Philips A02E Service Manual page 64

EN 96 9.
8. Wait for 200 ms and execute a cold start when there is no
microcontroller-reset signal. This is considered as "medium
mains interruption".
9. After the cold start, the set should resume to the last status
of user settings.
9.4
Video
Inputs
HIP
Inputs
Figure 9-5 Signal processing A02- versus EMG-chassis.
The SALSA video processing part is a highly integrated
solution. It comprises only two ICs, the ADOC (Analogue
Digital One Chip) and the MPIF (Multi Platform InterFace),
while in the EMG-chassis, this was handled by four ICs (HIP,
PICNIC, PROZONIC, and HOP).
The MPIF uses a nominal 8V and 5V supply, while the ADOC
requires nominal supplies of 1.8V and 3.3V.
The video processing of the SALSA system can be spilt into six
parts:
•
Initial source selection and analogue to digital conversion
performed by MPIF.
•
Demodulator (VIDDEC) performed by the ADOC.
•
Front End Features (FEF) performed by the ADOC.
•
Memory Based Features (MBF) performed by the ADOC.
•
Back End Features (BEF) performed by the ADOC.
•
Digital Output Processing (DOP) performed by the ADOC.
9.4.1
MPIF Analogue Frond End
Introduction
The MPIF (Multi Platform InterFace, type number PNX3000,
item number 7100) is an analogue video and audio pre-
processing unit for the ADOC TV processor. It contains the
high frequent IF part and all the analogue video and audio
source switching for external in- and outputs. The MPIF can
handle CVBS, Y/C, RGB (1fH/2fH) and YPbPr (1fH/2fH) video
signals as well as stereo, I2S, and second sound IF audio
signals. The MPIF converts the selected video and audio
streams from the analogue to the digital domain. Via three
high-speed serial data links (I2D), the digitised audio and video
signals are streamed to the ADOC IC for further processing.
Following figure shows the MPIF block diagram.
Video
Video
IF
IF Processing
Video
Base
band
Sound
Sound IF
IF
Processing
Sound
low-IF
AM
Demod.
Audio
Base
band
Figure 9-6 MPIF block diagram
A02E Circuit Descriptions, Abbreviation List, and IC Data Sheets
EMG
PICNIC PROZONIC
A02 SALSA
MPIF ADOC
CL 36532058_063.eps
Control Video
CVBS_out
Video
Video
output
ADC
Selection
Video I2D
Multi-
Source plexer Link
Selection
Sound
Sound
2nd IF
IF ADC
Selection
Audio Audio
Base band Base band
Selection ADC
Audio
I2C
Output
Clocking
Interface
Selection
CL 36532058_065.eps
LR_out
Some MPIF features:
•
IF Processing:
–
–
–
•
Video base band switching:
–
–
•
Audio base band switching.
•
Video and audio A/D conversion.
•
I2D formatter:
–
•
HOP HOP SCART output buffers.
Vision IF
The video signal is demodulated by means of an alignment-
free PLL carrier regenerator with an internal VCO. This VCO is
calibrated by means of a digital control circuit, which uses an
external crystal frequency as reference. The frequency setting
for the various standards (33.4, 33.9, 38.0, 38.9, 45.75 and
271003
58.75 MHz) is realised via the I2C bus.
The AFC output is generated by the digital control circuit of the
IF-PLL demodulator and can be read via the I2C bus.
The AGC-detector operates on top sync or top white level.
The MPIF IC has an integrated sound trap filter. The trap
frequencies can be switched via the I2C-bus.
Also, a group delay correction filter is integrated. The filter can
be switched between the PAL BG curve and a flat group delay
response characteristic. This has the advantage that in multi-
standard receivers the video SAW filter does not need to be
switchable (cost effective).
Sound IF
The MPIF has a separate sound IF input to enable Quasi Split
Sound (QSS) applications. The sound IF amplifier is similar to
the vision IF amplifier and has a gain control range of about 55
dB.
The AGC detector measures the SIF carrier levels (average
level of AM or FM carriers) and ensures a constant signal
amplitude for the AM demodulator and QSS mixer.
For applications without SIF SAW filter, the IC can also be used
in intercarrier mode. In this mode, the composite video signal
from the VIF amplifier is fed to the QSS mixer and converted to
the intercarrier frequency. AM sound demodulation is realised
in the analogue domain with the QSS mixer.
Source Selection
The following selector parts can be identified:
•
CVBS/YC source selector. The video input selector
consists of four independent source selectors, that can
select between the CVBS signal coming from the IF part
and four external CVBS signals. Two of the external CVBS
inputs can also be used as YC input. One selector is used
for selection of the primary video channel. A second
selector selects the CVBS or YC signal for the secondary
channel. The third and fourth selectors are used for
selection of analogue CVBS outputs A and B for SCART or
Sound line output. The primary channel can be a CVBS or YC
signal. If an YC signal is selected for the secondary
channel or external CVBS outputs A or B, the luminance
and chrominance signals are added so that a CVBS signal
is obtained. The video identification circuit detects the
presence of a video signal on the CVBS_IF input (CVBS0).
I2D I2D
The identification output can be read via I2C bus and is
normally used to detect transmitters during search tuning.
•
RGB/YPbPr source selector. The IC has two RGB inputs.
Both inputs can also be used as YPbPr input for connection
of video sources with an YPbPr output like a DVD player.
The RGB inputs can also be used for fast insertion of RGB
I2C
signals (for instance on screen display menu's) in the
primary CVBS signal. The fast insertion switch is located in
the digital video processor. The RGB signals are converted
281003
to YUV before further processing. The YUV output signal is
digitised with the help of two A to D converters. The U and
Amplifier, AGC.
Down mixer to base band.
Sound trap, low pass filter.
CVBS, Y/C.
RGB, YPbPr (1fH/2fH).
Data transfer to ADOC.