US 5,672,975 AGranted

Two-wire level transmitter

AssigneeRosemount Inc.

InventorsJohn A. Kielb, Richard L. Nelson, Scott D. Manicor

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Abstract

A level transmitter for use in a process application measures height of a product in a tank. The level transmitter includes a microwave antenna directed into the tank. A low power microwave source sends a microwave signal through the microwave antenna. A low power microwave receiver receives a reflected microwave signal. Measurement circuitry coupled to the source and receiver initiates transmitting of the microwave signal and determines product height based upon the received, reflected signal. Output circuitry coupled to a two-wire process control loop transmits information related to product height over the loop. Power supply circuitry in the level transmitter coupled to the two-wire process control loop receives power from the loop which powers the level transmitter including the microwave source and the microwave receiver.

Claims15

Dependent claims

A level transmitter using microwaves coupleable to a two-wire process control loop for measuring height of a product in a tank, comprising:

a microwave antenna directable into the tank;
a low power microwave source for sending a microwave signal through the microwave antenna into the tank;
a low power microwave receiver for receiving a reflected microwave signal from the tank;
measurement circuitry coupled to the source and receiver for initiating transmission of the microwave signal and determining product height based upon the received signal;
output circuitry coupled to the two-wire process control loop for transmitting information related to product height over the loop;
power supply circuitry coupled to the two-wire process control loop for receiving power from the loop to provide the sole source of power for the low power microwave source, the low power microwave receiver, measurement circuitry, and output circuitry in the level transmitter.

3 more elements

Dependencies are inferred from the claim text.