(4) A translation must be made from dBm0 to dBrn0 or dBrnc0.
translate dBm0 to dBrn0, add 90 to the dBm0 reading; then add the
appropriate correction factor at the frequency of the interfering tone, as
indicated in figure 1-9, to produce dBrnc0.
Assume that the frequency of the interfering tone is 400
Hz. In figure 1-9, 400 Hz on the C-message weighting curve
gives a correction factor of -11 dB. Add 90 to -30 dBm0 to
obtain +60 dBrn0.
Now add +60 dBrn0 to -11 dB to obtain
C-message weighting curve.