ADV7189 Datasheet, PDF (31/104 Pages) Analog Devices – Multiformat SDTV Video Decoder

v740a 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. SDP Y S-VHS 18 Extra Wideband Filter (CCIR 601 Compliant)
v740a COMBINED Y ANTIALIAS, PAL NOTCH FILTERS,
Y RESAMPLE
0
–10
–20
–30
–40
–50
–60
–70
0
2
4
6
8
10
12
FREQUENCY (MHz)
Figure 14. SDP Y S-VHS 18 Extra Wideband Filter (CCIR 601 Compliant)
v740a COMBINED Y ANTIALIAS, NTSC NOTCH FILTERS,
Y RESAMPLE
0
–10
–20
–30
–40
–50
–60
–70
0
2
4
6
8
10
12
FREQUENCY (MHz)
Figure 15. SDP Y S-VHS 18 Extra Wideband Filter (601)
ADV7189
YPM[2:0] Y Peaking Filter Mode (SDP), Address 0x02, [2:0]
Allows the user to select peaking. This function allows the user
to boost/attenuate luma signals around the color subcarrier
frequency. Selecting YPM = 000,001,010,011 sharpens the
image; YPM = 101,110,111 attenuates the luma around the color
subcarrier. In cases of incomplete cancellation in the Y comb
filter, this could be used to attenuate any residual C components
(hanging dots) in the Y output at the cost of a softer image.
Table 62. YPM Function
Filter Response (Peak Position)
YPM[2:0] Composite (2.6 MHz)
S-VHS (3.75 MHz)
000
+4.5 dB
+9.25 dB
001
+4.5 dB
+9.25 dB
010
+4.5 dB
+5.75 dB
011
+1.25 dB
+3.3 dB
100*
0
0
101
–1.25 dB
–3.0 dB
110
–1.75 dB
–8.0 dB
111
–3.0 dB
–8.0 dB
*Default value.
SDP CHROMA FILTER
Data¹⁰ from the digital fine clamp block is processed by two sets
of filters:
• Chroma Antialias Filter (CAA). The ADV7189
oversamples 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 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
together.
10 _{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.
Rev. A | Page 31 of 104