ADV7311 datasheet(49/84 Pages) AD

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REV. A

ADV7310/ADV7311

–49–

HD SHARPNESS FILTER CONTROL AND

ADAPTIVE FILTER CONTROL

[Subaddress 20h, 38h–3Dh]

There are three filter modes available on the ADV7310/ADV7311:

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 the figures below, the following register settings must

be used: HD sharpness filter must be enabled and HD adaptive

filter enable must be set to disabled.

To select one of the 256 individual responses, the according

gain values for each filter, which range from –8 to +7, must

be programmed 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 gain

filter control, the HD sharpness filter must be enabled and HD

adaptive filter enable must be enabled.

The derivative of the incoming signal is compared to the three pro-

grammable 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 adap-

tive filter gain 1, 2, 3 registers and HD sharpness filter gain

According to the settings of the HD adaptive filter mode control,

there are two adaptive filter modes available:

1. 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 sharp-

ness filter gain, HD adaptive filter gain 1, 2, 3 are applied when

needed. The Gain A values are fixed and cannot be changed.

2. 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. 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.

FREQUENCY (MHz)

0.5

0.6

0.7

0.8

0.9

1.0

1.1

1.2

1.3

1.4

1.5

FILTER A RESPONSE (Gain Ka)

FREQUENCY (MHz)

0.5

0.6

0.7

0.8

0.9

1.0

1.1

1.2

1.3

1.4

1.5

FILTER B RESPONSE (Gain Kb)

FREQUENCY (MHz)

1.0

1.1

1.2

1.3

1.4

1.5

1.6

02468

INPUT

SIGNAL:

STEP

FREQUENCY RESPONSE IN SHARPNESS

FILTER MODE WITH Ka = 3 AND Kb = 7

SHARPNESS AND ADAPTIVE FILTER CONTROL BLOCK

Figure 43. Sharpness and Adaptive Filter Control Block

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