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EN 126
9.
EM5A P/M
The 50 Hz YUV signals, coming from the HIP, are fed to the
PICNIC via an anti-aliasing filter.
The (AABB) frame frequency doubling is done by the PICNIC
(SAA4978, 160 pins QFP) together with a field memory
(MEM1). This IC can handle most 100 Hz functions (except
Progressive Scan).
The PICNIC has an internal CPU and a (small) integrated
ROM. The actual FBX7 software is located in an external ROM
(item 7711). In order to limit the number of connections
between the PICNIC and the external ROM, a number of lines
are used twice. The lines A8 to A15 are fixed lines, while the
lines A0 to A7 are made switchable with the eight data lines of
the ROM. This is done via a Latch (item 7712), which is
controlled by pin 139 of the PICNIC (the ALE signal).
Via bus 'C', a digitalised signal is presented to FM1 (Field
Memory 1), which is used for the 50 to 100 Hz conversion. The
signal goes further via the data-bus to the FALCONIC. This IC
has the following functions:
•
Line flicker reduction.
•
Digital Noise Reduction (DNR).
•
Progressive scan (262.5 - 525 or 312.5 - 625 lines per
frame).
At the end, the digital YUV signals enter, via FM4 and FM5, the
Eagle IC.
This IC has the following functions:
•
Luminance Transient Improvement (LTI).
•
Peaking.
•
Programmable number of lines.
•
Programmable number of pixels per line.
•
Demo mode (split screen).
•
Improved colour transients (CTI) and colour enhancement
(TOPIC).
•
Improved vertical zoom.
The digital YUV-signals from the Eagle go, via a passive output
filter, to the HOP.
9.8.3
PICNIC/FALCONIC (Diagram B3a and B3b)
The PICNIC is used for the 100Hz conversion and has the
following functions:
•
The ADC.
•
The DAC.
•
The 100 Hz conversion.
•
Dual screen compression
•
The Panorama mode.
•
Automatic Aspect Ratio Adaptation (AARA)
•
Colour Transient Improvement (CTI)
•
The contrast improvement (Dynamic Contrast).
All these functions are integrated in one IC: SAA4978H, 160
pins QFP
ADC/DAC
•
Analogue to Digital conversion is done with three identical
9-bit ADCs.
•
Digital to Analogue conversion uses three identical 10-bit
DACs.
In the PICNIC there are three nine bits ADCs present for Y, U,
and V. For digitising the Y (luminance), nine bits are used (to
realise a more detailed picture). These nine bits are only
internally used. Via dithering, the nine bits are reduced to eight
bits and this data is stored into memory. The data in the
memory is fed back to the PICNIC and via un-dithering the data
is again reproduced to nine bits for processing.
U/V (colour difference signals) is also sampled with nine bits.
These two nine bit data streams are multiplexed to four bits
data streams. As the perception for colours by the human eye
is less sensitive as for luminance, this reduction is allowed.
100 Hz Conversion
The main task of the PICNIC is the conversion from 50Hz to
100Hz for YUV and HV-sync. In order to remove "large area
flicker" (especially visible in a white picture), the field-rate of the
Circuit Descriptions and Abbreviation List
Y DEC
U DEC
V DEC
HA
VA
Y DEC
U DEC
V DEC
HA
VA
video is doubled by the FBX6. A 50/60 Hz frame frequency is
converted to 100/120 Hz. In addition, the line frequency (16
kHz) is doubled (32 kHz).
Basically, when the video input contains fields A, B etc., the
conversion provides an AABB sequence on the display. The
actual conversion is done in the first Field Memory (by reading
it twice at double speed, while writing it once.
7709
BUS A
BUS
BUS
B
BUS C
BUS
PICNIC/SAA4978H
2
I C
100Hz CONFIGURATION
7709
BUS A
BUS
BUS
B
BUS
BUS C
PICNIC/SAA4978H
2
I C
NATURAL MOTION
Figure 9-14 100 Hz conversion
For extra 100 Hz features, it is possible to add an extra IC to
the PICNIC. This IC, called the 'Field And Line CONverter IC'
(FALCONIC), has three modes:
•
100 Hz (to eliminate field flicker). Only one memory IC
(7714) is used to store one frame. It displays an AABB
sequence.
•
Digital Scan (to additional eliminate line flicker). Together
with two memory ICs (7714 and 7740), it displays an
AA'BB' or ABAB sequence.
•
Natural Motion (to additional eliminate movement
juddering). Together with two memory ICs (7714 and
7740), it displays an AB'A'B sequence.
Further features of the PICNIC:
•
Dual Screen Compression. The PICNIC can provide
horizontal video compression up to 50 %. The compress
mode can be used to display dual screens with Teletext
(only for wide-screen sets).
•
The Panorama Mode. To fit 4:3 pictures into a 16:9
display, it is possible to apply a panoramic horizontal
distortion, to make a screen-fitting picture without black
sidebars or lost video. The centre horizontal gain is
programmable and the side gain is automatically adapted
to make a screen-fit.
•
Automatic Aspect Ratio Adaptation (AARA). This
feature uses data from the "black bar detection circuit" to
adapt the vertical and horizontal amplitude to an aspect
ratio belonging to the display, without the black bars.
•
Colour Transient Improvement (CTI). At CVBS video
signals, the bandwidth of colour signals is limited to 1/4 of
the luminance bandwidth. Transients between areas of
different colours are therefore not very sharp. The PICNIC
can steepen these transients artificially with a time
manipulation algorithm.
7714
M
E
M
1
BUS D
Y FEAT
U FEAT
V FEAT
HD100
VD100
7726
7714
7740
F
M
M
A
E
E
L
M
A
B
M
C
1
2
O
N
F
C
I
C
BUS D
Y FEAT
U FEAT
V FEAT
HD100
VD100
CL 16532044_015.eps
090501
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