are individually performed for decoding, but FIC and MSC are collectively performed for demodulation, and S34 and S35 of such DAB radio are performed. In the demodulation, re-demodulation of the FIC and MSC of the normal one will be performed together.

[Brief description of drawings]

FIG. 1 is a diagram showing a structure of a DAB transmission frame.

FIG. 2 is a system configuration diagram of a car radio for DAB.

FIG. 3 is a flowchart of a demodulation / decoding processing program.

[Explanation of symbols]

10 DAB car radio (digital broadcasting receiver)

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Claims (5)

(57) [Claims] 1. A digital broadcast receiver (10) for receiving a digital broadcast transmitted by a transmission frame having a plurality of sections of different coding systems, at least decoding is performed for each section, and
An error check is performed for each section, the error rate for each section is checked, and if it is determined that there is no mutual relationship between the level ranges in which the error rate for each section is classified, demodulation and / or Alternatively, a digital broadcast receiver characterized in that it is determined that an abnormality has occurred in the decoding process. 2. When it is determined that an abnormality has occurred in the demodulation and / or decoding processing, processing for coping with the abnormality in the demodulation and / or decoding processing is performed. The described digital broadcasting receiver. 3. The process for coping with abnormalities in the demodulation and / or decoding process is a process for re-implementing the demodulation and / or decoding for at least one of the sections having a higher error occurrence rate. The described digital broadcasting receiver. 4. When the classification with the higher error occurrence rate is related to the service component of voice, the processing for coping with the abnormality in the demodulation and / or decoding processing includes suspension of voice output from the voice output means. The digital broadcast receiver according to claim 2 or 3, characterized in that. 5. The transmission frame has two sections having different coding methods, one of which is an interleaved section and the other of which is a non-interleaved section. A digital broadcasting receiver according to claim 1.