JP2001339367A - Digital broadcast receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a digital broadcast receiver that can stably conduct switching to an operation for stopping service provision due to a deteriorated error rate by the attenuation due to rain or the like at the reception of a hierarchical transmission broadcast program and stably switching to an operation even when the reception of a lower layer is restored from the service stop operation. SOLUTION: A control section 13 analyzes the modulation system of each slot on the basis of transmission information acquired from a TMCC decode section 6 and slot information, generates slot selection information of the same modulation system and supplies the information to an error correction section 4. The error correction section 4 gives the error rate information of only a slot designated by the slot selection information to the control section 13. The control section 13 performs switching of a modulation system on the basis of the error rate information of only the designated slot.

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, and more particularly to a digital broadcast receiver capable of stably switching a plurality of modulation systems.

[0002]

2. Description of the Related Art In recent years, digitalization of broadcasting has been progressing.
In Japan, BS digital broadcasting using BS is scheduled from 2000. In BS digital broadcasting, a plurality of transport streams (hereinafter, referred to as TS) are provided for one frequency.
Are mixed, and multiple modulation methods can be mixed. Multiple modulation methods are TC8PSK, QP
There are three modulation schemes, SK and BPSK, which are systems for overcoming reception impairment due to rainfall attenuation or the like peculiar to BS, and are generally called hierarchical transmission.

[0003] Hierarchical transmission refers to a modulation scheme such as TC8PSK, which has a high transmission efficiency, which is a high hierarchy part, and a modulation scheme, which has a low transmission efficiency but a high resistance to rain attenuation, which is a low hierarchy part.
This is a transmission method mixed in one TS and one service. In order to correctly demodulate these mixed modulation schemes, the digital broadcast receiver demodulates the basic information by demodulating the TMCC information in which information on the modulation scheme being broadcast is inserted, and modulates the main signal. The system information is read and a demodulation processing operation is performed according to the information.

FIG. 3 is a diagram for explaining an outline of a transmission system of BS digital broadcasting. FIG. 3A shows a data frame configuration of BS digital broadcasting, where one frame is composed of a group of 48 TSs. FIG. 3B shows TMCC in the header of each TS in FIG. 3A.
The frame structure of the signal is shown.
Information on the configuration of each TS is inserted in the MCC information. FIG. 3C shows the internal structure of the TMCC information. The relative TS / slot information 144 bits and the relative TS / TS-I indicating which transport (TS-ID) each slot belongs to.
D-corresponding information 128 bits and transmission mode information 40bi indicating in which transmission mode (modulation method) the TS-ID is transmitted
t etc. are included.

FIG. 3D shows the structure of the transmission mode information in the TMCC information, and shows the data value of the transmission mode information and the corresponding modulation method and coding rate. The data value 0010 indicates that the modulation method is QPS
K and the coding rate is 1/2. In the BS digital broadcast receiver, in the normal channel selection, first, after selecting the BS-IF frequency, the BPSK demodulation processing is performed to obtain TMCC information that is transmission information, and belongs to a desired TS-ID among all slots. A desired TS can be obtained by performing selection and demodulation processing after confirming which TS is used and in which modulation scheme the TS is transmitted.

FIG. 2 is a block diagram showing a conventional BS digital broadcast receiver. In FIG. 2, a BS not shown
The BS-IF signal received by the antenna is supplied to the BS front end unit 1. BS front end part 1
After the desired BS-IF frequency is selected according to the channel selection instruction from the control unit 13 and the received signal is subjected to I / Q detection,
And the baseband signals of Q and Q are supplied to the AD unit 2. The AD unit 2 converts the I and Q baseband signals into digital signals and supplies them to the PSK demodulation unit 3.

The PSK demodulation unit 3 performs demodulation processing such as carrier reproduction and clock reproduction to obtain a demodulated digital signal.
It is supplied to the error correction unit 4. The error correction unit 4 corrects the error of the demodulated digital signal and performs deinterleaving and the like.
The TS data is obtained and supplied to the TS selection output unit 5 together with the clock. At the same time, TMCC information in the header part of the TS data is extracted and supplied to the TMCC decoding unit 6. The TMCC decoding unit 6 decodes the obtained TMCC information and supplies transmission information and selected TS information to the control unit 13. The TS selection output unit 5 selects specific TS data from the digital signal based on the selected TS information from the control unit 13 and
To supply.

The DEMUX unit 7 decodes and sorts data, and supplies audio data to the audio decoding unit 8 and video data to the MPEG-VIDEO decoding unit 10, respectively. The audio decoder 8 decodes the audio data and supplies it to the D / A audio output processor 9. The D / A audio output processing unit 9 performs an analog conversion process, obtains an analog audio signal, and outputs it from an analog audio output terminal. On the other hand, the MPEG-VIDEO decoding unit 10
MPEG2 is decoded and supplied to the Graphic unit 11. The Graphic unit 11 adds a Graphic to this, and
/ A video output processing unit 12. The D / A video output processing unit 11 performs an analog conversion process to obtain an analog video signal, which is output from an analog video output terminal.
The control unit 13 also performs various controls in the BS digital broadcast receiver, such as ON / OFF control of the power supply unit 14.

On the other hand, error rate information based on error correction is supplied from the error correction section 4 to the control section 13, and this information is used to grasp the reception state of the receiver on the receiver side. For example, when a hierarchically transmitted service is received, the control unit 13 constantly monitors the error rate information, and when the error rate deteriorates due to rain attenuation and the normal service becomes difficult, Switches the modulation scheme from a higher hierarchy to a lower hierarchy. Then, when the error rate further deteriorates, the presentation of the service is stopped, and the output of video, audio, and the like is stopped. Conversely, if the error rate is improved, the reverse process is followed to resume the service presentation.

[0010]

In the conventional receiver described above, the error rate information supplied from the error correction section 4 is the error rate information of all the selected TSs. That is, it includes a high layer portion and a low layer portion. In general, in hierarchical transmission, the number of slots in the higher layer is much larger than the number of slots in the lower layer, so that the error rate information supplied from the error correction unit 4 is governed by the information of the higher layer.
As a result, when rainfall attenuation occurs, switching to a lower hierarchy operates stably.

[0011] However, in the case of switching to the operation in which the presentation of the service must be stopped in the state of being received by the low-layer transmission and returning to the low-layer from the stop of the service, the error rate information becomes high. Since the information is controlled by the hierarchical information, there has been a serious problem that the switching operation cannot be stably performed. The present invention has been made to solve the above-described problems, and at the time of receiving a layered transmission broadcast,
Digital broadcast reception that can switch stably even when the error rate deteriorates due to rain attenuation and the like, so that the service presentation must be stopped, and when the service is returned to a lower level after the service is stopped. The purpose is to provide a machine.

[0012]

In order to achieve the above object, in a digital broadcast receiver for receiving a digital broadcast in which a plurality of modulation schemes are mixed in one transmission frequency, a desired BS- Select the signal of IF frequency,
A BS front-end section for outputting I and Q baseband signals, an AD section for digitally converting the I and Q baseband signals and outputting the demodulated digital signals; A PSK demodulation unit that outputs error correction of the demodulated digital signal, an error correction unit that outputs TMCC information and error rate information in the TS data, and a decoding unit that decodes the TMCC information. A TMCC decoding unit that outputs the received transmission information and selected TS information, a TS selection output unit that selects and outputs specific TS data from the TS data based on the selected TS information, and decodes the specific TS data. A DEMUX unit that performs a sorting process and outputs audio data and video data, and a control unit that controls various operations in the digital broadcast receiver.The control unit includes the TMCC Analyzing the modulation scheme of each slot based on the obtained transmission information from the code unit,
Create slot selection information of the same modulation method and supply it to the error correction unit, obtain error rate information of only the slot specified by the slot selection information from the error correction unit, based on the error rate information It is an object of the present invention to provide a digital broadcast receiver characterized by performing switching control of a modulation method.

[0013]

FIG. 1 is a block diagram showing an embodiment of a BS digital broadcast receiver according to the present invention. In FIG. 1, a BS-IF signal received by a BS antenna (not shown) is supplied to a BS front end unit 1. The BS front-end unit 1 selects a desired BS-IF frequency according to a channel selection instruction from the control unit 13 and
/ Q detection, then output I and Q baseband signals,
It is supplied to the AD unit 2. The AD unit 2 converts the I and Q baseband signals into digital signals and supplies them to the PSK demodulation unit 3.

The PSK demodulation unit 3 performs demodulation processing such as carrier reproduction and clock reproduction to obtain a demodulated digital signal.
It is supplied to the error correction unit 4. The error correction unit 4 corrects the error of the demodulated digital signal and performs deinterleaving and the like.
The TS data is obtained and supplied to the TS selection output unit 5 together with the clock. At the same time, TMCC information in the header part of the TS data is extracted and supplied to the TMCC decoding unit 6. The TMCC decoding unit 6 decodes the obtained TMCC information and supplies transmission information and selected TS information to the control unit 13. The TS selection output unit 5 selects specific TS data from the digital signal based on the selected TS information from the control unit 13 and
To supply.

The DEMUX unit 7 decodes and sorts data, and supplies audio data to the audio decoding unit 8 and video data to the MPEG-VIDEO decoding unit 10, respectively. The audio decoder 8 decodes the audio data and supplies it to the D / A audio output processor 9. The D / A audio output processing unit 9 performs an analog conversion process, obtains an analog audio signal, and outputs it from an analog audio output terminal. On the other hand, the MPEG-VIDEO decoding unit 10
MPEG2 is decoded and supplied to the Graphic unit 11. The Graphic unit 11 adds a Graphic to this, and
/ A video output processing unit 12. The D / A video output processing unit 11 performs an analog conversion process to obtain an analog video signal, which is output from an analog video output terminal.
The control unit 13 also performs various controls in the BS digital broadcast receiver, such as ON / OFF control of the power supply unit 14.

The control unit 13 of the present invention includes the TMCC decoding unit 6
Based on the transmission information acquired from, the modulation scheme of each slot is analyzed, and slot selection information of the same modulation scheme is created and supplied to the error correction unit 4. The error correction unit 4 acquires the error rate information of only the slot specified by the slot selection information supplied from the control unit 13, and
To supply. The control unit 13 determines, based on the error rate information of only the slot specified by the slot selection information,
Switches the modulation method. Thereby, the control unit 13
Since it is possible to monitor only the error rate information of the modulation method of the lower hierarchy, switching to stop the service presentation of the receiver due to rain attenuation during reception at the lower hierarchy,
In a state where the service presentation of the receiver is stopped, it is possible to stably switch to the return to the lower hierarchy by detecting that the error rate of the lower hierarchy has decreased.

[0017]

According to the digital broadcast receiver of the present invention, when the hierarchical transmission broadcast is received, the error rate deteriorates due to rainfall attenuation and the like, and the switching to the operation in which the presentation of the service must be stopped and the stop of the service are performed. There is an extremely excellent effect that the switching operation can be performed stably even in the case of returning to the lower hierarchy from the above.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a block diagram showing a conventional example.

FIG. 3 is a diagram for explaining an outline of a transmission method of BS digital broadcasting.

[Explanation of symbols]

 Reference Signs List 1 BS front end section 2 AD section 3 PSK demodulation section 4 Error correction section 5 TS selection output section 6 TMCC decoding section 7 DEMUX section 8 Audio decoding section 9 D / A audio output processing section 10 MPEG-VIDEO decoding section 11 Graphic section 12 D / A video output processing unit 13 Control unit 14 Power supply unit

Claims (1)

[Claims] 1. A digital broadcast receiver for receiving a digital broadcast in which a plurality of modulation schemes are mixed in one transmission frequency, wherein a signal of a desired BS-IF frequency is selected from an input signal and a base of I and Q is selected. A BS front-end unit that outputs a band signal; an AD unit that converts the I and Q baseband signals into digital signals and outputs the converted signals; a PSK demodulator that performs a demodulation process on an output signal of the AD unit and outputs a demodulated digital signal A TS data obtained by error-correcting the demodulated digital signal, an error correction unit that outputs TMCC information and error rate information in the TS data, and transmission information obtained by decoding the TMCC information. Select TS
A TMCC decoding unit that outputs information; a TS selection output unit that selects and outputs specific TS data from the TS data based on the selected TS information; and decodes and sorts the specific TS data and performs audio processing. A DEMUX unit that outputs data and video data, and a control unit that controls various operations in the digital broadcast receiver.The control unit is configured to control each slot based on transmission information obtained from the TMCC decoding unit. Analyze the modulation method, create slot selection information of the same modulation method and supply it to the error correction unit, to obtain from the error correction unit only the error rate information of the slot specified by the slot selection information, A digital broadcast receiver for performing switching control of a modulation method based on the error rate information.