Asynchronous Metal Detector Sampling Without Synchronous Timing
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Solution Overview
Problem
Existing metal detectors face challenges with false alarms due to ferromagnetic components in soil and other metallic objects, and they require synchronous sampling to maintain accuracy, which limits the flexibility and increases costs.
Innovation Solution
The method involves asynchronous sampling of voltage signals using a high-resolution ADC, allowing for dynamic coefficient adjustments to track signal phase information accurately, eliminating the need for synchronization and enabling operation at any required frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If synchronous sampling is used to maintain signal accuracy, then measurement precision is improved, but device complexity and cost increase due to additional electronic components and synchronization requirements
Solution Approach 1:
The patent extracts and eliminates the synchronization requirement from the sampling system. By using asynchronous sampling without synchronization to the transmitter frequency, the system removes the need for synchronous integrators and related electronic components while maintaining measurement accuracy through post-processing of the sampled data.
Solution Approach 2:
The patent replaces the hardware-based synchronous sampling mechanism with a software/digital processing approach. Instead of using synchronous integrators and timing circuits, the system uses asynchronous sampling followed by digital signal processing to achieve the same measurement objectives with simpler electronics.
2Measurement precision
If synchronous sampling is used to ensure accurate signal measurement, then measurement precision is improved, but adaptability decreases due to fixed sampling frequency requirements
Solution Approach 1:
The patent introduces dynamic adaptability by allowing the sampling frequency to be independent of the transmitter frequency. The system can dynamically adjust sampling parameters and use variable integration periods to accommodate different operating conditions and frequency requirements, enhancing versatility while maintaining accuracy.
Solution Approach 2:
The patent changes the fundamental parameter relationship between sampling frequency and transmitter frequency. By decoupling these parameters and allowing asynchronous operation, the system gains flexibility to operate at any transmitter frequency without being constrained by fixed sampling rate requirements, thus improving adaptability.
3Reliability
If multi-frequency operation is used to reduce false alarms, then reliability is improved, but device complexity increases due to multiple frequency generation and switching components
Solution Approach 1:
The patent makes the asynchronous sampling system universal by designing it to handle multiple frequencies simultaneously or sequentially without requiring frequency-specific sampling circuits. The same asynchronous sampling architecture works for single-frequency, multi-frequency, and time-domain operations, reducing the need for separate electronic components for each mode.
4Measurement precision
If high-resolution ADC is used for asynchronous sampling, then measurement precision is improved, but use of energy increases due to higher power consumption of high-resolution converters
Solution Approach 1:
The patent applies partial action by using high-resolution ADC only when necessary for the specific measurement requirements. The system can adjust the effective resolution used based on the application needs, and the asynchronous sampling allows for optimized integration periods that reduce the burden on the ADC, thereby managing power consumption more effectively.
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 the occurrence of false alarms, enhances the accuracy of in-phase and quadrature component calculations, and allows for more flexible frequency selection, while also reducing the need for additional electronic components and associated costs.
Implementation Method 1
the transmitter unit (3) generating a single frequency, multifrequency of pulsed magnetic field and providing the electrical reception of the magnetic field by the receiver unit (4)
Implementation Method 2
The 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.