JP2008048201A - Digital broadcasting receiver - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that the reference clock for voice outputting and image displaying on a backend unit side cannot synchronize with that on a broadcasting station side, resulting in missing of frames or breaking off of sound, since packet transmission is used for TS signal transmission between units if the receiver for receiving digital broadcasting signals are separated into a frontend unit 100 and a backend unit 200. <P>SOLUTION: Transmission/reception buffers 16 and 19 are provided before and after packet transmission of TS signals between the frontend unit 100 and the backend unit 200, to compensate missing of frames and breaking off of sound. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a receiving apparatus for receiving a digital broadcast signal, and in particular, the receiving apparatus includes a front end unit including a tuner and a demodulator, and a back end including a transport stream decoder, an audio decoder, a video decoder, and a presentation processing unit. The present invention relates to a digital broadcast receiver separated into end units.

  Terrestrial digital broadcasting enables various services, one of which is broadcasting for mobile devices. With this service, terrestrial digital broadcast programs can be enjoyed on the go or on the way to work by using a mobile terminal such as a mobile phone. Therefore, it is expected that portable terminals that can receive terrestrial digital broadcasting will be increasingly popularized.

  As a conventional digital broadcast receiver, for example, the configuration of an integrated receiver described in FIG. 3A of ARIB TR-B14 “terrestrial digital television broadcast operation regulations” (Non-Patent Document 1) is generally known. Yes.

  FIG. 3 is a block diagram in which the configuration of the receiving apparatus described in Non-Patent Document 1 is simplified. 1 is an antenna that receives a digital broadcast, 2 is a tuner that selects a predetermined digital broadcast, and 3 is a tuner 2. A demodulator that demodulates a digital broadcast signal received via a signal and converts it into a transport stream signal (hereinafter referred to as a TS signal), 4 a transport stream that decodes the TS signal and separates it into an audio signal and a video signal Decoder (hereinafter referred to as TS decoder) 5 is an audio decoder for audio decoding the audio signal separated by the TS decoder 4, and 6 is a D / A for converting the digital audio signal output from the audio decoder 5 into analog An audio signal converted into an analog signal by the converter is output as audio from the speaker 7. On the other hand, the video signal separated by the TS decoder 4 is subjected to video decoding processing by the video decoder 8. 9 is a presentation processing unit that synthesizes the video signal from the video decoder 8 and character data, 10 is an LCD that displays the video signal input from the presentation processing unit on the screen, and 11 is a synchronization signal from the demodulation unit 3. And a reference clock generator for generating a reference clock. The reference clock of the reference clock generation unit 11 is synchronized with the reference clock on the broadcasting station side, and is supplied to the TS decoder 4, the audio decoder 5, the D / A converter 6, the video decoder 8, and the presentation processing unit 9. . Reference numeral 12 denotes a control unit that controls each part of the receiving apparatus.

  That is, the digital broadcast received by the antenna 1 is selected by the tuner 2 and input to the demodulator 3. The demodulator 3 demodulates the input digital broadcast signal, inputs the TS signal to the TS decoder 4, and inputs a synchronization signal synchronized with the reference clock on the broadcast station side to the reference clock generator 11. The TS decoder 4 separates the audio signal and the video signal by decoding the TS signal input from the demodulator 3. Here, the TS signal actually includes other data as well as the audio signal and the video signal, and this other data signal is also separated by the TS decoder 4 and processed by the control unit 12, but for convenience of explanation. This processing is omitted.

  The audio signal separated by the TS decoder 4 is subjected to audio decoding processing by the audio decoder 5, further converted into an analog signal by the D / A converter 6, and then supplied to a speaker for audio output. On the other hand, the video signal separated by the TS decoder 4 is subjected to video decoding processing by the video decoder 8 and supplied to the presentation processing unit 9. The presentation processing unit 9 synthesizes character data such as subtitles with the video signal supplied from the video decoder 8 and inputs it to the LCD 10, thereby displaying an image on the screen of the LCD 10.

  Here, it is necessary to synchronize the audio output from the speaker 7 and the image output from the LCD with the reference clock of the transmitter on the broadcast station side. Otherwise, momentary sound interruptions and frame dropping of images will occur. Therefore, the reference clock generation unit 11 is configured to generate a reference clock based on the synchronization signal from the demodulation unit 3 and supply it to each unit. That is, the demodulator 3 can reproduce the clock having the same accuracy as the clock used when the TS signal is transmitted from the broadcasting station side from the serial data of the TS signal. A reference clock synchronized with the clock can be supplied to the TS decoder 4, the audio decoder 5, the D / A converter 6, the video decoder 8, and the presentation processing unit 9.

ARIB TR-B14 “Operational Rules for Digital Terrestrial Television Broadcasting”

  A digital broadcast receiving apparatus described in Non-Patent Document 1 includes a front end unit composed of a tuner 2 and a demodulation unit 3, a back end unit composed of a TS decoder 4, an audio decoder 5, a video decoder 8, and a presentation processing unit. Are configured as a single unit. However, on the product concept, there is a demand for a new concept in which the front end portion and the back end portion are configured as separate units. For example, a mobile terminal such as a mobile phone is originally equipped with a CPU and hardware for moving image processing, and if these are used for signal processing of the back-end unit, the front-end unit is a separate unit. A digital broadcast receiver can be obtained by connecting to a portable terminal. That is, if a front end unit is prepared, a digital broadcast can be received and viewed simply by connecting to an existing portable terminal. In addition, in the case of a mobile phone, due to the increase in functionality, several interfaces for connecting to external devices are already provided, so there is no need to provide a new interface.

  On the other hand, assuming that the front end unit and the back end unit are configured as separate units, it is conceivable to use a USB interface to connect the two units. Although the USB interface is general-purpose, it is basically packet transmission, and therefore, the reference clock synchronized with the reference clock on the broadcasting station side cannot be generated by the back-end unit. Therefore, if you continue watching for a long time, the TS signal will be depleted or overflowed in the back-end unit, frame dropping will occur in the image display, and momentary sound interruption or noise will occur in the audio playback. .

  The present invention has been made in view of the above-described problems. The digital broadcast receiving apparatus is separated into a front end unit and a back end unit, frame dropping occurs in image display, and instantaneous sound interruption occurs during audio reproduction. The purpose is to suppress the generation of noise.

A digital broadcast receiving apparatus according to the present invention includes a demodulator that demodulates a received digital broadcast signal to obtain a transport stream signal, a first buffer that temporarily stores the transport stream signal demodulated by the demodulator, A front-end unit comprising a packet transmission unit for sequentially extracting a part of a transport stream signal stored in one buffer and transmitting the packet;
A packet receiver for receiving a packet signal transmitted from the packet transmitter; a second buffer for temporarily storing the transport stream signal received by the packet receiver; and a transport stream sequentially extracted from the second buffer A transport stream decoder that separates a signal into an audio signal and a video signal, an audio processing unit that supplies the audio signal separated by the transport stream decoder to a speaker and outputs the audio, and the transport stream decoder The front end unit comprising: a display processing unit that supplies a video signal to a display unit to display an image; and a reference clock generation unit that supplies a reference clock to the transport stream decoder, the audio processing unit, and the display processing unit; Is provided separately The is made includes a back-end unit.

The digital broadcast receiving apparatus according to the present invention includes a demodulator that demodulates the received digital broadcast signal to obtain a transport stream signal, a first buffer that temporarily stores the transport stream signal demodulated by the demodulator, A front-end unit comprising a packet transmission unit for sequentially extracting a part of the transport stream signal accumulated in the first buffer and transmitting the packet,
A packet receiver that receives the packet signal transmitted from the packet transmitter; a second buffer that temporarily stores the transport stream signal received by the packet receiver; and a transport stream that is sequentially extracted from the second buffer A transport stream decoder that separates a signal into an audio signal and a video signal, an audio processing unit that supplies the audio signal separated by the transport stream decoder to a speaker and outputs the audio, and the transport stream decoder A display processing unit that supplies a video signal to the display unit to display an image, and a synchronization signal is input from the demodulating unit via a signal line, and a reference clock is supplied to the transport stream decoder, the audio processing unit, and the display processing unit. From the supplied reference clock generator That is made includes a back-end unit provided separately from the aforementioned front-end unit.

  According to the present invention, the digital broadcast receiving apparatus is separated into a front end unit and a back end unit, and transmission and reception of transport stream signals between both units are performed by packet transmission, and from the front end unit to the back end unit. Since the first buffer for temporarily storing the transport stream signal to be transmitted and the second buffer for temporarily storing the transport stream signal transmitted from the front end unit to the back end unit are provided, the first and second buffers are provided. Fluctuations in the data transfer rate due to packet transmission can be absorbed, and frame dropping in image display, instantaneous sound interruption and noise generation in audio reproduction can be suppressed.

  According to the present invention, the digital broadcast receiver is separated into a front end unit and a back end unit, and transport stream signals are transmitted and received between both units by packet transmission. A first buffer for temporarily storing a transport stream signal to be transmitted to the unit and a second buffer for temporarily storing a transport stream signal transmitted from the front end unit to the back end unit are provided and generated by the demodulator of the front end unit. Since the reference clock is supplied to the reference clock generation unit of the backend unit and the reference clock is supplied to each unit, the first and second buffers can absorb fluctuations in the data transfer rate due to packet transmission. When A, it is possible to synchronize the reference clock of the back end unit and the reference clock of the broadcast station, the occurrence of dropped frames in the image display, it is possible to prevent the occurrence of instantaneous sound interruption and noise in the audio playback.

  Hereinafter, a digital broadcast receiving apparatus according to Embodiment 1 of the present invention will be described with reference to the block diagram of FIG.

  In FIG. 1, the same reference numerals as those in FIG. Reference numeral 100 denotes a front-end unit, and reference numeral 200 denotes a back-end unit. These two units are configured as separate units. 13 is an encryption unit that encrypts the TS signal demodulated by the demodulation unit 3, 14 is a control unit that controls the front-end unit 100, and 15 is a TS signal encrypted by the encryption unit 13 and the control unit 14. A command / data demultiplexing unit 16 that multiplexes control commands to be transmitted to the back-end unit, 16 is a transmission / reception buffer that temporarily stores TS signals and control commands multiplexed by the command / data demultiplexing unit 15, and 17 A USB interface on the front end unit 100 side that sequentially takes out TS signals and control commands temporarily stored in the transmission / reception buffer 16, packetizes and transmits them, and 18 is a back end unit side connected to the USB interface 17 via a USB cable. USB interface, 19 is this USB interface A transmission / reception buffer that temporarily stores TS signals and control commands transmitted from the front end unit 100 via the interface 18, and a TS signal and control commands that are temporarily stored in the transmission / reception buffer 19 are sequentially extracted. And a command / data demultiplexing unit. The control command separated by the command / data demultiplexing unit 20 is transmitted to the control unit 21 that controls the back-end unit 200, and the TS signal is supplied to the encryption / decryption unit 22 for decryption.

  That is, the digital broadcast receiver of FIG. 1 is separated into a front end unit 100 and a back end unit 200. Therefore, the control parts 14 and 21 are provided in each unit. These control units 14 and 21 are sub-control units in which the control unit 21 on the back-end unit 200 side functions as a main control unit, and the control unit 14 on the front-end unit 100 side functions under the command of the control unit 21. is there. Further, in order to protect the copyright of the broadcast content transmitted by the TS signal, the front end unit 100 is provided with an encryption unit 13 for encrypting the TS signal, and the back end unit 200 side is provided with an encryption / decryption for decrypting the encryption. A conversion unit 22 is provided.

  Next, the operation will be described. The digital broadcast received by the antenna 1 is selected by the tuner 2 and input to the demodulator 3. The demodulator 3 demodulates the input digital broadcast signal and outputs the TS signal to the encryption unit 13. The encryption unit 13 encrypts the TS signal demodulated by the demodulation unit 3 and outputs it to the command / data demultiplexing unit 15. The command / data demultiplexing unit 15 multiplexes the encrypted TS signal and the control command from the control unit 14 and temporarily stores them in the transmission / reception buffer 16. The TS signals and control commands stored in the transmission / reception buffer 16 are sequentially read out by the USB interface 17, packetized, and transmitted to the USB interface 18 of the back-end unit 200. The TS signal and control command transmitted to the USB interface 18 are temporarily stored in the transmission / reception buffer 19 and then sequentially read out to the command / data demultiplexing unit 20. The command / data demultiplexing unit 20 demultiplexes the multiplexed TS signal and control command, outputs the TS signal to the encryption / decryption unit 22, and outputs the control command to the control unit 21.

  Here, the control command of the control unit 14 is transferred to the control unit 21 as described above. However, the control command from the control unit 21 to the control unit 14 is a route opposite to the above, and the command / data demultiplexing unit. 20, the transmission / reception buffer 19, the USB interface 18, the USB interface 17, the transmission / reception buffer 16, and the command / data demultiplexing unit 15.

  Next, the TS signal input to the encryption / decryption unit 22 is input to the TS decoder 4 after being decrypted. The TS decoder 4 separates the audio signal and the video signal by decoding the TS signal input from the encryption / decryption unit 22. The audio signal separated by the TS decoder 4 is subjected to audio decoding processing by the audio decoder 5, further converted into an analog signal by the D / A converter 6, and then supplied to a speaker for audio output. On the other hand, the video signal separated by the TS decoder 4 is subjected to video decoding processing by the video decoder 8 and supplied to the presentation processing unit 9. The presentation processing unit 9 synthesizes character data such as subtitles with the video signal supplied from the video decoder 8 and inputs it to the LCD 10, thereby displaying an image on the screen of the LCD 10.

  In the digital broadcast receiving apparatus of FIG. 1, the audio output and the image are displayed by the reference clock supplied from the reference clock generation unit 11, but this reference clock is not necessarily synchronized with the reference clock on the broadcast station side. In addition, since transmission of TS signals between the front end unit 100 and the back end unit 200 is packet transmission, fluctuations in the data transmission rate also occur. However, since the transmission / reception buffers 16 and 19 are provided to compensate for frame dropping of the image display or sound output interruption that may occur due to these factors, the digital broadcast can be viewed without receiving these obstacles. be able to.

  FIG. 2 is a block diagram showing a digital broadcast receiving apparatus according to Embodiment 2 of the present invention. The difference between the second embodiment and the first embodiment is that the demodulator 3 of the front end unit derives a reference clock that is synchronized with the reference clock of the transmitter on the broadcast station side, and uses this reference clock as the back end unit 200. This is the point that it is supplied to the reference clock generator 11. With this configuration, audio output and image display synchronized with the reference clock on the broadcast station side can be performed. In the second embodiment, one signal line for connecting the demodulator 3 and the reference clock generator 11 is required. However, the transmission / reception buffers 16 and 19 only have to compensate for fluctuations in the packet transmission rate, so the capacity is reduced. can do.

  In the present invention, a device for receiving digital broadcasting is separated into a front-end unit and a back-end unit, and a mobile phone can be used as a back-end unit.

It is a block block diagram which shows the digital broadcast receiver which concerns on Embodiment 1 of this invention. It is a block block diagram which shows the digital broadcast receiver which concerns on Embodiment 2 of this invention. It is a block block diagram which shows the conventional digital broadcast receiver.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Antenna 2 Tuner 3 Demodulation part 4 Transport stream decoder 5 Audio decoder 7 Speaker 8 Video decoder 10 LCD 11 Reference clock generation part 13 Encryption part 15 Command data demultiplexing part 16 Transmission / reception buffer 17 USB interface 18 USB interface 19 Transmission / reception buffer 20 Command / Data Demultiplexing Unit 22 Encryption / Decryption Unit 100 Front End Unit 200 Back End Unit

Claims (5)

A demodulator that demodulates the received digital broadcast signal to obtain a transport stream signal, a first buffer that temporarily stores the transport stream signal demodulated by the demodulator, and a transport stream signal that is stored in the first buffer A front-end unit consisting of a packet transmission unit that sequentially extracts and transmits packets.
A packet receiver that receives the packet signal transmitted from the packet transmitter; a second buffer that temporarily stores the transport stream signal received by the packet receiver; and a transport stream that is sequentially extracted from the second buffer A transport stream decoder that separates a signal into an audio signal and a video signal, an audio processing unit that supplies the audio signal separated by the transport stream decoder to a speaker and outputs the audio, and the transport stream decoder The front end unit comprising: a display processing unit that supplies a video signal to a display unit to display an image; and a reference clock generation unit that supplies a reference clock to the transport stream decoder, the audio processing unit, and the display processing unit; Is provided separately Digital broadcast receiving apparatus characterized by comprising a back-end units. A demodulator that demodulates the received digital broadcast signal to obtain a transport stream signal, a first buffer that temporarily stores the transport stream signal demodulated by the demodulator, and a transport stream signal that is stored in the first buffer A front-end unit consisting of a packet transmission unit that sequentially extracts and transmits packets.
A packet receiver that receives the packet signal transmitted from the packet transmitter; a second buffer that temporarily stores the transport stream signal received by the packet receiver; and a transport stream that is sequentially extracted from the second buffer A transport stream decoder that separates a signal into an audio signal and a video signal, an audio processing unit that supplies the audio signal separated by the transport stream decoder to a speaker and outputs the audio, and the transport stream decoder A display processing unit that supplies a video signal to the display unit to display an image, and a synchronization signal is input from the demodulating unit via a signal line, and a reference clock is supplied to the transport stream decoder, the audio processing unit, and the display processing unit. From the supplied reference clock generator That, from the above front end unit digital broadcast receiving apparatus characterized by comprising a back-end unit provided separately. The front end unit includes an encryption unit that encrypts the transport stream signal demodulated by the demodulation unit and stores the encrypted transport stream signal in the first buffer. 3. The digital broadcast receiving apparatus according to claim 1, further comprising an encryption / decryption unit that encrypts / decrypts the transport stream signal extracted from the buffer and supplies the transport stream signal to the transport stream decoder. 3. The digital broadcast receiving apparatus according to claim 1, wherein the packet transmission unit of the front end unit and the packet reception unit of the back end unit are connected by a USB cable. The front end unit and the back end unit have a control unit that controls each part, and the control unit on the front end unit side operates under the control of the control unit on the back end unit side. The digital broadcast receiving apparatus according to claim 1 or 2, characterized in that

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