ADV7192KST datasheet(42/69 Pages) AD

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ADV7192

–42–

REV. 0

DNR17

DNR16

DNR15

DNR14

DNR13

DNR12

DNR11

DNR10

DNR THRESHOLD

DNR DNR DNR DNR DNR DNR

0000

••••

•

••••

•

••••

•

1111

2 PIXELS

4 PIXELS

DNR16

BORDER AREA

8 PIXELS

16 PIXELS

DNR17

BLOCK SIZE

CONTROL

Figure 87. DNR Register 1

DNR2 BIT DESCRIPTION

DNR Input Select (DNR20–DNR22)

Three bits are assigned to select the ﬁlter which is applied to the

incoming Y data. The signal which lies in the passband of the

selected ﬁlter is the signal which will be DNR processed. Figure 88

shows the ﬁlter responses selectable with this control.

DNR Mode Control (DNR23)

This bit controls the DNR mode selected. A Logic 0 selects

DNR mode, a Logic 1 selects DNR Sharpness mode.

DNR works on the principle of deﬁning low amplitude, high-

frequency signals as probable noise and subtracting this noise

from the original signal.

In DNR mode, it is possible to subtract a fraction of the signal

which lies below the set threshold, assumed to be noise, from

the original signal. The threshold is set in DNR Register 1.

When DNR Sharpness mode is enabled it is possible to add a

fraction of the signal which lies above the set threshold to the

original signal, since this data is assumed to be valid data and

not noise. The overall effect being that the signal will be boosted

(similar to using Extended SSAF Filter).

FREQUENCY – MHz

0.4

0.6

0.2

234

0.8

FILTER D

FILTER C

FILTER B

FILTER A

Figure 88. Filter Response of Filters Selectable

FILTER OUTPUT

< THRESHOLD ?

GAIN CONTROL

BLOCK SIZE CONTROL

BORDER AREA

BLOCK OFFSET

GAIN

CORING GAIN DATA

CORING GAIN BORDER

FILTER BLOCK

FILTER OUTPUT

> THRESHOLD

DNR

OUT

MAIN SIGNAL PATH

Y DATA

INPUT

NOISE SIGNAL PATH

SUBTRACT

SIGNAL IN

THRESHOLD

RANGE

FROM

ORIGINAL

SIGNAL

DNR

MODE

FILTER OUTPUT

> THRESHOLD ?

GAIN CONTROL

BLOCK SIZE CONTROL

BORDER AREA

BLOCK OFFSET

GAIN

CORING GAIN DATA

CORING GAIN BORDER

FILTER BLOCK

FILTER OUTPUT

< THRESHOLD

DNR

OUT

MAIN SIGNAL PATH

Y DATA

INPUT

NOISE SIGNAL PATH

ADD

SIGNAL

ABOVE

THRESHOLD

RANGE

ORIGINAL

SIGNAL

DNR

SHARPNESS

MODE

Figure 89. Block Diagram for DNR Mode and DNR Sharp-

ness Mode

Block Offset (DNR24–DNR27)

Four bits are assigned to this control which allows a shift of the

data block of 15 pixels maximum. Consider the coring gain

positions ﬁxed. The block offset shifts the data in steps of one

pixel such that the border coring gain factors can be applied at

the same position regardless of variations in input timing of the

data.

O X X X X X X O

APPLY DATA

CORING GAIN

APPLY BORDER

CORING GAIN

DNR27-DNR24

= 01HEX

OFFSET

CAUSED BY

VARIATIONS IN

INPUT TIMING

O X X X X X X O

Figure 90. DNR27–DNR24 Block Offset Control

ADV7192KST Datasheet(PDF) 42 Page - Analog Devices

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