Browse Prior Art Database

5 Way Interlaced Television Picture

IP.com Disclosure Number: IPCOM000073988D
Original Publication Date: 1971-Feb-01
Included in the Prior Art Database: 2005-Feb-23
Document File: 2 page(s) / 47K

Publishing Venue

IBM

Related People

Duke, KA: AUTHOR

Abstract

A standard broadcast television picture in the United States consists of 525 lines which are scanned 30 times a second. To reduce the flicker apparent to the viewer, the picture is scanned from top to bottom 60 times a second and alternate frames are interlaced. Each frame thus consists of 262 1/2 lines.

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5 Way Interlaced Television Picture

A standard broadcast television picture in the United States consists of 525 lines which are scanned 30 times a second. To reduce the flicker apparent to the viewer, the picture is scanned from top to bottom 60 times a second and alternate frames are interlaced. Each frame thus consists of 262 1/2 lines.

The drawing illustrates a TV system where each 60 cycles/second frame consists of 262 2/5 lines. This results in a 5-way interlace giving a complete picture of 1312 lines, 12 times per second. An odd 2/5 line per frame is chosen (rather than 1/5 line) since this produces an "interlaced-interlace" and reduces the stroboscopic effect between adjacent lines in consecutive frames.

The line frequency is generated by multiplying the basic frame frequency of 60 cycles/second by the total number of lines in each complete picture and then dividing by the interlace number. In a 5-way interlace system, the basic 60 cycles/second must be multiplied by 1312 (=32x41). The basic frequency is multiplied by 32 by standard techniques to produce 1920 cycles/second. This frequency is multiplied by 41 by generating two frequencies which, when added together, produce the desired frequency, i.e., the sum of 16 and 25 times 1920 cycles/second.

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