Spurious Emissions Measurement Concepts - Keysight X Series Measurement Manual

Concepts
MSR 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.
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.
In the MSR, frequency range from 10 MHz below OB Start Freq to 10 MHz
above OB Stop Freq is excluded from the measurement frequency range even
when offset ranges include it unless Operating Band is None.Intermodulation
test is supported in this measurement. The intermodulation interference
frequency range specified by the parameters under the Intermod menu is
excluded from the measurement when interference power present is on.
Keysight N9083A & W9083A Measurement Guide 59