How do you allocate bandwidth?

Mr. Dominic,I came across your CET Tech Info Blog and wanted to thank you for your efforts to educate the public on television’s conversion to digital. I have a question for you; hopefully it is not too advanced for the blog but if so maybe you can answer it for me anyway. When analyzing the signal that WCET-DT sends out, in additional to the video and audio streams for CET-HD and CET-World, I notice some other data streams that are not present in other local stations’ signals. I’ve noticed that these data streams can use up 2Mbps or more of the 19Mbps available in an 8VSB channel. Could you tell me what these additional data streams are?On a possibly related note, my television’s guide system (TV Guide on Screen) provides me with programming information for all of the channels I receive. I am OTA-only (why pay for TV when you can get great HD from CET and other local stations) so I am wondering where my TV gets the data from! I have heard rumors that some PBS stations send this data, encoded in their channels. Is this true?Thanks,Zak Lewis————————————

Zak,

     First let me apologize for the tardy response. Your comment ended up my “profile area” and I don’t go there often. Normally the questions and comments are appended to the blog itself. In any case thanks for the questions. I checked with our head of engineering so I was certain to give you the right info. He feels that you may be mistaken about 2 Mbps,. He noted that if your are looking at “World” being statmuxed on your analyzer but we can’t tell for sure without seeing the equipment you are using. Our current stream, before statmuxing, on air is: 14,500,000 for CET-HD 2,500,000 for World 300,000 for the Ohio EAS (audio only that you won’t be able to monitor),  128,000 for DEAS 1,640,000 unused In addition, with a stream analyer you will not see: 250,000 for Aux Data 200,000 for Carousel 

      The Gemstar/TV Guide On Screen is broadcast on 4 lines in the vertical interval of our analog. Most major cities also have a backup of the TV Guide being broadcast on one of the commercial stations. In October it was removed from the digital stream so is only being sent on analog at this time.

      Hope this helps, jack

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