Spurious Emissions Measurement Concepts; Purpose; Measurement Method - Keysight X Series Measurement Manual

Concepts

Spurious Emissions Measurement Concepts

Spurious Emissions Measurement Concepts

Purpose

Spurious signals can be caused by different combinations of signals in the
transmitter. The spurious emissions from the transmitter should be minimized to
guarantee minimum interference with other frequency channels in the system.
Harmonics are distortion products caused by nonlinear behavior in the transmitter.
They are integer multiples of the transmitted signal carrier frequency.
This measurement verifies the frequency ranges of interest are free of interference by
measuring the spurious signals specified by the user defined range table.

Measurement method

The table-driven measurement has the flexibility to set up custom parameters such as
frequency, span, resolution bandwidth, and video bandwidth. Up to the top 40 spurs
can be viewed
For each range that you specify and activate, the analyzer scans the band using the
specified Range Table settings. Then using the Peak Excursion and Peak Threshold
values determines which spurs to report.
As each band is swept, any signal which is above the Peak Threshold value and has a
peak excursion of greater than the Peak Excursion value will be added to a list of
spurs displayed in the lower results window. A total of 200 spurs can be recorded for
one measurement, with a limit of 10 spurs per frequency range. To improve
repeatability, you can increase the number of averages.
From the spurs in the list, those with peak amplitude greater than the Absolute Limit
for that range will be logged as a measurement failure and denoted by an 'F' in the
'Amplitude' column of the table. If no spurs are reported, but the measured trace
exceeds the limit line for any range, the fail flag is set to fail.
This measurement has the ability to display two traces using different detectors on
the display simultaneously. All spur detection and limit line testing are only applied
to the trace associated with Detector 1, which will be colored yellow. The trace
associated with Detector 2 will be colored cyan.
If the sweep time for the range exceeds 2 seconds, a flashing message
"Sweeping...Please Wait" will appear in the annunciator area. This advises you that
the time to complete the sweep is between 2 and 2000 seconds, and is used as
without it the display would appear stagnant and you may think the measurement is
not functional.
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