View attachment 3286
1970 distance separation requirements in miles for Class A to Class A, for 0 kHz, 200 kHz, 400 kHz, and 600 kHz separations. 5 miles for the 10.6/10.8 separation.
I would hope that proposals would allow mainly contour overlap restrictions to be used for allotments, like 88-92 MHz NCE-FM rules continue to use. But for allotment models, to maximize the number of possible allotments with limited expanded band frequencies, a 3 kW/100 meter two dimensional packing model should be used. The service area from this exceeds the vast majority of 250 watt translators, even the super HAAT translators.
It seems a little late in the game to propose that new expanded band frequencies have 54 dBu protection rather than 60 dBu (1 mV/M), originally the protected contour for ALL classes of FM stations in the United States. Only Class B protection was changed to 54 dBu in the early 1960s, and much later 57 dBu for the new Class B1. Even then, the protection was esoteric, known mostly to engineering consultants and FCC engineers. It was lost in the details of the distance separation requirements, which were a hodge podge of inconsistent government/industry compromise results, which were rounded UP to the next 5 mile increment. Using the FCC FM Propagation utility at FCC.gov, the secrets of the actual distance providing 60 dBu protection for Class A to Class A 3 kW facilities are revealed. It's actually 100 km/62 miles for 0 kHz, 61 km/38 miles for 200 kHz separations. Newer rule makings are more logical and consistent with protected and interfering contours, but remnants like this remain. There are other remnants, despite all the changes.
The NPRM Comments are likely to push in every direction. It will likely be a rocky ride.