47 C.F.R. § 80.761
The following graphs must be employed where conversion from one to the other of the indicated types of units is required.
(b) Graph 2. To convert microvolts across 50 ohms to received power in dBW, find the signal in microvolts on the horizontal axis. Move vertically to the diagonal line, then move right horizontally to read dBW.


(c) Graph 3. To convert received power in dBW to field intensity in dBu find the received power in dBW on the horizontal axis. Move vertically to the diagonal line, then move right horizontally to read dBu.
