Kaman DIT-5200L - Manual (Page 18)

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Kaman Precision Products PART NO: 860522-001
www.kamansensors.com Last Revised 11/16/2012
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APPENDIX C TERMINOLOGY
Null Gap
The point at which a target is equidistant from each sensor of a differential pair. The system
output at null = 0VDC. The actual gap is measured from the sensor face to the corresponding
target face and includes a required offset (null gap = offset plus maximum measuring range).
Offset
The minimum distance between the sensor face and the target. Offset is necessary to both
prevent the target from striking the sensor face and to optimize performance (offset = null gap
minus max range).
Measuring Range
The full range of target motion over which the various specifications such as resolution, linearity,
and sensitivity can be met. The differential sensor arrangement yields a bipolar output and
measuring range is expressed as + and – value either side of the null position (measuring range =
null gap minus the offset).
Sensitivity (scale/gage factor)
Output voltage per unit of displacement. Usually expressed as millivolts per mil (0.001”) or per
millimeter.
Linearity (or non-linearity)
The maximum deviation of any point of a calibrated system’s output from a best fit straight line.
Expressed in actual units, e.g., micro-inches or as a percentage of the full range (the full scale
output times 2).
Equivalent RMS Input Noise
A figure of merit used to quantify the noise contributed by a system component. It incorporates
into a single value, several factors that influence a noise specification such as signal-to-noise
ratio, noise floor, and system bandwidth. Given a measuring systems sensitivity/scale factor and
the level of “white” noise in the system, Equivalent RMS Input Noise can be expressed using
actual measurement units.
Effective Resolution
An application dependent value determined by multiplying the Equivalent RMS Input Noise
specification by the square root of the measurement bandwidth.
Example: an application with a 100 Hz bandwidth using a DIT-5200 with an Equivalent RMS Input
Noise level of 0.2nm/
Hz results in a system with an effective resolution of 0.2nm/ Hz x 100 Hz
or 2nm .