User's Manual

Page 144 SITRANS LR560 (PROFIBUS PA) – OPERATING INSTRUCTIONS 7ML19985LT01
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Glossary
dielectric constant (DK): the ability of a dielectric to store electrical potential energy under the
influence of an electric field. Also known as Relative Permittivity. An increase in the
dielectric constant is directly proportional to an increase in signal amplitude. The value is
usually given relative to a vacuum /dry air: the dielectric constant of air is 1
1
.
echo: a signal reflected with sufficient magnitude and delay to be perceived as a signal
distinct from the one directly transmitted. Echoes are frequently measured in decibels
relative to the directly transmitted signal.
Echo Confidence: describes the quality of an echo. Higher values represent higher quality.
Echo threshold defines the minimum value required for an echo to be accepted as valid
and evaluated.
Echo Lock Window: a window centered on an echo in order to locate and display the echo’s
position and true reading. Echoes outside the window are not immediately processed.
Echo Marker: a marker that points to the processed echo.
Echo Processing: the process by which the radar unit determines echoes.
Echo Strength: describes the strength of the selected echo in dB above 1 μV rms.
Echo Profile: a graphical display of a processed echo.
false echo: any echo which is not the echo from the desired target. Generally, false echoes are
created by vessel obstructions.
frequency: the number of periods occurring per unit time. Frequency may be stated in cycles
per second.
hertz (Hz): unit of frequency, one cycle per second. 1 Gigahertz (GHz) is equal to 10
9
Hz.
inductance: the property of an electric circuit by virtue of which a varying current induces an
electromotive force in that circuit or in a neighboring circuit. The unit is a Henry.
lens antenna: an antenna consisting of a radiator and microwave lens to enhance the antenna
gain.
microwaves: the term for the electromagnetic frequencies occupying the portion of the radio
frequency spectrum from 1 GHz to 300 GHz.
multiple echoes: secondary echoes that appear as double, triple, or quadruple echoes in the
distance from the target echo.
Near Blanking: see Blanking
nozzle: a length of pipe mounted onto a vessel, that supports the flange.
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.