adv7390 Analog Devices, Inc., adv7390 Datasheet - Page 55

• Manufacturer Part Number: adv7390
• Description: Low Power, Chip Scale 10-bit Sd/hd Video Encoder
• Manufacturer: Analog Devices, Inc.

ED/HD SHARPNESS FILTER AND ADAPTIVE FILTER
CONTROLS
Subaddress 0x40, Subaddress 0x58 to Subaddress 0x5D
There are three filter modes available on the ADV739x:
sharpness filter mode and two adaptive filter modes.
ED/HD Sharpness Filter Mode
To enhance or attenuate the Y signal in the frequency ranges
shown in Figure 74, the ED/HD sharpness filter must be
enabled (Subaddress 0x31, Bit 7 = 1) and the ED/HD adaptive
filter must be disabled (Subaddress 0x35, Bit 7 = 0).
To select one of the 256 individual responses, the corresponding
gain values, ranging from −8 to +7 for each filter, must be
programmed into the ED/HD sharpness filter gain register at
Subaddress 0x40.
ED/HD Adaptive Filter Mode
In ED/HD adaptive filter mode, the following registers are used:
•
•
•
•
•
•
•
To activate the adaptive filter control, the ED/HD sharpness
filter and the ED/HD adaptive filter must be enabled
(Subaddress 0x31, Bit 7 = 1, and Subaddress 0x35, Bit 7 = 1,
respectively).
ED/HD Adaptive Filter Threshold A
ED/HD Adaptive Filter Threshold B
ED/HD Adaptive Filter Threshold C
ED/HD Adaptive Filter Gain 1
ED/HD Adaptive Filter Gain 2
ED/HD Adaptive Filter Gain 3
ED/HD sharpness filter gain register
SIGNAL:
INPUT
STEP

1.5
1.4
1.3
1.2
1.1
1.0
0.9
0.8
0.7
0.6
0.5
FILTER A RESPONSE (Gain Ka)
FREQUENCY (MHz)
SHARPNESS AND ADAPTIVE FILTER CONTROL BLOCK
Figure 74. ED/HD 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
Rev. 0 | Page 55 of 96
FILTER B RESPONSE (Gain Kb)
FREQUENCY (MHz)
The derivative of the incoming signal is compared to the three
programmable threshold values: ED/HD Adaptive Filter
Threshold A, Threshold B, and Threshold C (Subaddress 0x5B,
Subaddress 0x5C, and Subaddress 0x5D). The recommended
threshold range is 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 the
ED/HD Adaptive Filter Gain 1, Gain 2, and Gain 3 registers
(Subaddress 0x58, Subaddress 0x59 and Subaddress 0x5A), and
the ED/HD sharpness filter gain register (Subaddress 0x40).
There are two adaptive filter modes available. The mode is
selected using the ED/HD adaptive filter mode control
(Subaddress 0x35, Bit 6):
•
•
ADV7390/ADV7391/ADV7392/ADV7393
Mode A is used when the ED/HD adaptive filter mode
control is set to 0. In this case, Filter B (LPF) is used in the
adaptive filter block. In addition, only the programmed
values for Gain B in the ED/HD sharpness filter gain
register and ED/HD Adaptive Filter Gain 1, Gain 2, and
Gain 3 registers are applied when needed. The Gain A
values are fixed and cannot be changed.
Mode B is used when ED/HD adaptive filter mode control 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 ED/HD sharpness
filter gain register and ED/HD Adaptive Filter Gain 1, Gain 2,
and Gain 3 registers become active when needed.
1.6
1.5
1.4
1.3
1.2
1.1
1.0
FREQUENCY RESPONSE IN SHARPNESS
0
FILTER MODE WITH Ka = 3 AND Kb = 7
2
FREQUENCY (MHz)
4
6
8
10
12