KR100785202B1 - Digital broadcast receiving method and system - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital broadcast reception technology. In order to receive digital broadcast using a broadcast reception system having a tuner, the broadcast stream received through the tuner is demodulated by 8-VSB (Vertigial Sideband) and then decoded. Outputting a broadcast signal of high definition (HD), detecting a reception error rate of the reception broadcast stream, and comparing the detected reception error rate with a preset threshold, and if the detected reception error rate is greater than the preset threshold; And demodulating and decoding the received broadcast stream using an orthogonal frequency division multiplexing (OFDM) scheme to output a broadcast signal of standard definition (SD). According to the present invention, a user having a digital broadcasting system can watch HD broadcasting in a fixed place and watch SD broadcasting while moving.

Description

Digital broadcasting reception method and system {METHOD AND SYSTEM FOR RECEVING OF DIGITAL BROADCAST STREAM}

1 is a diagram showing the structure of a broadcast receiving system according to a preferred embodiment of the present invention;

2 is a flowchart illustrating an operation procedure for broadcast reception according to a preferred embodiment of the present invention.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to broadcast reception technology in a broadcast system, and more particularly, to a digital broadcast reception method and system suitable for receiving digital broadcast on the go.

The digital revolution for television began in the early 1990s when first satellite operators began broadcasting signals in digital form. Since then, it has begun to replace existing terrestrial analog NTSC television systems with digital television (DTV) systems.

Several simultaneous standard definition television (SDTV) imaging systems or single high definition television (HDTV) video will typically constitute digital television programming broadcasts.

SDTV is roughly regarded as the same level of quality as today's analog television broadcasts, and HDTV is about a number of higher definition video standards that greatly improve the quality of the picture and sound on the screen. Both of these broader television standards are considered to be within the ATSC (Advanced Television Systems Committee) standard, a new standard launched in 1994 by the United States for terrestrial broadcasts.

HDTV standard images allow up to six times the resolution of analog television images, and up to 60 frames per second in time resolution, twice the current NTSC resolution. The movement looks smooth and the picture is clear enough to sit very close to a very large screen. The picture is displayed in a panoramic 16: 9 horizontal-to-vertical aspect ratio to make it more like a movie and add a realistic feel to the TV. HDTV video signals contain nearly four to five times the data of NTSC video.

However, ATSC standard 8VSB (Vertigial Sideband) transmission method is single carrier digital broadcasting, compared to Orthogonal Frequency Division Multiplexing (OFDM), which is a multicarrier transmission method of Digital Video Broadcasting-Terrestrial (DVB-T). Very vulnerable The reason is that 8VSB demodulation can carry only one large HD stream in one physical channel and is more vulnerable to multipath fading channel than OFDM.

In such a situation, OFDM can be solved through FEC (Forward Error Correction) because only a few channels of the multi-carriers are damaged. However, in case of 8VSB, the transmission channel itself is vulnerable. There was a problem that it is vulnerable to mobile reception.

The present invention is to overcome the above-mentioned limitations of the prior art, and an object thereof is to provide a method and a system capable of receiving digital broadcasting while moving.

Another object of the present invention is to provide a method and system for performing digital broadcasting during movement, which demodulates using 8 VSB scheme in a fixed place and performs OFDM demodulation scheme during movement.

In one aspect of the present invention, a method for receiving digital broadcasting using a broadcast receiving system having a tuner, and demodulating and decoding a broadcast stream received through the tuner in 8-VSB (Vertigial Sideband) scheme to obtain high quality (HD). Outputting a broadcast signal), detecting a received error rate of the received broadcast stream, comparing the detected received error rate with a preset threshold value, and the detected received error rate is greater than the preset threshold value. The method includes demodulating the received broadcast stream using an orthogonal frequency division multiplexing (OFDM) scheme and decoding the received broadcast stream to output a broadcast signal of standard definition (SD).

According to another aspect of the present invention, a digital broadcast reception system includes a radio frequency (RF) unit for receiving a broadcast signal modulated in various ways, and a broadcast stream transmitted from the RF unit to an intermediate frequency for demodulation for each broadcast mode. A preset threshold value for a tuner unit which detects and transmits the received error rate of the broadcast stream to the controller, a decoder that decodes the broadcast stream delivered from the tuner unit, and an error rate received from the tuner unit. If large, the 8-VSB (Vertigial Sideband) scheme is terminated, the Orthogonal Frequency Division Multiplexing (OFDM) scheme is demodulated, and the error rate detected during the demodulation of the OFDM scheme is compared with a preset threshold. Or the same, the control unit for transmitting a command signal to the tuner unit to terminate the OFDM scheme and perform 8-VSB demodulation; It includes a display for displaying a broadcast signal received from the decoder group.

Hereinafter, the operating principle of the present invention will be described in detail with reference to the accompanying drawings. In the following description of the present invention, when it is determined that a detailed description of a known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted. Terms to be described later are terms defined in consideration of functions in the present invention, and may be changed according to intentions or customs of users or operators. Therefore, the definition should be made based on the contents throughout the specification.

According to the present invention, when a fixed location is used, an 8VSB method is used to receive a high-definition HD broadcast, and a high-speed bus, a mobile home, or a mobile digital device displays the SD broadcast by applying the OFDM method. Since SD streams are not divided into a single physical band like HD streams but are divided into several parts, if the streams are transmitted and sent in multiple places, the reception of the streams will not only increase the sensitivity of reception, but also can receive them on the move. .

1 is a diagram showing the structure of a digital broadcast receiving system according to a preferred embodiment of the present invention.

Referring to FIG. 1, the digital broadcast reception system includes an RF unit 102, a tuner unit 104, a decoder 114, a control unit 116, a display unit 120, and an I2C communication unit 118. . When the RF unit 102 receives a broadcast signal modulated in various ways and transmits a stream thereof to the tuner unit 104, the tuner unit 104 uses an intermediate frequency (PLL) in a phase locked loop (tuner chip). IF: Intermediate Frequency). Demodulation of various modes is performed by using the frequency band 6, 7, 8 MHz through this intermediate frequency.

Specifically, demodulation methods include ATSC's 8-VSB method, ISDB-T (Integrated Service Digital Broadcasting-Terrestrial), DVB-T (Digital Video Broadcasting-Terrestrial Television) COFDM (Coded Orthogonal Frequency Division Modulation) method, and DVB-C ( There are Quadrature Amplitute Modulation (QAM) method of Digital Video Broadcasting-Cable, and IF filter should be able to support demodulation of various methods as described above. Although only the VSB demodulation chip 106 and the COFDM demodulation chip 108 are illustrated in the embodiment of FIG. 1, the demodulation chip supported according to the implementation method of the digital broadcast reception system may be configured differently.

Thereafter, the demodulated broadcast signal is input to the decoder 114, and the decoder 114 performs decoding under the control of the controller 116, and transmits the decoded broadcast signal to the display unit 120. The output is for viewing.

One added portion here is mobility. This mobility is not manually selected by the user, but is set to be automatically selected on the broadcasting system. Therefore, the criterion for determining the mobility is to determine the mobility with the error rate (error rate) from the error pin of the tuner unit 104 during ATSC demodulation. The VSB method transmits only one stream in the physical band, which can be extremely weak against errors. In other words, when moving, the tuner 104 cannot receive the correct broadcast using only one stream, resulting in high error rate.

However, the COFDM scheme has a strong advantage against errors because the code division scheme receives the best band from multiple stream bands. So you get an error that can be covered to some extent when you move. Therefore, when the error rate is large, the demodulation method is changed from the VSB method to the COFDM method.

To this end, the control unit 116 continuously performs communication (control signal and data transmission / reception) with the tuner unit 104 through a communication unit such as I2C 118, and grasps the type of the received stream to demodulate the current situation. Is to choose a chip to perform. That is, the control unit 116 receiving the error rate information detected from the tuner unit 104 selects a different broadcast format from the ATSC according to the error rate, and then transmits the corresponding command to the tuner unit 104, thereby tuning the tuner unit 104. In step 116, the control unit 116 performs demodulation using a broadcast format.

2 is a flowchart illustrating an operation procedure for receiving digital broadcast according to an embodiment of the present invention.

Referring to FIG. 2, the mobile station enters the viewing mode in step 200, demodulates the broadcast stream using the ATSC 8-VSB scheme in step 202, and performs demodulated decoding in step 204 to display the decoded HD broadcast signal in step 206. do. Thereafter, when the broadcast receiving system is moved in step 208, that is, when the error rate detected by the tuner is greater than the preset threshold, the HD broadcast is no longer visible. In step 210, the demodulation method is toggled. In step 212, OFDM demodulation is performed. In other words, the ISDB-T or DVB-T format broadcasts are not received in the ATSC format.

Since the OFDM signal is received as described above, the demodulated signal in step 212 is decoded in step 214 to display a broadcast signal of SD quality in step 216.

At this time, for example, if the user moves somewhere while watching the MBC broadcast with 8-VSB, the user wants to watch the same MBC broadcast even when the broadcast format is converted to OFDM. Therefore, the controller must set in advance so that the broadcasting channels for each broadcasting method are matched.

In step 218, the mobile device moves and stays in one place. In this case, since the error rate is less than or equal to the preset threshold, the method returns to step 202 to perform demodulation in the 8-VSB method. However, if it is still moving in step 218 or if the error rate is greater than the preset threshold, the flow proceeds to step 220 to maintain the demodulation state of the OFDM.

As described above, when fixed in one place, the 8VSB method is used to receive high-definition HD broadcast, and the high-speed bus, mobile home, or mobile digital device displays the SD broadcast by applying the OFDM method. It is possible to receive digital broadcasts during the course.

Meanwhile, according to a preferred embodiment of the present invention, when it is determined that the broadcast receiving system is moving (that is, when the error rate exceeds a preset threshold), the broadcast stream received through the tuner is demodulated using the COFDM method instead of the VSB method. As described above, the present invention is not necessarily limited thereto. Of course, the present invention may be applied to any method (eg, QAM demodulation) as long as it supports both HD and SD broadcasts.

In the present invention operating as described in detail above, the effects obtained by the representative ones of the disclosed inventions will be briefly described as follows.

The present invention has the effect that the user with a digital broadcast receiving system can watch HD broadcast in a fixed place, and watch SD broadcast while on the move.

Claims (8)

A method of receiving digital broadcasting using a broadcast receiving system having a tuner, Demodulating and decoding the broadcast stream received through the tuner in the 8-VSB (Vertigial Sideband) method to output a high definition (HD) broadcast signal; Detecting a reception error rate of the reception broadcast stream and comparing the detected reception error rate with a preset threshold value; If the detected reception error rate is greater than the preset threshold, demodulating the received broadcast stream using an orthogonal frequency division multiplexing (OFDM) scheme and decoding the received broadcast stream to output a SD signal; Digital broadcast receiving method comprising a. The method of claim 1, If the reception error rate detected during the demodulation of the OFDM scheme is less than or equal to a preset threshold, the demodulation of the OFDM scheme is terminated, and then demodulation of the 8-VSB scheme is performed to output a broadcast signal of HD quality. Digital broadcast receiving method. The method of claim 1, The 8-VSB scheme is an HDSC broadcast of ATSC, and the OFDM scheme is an SDDB of ISDB-T or DVB-T. The method of claim 1, And when the 8-VSB type specific broadcast signal is output, matching the OFDM type service broadcast to output a broadcast signal corresponding to the specific broadcast. As a digital broadcast receiving system, A radio frequency (RF) unit for receiving broadcast signals modulated in various ways; A tuner unit which converts the broadcast streams transmitted from the RF unit into an intermediate frequency, demodulates each broadcast mode, and transmits the demodulated signal to a decoder, detects a reception error rate of the broadcast stream, and transmits the received error rate to a controller; A decoder for decoding the broadcast stream delivered from the tuner unit; If the error rate received from the tuner is greater than a preset threshold, 8-VSB (Vertigial Sideband) method is terminated, OFDM (Orthogonal Frequency Division Multiplexing) method is performed, and demodulation is performed. A control unit for transmitting a command signal to the tuner unit to terminate the OFDM scheme and perform 8-VSB demodulation if the error rate detected during the demodulation of the OFDM scheme is smaller than or equal to a preset threshold value; A display unit for displaying the broadcast signal received from the decoder System for receiving a digital broadcast on the move comprising a. The method of claim 5, And digital communication reception (I2C) communication between the tuner unit and the control unit to transmit and receive control signals and data. The method of claim 5, The 8-VSB scheme is a high definition (HD) channel broadcast of ATSC, and the OFDM scheme is a standard definition (SD) multichannel broadcast of ISDB-T or DVB-T. The method of claim 5, The control unit, if the specific broadcast of the 8-VSB method is transmitted, the digital broadcast receiving system, characterized in that the OFDM broadcast service broadcast matching to transmit the broadcast corresponding to the specific broadcast.

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