• When called on a repeater, you get the distance to that specific repeater.
• When called on a source transmitter with active repeaters, you get the range to the closest of those refs.

Some key differences between this function and ObjectReference.GetDistance(...):

• This function is only valid when run on active, limited-range radio transmitters on frequencies detectable by the Pipboy. Transmitter refs become active when they are both Enabled and filling a Quest Alias.
• This function only returns a valid distance if the player is within the transmitter's outer radius (Max Weak Distance). OnPipboyRadioDetection can be used to determine when this is the case.
• This function will 'go through teleport doors', returning the cumulative straight-line distance from the ref to the player based on a pathfinding search.
• Distance to active transmitters is updated twice a second if no pathfinding search is required (ref & player in the same space), and once every 5 seconds otherwise.

• ObjectReference
• Game.IsPlayerInRadioRange(...)
• OnPipboyRadioDetection - ObjectReference