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have bottom clamp, the chroma inputs have average
clamp, and the RGB switch has bottom clamp circuits at
the inputs. The R/C inputs can be switched to average
clamp for chroma signals via I2C bus.
Two pre-selectors BA 7652 are additionally used: One for
switching between Y- Rear and Front, the second for
switching between Chroma- Rear and Front signal. Both
pre-selectors are controlled via IS1 and IS2 from the
analogue board C.
CVBS Signals:
There are two CVBS input connection possibilities: Front
chinch (E5) and Rear Chinch In (E3). Both CVBS sources
are connected direct to the STV 6410 and routed to Rear
Out 1 and Rear Out 2 via the 75-Ohm driver BA 7623. Both
CVBS output sockets are connected to BA 7623 in
parallel.
Independent of the input signal quality (CVBS, S-Video or
Y/UV) the digital board supplies also S-Video and Y/UV
signals to the corresponding sockets.
S-Video Signals:
There are also two S-Video input connection possibilities:
Front (E4) and Rear (E2) S-Video In which are connected
to the pre-selector IC's BA 7652. One is used for Y, the
other for Chroma switching. The output of the pre-selector
switches is connected to the STV 6410, and then the
signal is routed via the 75-Ohm driver BA 7623 to the Rear
Out S-Video socket.
Also the video quality will be S-Video, the digital board
supplies also CVBS and Y/UV to the corresponding
sockets.
Y/UV Signals:
The Y/UV In signal is routed direct to the digital board,
there is no Y/UV IN -> Y/UV Out loop through in low power
standby. As the digital board supplies only RGB signals, a
RGB Y/UV matrix is used. This matrix consists of the
operational amplifier TSH95 which generates the U and V
signals according the formulas: 2U=B-0,338R-0,661G,
2V=R-0,838G-0,161B. Then the signals are routed to the
UV Output sockets via the 75-Ohm driver BA 7623. The
corresponding Y signal is coming from the digital board via
the STV 6410. The 75 Ohm Y socket is driven by the 75-
Ohm driver BA 7623 and finally connected to the of the Y/
UV Output.
Detection of Status-Information
WSS on Y/C-Plug:
• Picture-Ratio-Information (16:9 or 4:3) on SVHS-
connections is coded via the average DC-level of the
Chroma-signal-line, detection is realised by using an
analogue-input-port of the CC-C.
• ADC- value lower or equal 40h ( 4:3-picture-ratio
delivered
• ADC-value greater 40h ( 16:9-picture-ratio available on
plug
• Y/C-Rear is determined via Port40/AIN3 (Pin14) of CC
(WSRI-line) and Port41/AIN4 (Pin15) is used for Y/C-
Front (WSFI-line).
Generation of Status-Information
WSS on Y/C-Plug:
The appropriate DC-level on Chroma-signal-line for Y/C-
Rear-Out is produced via Port57 (Pin10) of the CC-C
(WSRO-line).
• 4:3 - Picture-ratio supported on Y/C-Plug: Port57 set to
0
• 16:9 - Picture-ratio supported on Y/C-Plug: Port57 set
to 1
4.9 Audio routing Analogue board (Europe / Nafta)
General Description:
The Audio- I/O switching is realised by the STV6410 I/O
switch.
By I
2
C Bus (SDA-0/SCL-0) it is possible to control all the
Audio in- and outputs (for detailed Information we refer to
the STV6410 routing overview).
Analog audio coming from DV-Board and second rear
Cinch input is routed via MSP3415 to the STV 6410. After
selecting the audio source via STV 6410, the signal must
be transformed into the digital domain. For this, the UDA
1360TS (ADC) is responsible. An input-voltage of up to
2Vrms can be handled from the IC´ s. For further
processing, the UDA 1360TS (ADC) delivers the data-in
I
2
S format to the digital-board. After a certain delay the
(processed) data come back from the digital board to the
UDA 1328 (DAC). The UDA 1328 (DAC) transforms the
I
2
S data back into the analog domain and feeds the signals
direct to the MC33078 (OPV). From the MC33078 (OPV)
the signals are delivered back to the STV 6410 and also
direct to the 2nd rear out Cinch. The other outputs (Scart,
Cinch) are supported by the STV 6410.
Detailed Description STV 6410:
2
The STV 6410 is an I
C bus controlled audio and video
switch matrix, which is able to handle audio input signals
up to 2 Vrms.
The used outputs are equipped with internal level
adjustment possibility. Low distortion and very good
channel separation is a typical peculiarity of this IC. The
output resistance is very low and the frequency bandwidth
is up to 50 kHz.
Detailed Description UDA 1360:
The UDA 1360TS is a stereo Analog-to-Digital Converter
employing bitstream conversion techniques.
The UDA supports the I
2
S-bus data format and the MSB-
justified data format with word lengths of up to 20 bits. The
IC supports also 2Vrms input signals and is designed for
3V3 supply voltage.
The device is able to handle system clocks of 256fs and
384fs.
Typical THD+N at 0dB is -85dB and a S/N performance up
to 97dB is possible.
DRX-1
81
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