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4
Expanding Your Measurement Experience
Status messages
This section describes the status messages that appear on the display as the
system performs its calibration routines.
Determining Presence of Beat Note...
beatnote is present within the system's detection range.
Verifying Zero-Beat...
within 5% of the estimated Peak Tuning Range of the system. The system's
Peak Tuning Range is the portion of the voltage-controlled-oscillator (VCO)
source's tuning range being used for the measurement.
When the system measures the phase noise of a signal source using the Phase
Lock Loop technique (the technique being used in this example) it requires
that one of the two sources used in the setup is a VCO. As you will see later in
this demonstration, you are required to estimate the tuning range of the VCO
source you are using when you set up your own Phase Lock Loop
measurements.
Zero beating sources...
adjusted, if necessary, to position the beatnote within the 5% range. The
adjustment is made with the tune voltage applied to the VCO source set at its
nominal or center position.
Measuring the VCO Tuning Constant... The tuning sensitivity (Hz/V) of the VCO
source is now precisely determined by measuring the beatnote frequency at
four tune voltage settings across the tuning range of the VCO source. Linearity
across the tuning range is also verified
Measuring the Phase Detector Constant... The transfer characteristics (V/rad)
of the test set's phase detector are now determined for the specific center
frequency and power level of the sources being measured.
Measuring PLL suppression... The required correction data is created to
compensate for the phase noise suppression which occurs within the
bandwidth of the phase lock loop created for this measurement. The computer
displays the PLL suppression curve and associated measurement values.
74
An initial check is made to verify that a
The frequency of the beatnote is measured to see if it is
The center frequencies of the sources are now
Agilent E5505A User's Guide
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