2100-900-01 Rev. D / September 2011 Return to Section Topics 4-29
Model 2100 6 1/2-Digit Resolution Digital Multimeter User’s Manual Section 4: Front Panel Operations
Figure 4-24
Making a dB measurement from the front panel
To make a dB measurement from a remote interface:
Use the following commands from your PC terminal to make the dB measurement:
CALCulate:FUNCtion DB
CALCulate:STATe {OFF|ON}
CALCulate:STATe?
CALCulate:DB:REFerence {<value>|MINimum|MAXimum}
dBm
Definition
With dBm selected, a voltage measurement is displayed as the level of power (relative to 1
milliwatt) dissipated through a reference resistance. The reference resistance is adjustable in the
Model 2100 Digital Multimeter. The calculation of dBm is defined as below:
dBm = 10 x log(V
2
in
/Z
ref
)/1mW
NOTE Vin is the input signal voltage; Zref is the reference resistance. Changing the reference
resistance will not affect the stored relative reference value. The Zref is adjustable, with a
range from 50 to 8000 (the default value is 600 ). The user-selected reference
value is stored in volatile memory and will be cleared after the multimeter has been shut-
off. This feature is available for DCV and ACV only.
Setting the reference resistance
You can set the reference resistance either through the front panel or from a remote interface.
To set the reference resistance from the front panel:
1. Press the CONFIG + SHIFT + MIN/MAX keys.
2. Use the PREV and NEXT keys to move through the digits and the up and down arrow keys
to increase or decrease the numbers to the desired value.
3. Press ENTER to set the value (refer to Figure 4-25 for the location of the keys used).
FILTER
NEXT
PREV
DIGITS
RATIO
%
MIN/MAX
NULL
ESC
ENTER
AUTO
SINGLE
TRIGGER
STORE
RECALL
LOCAL
SHIFT
CONFIG
MENU
AUT O
DCV
ACV
22
FREQ
CONT
TEMP
4 WIRE
RATIO
V
INPUT
PEAK
200V
PEAK
HI
LO
PEAK
500V
3A
RMS
INPUTS
3A 250V
FRONT/REAR
AMPS
R
1000V
REF
CAT 1000V
CAT 600V
LOCK
SETUP
ACV
22
FUNCTION
DCI ACI
4
PERIOD
LIMITS MX+B
dB
EXTRIG
HOLD
MATH
TRIGGER MEMORY
dBm
RANGE
DISPLAY
NEXT
PREV
POWER
OFF
ON
SENSE
F
NULL
SHIFT
DCV
ACVACV
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