Rosemount Tank Radar Ab

Lars Ove Larsson

Mikael Kleman

Olov Edvardsson

Håkan Delin

Anders Jirskog

Urban Blomberg

Lennart Hägg

Jan Westerling

Mikael Eriksson

Christer Frövik

Marianne Öder

Katarina Vilhelmsson

Per Holmberg

Kenneth Adolfsson

Christer Joshua FRÖVIK

A radar level gauge comprising transceiver circuitry configured to obtain a tank signal including a peak representing a surface echo, and at least one peak caused by a ghost echo in a neighborhood of the surface echo. The gauge further includes a tank signal filter receiving the tank signal as input and providing an echo threshold profile, the threshold profile having at least one local maximum substantially coinciding with one of the peaks in the tank signal, and processing circuitry configured to use the echo threshold profile to disregard peaks in the tank signal which are associated with ghost reflections. The filtering of the tank signal thus provides an adaptive threshold, which is aligned with the peak(s) in the tank signal. By using this threshold in the surface echo identification, at least some ghost echoes occurring in the tank signal may be disregarded.

Adaptive echo threshold

A radar level gauge for determining a process variable of product in a tank, having processing circuitry configured to process a tank signal and, when no surface echo can be identified, enter a wait state. The wait state includes a) storing the tank signal in memory, b) obtaining a wait state tank signal, c) comparing the wait state tank signal with the stored tank signal to determine a tank signal difference measure, d) repeating steps b) and c) until the tank signal difference measure is greater than a predefined threshold, e) processing the wait state tank signal to identify a surface echo, and f) when no surface echo can be identified in the wait state tank signal, setting an alarm. By storing the tank signal when the wait state is entered, it is therefore possible to defer an alarm until the tank signal deviates from this stored tank signal.

Radar level gauging with wait state

A method for providing narrow-band interference unaffected measurement of a distance to a surface of a product kept in a tank, comprising mixing a return signal with a transmit signal to provide an intermediate frequency signal, and determining the distance, based on the intermediate frequency signal. The step of determining the distance further comprises dividing the intermediate frequency signal into a plurality of frequency portions, wherein each frequency portion corresponds to a frequency interval of the transmit signal, identifying disturbed frequency portions as frequency portions affected by narrow-band interference, and determining the distance based on frequency portions being unaffected by narrow-band interference. By dividing the IF-signal into frequency portions corresponding to frequency intervals of the transmit signal, frequency intervals where narrow-band interferences are present may be detected.

Radar level gauge with signal division

A radar level gauge system comprising a single conductor probe extending through a tubular mounting structure towards and into the product in the tank, a shielding structure radially spaced apart from the single conductor probe and extending along a top portion of the probe inside the mounting structure and past the lower end of the mounting structure, and processing circuitry connected to the transceiver for determining the filling level of the product in the tank. The shielding structure at least partly encloses the top portion of the single conductor probe, and is open in a radial direction to allow entry of the product. The shielding structure exhibits a total enclosing arc angle around the single conductor probe greater than 180&#xb0; inside the tubular mounting structure, and a total enclosing arc angle around the single conductor probe that decreases with increasing distance from the lower end of the mounting structure.

Single conductor probe radar level gauge system and tank arrangement

The present invention relates to a radar level gauge system comprising a signal propagation device; a microwave signal source; a microwave signal source controller; a mixer configured to combine a transmit signal from the microwave signal source and a reflection signal from the surface to form an intermediate frequency signal; and processing circuitry coupled to the mixer and configured to determine the filling level based on the intermediate frequency signal. The microwave signal source is configured to exhibit a phase noise greater than or equal to &#x2212;70 dBc/Hz @ 100 kHz offset from a carrier frequency for the transmit signal.

Low power radar level gauge system with integrated microwave circuit

The present invention relates to a radar level gauge system comprising a signal propagation device; a microwave signal source; a microwave signal source controller; a mixer configured to combine a transmit signal from the microwave signal source and a reflection signal from the surface to form an intermediate frequency signal; and processing circuitry coupled to the mixer and configured to determine the filling level based on the intermediate frequency signal.

Low power radar level gauge system

A method and a system for processing a reflected microwave signal generated by a radar level gauge system arranged to transmit microwaves towards the material in the tank, and receive a reflection of said microwave signal as a tank signal. The tank signal is processes by a plurality of processes, each process being adapted to determine a process variable in a specific region of the tank, each specific region corresponding to a predefined propagation distance range. Such multi-processing of the received tank signal has the advantage that each process can be optimized to that particular region of the tank. More specifically, a process concerned with a particular region of tank only needs to treat a portion of the tank signal.

Processing of tank signal in radar level gauge system

A method and system for determining a product level in a tank which determine a first level measure using emission of electromagnetic waves into the tank, detect a differential pressure, determine an observed density based on the detected differential pressure and the first level measure, and determine a second level measure based on the observed density and a currently measured differential pressure. The present invention is based on the realization that a level measurement based on differential pressure and an observed density can provide a valuable redundant level measurement, which can provide increased reliability and enable detection of errors.

Redundant level measurement in radar level gauging system

A tank gauging system for sensing product parameters of a product contained in a tank is disclosed. The system comprises a microwave-based level gauging unit and a temperature gauging unit. A controller of the system includes an external interface adapted to enable communication between the tank gauging system and an external control system; processing circuitry configured for management of communication over the external interface; and a power supply, which is enclosed in an explosion-proof housing and configured to supply intrinsically safe power to the gauging units, wherein the power supply has an essentially rectangular output characteristic. Further, an intrinsically safe two-wire bus connecting the controller and the gauging units is provided, wherein the two-wire bus is usable both for transmitting measurement signals related to the sensed product parameters from the gauging units to the controller and for providing intrinsically safe power from the controller to the gauging units.

Growing community of inventors

Linkoping, Sweden

Lars Ove Larsson