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Document Part No. E5500-90024Ed. 1.0
Refer to
Table
15-3. The spur marking criterion is a detected upward
change of more than X dB (where X is the value shown below) within
4 data points (a single data point noise peak will not be marked as a
spur). Note that the effective noise floor for detecting spurs is above
the plotted 1 Hz bandwidth noise by the bandwidth correction factor.
Table 15-3 Spurs on the Graph
Offset Frequency
<
100 kHz
>
100 kHz
To List the Marked Spurs
A list of spurs can be displayed by accessing the Spurs List function
in the View menu.
Forest of Spurs
A so called forest of spurs is a group of closely spaced spurs on the
phase noise plot. A forest of spurs is often caused by improper
shielding that allows stray RF energy to be picked up by the
unit-under-test wiring, etc. A breadboarded or prototype circuit
should be well shielded from external RF fields when phase noise
measurements are being made.
Table 15-4
shows actions to take to eliminate spurs.
E5500 Phase Noise Measurement System Version A.02.00
Evaluating Your Measurement Results
Problem Solving
Number of
Upward Change
Averages
for Marking Spurs
(dB)
<
4
30
≥
4
17
≥
8
12
≥
30
6
Any
4
15
15-15
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