RIGOL 
 ©   2007  RIGOL  Technologies,  Inc. 
  User‟s Guide for DM3000 Series 
4.  dBm Measurement 
This function applies to AC voltage and DC voltage measurements only. 
The dBm function is logarithmic, and is based on a calculation of power delivered to 
a reference resistance, relative to 1 milliwatt. 
 
Press           dBm, the display shows: 
 
Figure 2- 17 
 
                Table 2- 14 dB Measurement Function Menu Function Description 
 
 
The computation method of the dBm: 
dBm = 10 x Log
10
 [ (Reading
2
 / R
REF
) / 0.001W ] 
R
REF
 expressed measuring the resistance value in the actual electric circuit.