adv7340 Analog Devices, Inc., adv7340 Datasheet - Page 59

• Manufacturer Part Number: adv7340
• Description: Multiformat Video Encoder, Six 12-bit Noise Shaped Video Dacs
• 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 ADV7340/ADV7341:
a 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 72, the ED/HD sharpness filter must be
enabled (Subaddress 0x31, Bit 7) and the ED/HD adaptive filter
must be disabled (Subaddress 0x35, Bit 7).
To select one of the 256 individual responses, the corresponding
gain values, which range 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
The ED/HD Adaptive Filter Threshold A, B, and C registers, the
ED/HD Adaptive Filter Gain 1, 2, and 3 registers, and the
ED/HD sharpness filter gain register are used in adaptive filter
mode. To activate the adaptive filter control, the ED/HD
sharpness filter and the ED/HD adaptive filter must be enabled
(Subaddress 0x31, Bit 7, and Subaddress 0x35, Bit 7, respectively).
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 72. 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 59 of 88
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, B, and C (Subaddress 0x5B, Subaddress 0x5C, and
Subaddress 0x5D, respectively). 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, 2, and 3 registers (Subaddress
0x58, Subaddress 0x59, and Subaddress 0x5A, respectively), 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):
•
•
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, 2, and 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, 2, and 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
ADV7340/ADV7341
6
8
10
12