Keysight Technologies N5511A User Manual page 114

Absolute Measurement Examples
Single Channel Measurement
New Measurement
Close Define Window. From the File Menu: Measure, New Measurement.
When the "Do you want to perform a New Calibration and Measurement?"
prompt appears, click Yes.
Checking the Beat Note
While the connect diagram is still displayed, use an oscilloscope (connected to
the Monitor port on the test set) or a counter to check the beat note being
created between the reference source and your DUT.
Figure 6-8 Oscilloscope displaying monitor output of phase detector
The objective of checking the beat note is to ensure that the center frequencies
of the two sources are close enough in frequency to create a beat note that is
within the capture range of the system. The phase lock loop (PLL) capture
range is 5% of the peak tuning range of the VCO source you are using. (The
114 N5511A Phase Noise Test System User's Guide