VDP3104B Просмотр технического описания (PDF) - Micronas
Номер в каталоге
Компоненты Описание
производитель
VDP3104B Datasheet PDF : 72 Pages
| |||
VDP 31xxB
PRELIMINARY DATA SHEET
2.8.3. Dynamic Peaking
Especially with decoded composite signals and notch fil-
ter luminance separation, as input signals, it is neces-
sary to improve the luminance frequency characteris-
tics. With transparent, high-bandwidth signals, it is
sometimes desirable to soften the image.
In the VDP 31xxB, the luma response is improved by ‘dy-
namic’ peaking. The algorithm has been optimized re-
garding step and frequency response. It adapts to the
amplitude of the high frequency part. Small AC ampli-
tudes 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 sepa-
rate adjustment for signal overshoot and for signal un-
dershoot. 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 for notch filter
color decoding, the total system frequency responses
for both PAL and NTSC are shown in figure 2–16.
Transients, produced by the dynamic peaking when
switching video source signals, can be suppressed via
the priority bus.
dB
20
15
10
5
0
–5
–10
–15
–20
MHz
0
2
4
6
8
10
Fig. 2–15: Dynamic peaking frequency response
dB
20
15
10
CF= 3.2 MHz
dB
20
15
10
5
5
0
S-VHS
0
–5
–5
–10
–10
–15
–20
MHz
0
2
4
6
8
10
–15
–20
0
2
4
dB
20
15
CF= 3.2 MHz
dB
20
15
10
10
5
5
0
PAL/SECAM 0
–5
–5
–10
–10
–15
–20
0
2
4
6
8
MHz
10
–15
–20
0
2
4
dB
20
15
CF= 3.2 MHz
dB
20
15
10
10
5
5
0
NTSC
0
–5
–5
–10
–10
–15
–20
0
2
4
6
8
MHz
10
–15
–20
0
2
4
Fig. 2–16: Total frequency response for peaking filter and S-VHS, PAL, NTSC
16
CF= 2.5 MHz
MHz
6
8
10
CF= 2.5 MHz
6
8
MHz
10
CF= 2.5 MHz
6
8
MHz
10
Micronas
Share Link: 