Table of Contents
Advertisement
15
Evaluating Your Measurement Results
Evaluating the Results
15-4
E5500 Phase Noise Measurement System Version A.02.00
The Reference Source
It is important that you know the noise and spur characteristics of
your reference source when you are making phase noise
measurements. (The noise measurement results provided when using
this technique reflect the sum of all contributing noise sources in the
system.)
The best way to determine the noise characteristics of the reference
source is to measure them. If three comparable sources are available,
the Three Source Comparison technique can be used to determine
the absolute noise level of each of the three sources. If you are using
as your reference source, a source for which published specifications
exist, compare your measurement results against the noise and spur
characteristics specified for that source.
If you have obtained an actual (measured) noise curve for the
reference source you are using, you can use it to determine if your
measurement results have been increased by the noise of the
reference source. To do this, determine the difference (in dB)
between the level of the results graph and that of the reference
source. Then use the graph shown in
measurement results need to be decreased to reflect the actual noise
level of the UUT.
Figure 15-2 Graph Showing How Much to Decrease Measured Noise to
Compensate for Added Reference Source Noise
For example, applying the 7 dB difference in noise levels, shown in
Figure 15-3
at 10 kHz, to the graph, reveals that the measured results
should be decreased by about 1 dB at 10 kHz to reflect the actual
noise of the UUT.
Figure 15-2
to determine if the
Document Part No. E5500-90024 Ed. 1.0
Advertisement
Table of Contents
