Antenna System Measurements using Frequency Domain Reflectometry vs. Time Domain Reflectometry

2006 ◽  
Author(s):  
Steve Thomas
Keyword(s):  
Frequency Domain ◽  
Time Domain ◽  
Antenna System ◽  
Time Domain Reflectometry ◽  
Frequency Domain Reflectometry

Research of Aircraft Cable Fault Detecting Method Based on Hilbert Huang Transformation

2011 ◽  
Vol 214 ◽  
pp. 138-143
Author(s):  
Tao Jing ◽  
Lu Zhang ◽  
Xu Dong Shi ◽  
Li Wen Wang
Keyword(s):  
Frequency Domain ◽  
Short Circuit ◽  
Reference Signal ◽  
Open Circuit ◽  
Time Domain Reflectometry ◽  
Transform Method ◽  
Hilbert Huang Transform ◽  
Intermittent Faults ◽  
Time Frequency ◽  
Frequency Domain Reflectometry

Aircraft cable fault diagnosing is considered to be most important for engineering maintenance. Several methods for cables testing have been developed, such as TDR, FDR and TFDR. Time Domain Reflectometry (TDR) relays much on impedance changes on the fault position, which is hard to using in detecting high resistance defects, intermittent defects; Time Frequency Domain Reflectometry (TFDR) method is used to locate intermittent faults, continuous faults and cross-connection faults aircraft wire, however, the algorithm of TFDR is complex. To the "Hard Fault"(short circuit and open circuit), the Hilbert-Huang Transform method is used in determining the optimal bandwidth of the incident reference signal and analyzing the phase and amplitude difference of superimposed signal which from the incident signal and the reflected signal on defects. To the "Fray Fault", Time and Frequency Domain Reflectometry method can be used with the signal processing method with Hilbert-Huang Transform. The experimental results indicate that this method effectively detect all types of aircraft cable fault, particularly for short lengths of cable.

Thin Sample Time Domain Reflectometry for Nonideal Dielectrics

1974 ◽  
Vol 52 (24) ◽  
pp. 2463-2468 ◽  
Author(s):  
B. E. Springett ◽  
T. K. Bose
Keyword(s):  
Frequency Domain ◽  
Time Domain ◽  
Rise Time ◽  
Relaxation Times ◽  
Coaxial Line ◽  
Time Domain Reflectometry ◽  
Time Response ◽  
Thin Sample ◽  
Applied Pulse ◽  
Sample Time

The theoretical time response is derived for a pulse reflected from a thin sample of dielectric situated in a coaxial line. The dielectric is assumed to have a distribution of relaxation times. Specific account is taken of the finite rise time of the applied pulse. The equations developed are general and permit the interpretation of measurements without the necessity of transforming to the frequency domain. Explicit equations are developed for the Cole-Davidson and Cole-Cole representations of nonideal dielectrics. Some experimental examples are discussed to assess the utility of the technique.

Frequency analysis of time‐domain reflectometry (TDR) with application to dielectric spectroscopy of soil constituents

Geophysics ◽  
1999 ◽  
Vol 64 (3) ◽  
pp. 707-718 ◽  
Author(s):  
Richard Friel ◽  
Dani Or
Keyword(s):  
Dielectric Properties ◽  
Dielectric Permittivity ◽  
Frequency Domain ◽  
Time Domain ◽  
Dominant Role ◽  
Primary Objective ◽  
Time Domain Reflectometry ◽  
Complete Picture ◽  
Frequency Dependent ◽  
Additional Information

Standard analyses of time‐domain reflectometry (TDR) waveforms in environmental sciences use traveltime along waveguides and reflection amplitude to infer water content and bulk electrical conductivity, respectively. TDR waveforms contain additional information on the frequency‐dependent dielectric permittivity of media, which can be extracted through transformation of TDR waveforms into the frequency domain. The primary objective of this study was to provide a more complete picture of TDR responses in the frequency domain and to improve estimation of dielectric properties. The frequency content of TDR waveforms interacting with various constituents was measured and compared with predictions based on known dielectric properties and waveguide geometries. The study highlights the dominant role of the S11 scatter function, which describes how a TDR signal is modified by media properties and probe configuration. Scatter functions derived from transformed TDR waveforms into the frequency domain were used for estimation of frequency‐dependent dielectric properties of wet soils. The main results were (1) a more complete picture of TDR waveforms in the frequency domain; (2) estimation and use of scatter functions for TDR‐based dielectric permittivity estimation; and (3) highlights of potential usefulness and limitations of a commonly used TDR cable tester (Tektronix 1502B) and waveguide design for estimation of frequency‐dependent dielectric properties of porous media.

Time domain reflectometry of glass beads/magnetite mixtures: A time and frequency domain study

2005 ◽  
Vol 86 (22) ◽  
pp. 224102 ◽  
Author(s):  
Elisabetta Mattei ◽  
Alberto De Santis ◽  
Andrea Di Matteo ◽  
Elena Pettinelli ◽  
Giuliano Vannaroni
Keyword(s):  
Frequency Domain ◽  
Time Domain ◽  
Time Domain Reflectometry ◽  
Glass Beads
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