This morning I can get Irving North Central Patrol, Dallas North Central Division, Southeast Division. Could the cause be a DX or Tropo Situation?
This complex sits on a fairly high piece of land, but from Keller wouldn't it be almost impossible to grab those signals?
Not really.
I can usually hear Dallas on the west side of Fort Worth, losing them on the scanner using a gain-type whip sitting in a cup-holder somewhere on I-20 before I get into Weatherford. For one of the scanners on a roof top mag mount antenna, I usually don't lose them until I hit Weatherford itself. Dallas has a pretty healthy signal.
Irving, on the other hand, can be hit or miss. In most cases, you'd likely be able to hear them in Keller (depending on your antenna, how much interference around you, like cell towers, several other things). They do have
several towers, including one in the northwest part of the city, near the old power plant lake, near LBJ Fwy (I-635) & MacArthur.