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Tiernan VBI Data Transmission
01-0870-401B 01/03 73
Configuring Your
System
This section describes how to configure your system for successful end-to-end
processing of VBI data for each VBI scheme. For a detailed description of the
front panel or remote commands used to implement the various VBI schemes,
refer to the appropriate command sections found in this manual.
Tiernan Proprietary Closed Captions (Tiernan CC)
Using Tiernan proprietary closed captions, two lines of VBI information are
encoded per frame (one per field) at the expense of losing two lines of active
video (one per field). The encoded picture is simply shifted up one line to include
the last line of VBI and to exclude the last line of active video in each field.
This proprietary mode is intended as a method to transmit line 21 EIA-608 closed
captions in an NTSC system without incurring more bandwidth requirements.
Tiernan proprietary closed captions are supported on a composite analog NTSC or
component digital (525) format video signal.
Operational Considerations
Ensure that VBI teletext is disabled when closed captions are enabled, as teletext
overwrites all other VBI data.
Hardware Requirements
■ Encoders will properly process Tiernan closed captions with any of the
following modules: TVIP-6021, TVIP-6025, or TVIP-6001.
■ The TDR6 decoder processes VBI data in its standard configuration.
End-to-End Configuration
To configure the encoder and decoder for Tiernan proprietary closed captioning,
follow these steps:
Encoder
1. Ensure that Teletext is disabled. Issue the front panel command
Config>Service #>VBI>Teletext>Enable=off or the remote
TT ENABLE Off command.
2. Ensure that closed caption VBI data is included in the selected service video
input signal.
Encoded Picture Is Shifted
UP One Line
VBI Region
Line 21 Becomes First Line of Active Video
in Tiernan CC Mode
Line 261 is Last Line of Active Video in Tiernan CC Mode
Last Line of Normally Active Video Is Lost (Line 262)
1 line
1 line
Tiernan CC Field for an Encoded Picture Frame
Tiernan CC Mode is for NTSC Format Only