Soft dB SPM PLL User Guide - Manual (Page 17)

SPM - PLL User’s Manual 17
phase of board’s digital and analog chains. For
this signal the Signal control can be used to
present the absolute value or the shift value.
The reference value in the Operation Set-up tab
is used to compute the shift value.
Resonator Amplitude (filtered) Filtered resonator output amplitude (in V). The
low pass filter is applied to lower the noise on
this signal. For this signal the Signal control can
be used to present the absolute value or the
shift value. The reference value in the
Operation Set-up tab is used to compute the
shift value.
Excitation Amplitude (filtered)
Filtered excitation amplitude (in V). The low
pass filter is applied to lower the noise on this
signal. For this signal the Signal control can be
used to present the absolute value or the shift
value. The reference value in the Operation
Set-up controls is used to compute the shift
value.
Output #2, #3, #4 and #5 These selections represent the 16-bit signal
generated by the DSP on outputs #2, #3, #4
and #5. The output signals are selected with the
Mux menu of the Operation Set-up controls.
The user can select between the excitation
frequency, the resonator phase, the resonator
amplitude and the excitation amplitude. An
adjustable reference value is subtracted from
these signals to present the shift value. The
sensitivity of the output signal can be adjusted
with a range control. Also, an adjustable low
pass filter is used to lower the noise on all
signals.
4.10 Signal History
The signal history for both the excitation frequency shift and the resonator shift are presented on the
Signal History tab. The history length is adjustable and the user can clear the history graphs with the
Clear History control. These graphs are useful to analyze the long-term stability of the PLL and to
estimate the noise.