Spread Spectrum Geologic Signal Detection for Blind-Zone-Free Surveying
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Solution Overview
Problem
Existing shallow underground geological body detection methods face challenges in accuracy and efficiency due to limitations in frequency range and interference from conductive materials, leading to blind zones and reduced penetration depth.
Innovation Solution
A detection device using high-frequency pseudo-random spread spectrum coded sequence signals with a frequency range of 1 KHz to 300 KHz, generated by a transmitter and amplified through ground electrodes, synchronized with a receiver to collect and store geoelectric signals for precise underground structure mapping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high-density resistivity method is used to improve detection accuracy, then detection accuracy is improved, but detection efficiency deteriorates due to use of many ground electrodes
Solution Approach 1:
The patent changes the fundamental parameter of the detection method from electrical resistivity measurement to electromagnetic induction measurement. The system uses a transmitter to generate high-frequency electromagnetic signals (1-300 KHz) that induce currents in underground conductive bodies, and a receiver to detect the secondary electromagnetic fields. This parameter change eliminates the need for multiple ground electrodes while maintaining detection accuracy and significantly improving detection efficiency.
2Measurement precision
If frequency domain electromagnetic method is used to detect shallow geological bodies, then detection capability is improved, but detection depth deteriorates due to limited frequency range
Solution Approach 1:
The patent implements a dynamic frequency sweeping mechanism where the transmitter continuously varies the emission frequency from 1 KHz to 300 KHz. The system automatically adjusts the frequency based on the depth of the target geological body, using higher frequencies for shallow targets and lower frequencies for deeper targets. This dynamic frequency adjustment enables the system to detect both shallow and deep geological bodies effectively, overcoming the limitation of fixed frequency ranges.
3Measurement precision
If ground-penetrating radar is used to detect shallow geological bodies, then detection resolution is improved, but penetration ability deteriorates due to signal attenuation by conductive materials
Solution Approach 1:
The patent converts the harmful effect of conductive materials (water, clay soil) from signal attenuators into signal enhancers. Instead of using high-frequency radar waves that are strongly attenuated by conductors, the system uses electromagnetic induction to generate currents within the conductive materials themselves. These induced currents generate secondary electromagnetic fields that are detected by the receiver. The conductive materials that previously caused signal loss now become the source of the detectable signal, enabling effective detection in environments with high water content or clay soil.
4Length of stationary object
If transient electromagnetic method is used to detect shallow geological bodies, then detection depth is improved, but observation complexity deteriorates due to need for multiple modes
Solution Approach 1:
The patent creates a universal electromagnetic detection system that can detect geological bodies at all depths (from shallow to deep) using a single observation mode. The system achieves this through dynamic frequency sweeping and automatic depth adaptation algorithms. The transmitter can operate across the entire frequency range (1-300 KHz), and the receiver automatically adjusts its parameters based on the detected signal characteristics. This eliminates the need for separate shallow detection modes (like NanoTem) and deep detection modes (conventional Tem), unifying the observation process into a single versatile system.
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 effective detection of shallow geological bodies within 2-100 m depth with improved accuracy and efficiency by generating stable high-voltage signals and synchronized data collection, overcoming interference and blind zones.
Implementation Method 1
a signal transmitter configured to generate a pseudo-random combined rectangular wave signal... the power amplifier module is configured for outputting a pseudo-random combined rectangular wave signal to ground through a first ground electrode and a second ground electrode to form a transmitter circuit
Implementation Method 2
a synchronous signal receiver configured to... acquire a frequency response signal of a geoelectric field
Data Source
AI summary
A detection device for high-frequency pseudo-random spread spectrum coded sequence signal of shallow geologic body includes a signal transmitter and a synchronous signal receiver. The signal transmitter includes a first Mono-Chip Computer (MCU), a first Field Programmable Gate Array (FPGA), a power amplifier module, a direct-current (DC) power supply, a first display module, a first Global Position System (GPS) synchronization module, a first communication module, and a first memory module. The synchronous signal receiver includes a preamplifier circuit, a bandpass filter circuit, a program-controlled amplifier circuit, an analog to digital (AD) converter circuit, a second FPGA, a second MCU, a second communication module, a second display module, a second GPS synchronization module, and a second memory module. A method using the detection device is further provided.