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Service Manual CP-785F
Contrast reduction of defined area
Cursor
Special Graphics Characters with two planes, allowing four colours per character
32 software redefinable On-Screen display characters
4 WST Character sets (GO/G2) in single device (e.g. Latin, Cyrillic, Greek, Arabic)
G1 Mosaic graphics, Limited G3 Line drawing characters
WST Character sets and Closed Caption Character set in single device
Data Capture
The Data Capture section takes in the analogue Composite Vid o and Blanking Signal (CVBS),
and from this extracts the required data, which is then decoded and stored in memory.
The extraction of the data is performed in the digital domain. The first stage is to convert the
analogue CVBS signal into a digital form. This is done using an ADC sampling at 12MHz. The
data and clock recovery is then performed by a Multi-Rate Video Input Processor (MuIVIP).
From the recovered data and clock the following data types are extracted WST Teletext
(625/525), Closed Caption, VPS, WSS. The extracted data is stored in either memory (DRAM)
via the Memory Interface or in SFR locations.
Data Capture Features
- Video Signal Quality detector
- Data Capture for 625 line WST
- Data Capture for 525 line WST
- Data Capture for US Closed Caption
- Data Capture for VPS data (PDC system A)
- Data Capture for Wide Screen Signalling (WSS) bit decoding
- Automatic selection between 525 WST/625WST
- Automatic selection between 625WST/VPS on line 16 of VBI
- Real-time capture and decoding for WST Teletext in Hardware, to enable optimised
microprocessor throughput
- 10 pages stored On-Chip
- lnventory of transmitted Teletext pages stored in the Transmitted Page Table (TPT) and
Subtitle Page Table (SPT)
- Automatic detection of FASTEXT transmission
- Real-time packet 26 engine in Hardware for processing accented, G2 and G3 characters
- Signal quality detector for WST/VPS data types
- Comprehensive Teletext language coverage
- Full Field and Vertical Blanking Interval (VBI) data capture of WST data
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