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Chapter 3, TECHNICAL DESCRIPTION
3.3.30 Main Microprocessor - User Settings
3.4 General
3.4.01 Accuracy
3.4.02 Power-up Defaults
3-18
reference frequency. An auto-sensitivity operation is then performed, followed by an
auto-phase.
The Auto-Measure function is intended to give a quick setting of the instrument
which will be approximately correct in typical simple measurement situations. For
optimum results in any given situation, it may be convenient to start with Auto-
Measure and to make subsequent modifications to individual controls.
NOTE: The Auto-Measure function affects the setting of the AC Gain and AC
Gain Automatic controls during execution. Consequently, it may not operate
correctly if the AC Gain Automatic control is turned off. In this case, better results
will be obtained by performing Auto-Sensitivity followed by Auto-Phase functions.
Auto-Default
With an instrument of the design of the model 7124, where there are many controls
of which only a few are regularly adjusted, it is very easy to overlook the setting of
one of them. Consequently an Auto-Default function is provided, which sets all the
controls to a defined state. This is most often used as a rescue operation to bring the
instrument into a known condition when it is giving unexpected results. A listing of
the settings which are invoked by the use of this function can be found in
appendix D.
The non-volatile memory associated with the main microprocessor is used to store up
to eight complete instrument settings, which may be recalled or changed as required.
This makes it much easier for an instrument to be quickly configured for different
experiments.
This completes the description of the main functional blocks of the instrument.
When the demodulator is operating under correct conditions, the absolute gain
accuracy of the instrument is limited by the analog components in the signal channel,
and the absolute phase accuracy is limited by the analog components in both the
signal channel and the reference channel. The resulting typical accuracy is ±1.0
percent of the full-scale sensitivity and ±0.5 degree respectively.
All instrument settings are retained when the unit is switched off. When the
instrument is switched on again the settings are restored but with the following
exceptions:-
a) The REMOTE parameter is set to zero (front-panel control enabled).
b) The curve buffer is cleared.
c) Any sweep that was in progress at switch-off is terminated.
d) The display is turned on.
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