![](http://datasheet.mmic.net.cn/310000/ADV7302A_datasheet_16243964/ADV7302A_47.png)
REV. A
ADV7302A/ADV7303A
–47–
Table XXI. Adaptive Filter Control on Step Input Signal
Address
Register Setting
00h
01h
02h
10h
11h
15h
20h
38h
39h
3Ah
3Bh
3Ch
3Dh
FCh
38h
20h
00h
81h
80h
00h
ACh
9Ah
88h
28h
3Fh
64h
All other register settings are 00h.
When changing the Adaptive Filter Mode to Mode B
[Address 15h, Bit 6], the output in Figure 67 can be obtained.
: 674mV
@: 446mV
: 332ns
@: 12.8ms
Figure 67. Output Signal from Adaptive Filter Control
The adaptive filter control can also be demonstrated using the
internally generated crosshatch test pattern and toggling the Adap-
tive Filter Control Bit [Address 15h, Bit 7], shown in Table XXII.
Table XXII. Adaptive Filter Control on Internal Test Pattern
Address
Register Setting
00h
01h
02h
10h
11h
15h
20h
38h
39h
3Ah
3Bh
3Ch
3Dh
FCh
38h
20h
00h
85h
80h
00h
ACh
9Ah
88h
28h
3Fh
64h
SD DIGITAL NOISE REDUCTION
[Subaddresses 63h, 64h, and 65h]
DNR is applied to the Y data only. A filter block selects the high
frequency, low amplitude components of the incoming signal
(DNR input select). The absolute value of the filter output is
compared to a programmable threshold value (DNR threshold
control). There are two DNR modes available: DNR Mode and
DNR Sharpness Mode.
In DNR Mode, if the absolute value of the filter output is smaller
than the threshold, it is assumed to be noise. A programmable
amount (coring gain border, coring gain data) of this noise signal
will be subtracted from the original signal.
In DNR Sharpness Mode, if the absolute value of the filter
output is less than the programmed threshold, it is assumed to
be noise, as before. Otherwise, if the level exceeds the threshold,
now being identified as a valid signal, a fraction of the signal
(coring gain border, coring gain data) will be added to the origi-
nal signal in order to boost high frequency components and to
sharpen the video image.
In MPEG systems it is common to process the video information
in blocks of 8
8 pixels for MPEG2 systems, or 16
MPEG1 systems (block size control). DNR can be applied to the
resulting block transition areas that are known to contain noise.
Generally, the block transition area contains two pixels. It is pos-
sible to define this area to contain four pixels (border area.)
It is also possible to compensate for variable block positioning
or differences in YCrCb pixel timing with the use of the DNR
block offset.
16 pixels for
BLOCK SIZE CONTROL
BORDER AREA
BLOCK OFFSET
CORING GAIN DATA
CORING GAIN BORDER
GAIN
DNR CONTROL
FILTER
OUTPUT
> THRESHOLD
INPUT FILTER
BLOCK
FILTER OUTPUT
< THRESHOLD
DNR OUT
MAIN SIGNAL PATH
ADD SIGNAL
ABOVE THRESHOLD
RANGE FROM
ORIGINAL SIGNAL
DNR
SHARPNESS
MODE
NOISE
SIGNAL PATH
Y DATA
INPUT
BLOCK SIZE CONTROL
BORDER AREA
BLOCK OFFSET
CORING GAIN DATA
CORING GAIN BORDER
GAIN
DNR CONTROL
FILTER
OUTPUT
< THRESHOLD
INPUT FILTER
BLOCK
FILTER OUTPUT
> THRESHOLD
DNR OUT
MAIN SIGNAL PATH
SUBTRACT SIGNAL
IN THRESHOLD
RANGE FROM
ORIGINAL SIGNAL
DNR MODE
NOISE
SIGNAL PATH
Y DATA
INPUT
Figure 68. DNR Block Diagram