KR20030067994A - Channel switching apparatus and method for digital television - Google Patents

Abstract

PURPOSE: An apparatus and method for converting a channel of a digital TV are provided to convert digital broadcast into corresponding analog broadcasting when a digital broadcasting receiving state is poor. CONSTITUTION: An MPEG decoder(120) decodes a broadcasting signal tuned by a digital tuner(110) to output video and audio signals. An analog/digital converter(140) video-processes a signal demodulated by an analog tuner(130) to output digital video and audio signals. A video switch(150) selects one of the video signals of the MPEG decoder and the analog/digital converter. An on-screen processor(160) inserts a digital teletext signal into the selected video signal. An audio switch(170) selects one of the audio signals of the MPEG decoder and the analog/digital converter. An analog/digital converter(180) converts an automatic gain control value of the analog tuner into a digital value. A CPU(190) outputs the digital teletext signal to the on-screen processor, and switches the video switch and audio switch to convert digital broadcast into analog broadcast when a digital broadcast receiving sensitivity is poor.

Description

Channel switching device and method of digital TV {CHANNEL SWITCHING APPARATUS AND METHOD FOR DIGITAL TELEVISION}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to digital TVs, and more particularly, to a channel switching device and method in Integrated Digital TV (hereinafter, abbreviated as iDTV).

Currently, many broadcasting stations transmit digital broadcasts using empty channels while maintaining the existing analog broadcasts, and also transmit the same digital broadcasts as analog broadcasts.

In the UK, for example, there are five analog channels, with digital broadcasting having nine channels, five of which are identical to analog broadcasting.

In addition, in order to affect the analog TV signal, digital broadcasting transmits a digital high frequency (RF) signal at about 25 dB lower than the analog signal.

For this reason, currently sold digital TV is sold in the form of iDTV which has a digital tuner and an analog tuner at the same time.

Accordingly, the viewer may switch to the digital tuner or the analog tuner as needed to watch the broadcast.

On the other hand, the digital broadcast includes a data service and is transmitted.

For example, data services broadcast in the UK include digital teletext and subtitles.

Data service can ignore packets that have occurred after an error check by Cyclic Redundancy Check (CRC) .In the case of digital teletext, data packets in the form of object carousel are repeatedly transmitted. It can be done.

In other words, in digital broadcasting, all carousel data can be received except in severe error environment. If one carousel is completely received, it can continue to be used until the teletext scenario is updated.

Therefore, the digital TV can receive the data broadcast correctly even when it is difficult to watch the broadcast due to poor reception of the digital broadcast.

However, in the related art, whenever the reception sensitivity of the digital broadcast is not good, the viewer must bear the inconvenience of switching to analog broadcast that transmits the same broadcast service.

In addition, conventionally, when the reception of the digital broadcast is poor, there is a problem in that the teletext can only be displayed on the screen on which the error occurs even though the teletext is expressed without error in a state where viewing of digital video and audio is almost impossible.

Accordingly, a first object of the present invention is to provide an apparatus and method for channel switching of a digital TV, which is designed to switch to the same analog broadcast when the reception condition of the digital broadcast is not good to improve the conventional problem.

In addition, the present invention has a second object to display digital text by receiving digital data even when switching to analog broadcasting.

1 is a block diagram of a channel switching apparatus for an embodiment of the present invention.

2 is an operation flowchart for channel switching in the present invention.

Explanation of symbols on the main parts of the drawings

110: digital tuner 120: MPEG decoder

130: analog tuner 140, 180: analog to digital converter

150,170: switch 160: on-screen processing unit

190: CPI

The present invention provides a digital tuner that detects a digital channel from a digital broadcast signal, demodulates the detected modulated signal, and outputs it as a transport stream (TS). An MPEG decoder that decodes and outputs a video signal and an audio signal, an analog tuner that detects an analog channel from the analog broadcast signal and demodulates the detected modulated signal, and processes the image demodulated by the analog tuner as a digital signal. A first analog / digital (A / D) converter for outputting the converted video signal and the analog audio signal, a video switch for selecting one of the video signals of the MPEG decoder and the first analog / digital converter, and a video switch selected from the video switch Ounce to output digital teletext signal to video signal An lean (OSD) processor, an audio switch for selecting one of the audio signals of the MPEG decoder and the first analog / digital converter, a second analog / digital converter for digitally converting the AGC value of the analog tuner, and the digital tuner If it is determined that the reception sensitivity of the digital broadcast is poor by checking the AGC value and the output signal of the second analog / digital converter, the video switch and the audio switch are switched for analog broadcast viewing, and the data separated from the MPEG decoder is analyzed. And a CPU to output a teletext signal to the on-screen processing unit.

In addition, the present invention is to determine the reception sensitivity of the digital broadcast in order to achieve the above object, and if it is determined that the reception sensitivity of the digital broadcast is bad in the step of checking whether there is the same analog broadcast as the digital broadcast, and Determining the reception sensitivity of the analog broadcast if the analog broadcast is identical to the digital broadcast, switching to the analog broadcast channel if the reception sensitivity of the analog channel is good, and converting the analog broadcast to the digital broadcast. And inserting the teletext of the broadcast and displaying the same on the screen.

That is, when the reception sensitivity of the analog broadcast channel broadcast simultaneously with the digital broadcast is good, the present invention switches to the analog broadcast channel and decodes the digital teletext transmitted in a carousel form. It is displayed on the broadcast screen.

Hereinafter, the present invention will be described in detail with reference to the drawings.

1 is a block diagram of an apparatus for switching channels of a digital TV according to an embodiment of the present invention. As shown therein, a digital channel is detected from a digital broadcast signal, and the detected modulated signal is demodulated to a transport stream TS. The MPEG tuner 120 outputs a video tuner 110 by outputting a digital tuner 110, a broadcast tuned by the digital tuner 110, and outputs a video signal and an audio signal, and detects an analog channel from the analog broadcast signal and detects the analog channel. An analog tuner 130 for demodulating the modulated signal, an analog / digital converter 140 for outputting a video signal and an analog signal converted into a digital signal by image processing the signal demodulated by the analog tuner 130, In the video switch 150 which selects one of the video signals of the MPEG decoder 120 and the analog-to-digital converter 140, the video switch 150 An on-screen processing unit 160 for inserting and outputting a digital teletext signal to a selected video signal, an audio switch 170 for selecting one of audio signals of the MPEG decoder 120 and the analog-to-digital converter 140, and the analog The video switch 150 compares the analog / digital converter 180 for digitally converting the AGC value of the tuner 130 with the output signal of the digital tuner 110 and the output signal of the analog / digital converter 180. And a control circuit (CPU) 190 for controlling a switching operation of the audio switch 170 and outputting a teletext signal to the on-screen processing unit 160 by analyzing the data separated by the MPEG decoder 120. It is equipped with.

The operation and the effect of the embodiment of the present invention configured as described above will be described with reference to the operation flowchart of FIG. 2.

The digital tuner 110 detects a digital channel received by an antenna, demodulates the detected modulated signal, and outputs a transport stream TS to the MPEG decoder 120. The MPEG decoder 120 outputs the demodulated signal to MPEG. Decoding and outputting the video signal to the video switch 150, and at the same time output the audio signal to the audio switch 170, and also outputs the service data in the form of service name containing information about the program to the CPI (190).

The analog tuner 130 detects an analog channel received by an antenna, demodulates the detected modulated signal, and outputs an analog intermediate frequency signal to the analog / digital converter 140, and the analog / digital converter 140 The demodulated signal is image-processed to output a digitally converted video signal to the video switch 150 and the digitally converted audio signal is output to the audio switch 170.

At this time, when the viewer selects a digital broadcast or an analog broadcast, the CPI 190 controls switching between the video switch 150 and the audio switch 170.

Accordingly, the video switch 150 selects a video signal of a digital broadcast or an analog broadcast and outputs the video signal to the on-screen processor 160. Like the video switch 150, the audio switch 150 uses the audio of the digital broadcast or the analog broadcast. The signal is selected and output.

Accordingly, by properly processing the video and audio signals passed through the on-screen processor 160 and the audio switch 150, the viewer can watch the broadcast.

Meanwhile, information about a program is received in the form of a service name in the case of digital broadcasting, and ACMS information is received in the case of analog broadcasting.

When watching digital broadcasting, the CPI 190 decodes service data input from the MPEG decoder 120 and outputs a digital teletext signal to the on-screen processor 160.

Accordingly, the on-screen processing unit 160 inserts and outputs teletext to the video signal input from the video switch 150 so that teletext characters are displayed together with the image on the screen of the display device (not shown).

In addition, in case of digital broadcasting, the CPI 190 receives a digital AGC value from the digital tuner 110 and receives an analog AGC value from the analog tuner 130 through the analog / digital converter 180.

At this time, the CPI 190 determines the reception state of the digital broadcast by checking the digital AGC value and comparing it with a predetermined value.

Accordingly, when it is determined that the reception state of the digital broadcast is poor, the CPI 190 checks the digital type ACMS data input from the analog / digital converter 180 to determine whether there is an analog broadcast identical to the digital broadcast currently being viewed.

At this time, if it is determined that there is the same analog broadcast as the digital broadcast currently being watched, the CPI 190 checks the reception state of the analog broadcast by comparing the AGC value of the analog broadcast with a predetermined value.

Accordingly, when it is determined that the reception state of the analog broadcast is good, the CPI 190 switches the video switch 150 and the audio switch 170 to the output terminals of the analog / digital converter 170.

The CPI 190 decodes the service data input from the MPEG decoder 120 and outputs the digital teletext signal to the on-screen processor 160.

Accordingly, the on-screen processor 160 embeds the digital teletext signal from the CPI 190 into the video signal of the analog broadcast from the video switch 150 and outputs the digital audio signal of the analog broadcast from the audio switch 170. Is output through an analog-to-digital converter (not shown) so that a user can watch the teletext provided by the digital broadcast while watching the same analog broadcast.

As described in detail above, when the reception state of the digital broadcast is poor, the present invention can provide a desired broadcast without interruption by switching to the same analog broadcast as the digital broadcast, thereby providing the viewer with satisfaction.

Claims (4)

A digital TV for viewing digital broadcasting and analog broadcasting, comprising: a digital tuner that detects a digital channel from a digital broadcast signal, demodulates the detected modulated signal, and outputs it as a transport stream (TS); and a transformer in the digital tuner. MPEG decoder, which decodes the port stream to output video and audio signals, an analog tuner that detects analog channels from analog broadcast signals and demodulates the detected modulated signals, and processes the signals demodulated by the analog tuner. A first analog / digital (A / D) converter for outputting a video signal and an analog audio signal converted into a digital signal, a video switch for selecting one of the video signals of the MPEG decoder and the first analog / digital converter; Digital teletext on the video signal selected in the video switch An on-screen (OSD) processing unit for interleaving and outputting a signal, an audio switch for selecting one of an audio signal of the MPEG decoder and a first analog / digital converter, and a second analog / digital converter for digitally converting an AGC value of the analog tuner And comparing the output signal of the digital tuner with the output signal of the second analog / digital converter to control the switching operation of the video switch and the audio switch, and to analyze the data separated by the MPEG decoder to analyze the on-screen (OSD). And a processing unit (CPU) for outputting a teletext signal to the processing unit. The method of claim 1, wherein the CSI reads the broadcast information from the analog tuner when it is determined that the reception sensitivity of the digital broadcast is poor, and if there is an analog broadcast identical to the digital broadcast currently being viewed, And a video switch and an audio switch for switching analog broadcasts. A digital TV channel switching method comprising a digital tuner and an analog tuner for selectively watching a digital broadcast and an analog broadcast, comprising: a first step of determining a reception sensitivity of a digital broadcast currently being viewed; A second step of checking whether there is an analog broadcast identical to the digital broadcast if it is determined that the sensitivity is poor; and a third step of determining reception sensitivity of the analog broadcast if the analog broadcast identical to the digital broadcast is identified above; And a fourth step of switching to an analog broadcast channel when it is confirmed that the reception sensitivity of the broadcast is good. 4. The method of claim 3, further comprising inserting a teletext of a digital broadcast into the analog broadcast and displaying the digital text on the screen.