Radar Level Gauge Calibration Using Real-Time Sampler Delay
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Solution Overview
Problem
Conventional distance measuring devices using electromagnetic pulses struggle with high accuracy due to the fast duration of echo peaks, which require complex and expensive designs for real-time sampling, and temperature-dependent clock references in radar level gauges lead to significant measurement drift.
Innovation Solution
A device and method for calibrating a radar level gauge using a real-time sampler with a calibration signal of known frequency to determine the average sample time delay, allowing for accurate distance measurements by correlating the sampled signal with the calibration signal, thereby mitigating temperature-induced drift.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If real-time sampling is used to capture fast echo peaks, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent replaces complex hardware time-to-digital converters with a software-based calibration approach. A calibration signal with known frequency characteristics is used to determine average sample time delay, which is then applied to correct distance measurements. This substitutes complex sampling hardware with simpler sampling combined with post-processing calibration, reducing device complexity while maintaining measurement precision.
2Reliability
If temperature-stable clock reference is used, then reliability is improved, but device complexity and cost increase
Solution Approach 1:
The patent implements a calibration process where a calibration signal with known frequency is sampled, and the average sample time delay is determined from the sampled calibration signal. This creates a feedback mechanism that characterizes the sampler's timing behavior under actual operating conditions, allowing temperature-induced drift to be compensated without requiring expensive temperature-stable clock references.
Solution Approach 2:
The patent uses a calibration signal that copies the essential timing characteristics of actual measurement signals but with known frequency properties. By analyzing the sampled calibration signal, the system can determine average sample time delay and use this information to correct subsequent measurements, effectively creating a reference model for timing correction without requiring stable hardware references.
3Measurement precision
If conventional mixing is used to expand pulse response, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces complex analog mixing and time-expansion hardware with direct real-time sampling of the reflected pulse train. Instead of mixing the reflected signal with the transmitted signal to create time-expanded pulses, the system directly samples the reflected pulses at high speed and uses calibration-based timing correction to achieve precise range measurement, significantly simplifying the signal processing hardware.
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 precise distance measurements by stabilizing the sampling process against temperature variations, ensuring accurate and reliable operation in radar level gauges and other distance measurement applications.
Implementation Method 1
a real time sampler for receiving an input signal and sampling the input signal to provide a sampled input signal
Implementation Method 2
A distance measurement device, or ranging device, is based on the principle that an electromagnetic pulse is transmitted towards a surface or an object, and a reflected pulse is received
Implementation Method 3
an electromagnetic pulse is transmitted towards a surface or an object, and a reflected pulse is received
Implementation Method 4
The distance can then be determined based on the time-of-flight of the pulse to the surface or object and back
Data Source
Figure 1a~1b
Figure 2
Figure 3~4
AI summary
Calibration of a device using electromagnetic waves to determine a distance to a surface, which device comprises a pulse generator, a real time sampler and a calibration unit having a signal generator for generating a calibration signal with a predefined frequency. In a calibration mode, the real time sampler receives the calibration signal, and an average sample time delay of the sampler is determined based on the sampled calibration signal and the known calibration frequency. In a measurement mode, the real time sampler receives a reflection signal and the distance is determined based on a sampled reflection signal and the average sample time delay. Knowledge of the average delay of the sampler makes it possible to exactly determine the distance (in time and thus space) between two points in the sampled signal.