User`s guide

Table Of Contents
Absolute Measurement Examples
6
Agilent E5505A User’s Guide 155
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.
Making the measurement
1
Click the Continue button when you have completed the beatnote check
and are ready to make the measurement.
2
When the PLL Suppression Curve dialog box appears, select View
Measured Loop Suppression, View Smoothed Loop Suppression, and
View Adjusted Loop Suppression. See Figure 106 on page 156.
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.