SDA9254-2 Datasheet, PDF (4/32 Pages) Siemens Semiconductor Group – 2.6 MBit Dynamic Sequential Access Memory for Television Applications (TV-SAM) with On-chip Noise Reduction Filter

SDA 9254-2
SDC0 ... 11
Video Input ₁₂
Input
Luminance
DEMUX
8
8 _{Input Chrominance}
CLASS
3
Motion
Detector
K
4
Recursive
Filter
8
8
MUX
Memory
12 ^{Port C}
delayed
Luminance 8
8 ^{delayed Chrominance}
Memory
Port B
12
DEMUX
Clock and
Control
BLN SCB
UEB10381
Figure 3
Block Diagram of the Noise Reduction Filtering
To avoid artefacts in moving parts of the picture a motion detector is implemented to control the filter
coefficient K according to detected changes between two adjacent fields. The motion detector
performs a low pass filtering of the field differences and builds the absolute values. The results
control the filter coefficient K by choosing one of 13 predefined values between 1/4 and 1. The
characteristic of this assignment influences the amount of noise reduction and is adjustable via the
CLASS-pins. The calculation of the filter coefficient is practised for each pixel of the field.
Adjustment of the Characteristic of the Noise Reduction Filter
CLASS2 CLASS1 CLASS0 Amount of Noise Reduction
x
0
0
Low
x
0
1
Low-mid
0
1
0
Mid-high
1
1
0
High
x
1
1
Noise reduction off
These four possible adjustments put a wide field of different intensities of noise reduction at user’s
disposal.
The recursive filter also enables a reduction of cross color interference because the Motion Detector
exploits only luminance data.
Semiconductor Group
4
1998-01-16