ADV7196A_15 Datasheet, PDF (22/36 Pages) Analog Devices – Multiformat Progressive Scan/HDTV Encoder with Three 11-Bit DACs, 10-Bit Data Input, and Macrovision

ADV7196A
300
GAMMA CORRECTION BLOCK OUTPUT
TO A RAMP INPUT FOR VARIOUS GAMMA VALUES
250
SIGNAL OUTPUTS
200
0.3
0.5
150
100
SIGNAL
INPUT
1.5
1.8
50
0
0
50
100
150
200
250
LOCATION
Figure 36. Signal Input (Ramp) and Selectable Gamma
Output Curves
The gamma curves shown above are examples only, any user
defined curve is acceptable in the range of 16–240.
SHARPNESS FILTER CONTROL AND ADAPTIVE
FILTER CONTROL
There are three Filter modes available on the ADV7196A: one
Sharpness Filter mode and two Adaptive Filter modes.
SHARPNESS FILTER MODE
To enhance or attenuate the Y signal in the frequency ranges shown
in Figure 37, the following register settings must be used:
Sharpness Filter must be enabled (MR17 = “1”) and Adaptive
Filter Control must be disabled (MR57 = “0”).
To select one of the 256 individual responses, the according gain
values for each filter, which range from –8 to +7, must be pro-
grammed into the Filter Gain register.
ADAPTIVE FILTER MODE
The Adaptive Filter Threshold A, B, C registers, the Adaptive
Filter Gain 1, 2, 3 registers and the Filter Gain register are used
in Adaptive Filter mode. To activate the Adaptive Filter control,
Sharpness Filter must be enabled (MR17 = “1”) and Adaptive
Filter Control must be enabled (MR57 = “1”).
The derivative of the incoming signal is compared to the three pro-
grammable threshold values: Adaptive Filter Threshold A, B, C.
The edges can then be attenuated with the settings in Adaptive
Filter Gain 1, 2, 3 registers and Filter Gain register.
According to the settings of the Adaptive Mode control (MR56),
there are two Adaptive Filter Modes available:
1. Mode A: is used when Adaptive Filter Mode (MR56) is set
to “0.” In this case, Filter B (LPF) will be used in the adaptive
filter block. Also, only the programmed values for Gain B in
the Filter Gain, Adaptive Filter Gain 1, 2, 3 are applied when
needed. The Gain A values are fixed and can not be changed.
2. Mode B: is used when Adaptive Filter Mode (MR56) is set to
“1.” In this mode a cascade of Filter A and Filter B is used. Both
settings for Gain A and Gain B in the Filter Gain, Adaptive
Filter Gain 1, 2, 3 become active when needed.
INPUT SIGNAL: STEP
SHARPNESS AND ADAPTIVE FILTER CONTROL MODE
1.5
7
1.4
6
5
1.3
4
1.2
3
2
1.1
1
0
1.0
–1
0.9
–2
–3
0.8
–4
0.7
–5
–6
0.6
–7
–8
0.5
0
2
4
6
8
10
12
14
FREQUENCY – MHz
1.5
7
1.4
6
5
1.3
4
1.2
3
2
1.1
1
1.0
0
–1
0.9
–2
–3
0.8
–4
0.7
–5
–6
0.6
–7
–8
0.5
0
2
4
6
8
10
12
14
FREQUENCY – MHz
1.6
1.5
1.4
1.3
1.2
1.1
1.0
0
2
4
6
8
10
12
14
FREQUENCY – MHz
FREQUENCY RESPONSE IN SHARPNESS FILTER MODE
WITH K_A = 3 and K_B = 7
Figure 37. Sharpness and Adaptive Filter Control Mode
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