Student Resources for Satellite Information?

Hi, I'm a student researching cable TV and how it receives signals. Are there any specific resources for the satellites of AT&T and DirecTV? I found that they're geostationary, but is there information on the frequency range of their signals, whether those signals are received from multiple sources, and if there's a backup plan for when a service is disabled?

I've looked through different parts of the AT&T website, especially the satellite connectivity resources, but I can't find anything more technical to help me answer these things.

Thank you for any assistance.