16 GMC-I Gossen-Metrawatt GmbH
8 Alternating Voltage Level Measurement (dB)
The voltage level measurement is
used for determining the overall
damping or gain of a transmission
system (shown here as a two-port
network).
Voltage level [dB]
with V
1
= V
REF
(reference level rEF
vALUE
)
result > 1: gain; result < 1: damping
➭ Set the rotary switch to V .
➭ Briefly press the ESC|FUNC multifunction key.
The level measurement function is now active. The mea-
surement value is calculated from the effective value of the
alternating voltage component dependent upon the mea-
suring range (300 mV ... 1000 V), and appears at the digital
display. The present alternating voltage value (U
2
) is indi-
cated at the analog scale.
The default setting for the reference level corresponds to a
value of 0 dB = 0.775 V (1 mW at 600 Ω). This value (U
REF
)
can be changed in the “Setup” menu:
SEt ↵ rEF
dB
↵ XXXXX
dB
↵.
➭ Frequency measurement can be activated by briefly
pressing the multifunction key once again.
➭ If the ESC|FUNC mutlifunction key is pressed and held
(approx. 1 s), the instrument returns to voltage measure-
ment.
Note!
☞
No matching resistors have been installed into the
instrument. It takes measurements with a high input
resistance of 5 MΩ.
Input resistance for voltage measurement is listed
under technical data. In order to perform correct
measurements at non-terminated devices under
test, a matching resistor must be connected to the
terminals. Observe power dissipation at the match-
ing resistor!
dB Ranges
For inherent deviations (details on errors and/or tolerances)
the values of the voltage measurement ranges apply (see
page 48), whereas these data are only valid as from 10%
of the respective measuring range.
Measuring Ranges
Display Range at
Reference Voltage, U
REF
= 0,775 V
Resolution
300mV
3V
30V
300V
1000V
– 48 dB ... – 8 dB
– 28 dB ... + 12dB
– 8 dB ... + 32 dB
+ 2 dB ... + 52 dB
+ 22 dB ... + 63 dB
0.01 dB
0.01 dB
0.01 dB
0.01 dB
0.01 dB
0.01 dB
V
1
V
2
20
V
2
V
1
------log⋅=
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