The µSTM is the workhorse of the STM system, a low cost multi-lingual subtitling system. This system allows each cable head ends to choose the subtitling language for their region, for instance, spanish, portuguese, english or french. The four language data is sent with the video signal, recovered at the destination where subtitles in the selected language are inserted in the cable customer video signal.
In this implementation, eight bytes of information are sent per video frame. A special message packet numbering scheme
is used to detect potential data losses. This results in a one way communication channel with the following characteristics:
- approx. 240 bytes per second capacity
- 8 bit CRC error checking
- packet numbering for data loss detection
- packet repeated on even/odd field
The µSTM can also accept data from the serial port using the same protocol. The source is selected from a DIP switch at the front of the unit.
The subtitles are displayed as two lines of 32 characters, drawn in a matrix of twenty four by thirty two pixels.
Detailed description (PDF)
Designed by Gélogic inc.
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Fax: (450) 467-1982
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