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EN 124
9.
EM5A NTSC
in the picture, it is possible that the AGC setting is wrong. It is
also possible that the AGC-setting is mis-aligned, if the picture
deforms with a perfect signal. Then the IF-circuit is amplifying
too much.
The video IF-signal is fed to pins 2/3 of the PLL-controlled IF-
demodulator. The voltage-controlled oscillator of the PLL is
adjusted via the service menu 'IF AFC.' If the alignment is
correct, the displayed frequency in the installation menu is the
same as the applied frequency from a generator. The external
coil L5408 connected between pins 7/8 is used as reference.
The demodulated IF-video signal is available at pin 10 of the
HIP. In this video signal, there is a rest of the sound carrier,
which is filtered out by the sound trap 1407.
Then the signal is fed again to the HIP on pin 12, where the
group delay is corrected, dependent on the standard that is
received.
The CVBS-signal is available at pin 13 for further processing in
the set. Via TS7322, the signal is supplied to AV1 (monitor out)
and again back into the HIP (pin 14) to the source/record
selection.
To achieve Quasi Split Sound (QSS), the IF-signal is fed to the
HIP on pin 63/64 via SAW-filter 1405. The FM- modulated
signal is available on pin 5 and is fed to the audio demodulator
MSP34x2 (7651.)
9.6
Video: HD Jack Interface (Diagram N)
The Jack High Definition module covers the following functions:
1. RGB output selection.
2. Matrix circuit to convert YPbPr to RGB.
3. Sync slicer for YPbPr sync on Y, RGB sync on Green.
4. Sync selection.
5. Control Function.
6. Audio feed-through of signal source.
SND_R_in
SND_L_in
ATSC
YPbPr/
RGB_ATSC
MATRIX
RGB
RGB_PAL
PAL
MATRIX
Y/G
H-770-2
2fH
Sync slicer
H-770-3
H_in
V-770
V_in
I2C
Figure 9-10 Source Selection
9.6.1
RGB Output Selection
The module has two video inputs and one RGB output (going
into the set.)
The inputs can also handle 1080i-signals and 480p-signals
(both in RGB format and YPbPr format.)
(This selection circuitry is also needed to cope with the various
formats of the non-standardized HD set top box business.)
Video-input (3 cinches, reference number 1993-A-B-C):
Circuit Descriptions and Abbreviation List
SND_R_out
SND_L_out
A
TDA8601
TDA8601
B
RGB output
A,B
SW1
SW2
FBL
I01
I02
I03
HEF 4052
1,2
3
1,2
3
SW-3
I04 I05 I06
I/O Expander: M62320
CL 16532043_024.eps
•
YPbPr with sync on Y.
•
RGB with sync on green (note: cinch-inputs are normally
used for YPbPr input.)
Video-input (D-sub, reference number 1990):
•
YPbPr with sync on Y (note: D-sub input is normally used
for RGB-inputs only.)
•
RGB with sync on Green.
•
RGB with separate H and V Sync (called VGA in 480p.)
RGB output:
This RGB output of the board is signaled into the set (HOP-
section of SSB [B4].)
9.6.2
Matrix
The YPbPr-signal format is converted to RGB via the matrix
function. In 480p-format, the PAL matrix is used, otherwise the
ATSC matrix is used.
The matrix choice is made with TDA8601 (SW1, 7107.)
This switch is controlled via the command IO-1 (called MATRIX
SELECT in the figure.)
9.6.3
Sync Slicer
The sync slicer extracts the horizontal and vertical
synchronization signals for the HOP (in the set):
•
From the 3-level sync pulses Y of the 1080i YPbPr
•
From the 3-level sync pulses Green of the 1080i RGB
•
From the normal sync pulses of the 480p signal
Explanation of 3-level sync shown in picture:
+ 350
+ 300
0
P'
,P'
B
R
- 300
- 350
+ 700
FBL
+ 300
Y',R',G',B'
0
H_out
- 300
V_out
0
H
Example of a 2-level sync pulse: CVBS-signal with two levels
of sync (-300 mV, 0 mV)
Example of a 3-level sync pulse: ATSC-signal with three levels
of sync (-300 mV, 0 mV, +300 mV)
050601
The amplitudes of the Y, R, G, B signals are 700mV;
amplitudes of the Pb and Pr signals are 350mV.
9.6.4
Sync Selection
If the synchronization is derived from Y or Green, the H and V
sync from the sync-slicer must be selected.
•
When YPbPr-signal or RGB-signal is 480p-format: sync
signals will be V-770 and H-770-2 sync.
•
When YPbPr-signal or RGB-signal is 1080i-format: sync
signals will be V-770 and H-770-3 sync.
When the sync is separate (H and V), the sync of the source
must be selected.
Figure 9-11 3-level sync signal
CL 16532043_022.eps
080501
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