Table of Contents
Advertisement
MTTF (Mean Time to Fail)
The time interval in operating hours that can be expected until the first failure of
equipment. MTF can be calculated from direct observation or mathematically derived
through extrapolation.
MTTR (Mean Time to Repair)
The average time in hours required to repair failed equipment.
minimum use specifications
A compilation of specifications that satisfies the calibration requirements of a
measurement system or device. The minimum use specifications are usually determined
by maintaining a specified test uncertainty ratio between the calibration equipment and
the unit under test.
noise
A signal containing no useful information that is superimposed on a desired or expected
signal.
normal mode noise
An undesired signal that appears between the terminals of a device.
offset error
Same as zero error. The reading shown on a meter when an input value of zero is applied
is its offset or zero error.
precision
The degree of agreement among independent measurements of a quantity under the same
conditions. (Same as "repeatability.")
The precision of a measurement process is the coherence, or the closeness to the one
result, of all measurement results. High precision, for example would result in a tight
pattern of arrow hits on a target, without respect to where on the target the tight pattern
falls.
predictability
A measure of how accurately the output value of a device can be assumed after a known
time following calibration. If a device is highly stable, it is also predictable. If a device is
not highly stable, but its value changes at the same rate every time after calibration, its
output has a higher degree of predictability than a device that exhibits random change.
primary standard
A standard defined and maintained by some authority and used to calibrate all other
secondary standards.
process metrology
Tracking the accuracy drift of calibration and other equipment by applying statistical
analysis to correction factors obtained during calibration.
C
Appendices
Glossary
C-5
Advertisement
Table of Contents
