Datasheet

ADV7189B
Rev. B | Page 29 of 104
0
–10
–20
–30
–40
–50
–60
–70
010864212
04983-0-012
FREQUENCY (MHz)
COMBINED Y ANTIALIAS, S-VHS LOW-PASS FILTERS,
Y RESAMPLE
AMPLITUDE (dB)
Figure 12. Y S-VHS Combined Responses
The filter plots in 178HFigure 12 show the S-VHS 1 (narrowest) to
S-VHS 18 (widest) shaping filter settings.
179HFigure 14 shows the
PAL notch filter responses. The NTSC-compatible notches are
shown in
180HFigure 15.
0
–20
–40
–60
–80
–100
–120
010864212
04983-0-013
FREQUENCY (MHz)
AMPLITUDE (dB)
COMBINED Y ANTIALIAS, CCIR MODE SHAPING FILTER,
Y RESAMPLE
Figure 13. Y S-VHS 18 Extra Wideband Filter (CCIR 601 Compliant)
0
–10
–20
–30
–40
–50
–60
–70
010864212
04983-0-015
FREQUENCY (MHz)
COMBINED Y ANTIALIAS, NTSC NOTCH FILTERS,
Y RESAMPLE
AMPLITUDE (dB)
Figure 14. PAL Notch Filter Response
0
–10
–20
–30
–40
–50
–60
–70
010864212
04983-0-015
FREQUENCY (MHz)
COMBINED Y ANTIALIAS, NTSC NOTCH FILTERS,
Y RESAMPLE
AMPLITUDE (dB)
Figure 15 . NTSC Notch Filter Response
CHROMA FILTER
Data from the digital fine clamp block is processed by three sets
of filters. Note: the data format at this point is CVBS for CVBS
inputs, or chroma only for Y/C or Cr/Cb interleaved for YCrCb
input formats.
• Chroma Antialias Filter (CAA). The ADV7189B over-
samples the CVBS by a factor of 2 and the Chroma/UV
by a factor of 4. A decimating filter (CAA) is used to
preserve the active video band and to remove any out-of-
band components. The CAA filter has a fixed response.
• Chroma Shaping Filters (CSH). The shaping filter block
can be programmed to perform a variety of low-pass
responses. It can be used to selectively reduce the band-
width 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 without user intervention.
The plots in
181HFigure 16 show the overall response of all filters
together.