User`s guide

Making Measurements 4
N9340A User’s Guide 71
Making an Average Power Measurement
Average power measurements provide a key metric
in transmitter performance.
Base station transmit power must be set accurately
to achieve optimal coverage in wireless networks. If
the transmit power is set too high due to
inaccurate power measurements, undesired
interference can occur. If the transmit power is set
too low, coverage gaps or holes may occur. Either
case may affect system capacity and may translate
into decreased revenue for service providers.
Average power can be measured for the channel of
interest while the base station is active. All other
channels should be inactive. Average power is a
broadband measurement. If other signals (channels)
are present the analyzer will also measure their
power contributions.
The analyzer supports the U2000 Series USB power
sensors.
The U2000 Series USB power sensors do not need
manual calibration and zero routines performed.
Calibration and zeroing are performed without
removing the power sensor from the source,
through internal zeroing. With internal zeroing of
the U2000 Series USB power sensors, there is no
need to disconnect the sensor or power- off the
DUT. The U2000 Series do not require 50 MHz
reference signal calibration, allowing the factory
calibration to ensure measurement accuracy. For
best accuracy, users are recommended to perform
external zeroing for input signals below - 30 dBm.
CAU-CAUTION
The maximum power for the RF In port and the RF
Out/SWR port of the analyzer is +20 dBm (100 mW). The
maximum power for the Power Sensor port is +24 dBm
(300 mW). When directly coupled to a base station, the
analyzer can be damaged by excessive power applied to
any of these three ports.
To prevent damage, when directly coupling an analyzer to
a base station, use a high power attenuator between the
analyzer and the BTS.