adv7314 Analog Devices, Inc., adv7314 Datasheet - Page 50

• Manufacturer Part Number: adv7314
• Description: Multiformat 216 Mhz Video Encoder With Six Nsv 14-bit Dacs
• Manufacturer: Analog Devices, Inc.

ADV7314
HD Sharpness Filter Control and Adaptive Filter Control
[Subaddress 20h, 38h–3Dh]
There are three Filter modes available on the ADV7314:
sharpness filter mode and two adaptive filter modes.
HD Sharpness Filter Mode
To enhance or attenuate the Y signal in the frequency ranges
shown in Figure 42, the following register settings must be used:
HD sharpness filter must be enabled and HD adaptive filter
enable must be disabled.
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 HD sharpness filter gain register at Address 20h.
HD Adaptive Filter Mode
The HD adaptive filter threshold A, B, C registers, the HD
adaptive filter gain 1, 2, 3 registers, and the HD sharpness filter
gain register are used in adaptive filter mode. To activate the
adaptive filter control, HD sharpness filter must be enabled and
HD adaptive filter gain must be enabled.
INPUT SIGNAL:
STEP
1.5
1.4
1.3
1.2
1.1
1.0
0.9
0.8
0.7
0.6
0.5
Figure 42. Sharpness and Adaptive Filter Control Block Frequency Response in
Sharpness Filter Mode with Ka = +3 and Kb = +7
FILTER A RESPONSE (Gain Ka)
FREQUENCY (MHz)
SHARPNESS AND ADAPTIVE FILTER CONTROL BLOCK
1.5
1.4
1.3
1.2
1.1
1.0
0.9
0.8
0.7
0.6
0.5
–50–
FILTER B RESPONSE (Gain Kb)
FREQUENCY (MHz)
The derivative of the incoming signal is compared to the three
programmable threshold values: HD adaptive filter threshold
A, B, C. The recommended threshold range is from 16 to 235
although any value in the range of 0 to 255 can be used.
The edges can then be attenuated with the settings in HD adaptive
filter gain 1, 2, 3 registers and HD sharpness filter gain register.
According to the settings of the HD adaptive filter mode con-
trol, there are two adaptive filter modes available:
1. Mode A is used when adaptive filter mode is set to 0. In this
2. Mode B is used when adaptive filter gain is set to 1. In this
case, Filter B (LPF) will be used in the adaptive filter block.
Also, only the programmed values for Gain B in the HD
sharpness filter gain, HD adaptive filter gain 1, 2, 3 are applied
when needed. The Gain A values are fixed and cannot be
changed.
mode, a cascade of Filter A and Filter B is used. Both set-
tings for Gain A and Gain B in the HD sharpness filter gain,
HD adaptive filter gain 1, 2, 3 become active when needed.
1.6
1.5
1.4
1.3
1.2
1.1
1.0
0
FREQUENCY RESPONSE IN SHARPNESS
FILTER MODE WITH Ka = 3 AND Kb = 7
2
FREQUENCY (MHz)
4
6
8
10
REV. 0
12