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Reference Manual
00809-0100-4811, Rev DA
Section 2: Transmitter Overview
January 2015
Transmitter Overview
Section 2 Transmitter Overview
Theory of operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Application examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
System architecture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Process characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Vessel characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Components of the transmitter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Probe selection guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
2.1 Theory of operation
The Rosemount 3300 Series Radar Transmitter is a smart, two-wire continuous level transmitter
that is based on Time Domain Reflectometry (TDR) principles. Low power nano-second-pulses
are guided along a probe immersed in the process media. When a pulse reaches the surface of
the material it is measuring, part of the energy is reflected back to the transmitter, and the time
difference between the generated and reflected pulse is converted into a distance from which
the total level or interface level is calculated (see below).
The reflectivity of the product is a key parameter for measurement performance. A high
dielectric constant of the media gives better reflection and a longer measuring range. A calm
surface gives better reflection than a turbulent surface.
Figure 2-1. Measurement Principle
Time
Reference pulse
Level
Interface level
Signal amplitude
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