Closed-caption broadcasting and receiving method and apparatus thereof suitable for syllable characters

A closed-caption broadcast receiving method comprising the steps of:

• detecting horizontal and vertical sync signals of a received television signal;
• extracting a caption signal encoded in a last scanning line of said television signal by counting said horizontal sync signal in response to said detected vertical sync signal;
• restoring digital data from said extracted caption signal;
• detecting an error of said restored data;
• decoding a control code of said restored data and reading out character data corresponding to a character code from a font ROM (read only memory) in which said character data is stored and based on a syllable character completion type code, and storing said read-out character data in a display memory;
• and
• converting said character data stored in said display memory into a video signal to display said video signal on a display screen.

A closed-caption broadcasting apparatus for superimposing closed-caption information in a video signal and modulating an audio signal and said video signal to a television signal to transmit said modulated television signal in the air as a high frequency signal, the apparatus comprising:

• character information input means for inputting additional information related to at least one of a television scene, emergency news, and an announcement, as a 2-byte syllable character completion type code;
• control information input means for inputting 7-bit control information for reception control of a closed-caption broadcast;
• character code generating means for generating a data packet of an 18-bit character code by using an MSB (most significant bit) of each byte of said 2-byte syllable character completion type code as a caption word/additional information flag, replacing said MSB by a first value in case of said additional information, and adding a parity bit to each byte of said 2-byte syllable character completion type code;
• control code generating means for generating a data packet of an 18-bit control code by dividing said 7-bit control information into an upper 4 bits and a lower 3 bits, creating an upper byte by adding to said upper 4 bits a parity bit, control code discriminating bits of 2 bits, and a word/addition flag, creating a lower byte by adding to said lower 3 bits a first parity bit, a second parity bit, control code discriminating bits of 2 bits, and a caption word/additional information flag, and adding another parity bit to each of said upper and lower bytes;
• data packet modulating means for modulating said data packet generated by said character code generating means or said control code generating means by digital modulation to produce a caption signal;
• synchronous counter means for receiving horizontal and vertical sync signals of said video signal and counting said horizontal sync signal, said synchronous counter means being reset by said vertical sync signal;
• window signal generating means for receiving a counted value of said synchronous counter means and generating a window signal for selecting a predetermined line of each field;
• and
• switching means for selectively switching said video signal and said caption signal in response to said window signal.

A closed-caption receiving apparatus for receiving a caption signal from a received composite video signal, said apparatus comprising:

• a data extractor for extracting said caption signal from said composite video signal;
• a sync separator for separating a sync signal from said composite video signal to produce vertical and horizontal sync signals;
• a font ROM (read only memory) for storing character information corresponding to a syllable character completion type code;
• a RAM (random access memory) for storing address information of said font ROM;
• and
• caption processing means for analyzing said data extracted by said data extractor and detecting an existence of an error in said data, said caption processing means performing a corresponding control process if said data is identified as a control code as a result of the data analysis, while storing in said RAM only a code using said syllable character completion type code, and producing data read out from said font ROM, which is addressed by a value stored in said RAM, as another composite video signal.

A broadcasting system for generating a television signal by encoding a caption signal in a video signal, comprising:

• a video processor to process the video signal;
• and
• a caption encoder for generating and encoding the caption signal into the video signal, said caption encoder including
• a synchronous counter to receive sync signals from said video processor, to count a horizontal sync signal to select predetermined scanning lines of the video signal, and is reset by a vertical sync signal, and
• a switching unit to alternately output the video signal and the caption signal based upon the counted value to superimpose the caption signal in specific lines of the video signal, to generate the television signal.