DESCRIPTION

The IVT1.8* is a single-chip Teletext decoder IC for decoding 625-line based World System Teletext transmissions. The device is based on IVT1.0VPS and has reception facilities for the 5 MHz biphase VPS signal. It is intended for use in video recorders, in particular to implement the VPT facility (VCR programming via Teletext). With suitable software both VPT standards (EBU PDC System A and System B) can be accommodated to allow operation from any European VPT transmission. Automatic processing of packet 26

transmissions is also possible. No external memory is required as an 8K × 8 DRAM is included on-chip for up to 8 page storage. An enhanced mode allows 7 Fastext pages to be stored, with one chapter used to store

extension packets.

FEATURES

• Complete Teletext and VPS decoding in a single package

• Built-in 8K × 8 memory for up to 8 page storage

• Enhanced mode allows 7 Fastext pages and 8 pages of TOP to be captured

• Ability to request only subtitle pages

• Acquisition and decoding of VPS data

• Data valid output available to indicate reception of error-free VPS or packet 8/30/2 data

• Software and hardware compatible with SAA5246 and SAA5248

• Meshing display within boxes

• Separate data checking algorithms and pointers for each acquisition channel

• 24 : 18 Hamming checker

• Automatic packet 26 extension character processing

• Indication of Line 23 for external use

• 13.5 MHz clock output to drive external microcontroller

• Detection of Spanish transmissions to disable flicker-stopper

• Compatible with Philips’ one-chip TV IC (TDA836X) for scan-locking applications.