Metal Detector Asynchronous Demodulation for Converter Flexibility
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Solution Overview
Problem
Metal detectors require synchronous demodulation processes and synchronous analog-to-digital converters, which are cumbersome and limit the flexibility in using different types of converters.
Innovation Solution
A metal detector that employs asynchronous demodulation and sigma-delta analog-to-digital converters, utilizing a transmitter coil, receiver coil, receiver amplifier circuit, and a control unit with demodulation and correction units to process signals without synchronization, allowing for different types of converters and eliminating the need for synchronous demodulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If synchronous demodulation is used, then metal detection accuracy is maintained, but device complexity increases and flexibility is limited
Solution Approach 1:
The patent inverts the conventional synchronous demodulation approach by implementing asynchronous demodulation. Instead of requiring the demodulation process to be synchronized with the transmitter signal, the system processes signals asynchronously and corrects phase differences through computational methods, thereby eliminating the need for complex synchronization hardware and enabling greater flexibility in converter selection.
Solution Approach 2:
The patent replaces the mechanical/synchronization-based demodulation system with a computational approach. By substituting hardware synchronization mechanisms with software-based asynchronous processing and phase correction algorithms, the system achieves the same detection accuracy without the complexity of synchronous hardware requirements.
2Adaptability or versatility
If synchronous analog-to-digital converters are used, then demodulation accuracy is maintained, but the system requires precise synchronization which limits converter selection
Solution Approach 1:
The patent implements a feedback mechanism where the system continuously monitors and measures phase differences between the transmitter signal and receiver signal. This feedback information is then used to computationally correct the demodulated signals, maintaining measurement precision without requiring precise hardware synchronization or limiting converter type selection.
3Adaptability or versatility
If asynchronous demodulation is implemented, then converter flexibility is improved, but phase differences between signals must be corrected
Solution Approach 1:
The patent performs preliminary measurements of phase differences between the transmitter and receiver signals. By characterizing and storing these phase relationship data in advance, the system can efficiently correct for phase variations during operation without adding significant real-time processing complexity, thus maintaining converter flexibility while managing signal processing demands.
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
Enables metal detection without synchronous demodulation, facilitating the use of various converters and improving performance by correcting phase differences through asynchronous processing.
Implementation Method 1
A scanning signal in form of magnetic field emitted by a transmitter coil provided in the search head changes when it interacts with the metal object
Implementation Method 2
This altered magnetic field, is received by a receiving antenna and converted into a signal
Data Source
AI summary
A metal detector suitable for detecting a metal target under the ground includes: a transmitter switching circuit for switching the voltage of a transmitter signal, a transmitter coil for emitting the transmitter signal received from the transmitter switching circuit, a receiver coil induced by receiving the magnetic field and for generating a receiving signal of the magnetic field received, a receiver amplifier circuit for amplifying the receiving signal received from the receiver coil, an AD converter for converting the receiving signal and transmitter current from analog to digital, and a control unit connected to the AD converter for receiving the converted transmitter current and receiving signal, having a demodulation unit for obtaining amplitude and phase values, a correction unit for correcting phase differences in the transmitter current and receiver voltage, and a signal processing unit for operating a user interface based on the phase corrected receiving signal.