General Operating Information 2
Keysight U2020 X-Series User’s Guide 61
U2020 X-Series Features
List mode
List mode is a mode of operation where a predefined sequence of measurement 
steps can be programmed into the power sensor and repeatedly executed as 
many times as required. This mode is suitable for power and frequency sweeps 
which normally require changing the parameters via the appropriate SCPI 
commands before performing a measurement. The hardware handshaking 
communication between the power sensor and the signal source provides the 
fastest possible execution time in performing the test sequences.
Trigger and gating parameters control which part of the waveform to be included 
or excluded from the measurement. The list mode helps to analyze modulated 
signals with regular and time-slotted or frame structure. For example, eight 
time-slotted GSM bursts, LTE-FDD and LTE-TDD frames and sub-frames, 
WCDMA frames and slots, and time-slotted measurements are supported in this 
mode. The desired number of slots and their duration and exclusion intervals can 
be easily programmed.
Variable aperture size
In average only mode and at normal measurement speed, the time interval length 
used to measure the average power of the signal can be adjusted by setting the 
aperture size to between 125 μs and 200 ms. This is useful for CW signals and 
noise-like modulated signals such as FDD-LTE and WCDMA by performing 
measurements over the full frames or sub-frames.
Decreasing the aperture size will improve the measurement throughput but 
reduce the signal-to-noise ratio of the measured signal. However, increasing the 
aperture size will improve the signal-to-noise ratio of the measured signal but 
reduce the measurement throughput.
Refer to the U2020 X-Series Programming Guide for more information.