Data Sheet
ADV7180
NTSC Comb Filter Settings
COMB FILTERS
These settings are used for NTSC M/J CVBS inputs.
The comb filters of the ADV7180 have been greatly improved to
automatically handle video of all types, standards, and levels of
quality. The NTSC and PAL configuration registers allow the
user to customize the comb filter operation depending on which
video standard is detected (by autodetection) or selected (by
manual programming). In addition to the bits listed in this
section, there are some other internal controls (based on
Analog Devices proprietary algorithms); contact local Analog
Devices field engineers for more information.
NSFSEL[1:0], Split Filter Selection NTSC, Address 0x19[3:2]
The NSFSEL[1:0] control selects how much of the overall signal
bandwidth is fed to the combs. A narrow split filter selection
results in better performance on diagonal lines but more dot
crawl in the final output image. The opposite is true for selecting
a wide bandwidth split filter.
Table 53. NSFSEL Function
NSFSEL[1:0]
Description
Narrow
00 (default)
01
10
11
Medium
Medium
Wide
CTAPSN[1:0], Chroma Comb Taps, NTSC, Address 0x38[7:6]
Table 54. CTAPSN Function
CTAPSN[1:0]
Description
00
Do not use
01
NTSC chroma comb adapts three lines (three taps) to two lines (two taps)
NTSC chroma comb adapts five lines (five taps) to three lines (three taps)
NTSC chroma comb adapts five lines (five taps) to four lines (four taps)
10 (default)
11
CCMN[2:0], Chroma Comb Mode, NTSC, Address 0x38[5:3]
Table 55. CCMN Function
CCMN[2:0]
Description
Configuration
000 (default)
Adaptive comb mode
Adaptive three-line chroma comb for CTAPSN = 01
Adaptive four-line chroma comb for CTAPSN = 10
Adaptive five-line chroma comb for CTAPSN = 11
100
101
Disable chroma comb
Fixed chroma comb (top lines of line memory)
Fixed two-line chroma comb for CTAPSN = 01
Fixed three-line chroma comb for CTAPSN = 10
Fixed four-line chroma comb for CTAPSN = 11
Fixed three-line chroma comb for CTAPSN = 01
Fixed four-line chroma comb for CTAPSN = 10
Fixed five-line chroma comb for CTAPSN = 11
Fixed two-line chroma comb for CTAPSN = 01
Fixed three-line chroma comb for CTAPSN = 10
Fixed four-line chroma comb for CTAPSN = 11
110
111
Fixed chroma comb (all lines of line memory)
Fixed chroma comb (bottom lines of line memory)
Rev. G | Page 41 of 120
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