KR0182433B1 - Data bit transmitter-receiver and aspect ratio auto control system of tv receiver using front porch - Google Patents

Abstract

The present invention provides a data bit transmission / reception apparatus using a front porch that is capable of transmitting and receiving a predetermined data bit in a front porch section of a composite video signal, and a mode suitable for a broadcast signal using an aspect ratio of a television receiver. The aspect of the present invention relates to an aspect ratio automatic adjustment system of a television receiver.

In the present invention, a reference clock having a frequency corresponding to an integer multiple of the horizontal synchronous signal is generated based on the horizontal synchronous signal of the composite video signal, and counted using a counter so as to count a pulse signal corresponding to the front porch section of the video signal. Will generate In addition, by coding and decoding predetermined bit data in a section corresponding to the pulse signal, other information irrelevant to the broadcast signal is transmitted and received together with the video signal.

The data transmitted / received as the bit data may be set to aspect ratio data related to the aspect ratio of a broadcast signal or other broadcast information. When such a device is applied to a broadcasting system, adjustment of the output image according to the aspect ratio and the type of broadcasting The user's convenience can be greatly improved by being able to automatically adjust the image state.

Description

Data bit transceiver using front porch of composite video signal and automatic adjustment of aspect ratio of television receiver using the same

1 is a signal waveform diagram showing a composite video signal currently used in a broadcasting system.

2 is a signal waveform diagram corresponding to one horizontal scanning period of a composite video signal for explaining the basic concept of the present invention.

3 is a block diagram showing an apparatus for transmitting data bits using a front porch of a composite video signal according to an embodiment of the present invention.

FIG. 4 is a circuit diagram showing the configuration of the vertical blanking signal generator in FIG.

5 is a signal waveform diagram for explaining the operation of the apparatus shown in FIG.

6 is a block diagram showing the configuration of a reference clock generator and a coded section pulse generator in FIG.

7 is a configuration diagram showing the configuration of the data generator in FIG.

8 is a signal waveform diagram for explaining the operation of the configuration shown in FIG. 6 and FIG.

9 is a block diagram showing an apparatus for detecting data bits according to an embodiment of the present invention.

FIG. 10 is a signal waveform diagram for explaining the operation of the apparatus shown in FIG.

11 is a block diagram showing the configuration of an aspect ratio automatic adjustment system of a television receiver as an example of practical application of the present invention.

FIG. 12 is a block diagram showing another example of the configuration of a coded section pulse generator in FIG. 3; FIG.

* Explanation of symbols for main parts of the drawings

31: synchronization separator 32: vertical blanking signal generator

33: horizontal synchronization separator 34: reference clock generator

35: coding section pulse generator 36: data generator

41: integrating circuit 42: comparison circuit

43: monostable multivibrator 97: D flip-flop

118: horizontal deflection coil 119: vertical deflection coil

123: front porch data detection unit 124: deflection data storage unit

341: PLL circuit 342: voltage controlled oscillator

343: clock buffer 344: divider

351, 352, 361, 362: Counter 421: Comparator

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a broadcasting system, and more particularly, to a data bit transmitting / receiving apparatus using a front porch capable of transmitting and receiving a predetermined data bit in a front porch section of a composite video signal, and a television receiver using the same. An aspect ratio automatic adjustment system of a television receiver for automatically adjusting an aspect ratio to a mode suitable for a broadcast signal.

Recently, with the development of broadcasting technology, a technology for transmitting other data, such as text data or caption data, using a television broadcasting signal has been developed and used. Most of these transmission techniques do not carry a video signal in a television broadcasting signal. It is supposed to use the vertical blanking section.

FIG. 1 is a signal waveform diagram illustrating a general composite video signal, which is divided into a video signal section and a vertical blanking section, as shown in the drawing. Further, the vertical blanking section is assigned a vertical equalization pulse of 3H (H is a horizontal scanning period), a vertical synchronization pulse of 3H, a vertical equalization pulse of 3H, and a horizontal synchronization pulse of approximately 12H.

On the other hand, since the vertical blanking section is used as the return time of the scanning line in the television receiver, it is generally not displayed on the CRT (Cathode-ray Tube) of the television receiver.

Therefore, in most current broadcasting technologies, the vertical blanking section is used to transmit data unrelated to broadcast signals such as text multiplexing. In particular, each of the 10H to 21H sections suitable for transmitting such information is provided. The locations of are determined approximately for each use, and other new information is not allowed to be transmitted.

Accordingly, the present invention has been made in view of the above circumstances, and provides a data bit transmission apparatus using a front porch that can transmit arbitrary code information using a front porch section of a video signal section rather than a vertical blanking section. Has its main purpose.

Another object of the present invention is to provide a front porch data receiving apparatus capable of detecting code information added to a front porch section.

In addition, the present invention provides an aspect ratio automatic adjustment system of a television receiver that allows the aspect ratio of the video screen reproduced and output to the television receiver by automatically transmitting and receiving the aspect ratio data of the broadcast signal using the front porch according to the type of the broadcast signal. There is another purpose in providing it.

According to a first aspect of the present invention for realizing the above object, a data transmitting apparatus using a front porch includes horizontal synchronous separating means for separating horizontal synchronous signals from a composite video signal, and a predetermined frequency based on the horizontal synchronous signals. Reference clock generating means for generating a reference clock, coding section pulse generating means for generating a pulse signal corresponding to the front porch section of the video signal by counting the reference clock on the basis of the horizontal synchronization signal, and according to an external control signal Data generating means for generating predetermined data bits to be added to the video signal, and data adding means for adding data bits generated by the data generating means to the composite video signal based on the coding interval pulse. It is done.

In addition, the front porch data receiving apparatus according to the second aspect of the present invention for realizing the object has a horizontal synchronous separation means for separating the horizontal synchronous signal from the composite video signal, and having a predetermined frequency based on the horizontal synchronous signal Reference clock generating means for generating a reference clock, coding section pulse generation means for generating a pulse signal corresponding to the front porch section of the video signal by counting the reference clock on the basis of the horizontal synchronization signal, and corresponding to the coding section pulse And switching means for selectively inputting the composite video signal of the section, and data detecting means for detecting data bits from the composite video signal inputted by the switching means.

In addition, the aspect ratio automatic adjustment system of a television receiver according to the third aspect of the present invention for realizing the above object is a broadcast system in which the aspect ratio data of the broadcast signal is added to the front porch section of the composite video signal and transmitted. Data detection means for detecting data added to the front porch section of the signal, deflection data storage means for storing a plurality of deflection data corresponding to the aspect ratio of the video signal to be output on the CRT, and the data detection means And control means for reading out the deflection data storage means based on the detected data and performing deflection control on the video signal output to the CRT.

According to the present invention having the above-described configuration, a reference clock having a frequency corresponding to an integer multiple of the horizontal synchronous signal based on the horizontal synchronous signal of the composite video signal is generated and counted using a counter to count the video signal and the front porch. Generate a pulse signal corresponding to the interval. In addition, by coding and decoding predetermined bit data in a section corresponding to the pulse signal, other information irrelevant to the broadcast signal is transmitted and received together with the video signal.

The data transmitted / received as the bit data may be set to aspect ratio data related to the aspect ratio of a broadcast signal or other broadcast information. When such a device is applied to a broadcasting system, adjustment of the output image according to the aspect ratio and the type of broadcasting The user's convenience can be greatly improved by being able to automatically adjust the image state.

Hereinafter, an embodiment according to the present invention will be described with reference to the drawings.

First, the basic gist of the present invention will be described with reference to FIG.

2 is a waveform diagram showing an image signal of one horizontal scanning period (1H), which is composed of a horizontal synchronous pulse, a color burst signal, and an image signal. The front portion of the horizontal synchronous pulse, that is, the rear portion of the video signal, is called a front porch, and the rear portion of the horizontal synchronous pulse, that is, the front portion of the video signal, is called a back porch. The pulse and back porch sections are combined to form a horizontal blanking period.

In addition, the horizontal synchronous pulse has a length of 5 kHz, the front porch is 1.3 ㎲, the back porch is 4.5 ㎲, and the color burst signal is carried on the back porch portion.

The present invention is to transmit and receive desired data using the front porch by adding, for example, two bits of bit information to a front porch section having a length of 1.3 ms as shown by a dotted line in FIG.

FIG. 3 is a block diagram showing a data bit transmission apparatus using a front porch according to an embodiment of the present invention, and FIG. 5 is an operation waveform diagram of the device shown in FIG.

In FIG. 3, reference numeral 31 denotes a synchronization separator for separating the synchronization signal from the composite video signal of FIG. 5 (a), which is a predetermined slice level for the composite video signal as indicated by the dotted line in FIG. By performing the synchronization signal detection, the synchronization signal as shown in FIG. 5 (b) is separated and output.

In the drawing, reference numeral 32 denotes a vertical blanking signal generator for generating and outputting a vertical blanking signal from the sync signal [Fig. 5 (b)] output from the sync separator 31, which is shown in FIG. As described above, an integral circuit 41 for integrating the synchronization signal output from the synchronization separator 31 and a signal level output from the integration circuit 41 are set by the resistors R2 and R3. And a monostable multivibrator 43 which generates and outputs a vertical blanking signal based on the vertical synchronous detection signal corresponding to the vertical synchronous pulse section.

That is, as can be seen from FIG. 5 (b), the vertical synchronization pulse is generally set to have a lower duty ratio than the pulses of other signal sections. Therefore, when the horizontal synchronous pulse is integrated into the integrating circuit 41 of FIG. 4, the integrated value in the vertical synchronous pulse section is lower than that of the other sections as shown in FIG. 5 (c). When the reference voltage by R3) is input to the comparator 421 having the level indicated by the dotted line in FIG. 5 (c), a signal having a pulse width corresponding to the vertical synchronous pulse interval is output as shown in FIG. 5 (d). do.

On the other hand, when the pulse signal applied to the input terminal A1 rises to the high level, the monostable multivibrator 43 raises its output Q to the high level, and then to the capacitor C2 and the resistor R4. When the high level signal is not input through the input terminal A1 for a predetermined time by the time constant set by the output, the output is reduced to the low level.

Therefore, when the time constant value of the monostable multivibrator 43 is set to T in the fifth (e) degree, the output thereof is outputted. Is a signal corresponding to the vertical blanking section as shown in FIG. 5 (e).

In FIG. 3, reference numeral 33 denotes a horizontal synchronous separator that separates horizontal synchronous as shown in FIG. 5 (f) from the signal of FIG. 5 (b) output from the synchronous separator 31. It consists of a stable multivibrator.

Further, reference numeral 34 denotes a reference clock generator for generating and outputting 910f _H , which is, for example, a 910 divided signal of the horizontal synchronization frequency f _H , from the horizontal synchronization signal output from the horizontal synchronization separator 33. The reference clock output from the reference clock generator 34 and the vertical blanking signal E output from the vertical blanking signal generator 32 and the horizontal synchronization signal F output from the horizontal synchronization separator 33 are On the basis of this, a coding section pulse generator for generating a coding section pulse for adding data bits to a composite video signal.

FIG. 6 is a diagram showing the configuration of the reference clock generator 34 and the coding section pulse generator 35, which will be described with reference to the operation timing diagram shown in FIG.

In FIG. 6, the reference clock generator 34 compares the phase difference between the horizontal synchronization signal and the frequency signal applied from the divider 344 to be described later, and outputs a voltage signal corresponding to the phase difference. A PLL (Phase Locked Loop) circuit 341, a voltage controlled oscillator 342 for outputting a predetermined frequency signal in accordance with the voltage signal output from the PLL circuit 341, and a frequency output from the voltage controlled oscillator 342 And a clock buffer 343 for buffering the signal and a divider 344 for dividing the frequency signal output from the clock buffer 343 (1/910).

That is, in the above configuration, the voltage signal corresponding to the phase difference between the output signal of the frequency divider 344 and the horizontal synchronization signal is applied to the voltage controlled oscillator 342 so that the output frequency of the voltage controlled oscillator 342 is increased. The output frequency signal of the voltage controlled oscillator 342 is divided through the divider 344 to be input to the PLL circuit 341.

Accordingly, the horizontal synchronizing signal and the output signal of the divider 344 are adjusted so that their frequencies are the same, and when the frequency of the horizontal synchronizing signal is 15.734 KHz, the signal frequency output from the voltage controlled oscillator 342 is 14.318. MHz (910 x 15.734 KHz), and this frequency signal is output as a reference clock.

Meanwhile, the coding section pulse generator 35 may include first and second counters 351 and 352 for down counting a predetermined coefficient value based on the reference clock G output from the reference clock generator 351. And an AND gate AND2 for performing an AND operation on the output of the counters 351 and 352 and the vertical blanking signal applied by the vertical blanking signal generator 32.

Here, the first counter 351 executes down counting at the rising edge of the reference clock using the number of reference clocks G corresponding to the section T1 of FIG. The level detection signal is output. Further, the second counter 352 performs down counting at the rising edge of the reference clock using the number of reference clocks G corresponding to the T4 section of FIG. The level detection signal is output. The first and second counters 351 and 352 are cleared at the falling edge of the horizontal synchronization signal F to perform the counting operation again. The output of the first counter 351 is shown in FIG. 8 (h) and the output of the second counter 352 is shown in FIG. 8 (i).

Subsequently, the output of the first counter 351 and the inverted output of the second counter 352 are logically multiplied by the AND gate AND2, thereby adding data bits of the front porch as shown in FIG. 8 (j) in the AND gate AND2. The pulse signal corresponding to the section is output.

In addition, a vertical blanking signal E is input as one input of the AND gate AND2, in which the data bits according to the present invention are added to sections 10H to 21H to which normal character multicast data is added in FIG. It is to prevent becoming.

In FIG. 3, reference numeral 36 denotes a data generator for generating predetermined data bits to be added to the front porch of the composite video signal according to the control data DATA1 and DATA2.

FIG. 7 is a block diagram illustrating the configuration of the data generator 36. The first and second counters 361, which down count a predetermined count value based on the reference clock output from the reference clock generator 351 are shown in FIG. 362, a first AND gate AND5 for performing an AND operation on the output of the first counter 361 and the first control data DATA1 applied from the outside, and the output of the second counter 362. And a second AND gate AND6 for ANDing the second control data DATA2 applied thereto, and an ORG OR1 for logically outputting the outputs of the first and second AND gates AND5 and AND6. It is configured by.

In FIG. 7, IV1 to IV4 are inverters for delaying the respective outputs of the first and second counters 361 and 362 applied to the AND gates AND3 and AND4 for a predetermined time.

Here, the first counter 361 executes down counting at the rising edge of the reference clock using the number of reference clocks G corresponding to the section T2 of FIG. The level detection signal is output. In addition, the second counter 362 executes down counting at the rising edge of the reference clock using the number of reference clocks G corresponding to the section T3 of FIG. 8 as its initial value. The level detection signal is output. Since the first and second counters 361 and 362 are cleared by the logical product of the inverted signal of the output signal and the horizontal synchronizing signal F, the counting operation is performed again. From the counters 361 and 362, As shown in Figs. 8 (k) and (l), a pulse signal having a predetermined pulse width is output, wherein the widths of the pulse signals are inverters IV1, IV2 (IV3, IV4) and AND gate ( The width corresponding to the delay time in AND3) AND4 is set.

In FIG. 3, reference numeral AND1 denotes an AND gate that logically multiplies the pulse signal output from the coding section pulse generator 35 and the data bit output from the data generator 36, and 37 denotes the AND gate. An adder for adding the output of AND1 to the composite video signal, 38 is a modulator for modulating the composite video signal output from the adder 37, and 39 is an antenna for transmitting a broadcast signal to the airwave transmission network.

That is, in the data bit transmission apparatus using the front porch having the above-described configuration, the horizontal synchronous signal is separated from the composite video signal, and based on this, the frequency corresponding to N times the horizontal synchronous signal (910 times in the above example) is determined. It generates a reference clock signal having a.

Then, a pulse signal corresponding to the front porch section of the composite video signal is generated by a method of counting the reference clock by a predetermined value based on the horizontal synchronization pulse, and for example, a 2-bit data bit is added to the pulse section. The data will be sent.

9 is a block diagram showing a data bit detection apparatus of the front porch for detecting data bits added to the front porch in accordance with the above-described method.

In FIG. 9, reference numeral 91 denotes a synchronization separator for separating the synchronization signal as shown in FIG. 5E from the detected composite video signal, and 92 denotes a synchronization signal B output from this synchronization separator 91. A vertical blanking signal generating unit for generating and outputting a vertical blanking signal E corresponding to the horizontal synchronous pulse period of the vertical blanking section from the vertical blanking section, and 93 denotes a horizontal synchronous signal from the synchronous signal B output from the synchronous separating unit 91. A horizontal synchronous separating section for separating and outputting (F), 94 is an integer multiple of the horizontal synchronous signal F based on the horizontal synchronous signal F output from the horizontal synchronous separating section 93 (910 times in this example). The reference clock generator 95 generates and outputs a frequency signal G corresponding to the reference clock as a reference clock, and a 95 is a composite video signal based on the vertical blanking signal E, the horizontal synchronization signal F, and the reference clock G. In the signal section of the data bits added to the front porch section of the A coding section pulse generating section for generating a corresponding pulse signal J, these circuit sections being substantially identical in configuration to that in FIG.

In FIG. 9, reference numeral 96 denotes a switching unit which is turned on when the pulse signal J output from the coding section pulse generator 95 becomes high level, and 97 is output from the reference clock generator 94. The clock signal G to be used as an input clock, and the D input thereof is a D flip-flop coupled to the composite video signal A through the switching unit 96.

As shown in FIG. 10, the coding section pulse generator 95 outputs a high level signal corresponding to the data bit additional section of the input composite video signal A, and thus the coding section pulse signal ( When J) becomes high level, the switching unit 96 is turned on so that the composite video signal of the portion corresponding to the input terminal D of the D flip-flop 97 is applied.

On the other hand, the D flip-flop 97 is applied as a clock of the 10th (n) degree output from the reference clock generator 94 as its input clock, so that the D flip-flop 97 from the 10 (o Bit data corresponding to the data bits added to the front porch as shown in Fig. 2) are detected and output.

Therefore, according to the above embodiment, it is possible to transmit and receive predetermined bit data using the video signal section of the composite video signal, thereby enabling efficient use of the television broadcast signal.

Meanwhile, FIG. 11 illustrates a case where the apparatus for transmitting / receiving data bits using the front porch according to the present invention is applied to a practical broadcasting system, which is output on a CRT according to the type (aspect ratio) of a broadcast program transmitted from a broadcasting station. The aspect ratio of the video screen is set automatically.

In other words, in recent years, by widening the aspect ratio of the CRT to 16: 9 rather than the conventional 4: 3, wide television receivers have been developed and used to make the viewing environment of a television receiver look like a theater. Television receivers are also developed and used.

In addition, attempts have been made to produce and disseminate broadcast screens suitable for wide television receivers and cinema television receivers in which broadcasters ride on the above-described changes in television receivers.

Therefore, recently, a manufacturer of a television receiver manufactures and distributes a part of a television receiver in which an aspect ratio of an output image can be adjusted internally to fit a video screen transmitted from a broadcasting station.

In most cases, such a television receiver adjusts the aspect ratio of the output image by adjusting the deflection of the electron beam scanned on the CRT to a video signal.

However, in the above-described television receiver, since the mode selection for adjusting the aspect ratio of the output image is entirely dependent on the operation of the viewer, it is very cumbersome in use, and in the case of the elderly or children who have insufficient understanding about the television receiver, There is a problem that the function is not available.

On the other hand, using the data bit transmission and reception apparatus using the front porch according to the present invention described above, it is possible to easily realize the aspect ratio automatic adjustment system according to the video screen.

That is, considering the case of transmitting and receiving two-bit data bits in the front porch section of the video signal as described above, the broadcasting station uses the data bit transmission apparatus described above to display two characteristics of the video screen, as shown in Table 1 below. Bit data can be transmitted.

Each of the above data can be easily set by selectively setting the control data DATA1 and DATA2 applied to the data generator 36 to 1 or 0 in FIG.

11 is a block diagram showing the configuration of a television receiver in which a predetermined data bit is added and automatically adjusts the output aspect ratio of the television receiver according to the received broadcast signal.

In Fig. 11, reference numeral 111 is an antenna for receiving a frequency signal transmitted from a broadcasting station, 112 is a tuner for tuning a predetermined broadcast frequency from a frequency signal input through this antenna 111, and 113 is this tuner. An IF amplifying unit for amplifying the intermediate frequency signal IF output from 112, 114 converts an audio intermediate frequency signal SIF and an image intermediate frequency signal PIF from the IF signal output from the IF amplifier 113; It is a P / S separator to separate.

In the drawing, reference numeral 115 denotes an image detector which detects the image intermediate frequency signal PIF and outputs a composite image signal, and 116 denotes an image signal by processing the composite image signal output from the image detector 115. An image processor for outputting R (Red), G (Green), and B (Blue) signals corresponding to the 117, and the 117 drives the CRT based on the RGB signal output from the image processor 116 to display an image signal on the CRT. A CRT driver generates a corresponding video screen.

The CRT includes a vertical deflection coil 119 for deflecting the electron beam emitted from the cathode electrode (not shown) in the horizontal direction and a vertical deflection coil 118 for deflecting the beam in a horizontal direction in response to a deflection signal to be described later. ) Will be provided.

In FIG. 11, reference numeral 120 denotes a horizontal drive pulse and a vertical drive based on horizontal and vertical synchronization signals output from the image processor 116 and deflection data set by the controller 126 to be described later. A deflection control unit for outputting a pulse, 121 is a horizontal deflection unit for driving the horizontal deflection coil 118 based on the horizontal drive pulse output from the deflection control unit 120, 122 is output from the deflection control unit 120 It is a vertical deflection portion for driving the vertical deflection coil 119 based on the vertical drive pulse.

Reference numeral 123 denotes a front porch data detector for detecting bit data added to the front porch section from the composite video signal output from the video signal detector 115, as described above, and 124 denotes the deflection control unit ( The deflection data storage unit 125 stores a plurality of deflection data required for the deflection control of the 120, that is, the deflection data according to the aspect ratio of the image screen to be output on the CRT, and the front porch data detection unit 123. A detection data storage unit for storing the detected data.

Further, reference numeral 126 reads predetermined deflection data from the deflection data storage unit 124 according to the data detected by the front porch data detection unit 123, and then the deflection control unit 120 based on the deflection data. It is a control unit for adjusting the aspect ratio of the video screen output on the CRT to a form suitable for the broadcast signal by resetting.

That is, in the above configuration, when bit data added to the front porch section of the composite video signal is detected by the front porch data detection unit 123 and applied to the control unit 126, the control unit 126 first detects the detected data bit. The detection data is compared with the detection data stored in the data storage unit 125. If the data does not match as a result of the comparison, the deflection data corresponding to the bit data is read from the deflection data storage unit 124, and the deflection control unit 120 is reset based on the deflection data storage unit. The data stored in 125 is updated and registered as new detection data.

Therefore, according to the above embodiment, the aspect ratio of the video screen output to the CRT is automatically adjusted according to the type of broadcast program, thereby greatly improving the convenience of the viewer.

In addition, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the technical scope of the present invention.

For example, in the above embodiment, the present invention has been described using the case of adjusting the aspect ratio of a television receiver as an example, but the present invention is applied to other screen adjustments such as screen state adjustment according to the type of broadcast rather than the aspect ratio adjustment. Can be carried out.

In the above embodiment, a case in which data bits are added to all front porch sections of the entire video signal has been described as an example. However, this may be configured to add and receive data only for a specific front porch of the video signal.

FIG. 12 is a diagram corresponding to FIG. 3 and shows a configuration in which data is transmitted and received only for a predetermined front porch.

In FIG. 12, there is further provided a third counter 360 which is reset by the vertical blanking signal and which counts the horizontal synchronization signal and outputs a low level signal when the count value reaches a constant value.

The output of the third counter 360 is used as a reset signal of the first and second counters 351 and 352.

Therefore, in the above configuration, a predetermined data bit is added only to the front porch section of the video signal corresponding to the horizontal scanning period designated by the third counter 360, and when the above configuration is applied to the data receiving apparatus, Only data bits added to a particular horizontal scanning period are detected.

As described above, according to the present invention, it is possible to realize a data bit transmission / reception apparatus using a front porch that can transmit and receive arbitrary code information using the front porch section of the video signal section rather than the vertical blanking section.

In addition, according to the present invention, the aspect ratio of the television receiver to automatically adjust the aspect ratio of the video screen reproduced and output to the television receiver by transmitting and receiving the aspect ratio data of the broadcast signal using the front porch according to the type of the broadcast signal The system can be realized.

Claims (11)

Horizontal synchronous separating means for separating a horizontal synchronous signal from a composite video signal, reference clock generating means for generating a reference clock having a predetermined frequency based on the horizontal synchronous signal, and counting the reference clock based on the horizontal synchronous signal Coding section pulse generation means for generating a pulse signal corresponding to a front porch section of the video signal, data generation means for generating predetermined data bits to be added to the composite video signal according to an external control signal, and the coding section pulse. And data adding means for adding data bits generated by said data generating means to a composite video signal on the basis of the front porch of the composite video signal. The method of claim 1, wherein the coding section pulse generating means includes: a first counter for outputting a first detection signal indicating a start point of a front porch section, and a second counter for outputting a second detection signal indicating an end point of a front porch section. And a first logical multiplication means for logically multiplying the outputs of the first and second counters. 3. The method of claim 2, wherein the coding section pulse generating means comprises: a first counter for outputting a first detection signal indicating a start point of a front porch section, and a second counter for outputting a second detection signal indicating an end point of a front porch section; And a second logical multiplication means for logically multiplying the outputs of the first and second counters and the vertical blanking signal by the front porch of the composite video signal. The apparatus of claim 2 or 3, further comprising a third counter that counts horizontal synchronous pulses based on the vertical blanking signal, and outputs a third detection signal when the count value reaches a predetermined value. And a first counter and a second counter are reset by the third detection signal. The data generating means according to claim 1, wherein the data generating means counts the reference clock and outputs a detection signal when the count value reaches the first value, and counts the reference clock so that the count value is larger than the first value. A fifth counter for outputting a detection signal when the second value is reached, third logical multiplication means for logically multiplying the output of the fourth counter by the first data signal from the outside, and the second counter output from the outside of the fifth counter; And fourth logical multiplication means for ANDing the data signal, and logical OR means for ORing the outputs of the third and fourth logical multiplication means, wherein the fourth and fifth counters are provided to the horizontal synchronization signal and its output. And a data bit transmission apparatus using the front porch of the composite video signal, wherein the data bit is reset. Horizontal synchronous separating means for separating a horizontal synchronous signal from a composite video signal, reference clock generating means for generating a reference clock having a predetermined frequency based on the horizontal synchronous signal, and counting the reference clock based on the horizontal synchronous signal Coding section pulse generation means for generating a pulse signal corresponding to a front porch section of the video signal, switching means for selectively inputting a composite video signal in a section corresponding to the coding section pulse, and a composite image input by the switching means And a data detecting means for detecting data bits from the signal. The method of claim 6, wherein the coding section pulse generating means includes a first counter for outputting a first detection signal indicating a start point of a front porch section, and a second counter for outputting a second detection signal indicating an end point of a front porch section. And a first logical multiplication means for logically multiplying the outputs of the first and second counters. The method of claim 6, wherein the coding section pulse generating means includes a first counter for outputting a first detection signal indicating a start point of a front porch section, and a second counter for outputting a second detection signal indicating an end point of a front porch section. And a second logical multiplication means for logically multiplying the outputs of the first and second counters and the vertical blanking signal by the front porch of the composite video signal. 9. The apparatus of claim 7 or 8, further comprising a third counter that counts a horizontal synchronous pulse based on the vertical blanking signal, and outputs a third detection signal when the count value reaches a predetermined value. And a first counter and a second counter are reset by the third detection signal. The data using the front porch of the composite video signal according to claim 6, wherein the data detecting means comprises a D flip-flop coupled to an output terminal of the switching unit at a D input terminal thereof and operating according to the reference clock. Bit receiver. A broadcasting system in which aspect ratio data of a broadcast signal is added to a front porch section of a composite video signal and transmitted, comprising: data detecting means for detecting data added to the front porch section of a composite video signal, and an image to be output on a CRT. Deflection data storage means for storing a plurality of deflection data corresponding to the aspect ratio of the signal, and the deflection control for the video signal output to the CRT by reading the deflection data storage means based on the detection data by the data detection means An aspect ratio automatic adjustment system for a television receiver comprising a control means for executing.