Canon FACSIMILE BASIC 2000 Service Manual page 344

Here, let us try calculating the relationship between dBm indication and
dBV indication:
That is, if we added 2.2 dB to the value of the dBV indication, the result is
the dBm indication.
A–38
E
20 log – 20 log
10
0.775
E
= 20 (log – log
10
0.775
E 1
= 20 log ( ×
10
0.775 E
dBm = dBV + 2.2dB
E
10
1
E)
10
1
) = 20 log
10
0.775