Can you use one cable for both cable internet and DIRECTV at the same time?
In general, no. DIRECTV’s networking signals tend to occupy the same space that is used by many cable TV systems. The signals would interfere with each other and there would be problems.
However, if you do your research, and if your really only talking about internet, it’s sometimes possible. Many cablesystems put their internet signals between 5Mhz and 50Mhz so that they don’t interfere with their TV signals. If you’re only getting internet, sometimes it’s possible to use something like this Sonora SWMD3 diplexer. Two diplexers are used, one to combine the signals onto one cable and one to split them back out. This diplexer is specifically built to protect the signals DIRECTV needs.
However, you need to know that if you take on something like this, you’re probably running afoul of the terms of service from your cable provider, and there’s every possibility it won’t work. There’s even a small possibility that you could knock out internet service for people in the rest of the building. Our customer service reps recommend using a separate cable for DIRECTV and one for your cable system, because cable systems are all different and what works for one might not work for another.