Platinum TSS200 Manual

Platinum Kabler til pc'er og periferiudstyr TSS200

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Whitepaper: Spread Spectrum Time-Domain Reﬂ ectometry www.T3Innovation.com

SPREAD-SPECTRUM

TIME-DOMAIN

REFLECTOMETRY

SSTDR

WHITEPAPER:

MADE IN

USA

Whitepaper: Spread Spectrum Time-Domain Reectometry www.T3Innovation.com

IEEE SENSORS JOURNAL, VOL. 5, NO. 6, DECEMBER 2005 1469

Analysis of Spread Spectrum Time Domain

Reﬂectometry for Wire Fault Location

Paul Smith, Member, IEEE , Senior Member, IEEE , Member, IEEE, Cynthia Furse , and Jacob Gunther

Abstract—Spread spectrum time domain reﬂectometry (SSTDR)

and sequence time domain reﬂectometry have been demonstrated

to be effective technologies for locating intermittent faults on air-

craft wires carrying typical signals in ﬂight. This paper examines

the parameters that control the accuracy, latency, and signal to

noise ratio for these methods. Both test methods are shown to be

effective for wires carrying ACpower signals, and SSTDR is shown

to be particularly effective at testing wires carrying digital sig-

nals such as Mil-Std 1553 data. Results are demonstrated for both

controlled and uncontrolled impedance cables. The low test signal

levels and high noise immunity of these test methods make them

well suited to test for intermittent wiring failures such as open cir-

cuits, short circuits, and arcs on cables in aircraft in ﬂight.

Index Terms—Aging wire detection, arc detection, sequence time

domain reﬂectometry (STDR), spread spectrum time domain re-

ﬂectometry (SSTDR), time domain reﬂectometry (TDR), wire fault

detection.

I. INTRODUCTION

FOR MANY years, wiring has been treated as a system that

could be installed and expected to work for the life of an

aircraft [1]. As aircraft age far beyond their original expected

life span, this attitude is rapidly changing. Aircraft wiring prob-

lems have recently been identiﬁed as the likely cause of several

tragic mishaps [2] and hundreds of thousands of lost mission

hours [3]. Modern commercial aircraft typically have more than

100 km of wire [2]. Much of this wire is routed behind panels or

wrapped in special protective jackets, and is not accessible even

during heavy maintenance when most of the panels are removed.

Among the most difﬁcult wiring problems to resolve are those

that involve intermittent faults [4]. Vibration that causes wires

with breached insulation to touch each other or the airframe,

pins, splices, or corroded connections to pull loose, or “wet

arc faults” where water drips on wires with breached insulation

causing intermittent line loads. Once on the ground these faults

Manuscript received April 10, 2004; revised September 14, 2004. This work

was supported in part by the Utah Center of Excellence for Smart Sensors and in

part by the National Science Foundation under Contract 0097490. The associate

editor coordinating the review of this paper and approving it for publication was

Prof. Michael Pishko.

P. Smith is with VP Technology, LiveWire Test Labs., Inc., Salt Lake City,

UT 84117 USA (e-mail: psmith@livewiretest.com).

C. Furse is with the Department of Electrical and Computer Engineering, Uni-

versity of Utah, Salt Lake City, UT 84112 USA, and also with VP Technology,

LiveWire Test Labs., Inc., Salt Lake City, UT 84117 USA (e-mail: cfurse@

ece.utah.edu).

J. Gunther is with the Department of Electrical and Computer Engineering,

Utah State University, Logan, UT 84322-4120 USA (e-mail: jake@ece.usu.

edu).

Digital Object Identiﬁer 10.1109/JSEN.2005.858964

often cannot be replicated or located. During the few millisec-

onds it is active, the intermittent fault is a signiﬁcant impedance

mismatch that can be detected, rather than the tiny mismatch

observed when it is inactive. A wire testing method that could

test the wires continually, including while the plane is in ﬂight

would, therefore, have a tremendous advantage over conven-

tional static test methods.

Another important reason to test wires that are live and in

ﬂight is to enable arc fault circuit breaker technology [5] that is

being developed to reduce the danger of ﬁre due to intermittent

short circuits. Unlike traditional thermal circuit breakers, these

new circuit breakers trip on noise caused by arcs rather than re-

quiring large currents. The problem is that locating the tiny fault

after the breaker has tripped is extremely difﬁcult, perhaps im-

possible. Locating the fault before the breaker trips could enable

maintenance action.

This paper describes and analyzes one such method, based

on spread spectrum communication techniques that can do just

that. This method is accurate to within a few centimeters for

wires carrying 400-Hz aircraft signals as well as MilStd 1553

data bus signals. Results are presented on both controlled and

uncontrolled impedance cables up to 23 m long.

Early research on spread spectrum time domain reﬂectometry

(SSTDR) [6] has considered fault location tests on high voltage

power wires. Sequence time domain reﬂectometry (STDR) [7]

has been studied and used to test twisted pairs for use in commu-

nications. More recently, it has been demonstrated for location

of intermittent faults such as those on aircraft wiring [18]. These

test methods could be used as part of a smart wiring system

[2], and could provide continuous testing of wires on aircraft

in ﬂight, with automatic reporting of fault locations to facilitate

quick wiring repairs. This could be done by integrating the elec-

tronics into either the circuit breaker or into “connector savers”

throughout the system. In order for this to be feasible, the pro-

totype system that has been described here is being redesigned

as a custom ASIC, which should cost on the order of $10–$20

per unit in bulk. This paper focuses on the analysis of SSTDR

and STDR. Parameters required for these methods to function

as potential test methods on wires carrying 400-Hz ACor high

speed digital data such as Mil-Std 1553 are discussed. This anal-

ysis is critical to determine the system tradeoffs between speed,

accuracy, code length/system complexity, etc. This ideal anal-

ysis provides information on the expected accuracy, which is

veriﬁed with tests of near-ideal lossless controlled impedance

coax. The effect of realistic noncontrolled impedance cable is

also evaluated, and sources of error within a realistic system are

discussed.

Produkt Specifikationer

Mærke:	Platinum
Kategori:	Kabler til pc'er og periferiudstyr
Model:	TSS200
Vægt:	340 g
Produktfarve:	Black, Orange
Skærmtype:	LCD
Opbevaringstemperatur (T-T):	-20 - 60 °C
Relativ luftfugtighed ved drift (H-H):	10 - 90 %
Driftstemperatur (T-T):	0 - 50 °C
Dimensioner (BxDxH):	80 x 33 x 173 mm
Antal understøttede batterier:	4