Radio Mode Selectivity Block for Buried Conductor Detection
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Solution Overview
Problem
Existing detectors for locating buried current-carrying conductors lack selectivity and sensitivity, particularly in radio mode, and require multiple sweeps in different modes to detect and avoid conductors efficiently.
Innovation Solution
A radio mode selectivity block with beat frequency oscillators, an analogue to digital converter, and digital signal processing to enhance sensitivity and selectivity, allowing simultaneous processing of multiple frequency bands and modes, reducing the need for multiple sweeps and improving detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a detector uses multiple frequency bands for detecting buried conductors, then detection coverage and versatility are improved, but device complexity and processing requirements increase
Solution Approach 1:
The detector divides the VLF detection band into multiple sub-bands (16-20 kHz, 20-24 kHz, 24-28 kHz) with dedicated beat frequency oscillators for each. This segmentation allows simultaneous processing of multiple frequency bands through parallel oscillators, resolving the contradiction by organizing complexity into manageable, independent segments that can operate concurrently.
Solution Approach 2:
The detector employs a universal signal processing architecture where a single ADC and digital signal processor handle multiple frequency bands. The beat frequency oscillators generate reference signals that are mixed with the input signal, and the resulting difference frequencies are processed through common filtering and detection circuits, allowing one system to perform multiple detection functions across different frequency ranges.
2Adaptability or versatility
If the detector operates in multiple modes (passive and active), then functionality and detection capability are improved, but operational complexity increases
Solution Approach 1:
The detector merges passive radio mode detection and active mode detection into a single integrated system. The same magnetic sensors, ADC, and signal processing circuits handle both modes, with the mode selectivity block automatically switching between passive VLF detection and active induced current detection. This merging reduces operational complexity by providing a unified interface while maintaining multiple detection capabilities.
Solution Approach 2:
The detector implements dynamic mode switching capability where the system can automatically or manually transition between passive and active modes based on detection requirements. The mode selectivity block dynamically adjusts the signal processing path and oscillator configurations to match the selected mode, making the complex multi-functional system easy to operate through automatic adaptation.
3Measurement precision
If the detector requires multiple sweeps in different modes, then detection accuracy is improved, but productivity and efficiency decrease
Solution Approach 1:
The detector enables continuous multi-mode detection by simultaneously processing signals from multiple beat frequency oscillators across different frequency bands. Instead of requiring sequential sweeps in different modes, the system continuously monitors multiple frequency ranges in parallel, maintaining detection accuracy while eliminating the time loss associated with multiple separate sweeps.
Solution Approach 2:
The detector performs preliminary signal processing and filtering in the digital domain before final detection, allowing multiple frequency bands to be processed and analyzed simultaneously. The mode selectivity block prepares and pre-processes signals from all oscillators in advance, enabling accurate detection across multiple modes without requiring repeated physical sweeps.
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
The solution achieves improved sensitivity and selectivity, enabling accurate detection and localization of buried conductors in a single sweep across various frequency bands, enhancing user control and reducing operational time while maintaining cost-effectiveness.
Implementation Method 1
a plurality of beat frequency oscillators to centre the bandwidth of detection of the field strength signals of the detector on target very low frequency frequency bands
Implementation Method 2
magnetic sensors for converting the magnetic emissions into field strength signals
Implementation Method 3
multiplying means for multiplying the output of the summing means with said digitised signal
Data Source
Figure 1
Figure 2
Figure 3A
AI summary
A radio mode selectivity block (41) for a detector (1) for detecting a buried current carrying conductor comprises a plurality of beat frequency oscillators (53) to centre the bandwidth of detection of the detector (1) on target very low frequency (VLF) frequency bands. The frequencies of the beat frequency oscillators are chosen to fall within the VLF frequency bands used in a number of countries, so that the detector (1) can be used in radio mode in these countries without the need for local configuration.