Fluke 5790A Service Manual page 326

5790A
Service Manual
Flatness
A measure of output level variation for an voltage source as frequency is varied. Flatness
limits are normally specified as a ratio (%) to nominal output level at a reference
frequency.
Floor Error
A contribution to measurement or source uncertainty that is independent of reading or
output setting. In uncertainty specifications, floor error is often combined with fixed
range errors and expressed in units such as microvolts or counts of the least significant
digit. Also see "error".
Full Scale
The upper limit of measurement or source value for which a given uncertainty
specification applies, including any "overrange". Also see "overrange" and "range".
Gain Error
Same as scale error. An example of scale or gain error is, when the slope of a calibrator's
displayed output vs. its true output is not extly 1. A calibrator with only gain error (no
offset or linearity error), will read 0 V with 0 V on the display, but something other than
10 V with 10 V on the display.
Ground
The voltage reference point in a circuit. Earth ground is a connection through a ground
rod or other conductor to the earth, usually cessible through the ground conductor in an
power receptle.
Ground Loop
Undesirable current induced when there is more than one chassis ground potential in a
system of instruments. Ground Loops can be minimized by connecting all instruments in
a system to ground at one point.
Guard
A floating shield around sensitive circuitry inside an instrument. The guard provides a
low-impedance path to ground for common-mode noise and ground currents, thereby
eliminating errors introduced by such interference.
International System of Units
Same as "SI System of Units"; the cepted system of units. See also "units", "base units",
and "derived units".
Legal Units
The highest echelon in a system of units, for example the 1990 SI volt.
Life-Cycle Cost
The consideration of all elements contributing to the cost of an instrument throughout its
useful life. This includes initial purchase cost, service and maintenance cost, and the cost
of support equipment.
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