adv7194 Analog Devices, Inc., adv7194 Datasheet - Page 42

• Manufacturer Part Number: adv7194
• Description: Professional Extended-10? Video Encoder With 54 Mhz Oversampling
• Manufacturer: Analog Devices, Inc.

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 87
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).
ADV7194
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
0
0
•
•
•
1
1
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.
DNR27-DNR24
Y DATA
Y DATA
= 01HEX
INPUT
INPUT
14
0
0
•
•
•
1
1
DNR13
DNR THRESHOLD
13
0
0
•
•
•
1
1
12
DNR
MODE
NOISE SIGNAL PATH
MAIN SIGNAL PATH
DNR
SHARPNESS
MODE
NOISE SIGNAL PATH
MAIN SIGNAL PATH
0
0
•
•
•
1
1
O X X X X X X O O X X X X X X O
O X X X X X X O 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
FILTER BLOCK
FILTER BLOCK
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
APPLY BORDER
CORING GAIN
GAIN CONTROL
GAIN CONTROL
FILTER OUTPUT
< THRESHOLD ?
FILTER OUTPUT
> THRESHOLD ?
FILTER OUTPUT
FILTER OUTPUT
GAIN
GAIN
> THRESHOLD
< THRESHOLD
DNR10
OFFSET CAUSED BY
VARIATIONS IN INPUT
TIMING
SUBTRACT
SIGNAL IN
THRESHOLD
RANGE
FROM
ORIGINAL
SIGNAL
ADD
SIGNAL
ABOVE
THRESHOLD
RANGE
TO
ORIGINAL
SIGNAL
DNR
OUT
DNR
OUT