Reflected-Wave Processing Apparatus for Cable Defect Detection
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Solution Overview
Problem
Current reflected-wave measurement methods, particularly time-frequency domain (TFDR), face limitations in distance resolution and accuracy due to errors caused by high-frequency signal loss through lossy media and cross-terms generated in Wigner-Ville distributions, which affect the detection of cable defects and their positions.
Innovation Solution
A reflected-wave processing apparatus that uses a combination of a first reference signal with increasing frequency and a second reference signal with decreasing frequency, allowing for accurate detection of time delays and removal of cross-terms by analyzing both signals and applying localized Wigner-Ville distributions within the bandwidth of the reference signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If only a chirp signal of which a frequency increases over time is used as a reference signal, then the measurement method is simple, but the distance resolution is limited and errors increase for longer cables due to high-frequency signal loss
Solution Approach 1:
The patent combines two chirp signals with opposite frequency modulation directions (increasing and decreasing) to form a composite reference signal. This merging approach leverages the complementary characteristics of both signals to achieve superior distance resolution while maintaining measurement simplicity.
Solution Approach 2:
The reference signal is constructed as a composite of two chirp signals with opposite frequency trends. This composite signal structure compensates for the limitations of individual chirp signals, particularly the high-frequency loss issue in long cables, by distributing the measurement burden across both signal types.
2Loss of information
If a localized Wigner-Ville distribution is used during signal processing, then time-frequency analysis is achieved, but cross-terms are generated that degrade measurement accuracy
Solution Approach 1:
The patent converts the harmful cross-terms generated by Wigner-Ville distribution into useful information. By deliberately generating cross-terms through the interaction of two chirp signals with opposite frequency directions, the method creates distinctive cross-term patterns that can be used to identify and locate cable defects, transforming a previously harmful artifact into a beneficial diagnostic feature.
Solution Approach 2:
Instead of trying to eliminate cross-terms as conventional methods do, the patent inverts the approach by intentionally generating and utilizing cross-terms. The cross-terms from two oppositely-modulated chirp signals create a unique signature that enhances defect detection capability rather than degrading it.
Data Source
AI summary
A reflected-wave processing apparatus according to one embodiment of the present invention may comprise: a reference signal generation unit for applying, to a cable, a first reference signal, the frequency of which increases over time, and a second reference signal, the frequency of which decreases over time; a reflected-signal acquisition unit for acquiring a first reflected signal and a second reflected signal which are reflected from the cable upon applying the first and second reference signals thereto; and a signal analysis unit for analyzing the first and second reflected signals.