Dual Harmonic Output Filters Menu 2 - Ametek 7124 Instruction Manual

Precision lock-in amplifier
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ON
In this setting, the actual time constant used is chosen to be some multiple of the
reference frequency period, giving a much more stable output at low frequencies
than would otherwise be the case. Note that, depending on the reference
frequency, output time constants shorter than 100 ms cannot be used.
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 Output Filter Menu 2 key selects the Output Filter 2 Menu, while
pressing the Previous Menu key returns control to Main Menu 1.

5.6.05 Dual Harmonic Output Filters Menu 2

In dual harmonic mode, pressing the Output Filters Menu 2 key on Output Filters
Menu 1 accesses the Dual Harmonic Output Filters Menu 2, shown in figure 5-67.
The Dual Harmonic Output Filters Menu 2 has two controls affecting the
instrument's output low-pass filters, and a key to access the Output Filters Menu 1.
Changes to the setting of these controls can be made by using the adjacent
keys.
The controls operate as follows:-
TIME CONSTANT 2
This control, which duplicates the Main Display control of the same name, is used to
Chapter 5, FRONT PANEL OPERATION
Figure 5-67, Dual Harmonic Output Filters Menu 2
5-87

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