Note that the lines are numbered in the sequence in which these are actually scanned. During the first vertical trace actually The beam starts at A, and sweeps across the frame with uniform velocity to cover all the picture elements in one horizontal line.
At the end of this trace the beam then retraces rapidly to the left side of the frame as shown by the dashed line in the illustration to begin the next horizontal line. Note that the horizontal lines slope downwards in the direction of scanning because the vertical deflecting current simultaneously produces a vertical scanning motion, which is very slow compared with horizontal scanning.
The slope of the horizontal trace from left to right is greater than during retrace from right to left. The reason is that the faster retrace does not allow the beam so much time to be deflected vertically. After line one, the beam is at the left side ready to scan line 3, omitting the second line. However, as mentioned earlier it is convenient to number the lines as they are scanned and so the next scanned line skipping one line, is numbered two and not three.
This process continues till the last line gets scanned half when the vertical motion reaches the bottom of the raster or frame. As explained earlier skipping of lines is accomplished by doubling the vertical scanning frequency from the frame or picture repetition rate of 25 to the field frequency of 50 Hz. With the field frequency of 50 Hz the height of the raster is so set that Now the retrace starts and takes a period equal to 20 horizontal line periods to reach the top marked C.
These 20 lines are known as inactive lines, as the scanning beam is cut-off during this period. Thus the second field starts at the middle of the raster and the first line scanned is the 2nd half of line number The scanning of second field, starting at the middle of the raster automatically enables the beam to scan the alternative lines left un-scanned during the first field.
The vertical scanning motion otherwise is exactly the same as in the previous field giving all the horizontal lines the same slope downwards in the direction of scanning. As a result The inactive vertical retrace again begins and brings the beam back to the top at point A in a period during which 20 blanked horizontal lines to get scanned.
The ramparts were of earth, planted on the exterior slope with a thick mass of thorn-bushes, interlaced and strengthened by posts. Top Definitions Quiz Examples interlaced scanning. New Word List Word List. Save This Word! We could talk until we're blue in the face about this quiz on words for the color "blue," but we think you should take the quiz and find out if you're a whiz at these colorful terms. Words nearby interlaced scanning interjoist , interkinesis , interknit , interknot , interlace , interlaced scanning , interlacing arcade , Interlaken , interlaminar jelly , interlaminate , interlanguage.
Save Word. Definition of interlaced scanning. Love words? Start your free trial today and get unlimited access to America's largest dictionary, with: More than , words that aren't in our free dictionary Expanded definitions, etymologies, and usage notes Advanced search features Ad free!
Join Our Free Trial Now! Learn More About interlaced scanning. Share interlaced scanning Post the Definition of interlaced scanning to Facebook Share the Definition of interlaced scanning on Twitter. Statistics for interlaced scanning Look-up Popularity. Style: MLA.
0コメント