ASTRO VG-884, Инструкция по эксплуатации

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1 Type1,2,3 ( AGC only )
2 VHS
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Display returns to the initial screen.
6.2 Closed caption/V-Chip
6.2.1 Description and specifications
■ What is “closed caption (CC)”?
Closed captioning was developed in the United States, and it provides broadcasts with subtitles for the hearing impaired so
that people who are deaf or hard of hearing can enjoy movies and news programs.
The captions are “closed” in the sense that they are not displayed on the screen during normal playback. Conversely, the
Japanese-language subtitles and other such characters used with video content that is “burned into” the images from the start
are referred to as “open captions.”
Although closed captioning was originally developed as a technology for the hearing impaired, it is currently attracting the
attention of educators and language learners as a tool which helps develop “listening.”
The CC subtitle data is superimposed onto line 21 (first field) and line 284 (second field) of the NTSC output signals, and
output. The subtitle data has two modes, captions and text. Another available service is the Extended Data Service (EDS),
which transmits titles, ratings and other program information using line 284 (second field). The V-Chip described below uses
the EDS function.
A total of 32 characters can be displayed per line by CC. There are 15 lines, but the maximum number of lines is limited to 4
in the caption mode (CC1 to 4). All 15 lines can be displayed in the text mode (T1 to 4).
■
What is the “V-Chip”?
The V-Chip refers to a semiconductor chip that blocks out TV programs containing violence and sexual situations. “V” refers
to violence, and the viewing of programs is blocked out according to the ratings that are categorized by the extremity of the
program content. Once the ratings are set in a receiver (TV set) that incorporates the V-Chip function, the rating information of
EDS is decoded, and whether the programs are to be output to the screen is automatically determined.
■ Specifications of closed caption/V-Chip
Closed caption/V-Chip supports the TV signals of the following systems.
Closed caption/V-Chip is superimposed onto the composite signals and Y/C signals.
・ NTSC-M, NTSC-J, NTSC-443
・
PAL-60, PAL, PAL-M, PAL-Nc
* However, in a 625-line system (PAL, PAL-N, PAL-Nc), the caption data is superimposed onto 23 lines (335 lines).
The closed caption/V-Chip waveform is shown below. After the color burst comes a sine wave known as Clock Run-In and
then the start bit. The start bit is always “001.” Two bytes of data (Char1, Char2) are sent for each line. Char1 and Char2 are
decoded from LSB, and an odd parity is usually added to MSB (bit 8).