Difference between revisions of "UVSG Satellite Data"
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55 AA 41 2A 00 94 55 AA 54 50 52 45 56 55 45 20 47 55 49 44 45 00 D0 | 55 AA 41 2A 00 94 55 AA 54 50 52 45 56 55 45 20 47 55 49 44 45 00 D0 | ||
| − | In this example, the serial number being addressed is 2A, or the ASCII code for an asterisk. This means every machine that is listening to the satellite feed will act on this command. Then, a 00 to terminate the string, and a checksum (94). After the 55 AA, you see the mode byte (54, or T for '''T'''itle), and then an ASCII string (PREVUE GUIDE). Lastly, there is another 00 to terminate the string, and D0, the checksum for the entire string. | + | In this example, the serial number being addressed is 2A, or the ASCII code for an asterisk (*). This means every machine that is listening to the satellite feed will act on this command. Then, a 00 to terminate the string, and a checksum (94). After the 55 AA, you see the mode byte (54, or T for '''T'''itle), and then an ASCII string (PREVUE GUIDE). Lastly, there is another 00 to terminate the string, and D0, the checksum for the entire string. |
Revision as of 00:44, 22 May 2010
This was the format used by United Video Satellite Group to send data out at 2400 baud through the VBI of both WGN Superstation (from 1985 through 2005) and the C-band Prevue Channel feed (from 1988 through 1999). Many different types of information were sent out through this feed, including time/date information, system settings, channel listings, system updates, and information on previews/promos currently playing through the C-band feed.
Tin has successfully reverse engineered some parts of this format, and it is now possible to send our own messages to emulated or real EPG/Prevue machines over serial.
Overview
Every message always starts with the header "55 AA", followed by a select code, a 00, and a checksum. This is followed by another "55 AA", then a byte indicating which mode of command is being sent out, then the data of the command, which is usually followed by checksum.
For example, here's a command that will change the title of the EPG to "PREVUE GUIDE":
55 AA 41 2A 00 94 55 AA 54 50 52 45 56 55 45 20 47 55 49 44 45 00 D0
In this example, the serial number being addressed is 2A, or the ASCII code for an asterisk (*). This means every machine that is listening to the satellite feed will act on this command. Then, a 00 to terminate the string, and a checksum (94). After the 55 AA, you see the mode byte (54, or T for Title), and then an ASCII string (PREVUE GUIDE). Lastly, there is another 00 to terminate the string, and D0, the checksum for the entire string.