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EN 128
9.
EM5A P/M
To obtain above shown filter characteristic, filters are set at
three parameters (see A, B, and C). In this way, only the higher
frequencies are "lifted". After sending the luminance signal
through these filters, the filter output is added to the original
signal. In this way, the so-called "ears" are created, together
with the steeper slopes. These "ears" will give a contrast
improvement at details.
Both horizontal and vertical peaking is amplitude dependent:
the higher the signal jump, the lower the peaking. This is done
to avoid that high jumps get big "ears", because this will
introduce nasty contouring. To avoid peaking on noise levels,
coring is used. The coring threshold is set via the Auto TV
software, by means of the noise meter.
Therefore, the result is that only details are processed by the
peaking.
The horizontal peaking is also frequency dependent: it is
possible to perform peaking around three frequencies (when
combined, it is even possible to peak at variable frequencies).
In Auto TV, this feature is software coupled to the sharpness
meter, in order to get the most optimal filter characteristic.
The vertical peaking works on a fixed frequency.
Colour Enhancements
In the FBX6, the TOPIC handled the colour enhancement
features, such as: 'skin tone correction', 'blue stretch', and
'green enhancement'. In the new FBX7, all this is done by the
Eagle IC.
Output
The YUV signals presented to the HOP come from the Eagle.
These three signals have all the same circuitry so it is explained
once (for Y).
Y-EAGLE
(pin54)
GND
GND
Figure 9-18 YUV Output Filter
The YUV signals are first filtered by a 64 MHz passive filter
(L5739 with C's). Because the output signals from the Eagle
are too small to drive the HOP directly, they are amplified by the
circuit around TS7731 and TS7728. The gain is determined by
R3791, R3788, and R3807. For the Y-signal the gain is 2, for
the U-signal it is 1.33, and for the V-signal it is 1.05.
9.9
Video: Feature Box 7 (60 Hz signals)
The objective for this chassis is to reach a sharper picture by
means of a higher definition. This is achieved via the 'Pixel
Plus' feature. So what exactly is Pixel Plus?
For the Pal/Multi region, we can distinguish two situations: 50
Hz PAL signals or 60 Hz NTSC signals. This chapter describes
the 60 Hz situation and chapter 1.8 describes the 50 Hz
situation.
Circuit Descriptions and Abbreviation List
2700
3700
5700
GND
GND
+8V
7728
7731
5739
GND
GND
CL 26532041_076.eps
GND
GND
9.9.1
Introduction
The basic function of the Feature box (FBX) is picture
improvement, and depending on the version, several scan
conversion methods are possible. The PICNIC (SAA4978H) is
the central key component.
The feature box is integrated on the SSB.
In the Feature Box 7 (FBX7), a new IC is used, called the
'Eagle.' This IC performs the following picture improvements:
•
Horizontal: increases pixels per line from 840 to 1680 (the
number of pixels per line is doubled.) This, by itself, does
not mean an improvement in definition. To achieve that, the
new pixels are digitally processed inside the Eagle with
Luminance Transient Improvement (LTI) and Peaking.
This will give the new pixels extra picture information,
which results in steeper slopes and contrast improvement
in details.
•
Vertical: increases from 525p lines to 1050i lines. Also,
those new lines are processed inside the Eagle with LTI
and Peaking, again resulting in lines with extra picture
information.
•
The line frequency is fixed on 2 fH and the frame
frequency at 60 Hz. In addition, other modes, like 'Digital
Scan' are still possible.
•
The color enhancement features of the TOPIC are
performed by the Eagle.
9.9.2
Block Diagram
See Block Diagram FBX7 in previous chapter.
The 60 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 120 Hz functions (except
Progressive Scan.)
Y100
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 digitalized signal is presented to FM1 (Field
Memory 1), which is used for the 60 to 120 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.)
GND
•
Progressive scan.
170402
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 color transients (CTI) and color enhancement
(TOPIC.)
•
Improved vertical zoom.
The digital YUV-signals from the Eagle go, via a passive output
filter, to the HOP.
9.9.3
PICNIC/FALCONIC (Diagram B3A and B3B)
The PICNIC has the following functions:
•
The ADC.
•
The DAC.
•
Interlaced to progressive scan conversion.
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