It's not 100% exact. There was the ORB - Ostdeutscher Rundfunk Brandenburg. Which later (2003) merged with SFB - Sender Freies Berlin to RBB - Rundfunk Berlin

It's not 100% exact. There was the ORB - Ostdeutscher Rundfunk Brandenburg. Which later (2003) merged with SFB - Sender Freies Berlin to RBB - Rundfunk Berlin Brandeburg. Thus the middle serves the middle. And while Saxonia (Part of MDR) indeed goes to the east most point of Germany it's at least middle in North-South. But the most middle point (depending a little on exact definition) is in Thuringa (also part of MDR)