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Chapter 5, FRONT PANEL OPERATION
5.3.07 Output Offset & Expand Menu
5-14
the Fast time constant mode) than would otherwise be the case. In this setting,
the actual time constant will not change if the reference changes. Note that,
depending on the reference frequency, output time constants shorter than 100 ms
cannot be used.
AUTO
This is the same as the ON setting except that if the reference changes the time
constant will be recalculate to the nearest legal synchronous setting.
TIME CONSTANT MODE
This control has two settings, as follows:-
NORMAL
In this setting, the analog outputs are derived from the output processor. The
update rate is always 1 kHz, the output filter time constant can be set to values
between 5 ms and 100 ks in a 1-2-5 sequence, and all four output filter slope
settings are available.
FAST
In this setting, the analog outputs are derived directly from the core FPGA
running the demodulator algorithms. The update rate is increased to 1.0 MHz
when the time constant is set to any value from 10 µs to 500 ms but remains at
1 kHz for longer time constants. The output filter slope is restricted to either 6 or
12 dB/octave.
Pressing the Previous Menu key returns control to Main Menu 1.
When Main Menu 1 is displayed, pressing a key adjacent to the Offset & Expand
item accesses the Offset & Expand menu, which is shown in figure 5-10.
Figure 5-10, Output Offset & Expand Menu
The Offset & Expand menu has five controls affecting the instrument's X channel
and Y channel outputs. Changes to the setting of these controls can be made by using
the adjacent
keys, with the currently active selection being highlighted.
X OFFSET and Y OFFSET
These controls, which duplicate the Main Display X OFFSET and Y OFFSET controls,
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