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Transponder Setup For Local Stations

1066 Views 2 Replies 3 Participants Last post by  Stewart Vernon
I am trying to understand how the transponders work for the local stations.

I live in the San Antonio area, and don't have any OTA antenna, so just use the regular channel lineup for my local stations.

When I go into the "Point Dish" screen, it shows the same Sat and transponder for ALL the local HD stations, Sat 110, Transponder 25.

For the SD channels, it is all Sat 110 Transponder 23.

I know these are all spot beams, but how can all these different channels be on the same transponder ? Are they on different frequencies within the same transponder, or what ? :confused:

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A transponder is just a wideband transmitter on the satellite. If the channel they are sending through the satellite is narrower (less bandwidth) than the satellite transponder, they can multiplex as many as they want together until its full and send them at the same time. Sort of like 10 computers in your house can use one internet connection. The channels are assigned a Program ID, so the receiver at the other end knows which one of the several channels on the transponder you are wanting, and uses that much of the signal. SD is so narrow, you can usually fit most all the locals on one transponder.
I forget the numbers, especially since the changes to MPEG4 from MPEG2...

but, transponders that have only HD channels have had anywhere from 4-8 HD channels on them I believe.

Similarly, I think SD-only transponders have had 10-20 on them if I'm not mistaken.
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