COMBINED Y ANTIALIAS, CCIR MODE SHAPING FILTER,
Y RESAMPLE
0
–20
–40
–60
–80
–100
–120
0
2
4
6
8
10
12
FREQUENCY (MHz)
Figure 13. Y S-VHS 18 Extra Wideband Filter (CCIR 601 Compliant)
0
–10
–20
–30
–40
–50
–60
–70
0
COMBINED Y ANTIALIAS, PAL NOTCH FILTERS,
Y RESAMPLE
2
4
6
8
10
12
FREQUENCY (MHz)
Figure 14. Pal Notch Filter Responses
0
–10
–20
–30
–40
–50
–60
–70
0
COMBINED Y ANTIALIAS, NTSC NOTCH FILTERS,
Y RESAMPLE
2
4
6
8
10
12
FREQUENCY (MHz)
Figure 15. NTSC Notch Filter Responses
ADV7183A
CHROMA FILTER
Data from the digital fine clamp block is processed by two sets
of filters. The data format at this point is CVBS for CVBS
inputs, chroma only for Y/C, or U/V interleaved for YPrPb
input formats.
• Chroma Antialias Filter (CAA). The ADV7183A over-
samples the CVBS by a factor of 2 and the Chroma/PrPb
by a factor of 4. A decimating filter (CAA) is used to
preserve the active video band and remove any out-of-
band components. The CAA filter has a fixed response.
• Chroma Shaping Filters (CSH). The shaping filter block
(CSH) can be programmed to perform a variety of low-
pass responses. It can be used to selectively reduce the
bandwidth of the chroma signal for scaling or compression.
• Digital Resampling Filter. This block is used to allow
dynamic resampling of the video signal to alter parameters
such as the time base of a line of video. Fundamentally, the
resampler is a set of low-pass filters. The actual response is
chosen by the system with no requirement for user
intervention.
The plots in Figure 16 show the overall response of all filters.
CSFM[2:0] C Shaping Filter Mode, Address 0x17 [7]
The C shaping filter mode bits allow the user to select from a
range of low-pass filters for the chrominance signal. When
switched in automatic mode, the widest filter is selected based
on the video standard/format and user choice (see settings 000
and 001 in Table 62).
Table 62. CSFM Function
CSFM[2:0]
Description
000 (default) Autoselect 1.5 MHz bandwidth
001
Autoselect 2.17 MHz bandwidth
010
SH1
011
SH2
100
SH3
101
SH4
110
SH5
111
Wideband mode
Figure 16 shows the responses of SH1 (narrowest) to SH5
(widest) in addition to the wideband mode (in red).
Rev. B | Page 31 of 104