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5-8
Chapter 5, FRONT PANEL OPERATION
5.2.04 Control Options Menu
Figure 5-5, Control Options Setup Menu
This menu, shown in figure 5-5, has three controls affecting the line frequency
rejection filter, AC Gain control and output time constants, as follows:-
Linefilt
This control sets the mode of operation of the internal line frequency rejection filter.
Early instruments have two possible settings for this control, ON or OFF. Note that in
these units the filter introduces significant gain and phase errors when measuring
signals in the frequency range from 5 Hz to 500 Hz.
Instruments manufactured after June 1996 which are fitted with the updated filter
hardware offer four possible settings for the control, as defined by the following
table:-
Legend Function
OFF Line filter inactive
F Enable 50 or 60 Hz notch filter
2F Enable 100 or 120 Hz notch filter
F&2F Enable both filters
AC Gain
As discussed in section 3.2.04, the correct adjustment of the AC Gain in a DSP lock-
in amplifier is necessary to achieve the best results. This control allows the user to
select whether this adjustment is carried out automatically or remains under manual
control.