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Operating Information
2–24
AM700 Audio Measurement Set Service Manual
Figure 2–19: Configure system setup communicate menu
The Calibrate menu provides a soft key to start calibration. Calibration of the
analog acquisition system is done after touching the Calibrate Now soft key.
Offset changes that occur with temperature will be removed. If operating the
AM700 in conditions that permit large ambient temperature changes, a calibra-
tion of the analog system improves the accuracy of the measurements. If ambient
temperatures are stable, a calibration done infrequently is adequate to compen-
sate for component aging. A calibration should be done at the ambient operating
temperature to produce the best accuracy.
When Audio Analyzer, FFT Analyzer, or Monitor is the running application,
calibration switches the analog acquisition system to a known test signal (a
120 Hz symmetrical square wave) to acquire the positive and negative peak
values seen at the output of the A and B high resolution A/D converters and at
the output of the A and B high bandwidth A/D converters. The values obtained
are used to determine the DC offset of the acquisition system at the time of
calibration and the calibration factor needed to remove the offset from the
converted data values. The calibration constants obtained are stored and used
until a subsequent calibration is done.
If the Digital Interface Tester application is running when calibration is
performed, the digital acquisition system offset is calculated and the calibration
factor obtained is used to remove the offset from the peak-to-peak jitter
measurements.
System Calibration Menu