ST92195C STMicroelectronics, ST92195C Datasheet - Page 147

• Manufacturer Part Number: ST92195C
• Description: 48-96 Kbyte Rom Hcmos Mcu With On-screen Display And Teletext Data Slicer
• Manufacturer: STMicroelectronics

ST92195C/D - TELETEXT SLICER AND ACQUISITION UNIT
7.7 TELETEXT SLICER AND ACQUISITION UNIT
7.7.1 Introduction
The Teletext Slicer processes the incoming Com-
posite Video signal (CVBS1 pin) to extract Teletext
data.
The Acquisition Unit filters the data flow from the
slicer and transfers valid line data to the acquisi-
tion buffer where it is read by the TDSRAM inter-
face.
A Hamming decoding function is available for
checking or correcting data after storage.
The Acquisition unit also provides a Teletext signal
quality measure function to evaluate the quality of
the Teletext data reception by testing the HSYNC
pulses or the Hamming error numbers during the
VBI.
Figure 87. Acquisition & Slicing Unit Block Diagram
n
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SYNC
EXTRACTOR
TIMING
FROM
CONTROLLER
FROM/TO
CVBS1
TXTGC1
TXTGC0
Hcvbs
TXTSW
TXTESW
Teletext
Slicer Clock
-
+
DAC
Run-in Clock
Detector
Control
Slicing
Level
Sequencer
7.7.2 Main Features
Hardware framing code check
Hardware & software data prefiltering per
magazine
Real time hardware Hamming 8/4 check on
incoming data
Raw data storage of packets in physical order
Fully programmable storage address
2 acquisition paths for magazine pages and
service packets
Asynchronization between deflection and CVBS
Syncs.
CVBS signal quality measure through a "Bad TV
line" counter
Hamming 24/18 or 8/4 one-shot decoding.
Bit Clock
Extractor
Extractor
Data
FRWND
TTC
TTD
ACQUISITION
UNIT
VR02109C