Asynchronous Metal Detector Sampling for Accurate Phase Extraction
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Solution Overview
Problem
Existing metal detectors face challenges with false alarms due to ferromagnetic components in soil and limited frequency options, and synchronous sampling methods require precise synchronization, leading to errors and increased costs with additional electronic components.
Innovation Solution
The method employs asynchronous sampling using a high-resolution ADC to calculate in-phase and quadrature components with dynamic coefficients, allowing for faster phase tracking and reducing the need for synchronization, enabling operation at any frequency and eliminating unnecessary electronic components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If synchronous sampling is used to maintain phase and magnitude accuracy, then measurement precision is improved, but device complexity increases due to additional electronic components and synchronization requirements
Solution Approach 1:
The patent inverts the conventional approach by using asynchronous sampling instead of synchronous sampling. Rather than synchronizing the ADC to the transmitter frequency to maintain accuracy, the patent deliberately desynchronizes them and compensates through computational methods (phase unwrapping and frequency estimation algorithms), thereby eliminating the need for complex synchronization electronics while preserving measurement precision.
Solution Approach 2:
The patent replaces the mechanical/electronic synchronization system with a computational approach. Instead of using hardware synchronizers and phase-locked loops, the invention uses software-based algorithms to estimate frequency, calculate phase, and unwrap phase information from asynchronously sampled data, substituting complex hardware with simpler computational processing.
2Measurement precision
If synchronous sampling is used to ensure accurate signal representation, then measurement precision is improved, but the ADC selection range is limited due to frequency multiple requirements
Solution Approach 1:
The patent inverts the conventional requirement that ADC sampling frequency must be a multiple of the signal frequency. By using asynchronous sampling with no such restriction, the patent allows any ADC with sufficient resolution to be used, expanding the selection range while maintaining accurate signal representation through computational compensation methods.
Solution Approach 2:
The patent changes the fundamental parameter relationship between ADC sampling frequency and signal frequency. Instead of requiring fs = n*f (where n is an integer), the patent allows fs to be any value, and compensates for the resulting phase and frequency variations through dynamic calculation and phase unwrapping algorithms, thereby expanding ADC selection flexibility.
3Device complexity
If asynchronous sampling is used to expand ADC options and reduce complexity, then device complexity is reduced, but phase and magnitude accuracy deteriorates due to sampling shifts
Solution Approach 1:
The patent implements feedback through iterative frequency estimation and phase calculation. The system continuously estimates the signal frequency from asynchronously sampled data, uses this information to calculate expected phase values, compares them with actual measurements, and applies phase unwrapping corrections to maintain accuracy. This closed-loop computational feedback compensates for the inherent inaccuracies of asynchronous sampling.
Solution Approach 2:
The patent combines multiple computational techniques (frequency estimation algorithms, phase calculation methods, and phase unwrapping procedures) into a composite processing approach. This composite method integrates various algorithms that work together to compensate for asynchronous sampling effects, maintaining measurement precision despite the simplified hardware architecture.
4Reliability
If multi-frequency operation is used to reduce false alarms, then reliability is improved, but the number of frequency options remains insufficient for various ferromagnetic soils
Solution Approach 1:
The patent introduces dynamic frequency selection capability. Instead of being limited to fixed pre-programmed frequencies, the system can dynamically adjust the transmitter frequency based on soil conditions and target characteristics. The asynchronous sampling architecture allows the ADC to accurately capture signals at any frequency, enabling real-time frequency optimization to reduce false alarms in different ferromagnetic soil environments.
Solution Approach 2:
The patent creates a universal detection system that can operate at any frequency rather than being limited to specific discrete frequencies. The asynchronous sampling method with computational compensation serves multiple frequency detection needs simultaneously, making the system adaptable to various ferromagnetic soil conditions and target types without requiring separate hardware configurations for each frequency option.
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 false alarms, enhances signal analysis, and provides a more cost-effective solution with a wider range of ADC options, improving the accuracy and efficiency of metal detection.
Implementation Method 1
The voltage source that switched by the switching component is transferred to the transmitter unit and a magnetic field is generated proportional to the current by means of the transmitter coil. This magnetic field, also the target is located within, generates Eddy currents and causes regeneration of a magnetic field by the target.
Implementation Method 2
This magnetic field, also the target is located within, generates Eddy currents and causes regeneration of a magnetic field by the target.
Data Source
AI summary
This invention is related to the method providing computation of the signal frequency components in an acceptable accuracy in contravention of the shifts in the phase and the magnitude information caused by asynchronous sampling of the signals in the process of asynchronous sampling of metal detectors wherein the received signal by the receiver unit (4) divided into time intervals, say timing values those are far shorter than the sampling period and correspond to nearest probable sampling of the ADC (6); providing the computation of the sine and cosine coefficients or exponents of time constant coefficients of the said timing value from previously located or dynamically generated coefficient table; resulting the elimination of the requirement of synchronous sampling and the requirement of the signal period is multiple of the sampling period.