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Changing the Time-Domain Format
MultiView gives you three options for setting the time-domain format for traces, as shown below.
•
g-Force
Displays acceleration values from -2 g to +2 g. One g is the acceleration of gravity (approximately 32 ft/s
2
or 9.81
m/s
2
). With this vertical scale setting, when the AMS is sitting motionless and horizontal, the Z trace will show 1 g,
the X and Y traces will show 0 g, and the RMS trace will show 0.58 g. This is because the AMS senses the
acceleration of the earth’s gravitational field, which is 1 g in the vertical (Z) direction. You can also choose to
display the absolute value of acceleration in g-Force. Using the absolute value can be helpful when comparing
traces. When displaying absolute value, you will usually want to also use the high-pass filter (see
on page
•
Gal
Displays values in galileo units, where 1 g = 981 Gal. With this vertical scale setting, when the AMS is sitting
motionless and horizontal, the Z trace will show 981 Gal, the X and Y traces will show 0 Gal, and the RMS trace will
show 566 Gal. This is because the wafer senses the acceleration of the earth’s gravitational field, whi
ch is 981 Gal
in the vertical (Z) direction. You can also choose to display the absolute value of acceleration in Gals. Using the
absolute value can be helpful when comparing traces. When displaying absolute value, you will usually want to
also use the high-pass filter (see
on page
).
•
Energy
Displays the signal energy for the last specified number (
n)
of acceleration values. Signal energy is calculated using
the following formula.
1
N
n
∑
x
2
(k)
k =1
Where:
N
is the sample rate (1 KHz for the AMS).
n
is the number of samples, which is the sample size you have set for the frequency spectrum (see
Displaying the Frequency Spectrum
on page
x(k) is the kth sample of the acceleration in g-force. Using the energy format with appropriate
Go/No-Go tolerances can identify vibrations that
don’t have large amplitudes (and might not trip
the
Go/No-Go tolerances for g-force or Gals), but extend for longer periods of time.
Values that are too large to display are truncated.
Changing the time domain format can dramatically affect the range of values in the data, which affects the trigger
and Go/No-Go values, so when you change time domain format settings, MultiView automatically disables all
trigger and Go/No-Go tolerances. If you change the time-domain format, yo
u’ll need to adjust and re
-enable any
triggers or Go/No-Go tolerances. For more information, see
on page
Traces for Excessive Vibration Levels
on page
