PEDL87V21071-01
OKI Semiconductor
ML87V21071
c Detection of Basic Noise Status Signals
Detection of the basic noise status signal (YBDTO, CBDTO) involves comparing the average noise value
(YBAVRO[6:0], CBAVRO[6:0]) and the noise status comparison value (YAVR1[5:0] (SUB:53h-bit[5:0]),
CAVR1[5:0] (SUB:54h-bit[5:0])) of the blanking period. The noise status is switched when the new status has
continued for four frames or more.
The detection of the noise status signal has the hysteresis characteristic shown in Figure F2-1-6(4). You can
select the characteristic with YAH1(SUB:53h-bit[7]) and CAH1 (SUB:54h-bit[7]).
Table F2-1-7 (5) Luminance Blanking Period Noise Status Detection
Before transition
After transition
Condition
YBDTO
YBDTO
0
0
YBAVRO[6:0] ≤ YAVR1[5:0]
0
1
YBAVRO[6:0] > YAVR1[5:0]
YBAVRO[6:0] ≤ YAVR1[5:0] x (hysteresis
coefficient)
1
0
YBAVRO[6:0] > YAVR1[5:0] x (hysteresis
coefficient)
1
1
Table F2-1-7 (6) Chrominance Blanking Period Noise Status Detection
Before transition
After transition
Condition
CBDTO
CBDTO
0
0
0
CBAVRO[6:0] ≤ CAVR1[5:0]
CBAVRO[6:0] > CAVR1[5:0]
CBAVRO[6:0] ≤ CAVR1[5:0] x (hysteresis
coefficient)
CBAVRO[6:0] > CAVR1[5:0] x (hysteresis
coefficient)
1
0
1
1
1
Table F2-1-7 (7) Noise Status Reduction Direction Detection Hysteresis Settings
YAH1
Noise reduction direction
CAH1
switching coefficient
0
1
3/4
7/8
Basic noise status judgment
YBDTO=1,CBDTO=1
Noise reduction direction judging threshold value
Noise increase direction judging threshold value
Basic average noise value
YBAVRO[6:0]
YBDTO=0,CBDTO=0
0
CBAVRO[6:0]
Set with YAH1, CAH1
YAVR1[6:0]
CAVR1[6:0]
Figure F2-1-7 (4) Basic Noise Status Judgment Transition Diagram
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