Conference Paper

# Diagnostics and Prognostics of Electric Cables in Ship Power Systems via Joint Time-Frequency Domain Reflectometry

Dept. of Electr. Eng., South Carolina Univ., Columbia, SC

DOI: 10.1109/IMTC.2008.4547167 Conference: Instrumentation and Measurement Technology Conference Proceedings, 2008. IMTC 2008. IEEE Source: IEEE Xplore

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**ABSTRACT:**In this paper, wavelet-transform-based time–frequency domain reflectometry (WTFDR) is proposed for load impedance measurement. In order to measure the load impedance, the energy of the measured signal in the time–frequency domain, the phase difference between the reference signal and the reflected signal, the characteristic impedance, and the attenuation factor of the measured cable must all be known. Since the complex wavelet transform is composed of real and imaginary parts, the phase difference is easily obtained using the ratio of the real coefficient to the imaginary coefficient. In addition, the wavelet energy denotes the sum of the square of the modulus of the wavelet transform and describes the energy of the measured signal in the time and frequency domains. To accurately determine the characteristic impedance and attenuation factors, the power cable should be estimated as a coaxial cable. Using WTFDR with the complex mother wavelet and the estimated power cable, the load impedance can be obtained simply and accurately. Finally, real experiments for the evaluation of various load impedances are carried out to confirm the effectiveness and accuracy of the proposed method compared to the conventional time–frequency domain reflectometry.Measurement Science and Technology 08/2013; 24(9):095008. · 1.35 Impact Factor - [Show abstract] [Hide abstract]

**ABSTRACT:**In this paper, wavelet-transform-based time–frequency domain reflectometry (WTFDR) is proposed to reduce the blind spot in reflectometry. TFDR has a blind spot problem when the time delay between the reference signal and the reflected signal is short enough compared with the time duration of the reference signal. To solve the blind spot problem, the wavelet transform (WT) is used because the WT has linearity. Using the characteristics of the WT, the overlapped reference signal at the measured signal can be separated and the blind spot is reduced by obtaining the difference of the wavelet coefficients for the reference and reflected signals. In the proposed method, the complex wavelet is utilized as a mother wavelet because the reference signal in WTFDR has a complex form. Finally, the computer simulations and the real experiments are carried out to confirm the effectiveness and accuracy of the proposed method.Measurement Science and Technology 06/2012; 23(6). · 1.35 Impact Factor - [Show abstract] [Hide abstract]

**ABSTRACT:**In this paper we describe a low level method for detecting and locating faults in the electrical physical layer of automotive networks based on time-domain reflectometry. Especially for safety-critical networks this approach could be a valuable complement for the existing network management layers, since it has the potential to detect damaged cables and plugs even before they cause serious malfunctions. We illustrate the feasibility of the proposed method by analyzing several FlexRay clusters with- and without faults.Conference Record - IEEE Instrumentation and Measurement Technology Conference 01/2012;

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