FMCW Radar Level Gauge PLL Lock State Control

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Solution Overview

Problem

Conventional frequency modulated continuous wave (FMCW) radar level gauge systems are power hungry, making them less suitable for applications with limited power sources, such as field devices or wireless devices powered by batteries or solar cells.

Innovation Solution

A radar level gauge system that includes PLL circuitry and frequency modifying or amplifying circuitry, which only modifies the output signal when the PLL circuitry is in a locked state, reducing energy consumption by minimizing the time the frequency modifying circuitry is active and preventing unnecessary RF energy emission.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional FMCW radar level gauge systems continuously operate frequency modifying circuitry to ensure accurate filling level determination, then measurement precision is improved, but energy consumption increases

Engineering Contradiction:
Improvefilling level determination accuracyVSAvoidenergy consumption
Core Design Contradiction:
Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The frequency modifying circuitry is activated periodically only when the PLL circuitry achieves lock state, rather than operating continuously. This periodic activation based on lock state transitions reduces energy consumption while maintaining measurement accuracy during active periods.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The system dynamically adjusts the operation state of the frequency modifying circuitry based on the PLL lock state. When locked, the circuitry operates to ensure accurate measurements; when unlocked, it remains inactive to conserve energy, creating a dynamic adaptation to system conditions.

Inventive Principle:
Principle #15Dynamics

2Measurement precision

If frequency modifying circuitry operates continuously to maintain signal frequency for accurate measurements, then measurement precision is improved, but power consumption increases

Engineering Contradiction:
Improvefilling level determination accuracyVSAvoidpower consumption
Core Design Contradiction:
Measurement precisionVSUse of energy by stationary object

Solution Approach 1:

The frequency modifying circuitry operates periodically based on PLL lock state transitions rather than continuously. Power is consumed only during active measurement periods when the PLL is locked, reducing overall power consumption while maintaining measurement precision when needed.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The system uses the PLL lock state signal to automatically control the frequency modifying circuitry operation. The lock state itself triggers the activation/deactivation of the frequency modifying circuitry, creating a self-regulating power management mechanism.

Inventive Principle:
Principle #25Self-service

3Productivity

If the frequency modifying circuitry is activated early before PLL lock state to prepare transmit signals, then productivity is improved, but energy consumption increases due to premature operation

Engineering Contradiction:
Improvemeasurement readinessVSAvoidenergy waste
Core Design Contradiction:
ProductivityVSLoss of energy

Solution Approach 1:

The PLL circuitry prepares the output signal in advance, and the frequency modifying circuitry is activated immediately when lock state is achieved. This preliminary preparation of the PLL output, followed by immediate frequency modification upon locking, ensures quick measurement readiness without premature energy consumption.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system uses feedback from the PLL lock state signal to control the frequency modifying circuitry activation. The lock state provides real-time feedback on whether the PLL is ready, ensuring the frequency modifying circuitry operates only when necessary, eliminating energy waste from premature operation.

Inventive Principle:
Principle #23Feedback

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 reduces energy consumption and extends battery life in power-limited applications while maintaining accurate filling level determination, ensuring efficient operation and minimizing energy waste.

Implementation Method 1

PLL circuitry for generating an output signal, the PLL circuitry being configured to indicate a lock state of the PLL circuitry

Methodology Applied
Scientific EffectPhase-locked loop:

Implementation Method 2

frequency modifying circuitry connected to the PLL circuitry for receiving the output signal and for increasing a frequency of the output signal to form the transmit signal

Methodology Applied
Scientific EffectFrequency multiplication:

Implementation Method 3

The transmitted signal is reflected by the surface of the contents in the tank (or by any other impedance transition) and an echo signal, which has been delayed a certain time, is returned to the gauge

Methodology Applied
Scientific EffectReflection: Reflection

Implementation Method 4

The echo signal is mixed with the transmitted signal to generate a mixer signal, having a frequency equal to the frequency change of the transmitted signal that has taken place during the time delay

Methodology Applied
Scientific EffectMixing: Heterodyne

Implementation Method 5

a signal propagation device coupled to the transceiver for propagating a transmit signal towards a surface of the product, and for propagating a surface echo signal resulting from reflection of the transmit signal at the surface back towards the transceiver

Methodology Applied
Scientific EffectElectromagnetic wave propagation:

Data Source

PatentEP2965050B1FMCW radar level gauge with lock state control
Publication Date: 2019.07.10 ROSEMOUNT TANK RADAR
  • EP2965050B1 patent drawingFigure 1~2
  • EP2965050B1 patent drawingFigure 3
  • EP2965050B1 patent drawingFigure 4

AI summary

The present invention relates to a radar level gauge system comprising PLL circuitry for generating an output signal. The PLL circuitry is configured to indicate a lock state of the PLL circuitry; and signal modifying circuitry is connected to the PLL circuitry for receiving the output signal and for modifying at least one property of the output signal for forming the transmit signal. The signal modifying circuitry is arranged and configured to receive a PLL status signal indicative of the lock state of the PLL circuitry, and to modify the at least one property of the output signal in response to the PLL status signal indicating that the PLL circuitry is in a locked state.