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Chapter 5, FRONT PANEL OPERATION
5-20
Note that the time per step defined here also applies to oscillator amplitude sweeps -
see section 5.3.11.
ARMED
When this control is set to YES, the frequency sweep is armed. The sweep can then
be started in one of two ways:
a) If the LINK TO CURVE BUFFER control is set to YES then the sweep will be started
at the same time as a curve buffer acquisition starts (see section 5.3.24). This
mode allows the buffer to be used for frequency response measurements, whereby
the response of an external network or system is measured by sweeping the
oscillator frequency while recording the lock-in amplifier's outputs, for example
magnitude and phase. Since the curve buffer can be started using internal or
external triggers there is considerable flexibility for designing experiments.
In this mode the START control is grayed out as it is inactive.
a) If the LINK TO CURVE BUFFER control is set to NO then the START control above
it is highlighted, to indicate that it is active. In this mode, the frequency sweep is
independent of the curve buffer and is operated by pressing the adjacent
key. The control annotation changes depending on whether a sweep is running, as
follows:
START
Pressing the adjacent
changes to PAUSE
STOP
Pressing the adjacent
When a sweep has been started and the ARMED control is not shown, the
following two options are also available.
PAUSE
Pressing the adjacent
frequency. The control changes to CONTINUE
CONTINUE
Pressing the adjacent
present frequency. The control changes to PAUSE
Note that if the oscillator amplitude sweep (see section 5.3.11) is also armed then the
controls that start, pause, continue and stop on the Frequency Sweep menu will also
control the amplitude sweep. Similarly, if the frequency sweep is linked to the curve
buffer then the amplitude sweep will be as well.
LAW
This control defines the relationship of output frequency to time for the frequency
sweep, and has two options:-
LOGARITHMIC
Selects a logarithmic relationship. When in this mode, the frequency is defined
in terms of a percentage of the current frequency. For example, if the step size
were set to 10%, the start frequency to 1 kHz and the stop frequency to 2 kHz,
then the frequencies generated during the sweep would be:-
key starts the frequency sweep. The ARMED control
key stops the frequency sweep.
key pauses the frequency sweep at the present
key restarts the paused frequency sweep from the
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