Pulsed Radar Level Gauge Dual Integrator Startup

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Solution Overview

Problem

Current pulsed radar level gauge systems require a substantial power-up time due to slow step response from high-pass filtering, limiting energy-efficient intermittent operation and accurate filling level determination.

Innovation Solution

The system employs a dual feedback circuit architecture with a first integrator for fast startup and DC offset compensation, and a second integrator with a longer time constant for low-frequency signal preservation, allowing selective activation to reduce power consumption and improve measurement quality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a high-pass filter with very low frequency cut-off is used to remove DC-offset and temperature drift, then measurement accuracy is improved, but startup time increases significantly

Engineering Contradiction:
Improvefilling level determination accuracyVSAvoidstartup time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The feedback circuit is segmented into two distinct circuits: a first feedback circuit with a first integrator having a first time constant for fast DC offset compensation, and a second feedback circuit with a second integrator having a second time constant for accurate low-frequency signal preservation. This segmentation allows each circuit to be optimized for its specific function, resolving the contradiction between fast startup and measurement accuracy.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system dynamically switches between the first feedback circuit during startup to achieve fast response, and the second feedback circuit during normal operation to ensure measurement accuracy. This dynamic adaptation allows the system to optimize performance based on operational phase, eliminating the need to choose between fast startup and accurate measurement.

Inventive Principle:
Principle #15Dynamics

2Use of energy by moving object

If the radar level gauge system operates intermittently to save energy, then power consumption is reduced, but measurement accuracy deteriorates due to insufficient warm-up time

Engineering Contradiction:
Improvepower consumptionVSAvoidfilling level determination accuracy
Core Design Contradiction:
Use of energy by moving objectVSMeasurement precision

Solution Approach 1:

The first feedback circuit performs preliminary DC offset compensation during the brief active period before measurement, allowing the system to achieve accurate measurements quickly without requiring extended warm-up time. This preliminary action enables the system to skip the traditional slow startup phase and transition directly to accurate measurement mode.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system changes the time constant parameter dynamically by switching between the first integrator (short time constant) during startup and the second integrator (long time constant) during measurement. This parameter change allows the system to adapt its response characteristics to match the operational requirements of each phase.

Inventive Principle:
Principle #35Parameter changes

3Measurement precision

If a single integrator with long time constant is used for DC offset compensation, then measurement accuracy is maintained, but startup response becomes excessively slow

Engineering Contradiction:
ImproveDC offset compensation accuracyVSAvoidstartup response speed
Core Design Contradiction:
Measurement precisionVSSpeed

Solution Approach 1:

The feedback function is segmented into two separate circuits with different time constants. The first feedback circuit uses a short time constant for fast startup response, while the second feedback circuit uses a long time constant for accurate DC offset compensation. This segmentation eliminates the need to compromise between speed and accuracy in a single circuit.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system employs periodic switching between the first and second feedback circuits based on the operational phase. During startup, the first feedback circuit is activated for fast response, and during normal operation, the second feedback circuit is activated for accurate compensation. This periodic action allows the system to optimize performance for each phase.

Inventive Principle:
Principle #19Periodic action

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach enables fast startup and accurate filling level determination while minimizing power consumption, particularly beneficial for battery-powered or wireless radar level gauge systems.

Implementation Method 1

a first feedback circuit comprising a feedback loop including a first integrator having a first time constant

Methodology Applied
Scientific EffectIntegration:

Implementation Method 2

a second feedback circuit comprising a feedback loop including a second integrator having a second time constant being higher than the first time constant

Methodology Applied
Scientific EffectIntegration:

Implementation Method 3

the distance to the surface of the product is generally determined based on the time between transmission of an electromagnetic signal and reception of the reflection thereof

Methodology Applied
Scientific EffectTime of flight: Time of Flight

Implementation Method 4

systems that determine the distance to the surface based on the phase difference between a transmitted frequency-modulated signal and its reflection at the surface

Methodology Applied
Scientific EffectPhase difference:

Implementation Method 5

electromagnetic signals are radiated towards the product contained in the tank

Methodology Applied
Scientific EffectElectromagnetic radiation:

Implementation Method 6

The transmitted electromagnetic signals are reflected at the surface of the product, and the reflected signals are received by a receiver or transceiver

Methodology Applied
Scientific EffectReflection: Reflection

Data Source

PatentEP2572172B1Pulsed radar level gauge system and method with reduced start-up time
Publication Date: 2014.04.23 ROSEMOUNT TANK RADAR
  • EP2572172B1 patent drawingFigure 1~2
  • EP2572172B1 patent drawingFigure 3~4
  • EP2572172B1 patent drawingFigure 5~6a

AI summary

A radar level gauge system: first pulse generating circuitry generating a transmission signal; second pulse generating circuitry generating a reference signal, a propagation device arranged to propagate the transmission signal, and to return a reflected signal resulting from reflection of the transmission signal at the surface of a product, measurement circuitry, and processing circuitry for determining a value indicative of a filling level. The measurement circuitry comprises: a time-correlator for generating a sequence of values, a first feedback circuit arranged to receive a signal indicative of the sequence of values, and comprising a feedback loop including a first integrator having a first time constant; a second feedback circuit comprising a feedback loop including a second integrator having a second time constant being higher than the first time constant; and activation circuitry allowing selective activation of the first and the second feedback circuit.