b. The Department of the Army assigned responsibility for establishing
and maintaining the Army calibration system to the US Army Material
Development and Readiness Command (DARCOM).
The direction of the program
has been delegated through the Missile Materiel Readiness Command (MIRCOM)
to the Army Metrology and Calibration Center (AMCC), located at Redstone
Arsenal, Alabama. It is within this command structure that the who, where,
how, and why of the Army calibration system will be found.
2.
Calibration terms. Before proceeding further into this discussion, it
is desirable to pause and consider the terms that will be used in this and
succeeding lessons.
Familiarity with the following terms and definitions
will insure clarity and understanding of the discussion.
a. Metrology.
The science of measurement including development of
standards and systems for absolute and relative measurement.
b. Calibration. The comparison of an instrument with unverified values
(specifications) with an instrument, or measurement system, having known
values of greater accuracy to detect and correct any discrepancy in the
unverified values.
c. Measurement Standard.
An instrument, device, natural physical
constant, or materiel with known performance characteristics which is used
as a reference to establish the value and maintain accuracy of a measurement
system, instrument, or device.
Measurement standards are categorized as
follows:
(1) National Standard.
Measurement standards are maintained by the
National Bureau of Standards constituting the highest level of accuracy and
legal basis for measurement in the United Stated.
The Naval Observatory
maintains standards for time and time interval.
(2) Primary reference standards.
The source of the most accurate
measurements within the Army calibration system, the accuracy of which is
known and stated.
These standards are certified by, or directly derived
from, the National Bureau of Standards, are housed in an adequately
controlled environment, and normally maintained by the US Army Standards
Laboratory (USASL) at Redstone Arsenal, Alabama.
(3) Secondary Reference Standards.
Those standards with accuracy
certified as a result of comparison to primary standards. They are used to
certify the accuracy of subordinate standards and are housed in an
adequately controlled environment.
(4) Secondary transfer standards.
A set of measurement standards,
TMDE, and accessories which are used in a mobile or fixed facility
configuration by Area TMDE Support Teams (ATST). These are standards with
an accuracy certified as a result of comparison to secondary reference
standards.
They are used to certify the accuracy of test, measuring, and
diagnostic equipment.
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