Solartron Metrology AMETEK ORBIT ACS Series, Manual

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17 MEASUREMENT RESOLUTION, AVERAGING AND BANDWIDTH
The Orbit ACS has the ability to set the probes into three resolution options, 14 bit, 16 bit (default factory setting) and 18 bit. The table
below shows the best resolution (1 bit that is theoretically possible) with different probe measurement ranges.
It is important to consider the resolution that can be displayed (no of decimal places) and set the probe resolution accordingly. The SI
series can display up to 5 decimal places or 0.01um, so the probe resolution needs to be set to better than the displayed resolution
where possible. Equally, it is of little value trying to set the display to a resolution of 0.01um if the probe cannot achieve this.
Averaging improves the signal to noise ratio, but reduces the measurement bandwidth. Generally, using a higher resolution requires
more averaging. The averaging is expressed in terms of the number of base reading cycles for the probe where a reading cycle
corresponds to 256uS. The update rate of the Orbit ACS is 5mS (200Hz), an averaging of 16, corresponds to a bandwidth of
approximately 240Hz. The default factory setting is 16.
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Range mm 0.5 1 2 5 10 20
Resolution µm (18 bit) 0.00 0.00 0.01 0.02 0.04 0.08
Resolution µm (16 bit) 0.01 0.02 0.03 0.08 0.15 0.31
Resolution µm (14 bit) 0.03 0.06 0.12 0.31 0.61 1.22