HP 3150 EN - Manual (Page 209)

EN Fax trace report 207
Figure 85. Example of a successfully received fax
Explanation of DBM
-dBM values shown on the fax trace report are hexadecimal numbers.
Convert the value to a base-10 number and then divide by 5 to check
signal strength. Using the example above, where DBM=34:
34 (hex) = 52 (decimal) and 52/5 = 10.4
Assuming a negative value, -10.4 falls into the range of -10 to -43
(with -43 being a weak signal). -10.4 is, therefore, a strong signal.