Complex sentence: ARD and ZDF were the host broadcasting TV networks and producers of the TV signal, and they founded a company named BERTA which provided the signal in high-resolution HDTV for TV stations around the world.
Split into simpler sentences: ARD and ZDF are the host broadcasting TV networks and producers of the TV signal as well. They have founded a company named BERTA which will provide the signal in high-resolution HDTV for TV stations around the world.