KR100555955B1 - Digital television receiver - Google Patents

Abstract

The digital television receiver according to the present invention includes a program guide database in which frequencies for each digital channel are set, a tuner for tuning a digital broadcast signal at a predetermined frequency and transmitting a tuned digital broadcast signal, and a digital broadcast signal provided from the tuner. A demodulator for converting and transmitting transport stream data; a demux for storing transport stream data in a buffer; extracting and separating video, audio, and sync signals from transport stream data; And a microcomputer having an AFT module for providing a tuner with a frequency corresponding to the channel and changing the frequency of the digital channel to a predetermined range when the transport stream data stored in the buffer is smaller than a preset value. . In addition, the digital television receiver for providing the MFT function includes a fine adjustment key for adjusting a frequency for tuning and an MFT for changing the frequency of a digital channel to be tuned in response to a signal according to the operation of the fine adjustment key and providing the tuner with a tuner. It further includes a module.

As described above, the present invention provides the effect that the AFT or MFT can be tuned even if the frequency is changed due to loss due to external factors or long distance transmission during automatic channel tuning.

Description

Digital Television Receiver {DIGITAL TELEVISION RECEIVER}

1 is a block diagram showing a digital television receiver according to the prior art,

2 is an exemplary diagram illustrating a structure of a general digital broadcast signal.

3 is a block diagram illustrating a digital television receiver having AFT and MFT functions in accordance with the present invention.

<Description of the code | symbol about the principal part of drawing>

200: microcomputer 202: AFT module

204: MFT module 205: user control key

210: tuner 220: demodulator

230: demux 230a: buffer

240: program guide database 250: memory

260: video decoder 270: audio decoder

The present invention relates to a digital television receiver, and more particularly, to a digital television receiver for performing AFT (Auto Fine Tuning) and MFT (Manual Fine Tuning).

Digital TV broadcasting is not only within the TV receiver, but because the signals transmitted from the broadcasting station to the home are all digital signals, they provide clear picture quality and vivid sound quality compared to analog. Based on the number of points that can be displayed on the screen, the digital TV image has a width of 640 and a height of 1080, which is 7 times that of SDTV from a standard method (SDTV) having a resolution of 640 and 480. It offers 18 formats of video, ranging from high-definition video (HDTV) with resolution.

The sound adopts Dolby AC-3 system, and the clear three-dimensional sound that surpasses CD is reproduced vividly. In addition, such performance is not only improved in digital television, but also because data compression technology with high efficiency of 50 to 1 or more is used, the number of reserved channels can be increased for each broadcasting station based on SDTV, and bidirectional transmission is possible. It can also provide additional services that are completely different from analog TV.

The structure of a conventional digital TV receiver will be described with reference to FIGS. 1 and 2. 1 is a schematic configuration diagram of a digital TV receiver according to the prior art, and FIG. 2 is an exemplary diagram showing a structure of a signal used in general digital broadcasting.

In FIG. 1, the microcomputer 100 controls the program guide database 108 to provide arbitrary channel information to the tuner 102, and the tuner 102 of the microcomputer 100 of the broadcast signal received through the antenna. One RF channel is tuned according to the control, and an intermediate frequency of the broadcast signal of the tuned channel is tuned and output. The demodulator 104 converts the intermediate frequency signal by the tuning process into a baseband signal, and then converts the intermediate frequency signal into an MPEG transport 8 layer, that is, transport stream data, and provides it to the demux 106. Demux 106 separates audio data, video data and PSIP data from the transport stream data, respectively. The audio decoder 114 receives the audio data separated from the demux 106 and decodes the audio data according to the MPEG standard or the Dolby AC-3 standard to output to the speaker. The video decoder 112 receives the video data separated by the demux 106, decodes the signal according to the MPEG standard, and outputs it to the CRT. The demux 106 temporarily transmits the transport stream data output from the demodulator 104. A buffer 106a for storing is included.

The structure of the signal received by such a digital television receiver includes a data region and a compressed carrier frequency (Fs), as shown in FIG. 2, and the tuner 102 of the digital television receiver has an intermediate frequency (Fc), for example. For example, if the digital channel is 80 channels, tune to 561 MHz. That is, the tuner 102 tunes the digital channel 80 using the intermediate frequency Fc information for the digital channel 80 provided from the program guide database 108.

Referring to the automatic channel tuning process of the digital TV receiver having such a configuration, first, the microcomputer 100 extracts arbitrary channel information from the program guide database 108 and then provides the tuner 102 with the tuner 102. The tuner outputs the tuned data to the demodulator 104 by tuning using the intermediate frequency Fc provided from the program guide database 108 under the control of the microcomputer 102.

The demux 106 stores the transport stream data in the buffer 106a, and the microcomputer 100 reads the data stored in the buffer 106a to determine whether a synchronization signal exists and the size of the data is greater than or equal to a preset size. Judge.

As a result of the determination, when the synchronization signal exists and the size of the data is greater than or equal to the preset size, the microcomputer 100 determines that the tuned channel is a viewable channel and stores the tuned channel information in the memory 110.

The digital television receiver repeats this process to perform automatic channel tuning.

In general, in a digital television receiver, as in an analog broadcast, a signal is transmitted through the air or a cable, and thus, the compressed carrier frequency portion of the tuned signal is shifted by about -50KHz. For this reason, because the data stored in the buffer 106a of the demux 106 falls below a predetermined size, the digital television receiver tunes the next channel without properly tuning these channels.

However, despite the fact that the digital signal transmitted through the air or the cable is distorted, unlike the analog receiver, the AFT and MFT functions do not exist in the digital television receiver.

SUMMARY OF THE INVENTION An object of the present invention is to solve the problems of the prior art, and to provide a digital television receiver for performing AFT on a channel that is not tuned due to signal distortion during automatic channel tuning.

In order to achieve the above object, the present invention provides a digital television receiver comprising a program guide database in which frequencies for each digital channel are set, a tuner for tuning a digital broadcast signal at a predetermined frequency and transmitting a tuned digital broadcast signal. And a demodulator for converting and transmitting the digital broadcast signal provided from the tuner into transport stream data, storing the transport stream data in a buffer, and extracting and separating video, audio, and sync signals from the transport stream data. A demux for controlling the program guide database and providing a frequency corresponding to a predetermined digital channel to the tuner, and reading transport stream data stored in the buffer to be smaller than a preset value, the middle of the tuned digital channel. week An intermediate frequency added or subtracted to the 3.5Khz can include a microcomputer having an AFT module providing to the tuner.

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Hereinafter, exemplary embodiments will be described in detail with reference to the accompanying drawings. 3 is a block diagram illustrating a digital television receiver having AFT and MFT functions in accordance with the present invention.

Referring to FIG. 3, the digital television receiver according to the present invention includes a microcomputer 200, a user control key 205, a tuner 210, a demodulator 220, a demux 230, a program guide database 240, and a memory. 250, video decoder 260 and audio decoder 270.

The microcomputer 200 includes an AFT module 202 and an MFT module 204 and controls the program guide database 240 to provide the tuner 210 with arbitrary channel information, that is, an intermediate frequency corresponding to the digital channel. In response to the tuning failure, the AFT module 202 is driven to provide the tuner 210 with the calculated AFT intermediate frequency by subtracting or adding the predetermined frequency from the intermediate frequency of the digital channel that failed tuning.

In addition, the MFT module 204 of the microcomputer 200 provides the tuner 210 with the MFT intermediate frequency changed in correspondence with the signal generated by the operation of the user adjustment key 205 to perform user fine tuning when tuning. .

The frequency information of the digital channel tuned by such AFT, MFT or automatic tuning is stored in the memory 250 by the microcomputer 200.

The tuner 210 demodulates the tuned digital signal by tuning the digital broadcast signal to an intermediate frequency of the digital channel provided from the program guide database 240 according to the control of the microcomputer 200 among the broadcast signals received through the antenna. ) The tuner 210 also tunes the digital broadcast signal to the AFT intermediate frequency provided by the AFT module 202 to provide the tuned digital signal to the demodulator 220 or the MFT according to the user fine adjustment provided by the MFT module 204. The digital broadcast signal is tuned to an intermediate frequency to provide the tuned digital signal to the demodulator 220.

The demodulator 220 converts the intermediate frequency signal by the tuning process of the tuner 210 into a baseband signal, and then converts the intermediate frequency signal into an MPEG transport 8 layer, that is, the transport stream data, and provides it to the demux 230. do.

The demux 230 separates the audio data, the video data, and the PSIP data from the transport stream data, respectively, and temporarily stores the transport stream data in the buffer 230a during automatic tuning.

The audio decoder 270 receives the audio data separated from the demux 230, decodes it according to the MPEG standard or the Dolby AC-3 standard, and outputs the same to the speaker, and the video decoder 260 demux 230 Receives the separated video data from and decodes it according to MPEG standard and outputs it to CRT.

Referring to the automatic channel tuning process of the digital TV receiver having the AFT and MFT functions having the above configuration, first, the microcomputer 200 extracts the intermediate frequency information for any digital channel from the program guide database 240. The tuner 210 is provided to the tuner 210, and the tuner 210 outputs the tuned digital broadcast signal to the demodulator 220 as a result of tuning using an intermediate frequency provided from the program guide database 240 under the control of the microcomputer 200. do.

The demodulator 220 converts the digital broadcast signal into transport stream data and provides it to the demux 230. The demux 230 stores the transport stream data in the buffer 230a, and the microcomputer 200 The data stored in the buffer 230a is read to determine whether a synchronization signal exists and the size of the data is greater than or equal to a preset size.

As a result of the determination, when the size of the data stored in the buffer 230a is smaller than or equal to the preset size, the microcomputer 200 determines that the signal tuning for the digital channel is not performed, and drives the AFT module 202 which is an automatic fine tuning device.

The AFT module 202 provides the tuner 210 with an AFT intermediate frequency calculated by subtracting or adding a predetermined frequency from the intermediate frequency that fails to tune. For example, if the tuning fails at the intermediate frequency 561 MHz corresponding to the digital channel 80, the AFT module 202 calculates the intermediate frequency by adding or subtracting 3.5 KHz to the intermediate frequency 561 MHz, and then converting the calculated intermediate frequency to the tuner 210. To provide.

The tuner 210 provides the demodulator 220 with the tuned signal obtained by tuning the digital broadcast signal to the AFT intermediate frequency.

Accordingly, the demodulator 220 converts the signal provided from the tuner 210 into transport stream data and provides the demux 230, and the demux 230 stores the transport stream data in the buffer 230a. .

The AFT module 202 stores the AFT intermediate frequency provided to the tuner 210 in the memory 250 through the microcomputer 200 when the data stored in the buffer 230a is larger than or equal to a preset size.

If the data stored in the buffer 230a is less than the preset size, the AFT module 202 repeats the above process after changing the AFT intermediate frequency again.

When the digital broadcasting cannot be received due to a broadcasting station or other problem, the user operates the user adjusting key 205 to perform the user fine tuning to receive the digital broadcasting.

First, when a user operates the user adjustment key 205, the user adjustment key 205 outputs a signal according to the user operation to the MFT module 204. FIG.

The MFT module 204 adjusts the intermediate frequency based on the signal provided from the fine adjustment key 205 and provides the tuner 210 with the adjusted intermediate frequency (MFT intermediate frequency).

The tuner 210 tunes the digital broadcast signal to the MFT intermediate frequency and provides the tuned signal to the demodulator 220.

As in the AFT case, the signal tuned by the MFT intermediate frequency is converted into transport stream data by the demodulator 220 and stored in the buffer 230a of the demux 230.

Accordingly, the MFT module 204 determines whether the size of the data stored in the buffer 230a is greater than or equal to the preset size, and as a result of the determination, the MFT module 204 determines that the size of the MFT module 204 is greater than or equal to the preset size. The module 204 stores the MFT intermediate frequency provided to the tuner 210 in the memory 250 through the microcomputer 200.

If the data stored in the buffer 230a is less than the predetermined size, the MFT module 202 repeats the above process after changing the MFT intermediate frequency again in response to the signal provided from the user adjustment key 205. .

In the present invention, whether or not to tune is determined using the size of data and whether or not there is a synchronization signal. However, in another method, the signal noise ratio (SNR) and the code noise ratio (CNR) of data are used. It is also possible to decide whether to tune in.

As described above, the present invention provides the effect that the AFT or MFT can be tuned even if the frequency is changed due to loss due to external factors or long distance transmission during automatic channel tuning.

Claims (3)

delete delete In a digital television receiver, Program guide database that sets frequency per digital channel, A tuner for tuning the digital broadcast signal at a predetermined frequency and transmitting the tuned digital broadcast signal; A demodulator for converting and transmitting the digital broadcast signal provided from the tuner into transport stream data; A demux for storing the transport stream data in a buffer and extracting and separating video, audio, and sync signals from the transport stream data; The program guide database is controlled to provide the tuner with a frequency corresponding to a predetermined digital channel, and when the transport stream data stored in the buffer is read and smaller than a preset value, 3.5Khz is set as an intermediate frequency of the tuned digital channel. A microcomputer with an AFT module providing the tuner with added or subtracted intermediate frequencies Digital television receiver comprising a.

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