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Teletext Decoder - VIP011
Features
- Fast Access
- Four Inputs
- On-board PAL Encoder
- On-board Keyer
- RGBS & Key Outputs
- Can be used as source for in-vision Teletext
Overview
The VIP011 Teletext Decoder is based on a software controlled design. The use of a microprocessor enables the access time of the system to be greatly reduced.
In earlier decoders the user selected a page number and when that page was transmitted it was written to the screen. As the various databases increased in size the access time for page selection also increased.
The VIP 011 uses a system known as FASTTEXT which has now been implemented by many broadcasters. Along the lower edge of the displayed page are the titles of four other pages on a related topic. These are coloured red, green, yellow and cyan. For each of these, a page number is stored in the software for rapid retrieval of that page by pressing the the corresponding colour button on the control panel. A fifth index page is tagged in a similar manner.
The decoder has two independent acquisition circuits to acquire pages. The first retrieves the page requested directly by the user, which is then displayed and continuously updated. The second acquisition circuit retrieves approximately 60 other pages from the same magazine and then stores them in memory for instant display. several of these pages are related to the current display page by the FASTTEXT routes at the bottom of the displayed page.
If a page is requested that has already been stored in the memory, the page will be displayed instantly. The page header at the top of the screen will be red to show the page is from memory. When the page is re-transmitted by the broadcaster a few seconds later, the display will be updated and the page header will turn yellow. If the page requested was not in memory, because it was in a different magazine or because it did not exist, the page header will turn cyan and the current page number transmitted will roll through.
The VIP011 includes an on-board coder and keyer allowing encoded teletext to be keyed into the background picture. Two outputs of this mixed Teletext and background signal are provided together with an output of encoded Teletext alone- one use of either of these outputs could be used as a source for broadcasting teletext pages in-vision. RGB outputs of teletext, plus Mixed Sync and a Key signal (know as Fast Blanking or FB) are also provided, so encoding and keying can be done externally if required.
The unit is housed in a 19" 1U frame with controls located on the front panel of the unit. The controls are listed in the VIP011 Specification. An optional remote control facility is available,
Specifications
Operations| Video Input 1 to 4 | Selects on of the four video inputs |
| Keypad Buttons 0 to 9 | Selects page to be displayed between 100 and 999 |
| Text | Selects text or picture |
| Mix | Selects text superimposed on picture Cancelled by pressing text |
| Scroll Up/Down | Scrolls text up/down screen |
| Page Up/Down | Increments selected page upward/ downward |
| Index | Toggles between header page (100 or 400 for CH4) and Index page (199 or 699 for CH4) |
| Reveal | Reveals hidden text (e.g. concealed answers) |
| Update | When pressed, text is removed from the screen until a selected page is received, or if used with newsflash, when the news changes. Pressing Update when no text is displayed will reveal the clock |
| Hold | Holds the displayed sub-page and prevents it from updating |
| Red, Green, Yellow. Cyan | Selects one of the broadcaster's option pages There is also an "Expand" facility, which is selected by pressing Reveal and Update. Pressing once will change the display to the top 1/3rd of the text, pressing again will display the full page |
| VIDEO INPUTS | Composite Video: 4 off 1V into 75ohm |
| OUTPUTS |
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| POWER | 98-125V or 198-250V (20VA nominal) |
| MECHANICAL |
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| CONNECTOR TYPES |
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