ADV7191 Analog Devices, ADV7191 Datasheet - Page 41

• Manufacturer Part Number: ADV7191
• Description: Video Encoder with Six 10-Bit DACs and Video Encoder with Six DAC Outputs
• Manufacturer: Analog Devices

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
81 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 that 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).
0.8
0.6
0.4
0.2
1
0
0
FILTER C
FILTER D
1
DNR17
2
0
1
BLOCK SIZE
FREQUENCY – MHz
CONTROL
FILTER B
8 PIXELS
16 PIXELS
3
DNR17
FILTER A
4
DNR16
DNR16
5
BORDER AREA
0
1
2 PIXELS
4 PIXELS
6
DNR15
DNR14
DNR DNR DNR DNR DNR DNR
15
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 po-
sitions 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.
0
0
•
•
•
1
1
DNR27 – DNR24
Y DATA
Y DATA
INPUT
INPUT
14
0
0
•
•
•
1
1
DNR13
DNR THRESHOLD
= 01 HEX
13
0
0
•
•
•
1
1
DNR
MODE
NOISE SIGNAL PATH
MAIN SIGNAL PATH
DNR
SHARPNESS
MODE
NOISE SIGNAL PATH
MAIN SIGNAL PATH
12
0
0
•
•
•
1
1
FILTER BLOCK
FILTER BLOCK
O X X X X X X O
O X X X X X X O
O X X X X X X O
DNR12
11
•
•
•
1
1
0
0
APPLY DATA
CORING GAIN
10
0
1
•
•
•
0
1
0
1
•
•
•
62
63
DNR11
BLOCK SIZE CONTROL
BORDER AREA
BLOCK OFFSET
CORING GAIN DATA
CORING GAIN BORDER
BLOCK SIZE CONTROL
BORDER AREA
BLOCK OFFSET
CORING GAIN DATA
CORING GAIN BORDER
GAIN CONTROL
GAIN CONTROL
< THRESHOLD ?
> THRESHOLD ?
APPLY BORDER
CORING GAIN
FILTER OUTPUT
FILTER OUTPUT
ADV7190/ADV7191
FILTER OUTPUT
FILTER OUTPUT
GAIN
GAIN
> THRESHOLD
< THRESHOLD
O X X X X X X O
O X X X X X X O
O X X X X X X O
DNR10
SUBTRACT
SIGNAL IN
THRESHOLD
RANGE
FROM
ORIGINAL
SIGNAL
ADD
SIGNAL
ABOVE
THRESHOLD
RANGE
TO
ORIGINAL
SIGNAL
OFFSET
CAUSED BY
VARIATIONS IN
INPUT TIMING
DNR
OUT
DNR
OUT