BH20 Colocation 'frame calculator'


I am using the ‘frame calculator’ to ensure that some co-located BH20’s are within the 300 time bits as recommended in the ‘7.3.6 rel notes’…

However I have a strange problem, when I enter the Air Delay from the session screens into the calculator it gives the wrong distance…

I enter :
Air Delay = 1046 (which is for a 9.71mi link)
The calculator says :
Approximate distance (Actual/MaxRange) : 4.85 miles

That is half the correct distance… My questions are :

1. Is the calculator wrong?
2. Should I double the air delay I enter to get the right distance ?