VDP313XY データシートの表示（PDF） - Micronas
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VDP313XY Datasheet PDF : 76 Pages
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VDP 313xY
ADVANCE INFORMATION
2.10.3.Dynamic Peaking
Especially with decoded composite signals and notch
filter luminance separation, as input signals, it is nec-
essary to improve the luminance frequency character-
istics. With transparent, high-bandwidth signals, it is
sometimes desirable to soften the image.
In the VDP 313xY, the luminance response is
improved by dynamic peaking. The algorithm has been
optimized regarding step and frequency response. It
adapts to the amplitude of the high frequency part.
Small AC amplitudes are processed, while large AC
amplitudes stay nearly unmodified.
The dynamic range can be adjusted from −14 to
+14 dB for small high frequency signals. There is sep-
arate adjustment for signal overshoot and for signal
undershoot. For large signals, the dynamic range is
limited by a non-linear function that does not create
any visible alias components. The peaking can be
switched over to “softening” by inverting the peaking
term by software.
The center frequency of the peaking filter is switchable
from 2.5 MHz to 3.2 MHz. For S-VHS and notch filter
color decoding, the total system frequency responses
for both PAL and NTSC are shown in Fig. 2–13.
Transients, produced by the dynamic peaking when
switching to the picture frame can be suppressed
optionally
dB
20
15
10
5
0
–5
–10
–15
–20
MHz
0
2
4
6
8
10
Fig. 2–12: Dynamic peaking frequency response
dB
20
15
CF=3.2 MHz
dB
20
15
10
10
5
5
0
S-VHS
0
−5
−5
−10
−10
−15
−20
MHz
0
2
4
6
8
10
dB
20
15
CF=3.2 MHz
−15
−20
0
2
4
dB
20
15
10
10
5
5
0
PAL/SECAM 0
−5
−5
−10
−10
−15
−20
MHz
0
2
4
6
8
10
dB
20
15
CF=3.2 MHz
−15
−20
0
2
4
dB
20
15
10
10
5
5
0
NTSC
0
−5
−5
−10
−10
−15
−20
MHz
0
2
4
6
8
10
−15
−20
0
2
4
Fig. 2–13: Total frequency response for peaking filter and S-VHS, PAL, NTSC
CF=2.5 MHz
MHz
6
8
10
CF=2.5 MHz
MHz
6
8
10
CF=2.5 MHz
MHz
6
8
10
16
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