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The system's peak tuning range is derived from the tuning characteristics of
the VCO source you are using for the measurement.
relationship that typically exists between the VCO's peak-to-peak tuning range
and the tuning range of the system.
The system's drift tracking range is limited to a small portion of the peak
tuning range to minimize the possibility of measurement accuracy degradation
caused by non-linearity across the VCO's tuning range.
Peak tune range (PTR)
PTR is determined using two parameters:
• VCO tuning sensitivity (Hz/Volt)
• Total voltage tuning range (Volts)
PTR = (VCO Tuning Sensitivity) X (Total Voltage Tuning Range)
PTR = (100 Hz/V) X (10 V) = 1000 Hz
Figure 72 Capture and drift-tracking range with tuning range of VCO
As an Example:
A Peak Tuning Range of 1000 Hz provides the following ranges:
Capture Range = 0.05 X 1000 Hz = 50 Hz
Drift Tracking Range = 0.24 X 1000 Hz = 240 Hz
Tuning requirements
The peak tuning range required for your measurement depends on the
frequency stability of the two sources you are using. The signals from the two
sources are mixed in the system's phase detector to create a beatnote. In order
for the loop to acquire lock, the center frequencies of the sources must be close
Agilent E5505A User's Guide
Total peak-to-peak tuning range of VCO
Drift
tracking range
Capture
range
24%
5% 5%
VCO Source center frequency
Absolute Measurement Fundamentals
Figure 72
System
peak tuning range
24%
E5505a_capt_drift_trk_range
26 Feb 04 rev 1
5
illustrates the
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