Cable Fault Detection Using Orthogonal Frequency Multiplexing
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Solution Overview
Problem
Existing methods for detecting cable faults, such as time domain reflectometry (TDR) and frequency domain reflectometry (FDR), are inefficient due to increased measurement errors, limited resolution, and sensitivity to noise, requiring multiple measurements across a wide frequency band, thereby prolonging the detection time.
Innovation Solution
An apparatus and method that simultaneously apply multiple orthogonal measurement frequencies to a cable, using filters to estimate reflection coefficients, significantly reducing detection time by filtering each frequency independently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple measurement frequencies are applied sequentially across a wide frequency band to accurately detect cable faults, then measurement accuracy is improved, but detection time is significantly prolonged
Solution Approach 1:
The patent combines multiple measurement frequencies into a single composite measurement signal that contains multiple frequency components. By transmitting this combined signal through the cable and processing the reflected signal using frequency domain analysis, the system achieves accurate fault detection across multiple frequencies simultaneously, rather than sequentially measuring each frequency separately. This merging approach maintains measurement precision while dramatically reducing detection time.
Solution Approach 2:
The patent employs periodic modulation of measurement signals at different frequencies and uses synchronous detection techniques to extract fault information. By utilizing periodic actions at multiple frequencies within a single measurement cycle and applying frequency domain reflectometry principles, the system achieves both high measurement accuracy and reduced detection time through efficient signal processing.
2Reliability
If measurement frequency band is widened to improve detection reliability, then fault detection reliability is improved, but measurement complexity increases
Solution Approach 1:
The patent implements a universal measurement system that can operate across a wide frequency band by using a single measurement apparatus capable of generating and processing multi-frequency signals. The system uses frequency domain reflectometry techniques that are applicable across different frequency ranges, making the measurement device multi-functional and able to detect various types of cable faults (impedance mismatches, breaks, connectors) reliably without requiring multiple specialized instruments.
Solution Approach 2:
The patent introduces signal processing algorithms and frequency domain analysis methods as intermediaries between the measurement signal and fault detection. These intermediary processing steps enable the system to handle wide frequency bands efficiently by transforming complex multi-frequency measurements into manageable spectral information, thereby improving reliability while managing measurement complexity through sophisticated but integrated processing techniques.
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 allows for rapid and reliable detection of cable faults by minimizing noise interference and optimizing signal-to-noise ratio, thereby improving measurement accuracy and reducing the time required for fault detection.
Implementation Method 1
whether or not there is a fault is determined according to the phases of a reflected signal and the reference signal at a DTF in the conducting wire, that is, at a position at which the characteristic impedance of the conducting wire is discontinuous
Implementation Method 2
mixes an oscillation signal having a center frequency of 1.8 GHz, for example, a carrier frequency of a long term evolution (LTE) system generated by a local oscillator (LO), with a baseband sine signal having been subjected to up-conversion, for example, a measurement frequency signal (RF source) belonging to 20 MHz which is the band of use in the case of the LTE system, using a mixer to output only a baseband sine signal
Data Source
AI summary
An apparatus and method for detecting a cable fault which simultaneously apply a plurality of measurement frequencies mutually orthogonal to a cable and estimate reflection coefficients at the measurement frequencies using filters for filtering only the respective measurement frequencies to reduce a time taken to detect a cable fault.