Agilent Technologies E5500 Phase Noise Measurement System
7-43
Absolute Measurement Examples
Free-Running RF Oscillator
Figure 7-9
Oscilloscope Display of a Beatnote out of the Agilent/HP 70420A
Monitor Port
1. Estimate the system’s capture range (using the VCO source parameters
entered for this measurement). The estimated VCO tuning constant must
be accurate within a factor of 2. A procedure for Estimating the Tuning
Constant is located in this chapter.
NOTE
If you are able to locate the beatnote, but it distorts and then disappears as
you adjust it towards 0 Hz, your sources are injection locking to each other.
Set the beatnote to the lowest frequency possible before injection locking
occurs and then refer to Minimizing Injection Locking in the Problem
Solving section of this chapter for recommended actions.
NOTE
If you are not able to tune the beatnote to within the capture range due to
frequency drift, refer to Tracking Frequency Drift in the Problem Solving
section of this chapter for information about measuring drifting signals.