ADV7342 datasheet(58/88 Pages) AD

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ADV7342/ADV7343

Rev. 0 | Page 58 of 88

ED/HD SHARPNESS FILTER AND ADAPTIVE FILTER

CONTROLS

Subaddress 0x40, Subaddress 0x58 to Subaddress 0x5D

There are three filter modes available on the ADV7342/ADV7343:

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).

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

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.

FREQUENCY (MHz)

FILTER A RESPONSE (Gain Ka)

0.5

0.6

0.7

0.8

0.9

1.0

1.1

1.2

1.3

1.4

1.5

FREQUENCY (MHz)

FILTER B RESPONSE (Gain Kb)

0.5

0.6

0.7

0.8

0.9

1.0

1.1

1.2

1.3

1.4

1.5

FREQUENCY (MHz)

1.0

1.1

1.2

1.3

1.4

1.5

1.6

INPUT

SIGNAL:

STEP

FREQUENCY RESPONSE IN SHARPNESS

FILTER MODE WITH Ka = 3 AND Kb = 7

SHARPNESS AND ADAPTIVE FILTER CONTROL BLOCK

Figure 72. ED/HD Sharpness and Adaptive Filter Control Block

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