Table of Contents
Advertisement
Problem Solving
Discontinuity in the
Graph
Table 15-2 Potential Causes of Discontinuity in the Graph
Circumstance
Break between segments where
closely spaced spurs are resolved in
one segment but not in the next.
Erratic Noise: One or more segments
out of line with the rest of the graph.
Document Part No. E5500-90024Ed. 1.0
Table 15-1
If you need to know:
What to do about breaks in the noise graph
How to verify a noise level that is higher than
expected
How to verify unexpected spurs on the graph
How to interpret noise above the small angle line
Because noise distribution is continuous, a break in the graph is
evidence of a measurement problem. Discontinuity in the graph will
normally appear at the sweep-segment connections.
Table 15-2
identifies the circumstances that can cause discontinuity
in the graph.
Description
Closely spaced spurs that are
resolved in one sweep-segment but
not in the next can cause an
apparent jump in the noise where
they are not resolved.
This occurs when the noise level of
the source being used is
inconsistent over time. The
time-varying noise level causes the
overall noise present when one
segment is being measured to differ
from the level present during the
period when the next segment is
measured.
E5500 Phase Noise Measurement System Version A.02.00
Evaluating Your Measurement Results
Problem Solving
Refer to:
Discontinuity in the Graph
High Noise Level
Spurs on the Graph
Small Angle Line
Recommended Action
Use the Real-time Monitor to
evaluate the noise spectrum at the
break frequency on the graph. To
eliminate the break in the graph, you
may find it necessary to change the
Sweep-Segment Ranges so that the
measurement resolution remains
constant over the frequency range
where the spurs are located.
Repeat the noise measurement
several times for the segment that
does not match the rest of the
graph, and check for a change in its
overall noise level.
15
15-13
Advertisement
Table of Contents
