China Electronics Technology Instruments AV3672 Series, User Manual

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8 Basis of Network Measurement
8.6 Absolute Output Power
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Fig. 8.16 Connection in Group Delay Measurement
3) Select the S21 measurement mode.
4) Select the settings corresponding to the DUT, including:
a) Format: phase.
b) Scale: automatic scale.
c) Number of measurement points: select the appropriate number to avoid insufficient sampling.
5) Remove and calibrate the DUT.
6) Reconnect the DUT.
7) Set the group delay display format and the scale of measurement display to realize the best observation effect.
8) Increase the aperture and reduce the noise on the trace by the smoothing function of the analyzer. At the same
time, keep meaningful details. Take the following steps to increase the aperture:
a) Enable the smoothing function of the analyzer.
b) Change the smoothing aperture (max. 25% of the frequency span).
9) Read the group delay of the relevant frequency through the marker.
10) Print or save the data.
8.6 Absolute Output Power
The absolute output power is the relationship between the displayed absolute power (dBm or W) and frequency.
8.6.1 What is the absolute output power?
The absolute output power is the power of the reception port of the analyzer. This is the absolute power, not based
on the incident power or source power (or the ratio). The value indicated on the longitudinal axis of the grid is in
dBm in the logarithm amplitude format. It is the power tested based on 1mW.
0dBm=1mW
-10dBm=0.1mW
+10dBm=10mW
The value indicated on the vertical axis of the grid in the logarithm amplitude format is in W.
8.6.2 Why to measure the absolute output power?
If the absolute power instead of the relative power must be used as the amplifier output, the absolute output power
must be measured. In gain compression measurement, the absolution output power of the amplifier should be
measured based on 1dB compression. In order to improve the measurement accuracy, considerations must be given
to the following factors:
1) If necessary, fully attenuate the output power of the amplifier. Too high power may lead to the following results:
a) The output power is higher than the input compression level of the receiver of the analyzer, which may lead to