NCTI Consumer Digital Electronics Practice Test 2025 – The Comprehensive All-in-One Guide to Success!

Question: 1 / 400

Closed caption information is located on which line of the vertical blanking interval (VBI) signal?

Line 1

Line 10

Line 21

Closed caption information is embedded within the vertical blanking interval (VBI) of television signals, specifically on line 21. This is a crucial part of the signal because it allows for the simultaneous transmission of visual content and additional data, such as closed captions, without interrupting the main video feed.

Line 21 was standardized for closed captions in the NTSC television broadcasts, and it holds the data that is decoded by the television receiver to display subtitles or captions for the hearing impaired. The use of this specific line enables viewers to access captions while the program is being broadcasted, enhancing accessibility and providing a better viewing experience for those who need it.

Other lines of the VBI may carry different types of data, but line 21 is specifically designated for closed captioning in accordance with broadcast standards, making it the correct choice.

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Line 23

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