Kusam-meco M3500A, Руководство по эксплуатации

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84
4.3.7 dB/dBm
A. dB
Definition
The dB feature takes a DC or AC voltage measurement and displays it in
decibel unit in correspondence to a relative reference value. The
calculation of dB is listed below:
or
dB = (Input signal in dBm) – (relative value in dBm)
※
NOTE: The
in
V
is the input signal and the
ref
V
is the relative reference.
The dB measurement is applied to DC and AC voltage only. The relative
value is adjustable and is stored in a volatile memory. The range for the
relative value is between 0
dBm and 200 dBm .
How to set the relative value
User can either manually select a number for the relative reference or let
the multimeter
take the first reading (0 dB).
Front Panel Operation
Press SHIFT+ NULL buttons, and then use
◁
and
▷
to move
through the digits and
△
and
▽
buttons to increase or decrease the
numbers to your desired value. Press ENTER to set the value. The
locations of the buttons are shown with red rectangle frames in
Figure
4-21 .
Figure 4-21
) log( 20
Vref
V
dB in
× =