User's Manual

7ML19985KB01 SITRANS LR560 (mA/HART) – INSTRUCTION MANUAL Page 143
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Glossary
parameters: in programming, variables that are given constant values for specific purposes or
processes.
polarization: the property of a radiated electromagnetic wave describing the time-varying
direction and amplitude of the electric field vector.
polarization error: the error arising from the transmission or reception of an electromagnetic
wave having a polarization other than that intended for the system.
propagation factor (pf): where the maximum velocity is 1.0, pf is a value that represents a
reduction in propagation velocity as a result of the wave travelling through a pipe or
medium.
pulse radar: a radar type that directly measures distance using short microwave pulses.
Distance is determined by the return transit time.
radar: radar is an acronym for RAdio Detection And Ranging. A device that radiates
electromagnetic waves and utilizes the reflection of such waves from distant objects to
determine their existence or position.
range: distance between a transmitter and a target.
range extension: the distance below the zero percent or empty point in a vessel.
relative humidity: the ratio of the actual amount of moisture in the atmosphere to the maximum
amount of moisture the atmosphere could hold (which varies depending on the air
temperature).
relative permittivity: see dielectric constant.
repeatability: the closeness of agreement among repeated measurements of the same
variable under the same conditions.
shot: one transmit pulse or measurement.
speed of light: the speed of electromagnetic waves (including microwave and light) in free
space. Light speed is a constant 299, 792, 458 meters per second.
stillpipe: a pipe that is mounted inside a vessel, parallel to the vessel wall, and open to the
vessel at the bottom.
stilling-well: see stillpipe.
two wire radar: a low-energy radar. Can be loop powered, analog, intrinsically safe 4 to 20 mA,
or a digital (BUS) transmitter.
TVT (time varying threshold): a time-varying curve that determines the threshold level above
which echoes are determined to be valid.
waveguide antenna: a hollow, metallic tube that transmits a microwave signal to the product
target.