N.2.2. Measure Peak
The Measure Peak Range is determined by the position of the outer cursors. These cursors are
moved by dragging them with the mouse and should be positioned around the resonance peak
to be measured. Pressing Measure Peak will being the resonance peak measure. After the
Measure Peak is completed, the frequency at which the LIA Amplitude is at its maximum will be
marked with the middle cursor. The Frequency and Amplitude that was automatically marked
will be used to calculate the Signal/Drive Ratio, Q Factor of the cantilever, and 3dB width of the
peak.
N.2.3. Set Frequency
The middle cursor will automatically be positioned at the frequency at which the LIA Amplitude
was at its maximum value. The middle cursor can be moved with the mouse if a different
modulation frequency is desired. Pressing Set Frequency will have a different behavior if the
Drive Output is the Reference for a LIA or a PLL. When a LIA is used, Set Frequency sets the
Frequency and Drive Amplitude of the Drive Output. When a PLL is used, Set Frequency sets
the Center Frequency and Drive Amplitude of the Drive Output, sets the Phase Offset of the
PLL to prevent phase wrapping, and sets the Integral Cutoff Frequency of the PLL feedback
loops, and sets the initial Amplitude at which the PLL will try to maintain if the Constant Signal
mode is enabled.
N.2.4. Unwrap Phase
The Set Frequency procedure will correct for a phase wrap automatically but the Frequency
Sweep will still display the phase wrap. The Unwrap Phase procedure can be used to
automatically adjust the PLL Phase Offset and do another Measure Peak. The Set Frequency
button needs to be pressed after using the Phase Unwrap procedure.
Figure N.4. Unwrap Phase Procedure in Frequency Sweep
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