GW Instek GDM-8200A User Manual - Manual (Page 43)

ADVANCED MEASUREMENT
43
dBm/dB Measurement
Applicable to
(NOT applicable to ACV+DCV)
Background Using the ACV or DCV measurement result, the
GDM-8200A series calculates the dB or dBm value based
on a reference resistance value in the following way.
dBm 10 x log
10
(1000 x Vreading 2 / Rref)
dB dBm – dBmref
Parameters Vreading Input Voltage, ACV or DCV
Vref Reference voltage obtained by Rref/1mW
Rref Reference resistance simulating an output
load
dBmref Reference dBm value
Measure dBm
Activate dBm Press the Shift key followed by the
key. The 1st display shows dBm,
and the 2nd display shows the
reference resistance.
dBm result
appears
dBm Indicates dBm measurement
600Ω 2nd display indicates the reference resistance
Select
reference
resistance To change the reference resistance,
press the Up/Down key. The new
resistance appears in the 2nd display.
The following is the resistance list.
2 4 8 16 50 75 93
110 124 125 135 150 250 300
500 600 800 900 1000 1200 8000