469:
457:
787:
by measuring the time difference between when the impulse was sent and when the reflection returned. The sensors can output the analyzed level as a continuous analog signal or switch output signals. In TDR technology, the impulse velocity is primarily affected by the permittivity of the medium through which the pulse propagates, which can vary greatly by the moisture content and temperature of the medium. In many cases, this effect can be corrected without undue difficulty. In some cases, such as in boiling and/or high temperature environments, the correction can be difficult. In particular, determining the froth (foam) height and the collapsed liquid level in a frothy / boiling medium can be very difficult.
433:
409:
818:
strong relationship between the permittivity of a material and its water content, as demonstrated in the pioneering works of
Hoekstra and Delaney (1974) and Topp et al. (1980). Recent reviews and reference work on the subject include, Topp and Reynolds (1998), Noborio (2001), Pettinellia et al. (2002), Topp and Ferre (2002) and Robinson et al. (2003). The TDR method is a transmission line technique, and determines apparent permittivity (Ka) from the travel time of an electromagnetic wave that propagates along a transmission line, usually two or more parallel metal rods embedded in soil or sediment. The probes are typically between 10 and 30 cm long and connected to the TDR via coaxial cable.
445:
831:
any point along a coaxial cable changes with deformation of the insulator between the conductors. A brittle grout surrounds the cable to translate earth movement into an abrupt cable deformation that shows up as a detectable peak in the reflectance trace. Until recently, the technique was relatively insensitive to small slope movements and could not be automated because it relied on human detection of changes in the reflectance trace over time. Farrington and
Sargand (2004) developed a simple signal processing technique using numerical derivatives to extract reliable indications of slope movement from the TDR data much earlier than by conventional interpretation.
481:
421:
397:
577:
597:
the pulse encounters the short, no energy is absorbed at the far end. Instead, an inverted pulse reflects back from the short towards the launching end. It is only when this reflection finally reaches the launch point that the voltage at this point abruptly drops back to zero, signaling the presence of a short at the end of the cable. That is, the TDR has no indication that there is a short at the end of the cable until its emitted pulse can travel in the cable and the echo can return. It is only after this round-trip delay that the short can be detected by the TDR. With knowledge of the
563:
499:
551:
539:
527:
515:
90:
935:
713:. This includes abrupt changes in the characteristic impedance. As an example, a trace width on a printed circuit board doubled at its midsection would constitute a discontinuity. Some of the energy will be reflected back to the driving source; the remaining energy will be transmitted. This is also known as a scattering junction.
468:
875:
detection, localization and characterization of electrical defects (or mechanical defects having electrical consequences) in the wiring systems. Hard fault (short, open circuit) or intermittent defects can be detected very quickly increasing the reliability of wiring systems and improving their maintenance.
604:
A similar effect occurs if the far end of the cable is an open circuit (terminated into an infinite impedance). In this case, though, the reflection from the far end is polarized identically with the original pulse and adds to it rather than cancelling it out. So after a round-trip delay, the voltage
491:
These traces were produced by a commercial TDR using a step waveform with a 25 ps risetime, a sampling head with a 35 ps risetime, and an 18-inch (0.46 m) SMA cable. The far end of the SMA cable was left open or connected to different adapters. It takes about 3 ns for the pulse to
834:
Another application of TDRs in geotechnical engineering is to determine the soil moisture content. This can be done by placing the TDRs in different soil layers and measurement of the time of start of precipitation and the time that TDR indicate an increase in the soil moisture content. The depth of
817:
in soil and porous media. Over the last two decades, substantial advances have been made measuring moisture in soil, grain, food stuff, and sediment. The key to TDR's success is its ability to accurately determine the permittivity (dielectric constant) of a material from wave propagation, due to the
786:
device, the device generates an impulse that propagates down a thin waveguide (referred to as a probe) â typically a metal rod or a steel cable. When this impulse hits the surface of the medium to be measured, part of the impulse reflects back up the waveguide. The device determines the fluid level
596:
If the far end of the cable is shorted, that is, terminated with an impedance of zero ohms, and when the rising edge of the pulse is launched down the cable, the voltage at the launching point "steps up" to a given value instantly and the pulse begins propagating in the cable towards the short. When
867:
is used on aviation wiring for both preventive maintenance and fault location. Spread spectrum time domain reflectometry has the advantage of precisely locating the fault location within thousands of miles of aviation wiring. Additionally, this technology is worth considering for real time aviation
854:
Time domain reflectometry is used in semiconductor failure analysis as a non-destructive method for the location of defects in semiconductor device packages. The TDR provides an electrical signature of individual conductive traces in the device package, and is useful for determining the location of
321:
along the conductor; the resolution of such instruments is often the width of the pulse. Narrow pulses can offer good resolution, but they have high frequency signal components that are attenuated in long cables. The shape of the pulse is often a half cycle sinusoid. For longer cables, wider pulse
830:
settings including highway cuts, rail beds, and open pit mines (Dowding & O'Connor, 1984, 2000a, 2000b; Kane & Beck, 1999). In stability monitoring applications using TDR, a coaxial cable is installed in a vertical borehole passing through the region of concern. The electrical impedance at
378:(SSTDR) is used to detect intermittent faults in complex and high-noise systems such as aircraft wiring. Coherent optical time domain reflectometry (COTDR) is another variant, used in optical systems, in which the returned signal is mixed with a local oscillator and then filtered to reduce noise.
874:
Multi carrier time domain reflectometry (MCTDR) has also been identified as a promising method for embedded EWIS diagnosis or troubleshooting tools. Based on the injection of a multicarrier signal (respecting EMC and harmless for the wires), this smart technology provides information for the
286:
Generally, the reflections will have the same shape as the incident signal, but their sign and magnitude depend on the change in impedance level. If there is a step increase in the impedance, then the reflection will have the same sign as the incident signal; if there is a step decrease in
82:, then there will be no reflections and the remaining incident signal will be absorbed at the far-end by the termination. Instead, if there are impedance variations, then some of the incident signal will be reflected back to the source. A TDR is similar in principle to
1309:
Duncan, D.; Trabold, T.A.; Mohr, C.L.; Berrett, M.K. "MEASUREMENT OF LOCAL VOID FRACTION AT ELEVATED TEMPERATURE AND PRESSURE". Third World
Conference on Experimental Heat Transfer, Fluid Mechanics and Thermodynamics, Honolulu, Hawaii, USA, 31 October-5 November 1993.
492:
travel down the cable, reflect, and reach the sampling head. A second reflection (at about 6 ns) can be seen in some traces; it is due to the reflection seeing a small mismatch at the sampling head and causing another "incident" wave to travel down the cable.
480:
612:
The magnitude of the reflection is referred to as the reflection coefficient or Ï. The coefficient ranges from 1 (open circuit) to â1 (short circuit). The value of zero means that there is no reflection. The reflection coefficient is calculated as follows:
608:
Perfect termination at the far end of the cable would entirely absorb the applied pulse without causing any reflection, rendering the determination of the actual length of the cable impossible. In practice, some small reflection is nearly always observed.
1221:
Robinson, D. A., C. S. Campbell, J. W. Hopmans, B. K. Hornbuckle, Scott B. Jones, R. Knight, F. Ogden, J. Selker, and O. Wendroth, 2008. "Soil moisture measurement for ecological and hydrological watershed-scale observatories: A review."
1302:
Scarpetta, M.; Spadavecchia, M.; Adamo, F.; Ragolia, M.A.; Giaquinto, N. âłDetection and
Characterization of Multiple Discontinuities in Cables with Time-Domain Reflectometry and Convolutional Neural Networksâł. Sensors 2021, 21, 8032.
149:
and the subsequent observation of the energy reflected by the system. By analyzing the magnitude, duration and shape of the reflected waveform, the nature of the impedance variation in the transmission system can be determined.
161:
is applied, a step signal is observed on the display, and its height is a function of the resistance. The magnitude of the step produced by the resistive load may be expressed as a fraction of the input signal as given by:
329:
steps are also used. Instead of looking for the reflection of a complete pulse, the instrument is concerned with the rising edge, which can be very fast. A 1970s technology TDR used steps with a rise time of 25 ps.
20:
576:
721:
Time domain reflectometers are commonly used for in-place testing of very long cable runs, where it is impractical to dig up or remove what may be a kilometers-long cable. They are indispensable for
690:
239:
474:
TDR trace of a transmission line terminated on an oscilloscope high impedance input. The blue trace is the pulse as seen at the far end. It is offset so that the baseline of each channel is visible
939:
1415:
363:) is an analogous technique that measures the transmitted (rather than reflected) impulse. Together, they provide a powerful means of analysing electrical or optical transmission media such as
498:
456:
1211:
Robinson D.A., S.B. Jones, J.M. Wraith, D. Or and S.P. Friedman, 2003 "A review of advances in dielectric and electrical conductivity measurements in soils using time domain reflectometry".
774:
packages to measuring liquid levels. In the former, the time domain reflectometer is used to isolate failing sites in the same. The latter is primarily limited to the process industry.
287:
impedance, the reflection will have the opposite sign. The magnitude of the reflection depends not only on the amount of the impedance change, but also upon the loss in the conductor.
1201:
Pettinelli E., A. Cereti, A. Galli, and F. Bella, 2002. "Time domain reflectometry: Calibration techniques for accurate measurement of the dielectric properties of various materials".
486:
TDR trace of a transmission line terminated on an oscilloscope high impedance input driven by a step input from a matched source. The blue trace is the signal as seen at the far end.
1102:
1032:
799:
to identify potential faults in concrete dam anchor cables. The key benefit of Time Domain reflectometry over other testing methods is the non-destructive method of these tests.
432:
1363:
444:
1125:
1408:
1188:
and M. Schmidt. "Analysis of
Reflectometry for Detection of Chafed Aircraft Wiring Insulation". Department of Electrical and Computer Engineering. Utah State University.
977:
1983 Tektronix
Catalog, pages 140â141, the 1502 uses a step (system rise time less than 140 ps), has a resolution of 0.6 inch and a range of 2,000 feet.
808:
741:
leakage as it degrades and absorbs moisture, long before either leads to catastrophic failures. Using a TDR, it is possible to pinpoint a fault to within centimetres.
268:
70:
A TDR measures reflections along a conductor. In order to measure those reflections, the TDR will transmit an incident signal onto the conductor and listen for its
386:
These traces were produced by a time-domain reflectometer made from common lab equipment connected to approximately 100 feet (30 m) of coaxial cable having a
1401:
1424:
420:
562:
752:. The slight change in line impedance caused by the introduction of a tap or splice will show up on the screen of a TDR when connected to a phone line.
408:
1229:
Topp G.C., J.L. Davis and A.P. Annan, 1980. "Electromagnetic determination of soil water content: measurements in coaxial transmission lines".
618:
167:
1171:
1344:
1099:
1029:
835:
the TDR (d) is a known factor and the other is the time it takes the drop of water to reach that depth (t); therefore the speed of water
396:
1122:
968:
1983 Tektronix
Catalog, pages 140â141, the 1503 uses "1/2-sine-shaped pulses" and has a 3-foot resolution and a range of 50,000 feet.
864:
796:
375:
334:
1372:
1142:
745:
1276:
Farrington, S.P. and
Sargand, S.M., "Advanced Processing of Time Domain Reflectometry for Improved Slope Stability Monitoring",
944:
795:
The Dam Safety
Interest Group of CEA Technologies, Inc. (CEATI), a consortium of electrical power organizations, has applied
514:
1239:
Topp G.C. and W.D. Reynolds, 1998. "Time domain reflectometry: a seminal technique for measuring mass and energy in soil".
1082:
550:
1191:
Noborio K. 2001. "Measurement of soil water content and electrical conductivity by time domain reflectometry: A review".
839:(v) can be determined. This is a good method to assess the effectiveness of Best Management Practices (BMPs) in reducing
538:
526:
1666:
102:
1323:
1141:
G.Millet, S.Bruillot, D.Dejardin, N.Imbert, F.Auzanneau, L.Incarbone, M.Olivas, L.Vincent, A.Cremzi, S.Poignant, 2014.
1293:
1057:
904:
899:
350:
294:
to the TDR and displayed or plotted as a function of time. Alternatively, the display can be read as a function of
1676:
950:
301:
Because of its sensitivity to impedance variations, a TDR may be used to verify cable impedance characteristics,
1382:
1269:
Kane, W.F. & Beck, T.J. 1999. "Advances in Slope
Instrumentation: TDR and Remote Data Acquisition Systems".
390:
of 50 ohms. The propagation velocity of this cable is approximately 66% of the speed of light in a vacuum.
1311:
1574:
1620:
1523:
1263:
Dowding, C.H. & O'Connor, K.M. 2000b. "Real Time Monitoring of Infrastructure using TDR Technology".
894:
1256:
Dowding, C.H. & O'Connor, K.M. 2000a. "Comparison of TDR and Inclinometers for Slope Monitoring".
1156:
Hoekstra, P. and A. Delaney, 1974. "Dielectric properties of soils at UHF and microwave frequencies".
1625:
1518:
1388:
1271:
Field Measurements in Geomechanics, 5th International Symposium on Field Measurements in Geomechanics
1253:. (Ed. J.H. Dane and G.C. Topp), SSSA Book Series No. 5. Soil Science Society of America, Madison WI.
118:
47:
836:
827:
387:
298:
length because the speed of signal propagation is almost constant for a given transmission medium.
271:
333:
Still other TDRs transmit complex signals and detect reflections with correlation techniques. See
884:
598:
1393:
1645:
1335:
726:
722:
79:
125:. The total rise time consists of the combined rise time of the driving pulse and that of the
1671:
1473:
770:
The TDR principle is used in industrial settings, in situations as diverse as the testing of
738:
59:
1498:
826:
Time domain reflectometry has also been utilized to monitor slope movement in a variety of
730:
306:
246:
98:
75:
1083:
Feasibility of Reflectometry for Nondestructive Evaluation of Prestressed Concrete Anchors
8:
914:
19:
767:
device can be detected. Short circuited pins can also be detected in a similar fashion.
1630:
889:
771:
759:
of modern high-frequency printed circuit boards with signal traces crafted to emulate
1589:
1528:
1458:
1453:
1443:
1289:
1053:
783:
760:
749:
703:
275:
71:
44:
40:
1329:
871:
This method has been shown to be useful to locating intermittent electrical faults.
50:. It can be used to characterize and locate faults in metallic cables (for example,
1640:
1594:
954:
814:
756:
295:
24:
1635:
1584:
1448:
1106:
1036:
764:
302:
1569:
1028:
and Gunther, Jacob. "Analysis of Spread Spectrum Time Domain Reflectometry for
843:
709:
Any discontinuity can be viewed as a termination impedance and substituted as Z
601:
in the particular cable-under-test, the distance to the short can be measured.
1660:
1185:
1172:
Analysis of spread spectrum time domain reflectometry for wire fault location
1167:
1129:
1118:
1095:
1078:
1025:
868:
monitoring, as spread spectrum reflectometry can be employed on live wires.
368:
364:
346:
158:
138:
55:
1312:
https://www.mohr-engineering.com/guided-radar-liquid-level-documents-EFP.php
986:
1983 Tektronix Catalog, page 289, S-52 pulse generator has a 25-ps risetime.
1579:
1564:
1463:
698:
is defined as the characteristic impedance of the transmission medium and Z
291:
126:
51:
1599:
1533:
1503:
1483:
1123:
Feasibility of Spread Spectrum Sensors for Location of Arcs on Live Wires
909:
1278:
Proceedings of the Eleventh Annual Conference on Tailings and Mine Waste
89:
1604:
1493:
1478:
1284:
Smolyansky, D. (2004). "Electronic Package Fault Isolation Using TDR".
840:
39:) is an electronic instrument used to determine the characteristics of
582:
TDR of step into mated BNC connector pair; the peak reflection is 0.04
1543:
1538:
1468:
734:
504:
TDR of step into disconnected SMA male connector (non-precision open)
326:
122:
121:
takes to return. The limitation of this method is the minimum system
106:
1304:
1085:," IEEE Journal of Sensors, Vol. 9. No. 11, Nov. 2009, pp. 1322â1329
1548:
1488:
1343:, Application Note, Keysight Technologies, 31 May 2013, AN-1304-2,
605:
at the TDR abruptly jumps to twice the originally-applied voltage.
154:
110:
1508:
1438:
1423:
1098:, and J. Gunther, 2005. "Analysis of spread spectrum time domain
462:
TDR trace of a transmission line with an almost ideal termination
450:
TDR trace of a transmission line with a 1nF capacitor termination
438:
TDR trace of a transmission line with a short circuit termination
93:
Signal (or energy) transmitted and reflected from a discontinuity
1371:, Application Note, AEA Technology, Inc., AN201, archived from
146:
142:
999:, Instruction Manual, Beaverton, OR: Tektronix, September 1982
802:
1014:, Instruction Manual, Beaverton, OR: Tektronix, November 1971
318:
309:
locations and associated losses, and estimate cable lengths.
83:
113:
to the reflecting impedance can also be determined from the
1001:
First printing is 1982, but copyright notice includes 1971.
114:
809:
Measuring moisture content using time-domain reflectometry
748:, where they help determine the existence and location of
702:
is the impedance of the termination at the far end of the
317:
TDRs use different incident signals. Some TDRs transmit a
426:
TDR trace of a transmission line with an open termination
685:{\displaystyle \rho ={\frac {Z_{t}-Z_{o}}{Z_{t}+Z_{o}}}}
234:{\displaystyle \rho ={\frac {R_{L}-Z_{0}}{R_{L}+Z_{0}}}}
1258:
Geotechnical MeasurementsâProceedings of Geo-Denver2000
1249:
Topp, G.C. and T.P.A. Ferre, 2002. "Water content", in
763:. By observing reflections, any unsoldered pins of a
621:
249:
170:
1265:
Structural Materials Technology NDT Conference 2000
849:
157:is placed on the output of the reflectometer and a
684:
262:
233:
137:The TDR analysis begins with the propagation of a
858:
58:), and to locate discontinuities in a connector,
1658:
790:
755:TDR equipment is also an essential tool in the
520:TDR of step into disconnected APC-7mm connector
1361:
1143:"Aircraft Electrical Wiring Monitoring System"
1121:, Smith, P., Safavi, Mehdi, and M. Lo, Chet. "
821:
729:, as TDRs can detect resistance on joints and
1425:Electrical and electronic measuring equipment
1409:
340:
803:Used in the earth and agricultural sciences
1416:
1402:
1283:
1069:Hamilton Avnet part number P-3636-603-5215
129:or sampler that monitors the reflections.
1385:â TDR for Microwave/RF and Digital Cables
865:spread-spectrum time-domain reflectometry
797:Spread-spectrum time-domain reflectometry
376:spread-spectrum time-domain reflectometry
335:spread-spectrum time-domain reflectometry
1193:Computers and Electronics in Agriculture
1039:." IEEE Sensors Journal. December, 2005.
863:Time domain reflectometry, specifically
556:TDR of step into APC-7mm precision short
88:
18:
1288:. ASM International. pp. 289â302.
1132:". IEEE Sensors Journal. December 2005.
777:
746:technical surveillance counter-measures
568:TDR of step into APC-7mm precision open
544:TDR of step into APC-7mm precision load
532:TDR of step into APC-7mm precision open
1659:
374:Variations of TDR exist. For example,
1397:
1362:DeWinter, Paul; Ashley, Bill (2011),
1100:reflectometry for wire fault location
1109:". IEEE Sensors Journal 5:1469â1478.
1050:Undersea Fiber Communication Systems
744:TDRs are also very useful tools for
290:The reflections are measured at the
1350:from the original on 9 October 2022
74:. If the conductor is of a uniform
13:
1150:
414:Simple TDR made from lab equipment
402:Simple TDR made from lab equipment
312:
14:
1688:
1330:Work begins to repair severed net
1317:
1305:https://doi.org/10.3390/s21238032
1286:Microelectronics Failure Analysis
905:Optical time-domain reflectometer
381:
351:optical time-domain reflectometer
1337:Time Domain Reflectometry Theory
1324:Radiodetection Extended Training
1251:Methods of Soil Analysis. Part 4
1203:Review of Scientific Instruments
938: This article incorporates
933:
850:In semiconductor device analysis
575:
561:
549:
537:
525:
513:
497:
479:
467:
455:
443:
431:
419:
407:
395:
62:, or any other electrical path.
1158:Journal of Geophysical Research
1135:
1112:
1088:
1072:
951:General Services Administration
1063:
1042:
1018:
1004:
989:
980:
971:
962:
926:
859:In aviation wiring maintenance
591:
65:
23:Time-domain reflectometer for
1:
1389:TDR vs FDR: Distance to Fault
920:
791:Used in anchor cables in dams
586:vertical: 20 mρ/div
508:vertical: 0.5 ρ/div
281:
109:of the reflected signal. The
1621:Arbitrary waveform generator
1524:Transformer ratio arm bridge
1365:Step vs Pulse TDR Technology
7:
878:
822:In geotechnical engineering
813:A TDR is used to determine
584:horizontal: 200 ps/div
357:Time-domain transmissometry
105:can be determined from the
10:
1693:
1052:, Elsevier Science, 2002,
895:Noise-domain reflectometry
806:
570:horizontal: 20 ps/div
345:The equivalent device for
1667:Electronic test equipment
1626:Digital pattern generator
1613:
1557:
1519:Time-to-digital converter
1514:Time-domain reflectometer
1431:
1170:, and J. Gunther, 2005. "
1081:, P. Smith, M. Diamond, "
900:NicolsonâRossâWeir method
506:horizontal: 1 ns/div
341:Variations and extensions
132:
33:time-domain reflectometer
1231:Water Resources Research
716:
599:signal propagation speed
388:characteristic impedance
272:characteristic impedance
885:Frequency domain sensor
727:telecommunication lines
1677:Semiconductor analysis
1646:Video-signal generator
1383:TDR for Digital Cables
946:Federal Standard 1037C
940:public domain material
723:preventive maintenance
686:
264:
235:
94:
28:
1474:Microwave power meter
1273:: 101â105. Singapore.
1241:Soil Tillage Research
687:
265:
263:{\displaystyle Z_{0}}
236:
92:
60:printed circuit board
22:
16:Electronic instrument
1499:Peak programme meter
1260:: 80â81. Denver, CO.
1176:IEEE Sensors Journal
1048:José Chesnoy (ed.),
778:In level measurement
619:
247:
168:
1224:Vadose Zone Journal
1213:Vadose Zone Journal
1030:Wire Fault Location
915:Standing wave ratio
1631:Function generator
1105:2010-12-31 at the
1035:2010-12-31 at the
890:Murray loop bridge
855:opens and shorts.
772:integrated circuit
761:transmission lines
682:
260:
231:
95:
29:
1654:
1653:
1590:Spectrum analyzer
1529:Transistor tester
1459:Frequency counter
1454:Electricity meter
1444:Capacitance meter
997:S-6 Sampling Head
784:level measurement
737:, and increasing
704:transmission line
680:
322:widths are used.
276:transmission line
229:
1684:
1641:Signal generator
1595:Waveform monitor
1575:Network analyzer
1418:
1411:
1404:
1395:
1394:
1379:
1377:
1370:
1358:
1357:
1355:
1349:
1342:
1326:â ABC's of TDR's
1299:
1280:, October, 2004.
1145:
1139:
1133:
1116:
1110:
1092:
1086:
1076:
1070:
1067:
1061:
1046:
1040:
1022:
1016:
1015:
1012:7S12 TDR/Sampler
1008:
1002:
1000:
993:
987:
984:
978:
975:
969:
966:
960:
959:
958:
953:. Archived from
937:
936:
930:
815:moisture content
757:failure analysis
691:
689:
688:
683:
681:
679:
678:
677:
665:
664:
654:
653:
652:
640:
639:
629:
579:
565:
553:
541:
529:
517:
501:
483:
471:
459:
447:
435:
423:
411:
399:
269:
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266:
261:
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258:
240:
238:
237:
232:
230:
228:
227:
226:
214:
213:
203:
202:
201:
189:
188:
178:
78:and is properly
41:electrical lines
1692:
1691:
1687:
1686:
1685:
1683:
1682:
1681:
1657:
1656:
1655:
1650:
1636:Sweep generator
1609:
1585:Signal analyzer
1553:
1449:Distortionmeter
1427:
1422:
1375:
1368:
1353:
1351:
1347:
1340:
1334:
1320:
1296:
1153:
1151:Further reading
1148:
1140:
1136:
1117:
1113:
1107:Wayback Machine
1093:
1089:
1077:
1073:
1068:
1064:
1060:, p.171 (COTDR)
1047:
1043:
1037:Wayback Machine
1023:
1019:
1010:
1009:
1005:
995:
994:
990:
985:
981:
976:
972:
967:
963:
943:
934:
932:
931:
927:
923:
881:
861:
852:
824:
811:
805:
793:
782:In a TDR-based
780:
765:ball grid array
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313:Incident signal
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27:fault detection
17:
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1570:Logic analyzer
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1318:External links
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1184:Waddoups, B.,
1182:
1164:
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1134:
1128:2010-05-01 at
1119:Furse, Cynthia
1111:
1087:
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1026:Furse, Cynthia
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957:on 2022-01-22.
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844:surface runoff
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807:Main article:
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382:Example traces
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1378:on 2014-08-26
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1130:archive.today
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1024:Smith, Paul,
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369:optical fiber
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365:coaxial cable
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56:coaxial cable
53:
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43:by observing
42:
38:
34:
26:
21:
1672:Soil physics
1580:Oscilloscope
1565:Bus analyzer
1513:
1464:Galvanometer
1373:the original
1364:
1352:, retrieved
1336:
1285:
1277:
1270:
1264:
1257:
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1074:
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1011:
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996:
991:
982:
973:
964:
955:the original
945:
928:
873:
870:
862:
853:
837:infiltration
833:
828:geotechnical
825:
812:
794:
781:
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344:
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316:
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292:output/input
289:
285:
242:
164:
152:
136:
127:oscilloscope
96:
69:
52:twisted pair
36:
32:
30:
1600:Vectorscope
1534:Tube tester
1504:Psophometer
1484:Megohmmeter
1354:13 February
1226:7: 358-389.
1208::3553â3562.
1181::1469â1478.
1166:Smith, P.,
1163::1699â1708.
1094:Smith, P.,
910:Return loss
592:Explanation
159:step signal
72:reflections
66:Description
1661:Categories
1614:Generation
1605:Videoscope
1494:Peak meter
1479:Multimeter
1218:: 444â475.
921:References
841:stormwater
739:insulation
731:connectors
282:Reflection
153:If a pure
80:terminated
1544:Voltmeter
1539:Wattmeter
1469:LCR meter
1246::125â132.
1236::574â582.
1198::213â237.
750:wire taps
642:−
623:ρ
327:rise time
307:connector
191:−
172:ρ
123:rise time
107:amplitude
99:impedance
76:impedance
45:reflected
1558:Analysis
1549:VU meter
1489:Ohmmeter
1432:Metering
1345:archived
1186:C. Furse
1168:C. Furse
1126:Archived
1103:Archived
1096:C. Furse
1079:C. Furse
1033:Archived
879:See also
733:as they
111:distance
54:wire or
1509:Q meter
1439:Ammeter
735:corrode
694:Where Z
274:of the
270:is the
145:into a
117:that a
101:of the
1292:
1056:
349:is an
303:splice
243:where
147:system
143:energy
133:Method
48:pulses
1376:(PDF)
1369:(PDF)
1348:(PDF)
1341:(PDF)
942:from
717:Usage
325:Fast
319:pulse
296:cable
119:pulse
84:radar
25:cable
1356:2012
1290:ISBN
1054:ISBN
367:and
305:and
139:step
115:time
97:The
1174:".
725:of
361:TDT
37:TDR
1663::
1244:47
1234:16
1206:73
1196:31
1161:79
949:.
846:.
706:.
371:.
353:.
337:.
278:.
86:.
31:A
1417:e
1410:t
1403:v
1298:.
1216:2
1179:5
711:t
700:t
696:o
675:o
671:Z
667:+
662:t
658:Z
650:o
646:Z
637:t
633:Z
626:=
359:(
256:0
252:Z
224:0
220:Z
216:+
211:L
207:R
199:0
195:Z
186:L
182:R
175:=
35:(
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