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Document Part No. E5500-90024Ed. 1.0
4
Press [[REL MKR]], and MKR REF.
5
Press the [[DEFINE TRACE]] press the [[and the MATH
FUNCTION keys.
6
Using the --> key on the RF analyzer, offset the marker by the PLL
bandwidth. Read the offset frequency and noise level indicated at
the bottom of the display. (If the noise level falls below the
bottom of the display, the marker reading will still be correct. To
increase the vertical scale, press [[VERT SCALE]] press [[,
DEFINE DB/DIV, and enter 20 dB.)
7
Compare the average noise level at the PLL bandwidth offset to
the small angle criterion level shown on the graph in
The average noise level of the signal must remain below the small
angle line at all offset frequencies beyond the PLL bandwidth.
(The small angle line applies only to the level of the average noise.
Spur levels that exceed the small angle line will not degrade
measurement accuracy provided they do not exceed -40 dBc.)
Figure 6-12 Graph of Small Angle Line and Spur Limit
8
Continue moving the marker to the right to verify that the
average noise level remains below the small angle line.
9
Increase the span by a factor of ten by selecting FREQ and
DEFINE SPAN. Continue comparing the noise level to the graph.
10 Continue to increase the span width and compare the noise level
out to 100 kHz. (If the noise level exceeds the small angle line at
any offset frequency beyond the PLL bandwidth, note the offset
E5500 Phase Noise Measurement System Version A.02.00
Absolute Measurement Fundamentals
Evaluating Noise Above the Small Angle Line
6
Figure
6-12.
6-23
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