JAI AT-140GE - Manual (Page 31)

AT-140GE
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Fig.23 Variable Partial scan

How to calculate total line number and frame rate in variable partial scan mode
Frame rate (fps) = Horizontal frequency(21.938KHz) / Total lines
Total lines = ①OB period + ②Fast Dump period in the upper part of the frame (L) +
③ Effective image period (L) + ④Fast dump period in the lower part of frame
(L) + ⑤Blank period (L)
Where,
OB period = 4L (Fixed)
Blank period = 6L (Fixed)
Fast dump period for the upper part = Round up
4+Start line −1
4
+ 1
Fast dump period for the lower part = Roud up
1040−End line +2
4
Calculation example
Readout: 1/2 partial scan at the center (520L), Start line (261), End line (780)
OB period = 4L
Blank period =6L
Fast dump period for the upper part = (4+261-1) ÷4 +1= 66 + 1=67  67
Fast dump period for the lower part = (1040-780+2) ÷ 4 =65.5  66
Total lines = 4+67+520+66 +6 = 663
Frame rate = 21.938/ 663 =33.08 fps
Image Height
Image start line
/ end line
Minimum: 8 line Maximum: 1040 lines
Image starts at 1st line
Image starts at 1033rd line
This is in case image height is 8 line
1/8
1033
/1040
8 line
1040 lines