ADV7324_15 Datasheet, PDF (55/92 Pages) Analog Devices – Multiformat 216 MHz Video Encoder with Six NSV 14-Bit DACs

HD SHARPNESS FILTER AND ADAPTIVE FILTER
CONTROLS
[Subaddresses 0x20, 0x38 to 0x3D]
There are three filter modes available on the ADV7324: a
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 72, the HD sharpness filter must be enabled,
and the HD adaptive filter enable must be disabled.
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 HD sharpness filter gain register at
Address 0x20.
HD Adaptive Filter Mode
The HD Adaptive Filter Threshold A, HD Adaptive Filter
Threshold B, and HD Adaptive Filter Threshold C registers; the
HD Adaptive Filter Gain 1, HD Adaptive Filter Gain 2, and HD
Adaptive Filter Gain 3 registers; and the HD sharpness gain
register are used in adaptive filter mode. To activate the
adaptive filter control, the HD sharpness filter and the HD
adaptive filter must be enabled.
ADV7324
The derivative of the incoming signal is compared to the three
programmable threshold values: HD Adaptive Filter Threshold A,
HD Adaptive Filter Threshold B, and HD Adaptive Filter
Threshold C. The recommended threshold range is 16 to 235,
but any value between 0 and 255 can be used.
The edges can then be attenuated with the settings in HD
Adaptive Filter Gain 1, HD Adaptive Filter Gain 2, HD Adaptive
Filter Gain 3 registers, and HD sharpness filter gain register.
According to the settings of the HD adaptive filter mode
control, there are two adaptive filter modes available:
• Mode A is used when adaptive filter mode 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
HD sharpness filter gain and HD Adaptive Filter Gain 1,
HD Adaptive Filter Gain 2, and HD Adaptive Filter Gain 3
are applied when needed. The Gain A values are fixed and
cannot be changed.
• Mode B is used when adaptive filter mode is set to 1. In
this mode, a cascade of Filter A and Filter B is used.
Settings for Gain A and Gain B in the HD sharpness filter
gain and HD Adaptive Filter Gain 1, HD Adaptive Filter
Gain 2, and HD Adaptive Filter Gain 3 become active
when needed.
INPUT 
SIGNAL:
STEP
SHARPNESS AND ADAPTIVE FILTERS CONTROL BLOCK
1.5
1.5
1.4
1.4
1.3
1.3
1.2
1.2
1.1
1.1
1.0
1.0
0.9
0.9
0.8
0.8
0.7
0.7
0.6
0.6
0.5
FREQUENCY (MHz)
FILTER A RESPONSE (Gain K_A)
0.5
FREQUENCY (MHz)
FILTER B RESPONSE (Gain K_B)
1.6
1.5
1.4
1.3
1.2
1.1
1.0
0
2 4 6 8 10 12
FREQUENCY (MHz)
FREQUENCY RESPONSE IN SHARPNESS
FILTER MODE WITH K_A = 3 AND K_B = 7
Figure 72. Sharpness and Adaptive Filters Control Block
Rev. 0 | Page 55 of 92