Apparatus and methods for generating unambiguous large amplitude timing makers in time ...

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US006104200A
United States Patent [19] [11] Patent Number: 6,104,200
Hook [45] Date of Patent: Aug. 15, 2000
[54] APPARATUS AND METHODS FOR FOREIGN PATENT DOCUMENTS
GENERATING UNAMBIGUOUS LARGE
1444540 1/1976 United Kingdom .
AMPLITUDE TIMING MAKERS IN TIME
2216355 1/1989 United Kingdom .
DOMAIN REFLECTOMETRY SYSTEMS FOR
WO 89/12820 1/1989 WIPO .
MEASURING PROPAGATION VELOCITIES
OF RF PULSES TO DETERMINE MATERIAL OTHER PUBLICATIONS
LIQUID CONTENTS MOISTURE
Alharthi, A. and Lange, J ., Soil Water Saturation: Dielectric
Determination, Water Resources Research, vol. 23, No. 4,
[75] Inventor: William R. Hook, Shawnigan Lake,
pp. 591—595 (Apr, 1987).
Canada
(List continued on neXt page.)
[73] Assignee: Precision Moisture Instruments, Inc.,
Primary Examiner—Josie Ballato
Shawnigan Lake, Canada
Assistant Examiner—Jose M. Sohs
[57] ABSTRACT
[21] Appl. No.: 09/036,723
[22] Filed: Mar. 6, 1998 Time Domain Re?ectometry (“TDR”) methods and appara
tus for measuring propagation velocities of RF pulses to
Related US. Application Data determine material liquid contents, moisture pro?les, mate
rial levels and dielectric constants including: i) TDR probes
and/or probe adaptors, including series averaging probes and
[62] Division of application No. 08/335,101, Nov. 17, 1994, Pat.
multi-segment probes, all employing remotely operable,
No. 5,726,578, which is a division of application No.
08/071,748, Jun. 9, 1993, Pat. No. 5,376,888. normally open, variable impedance devices such as diodes;
ii) bias insertion and switching networks for rendering
[51] Int. Cl.7 ................................................... .. G01R 27/04 selected normally open variable impedance devices conduc
[52] US. Cl. ........................ .. 324/643; 324/533; 324/534; tive one at a time to establish precise unambiguous timing
324/601; 324/647
markers T1 . . . Tn; iii) an RF cable coupling the probe to a
[58] Field of Search ........................ .. 73/304 C; 324/643, TDR instrument; and, iv) a TDR instrument having: a) a
324/642, 632, 533, 534, 601 variable impedance device Control Section including a
Divide-By-2 circuit and a Diode Drive circuit; b) an RF
[56] References Cited section containing a Pulse Generator, a Sample-And-Hold
circuit, and a Variable Delay circuit; c) a Synchronous
U.S. PATENT DOCUMENTS Detection Section including a Repetition Rate Generator;
?lter, AC ampli?ers, Analog Multiplier and Low Pass Filter
3,551,677 12/1970 Brewster . connected in series and receiving sampled signals; d) a
3,757,222 9/1973 Oberbury . Delay circuit and AC ampli?er for transmitting a Synchro
3,771,056 11/1973 Zimmerman . nous Detector Reference signal to the Multiplier; and e),
3,789,296 1/1974 Caruso, Jr. et al. . capability for conditioning the TDR instrument to operate in
3,829,796 8/1974 Bakken .
a remotely shortable diode ON/OFF modulation mode or a
3,853,005 12/1974 Schendel . Time Delay modulation mode. Repetitively sampled re?ec
3,993,933 11/1976 Menninga .
tions are processed through a Synchronous Detection Sys
3,995,212 11/1976 Ross .
tem to convert square wave signals generated by the
4,013,950 3/1977 Falls .
Sample-And-Hold circuit into DC output signals V(T) rep
4,109,117 8/1978 Wrench, Jr. et al. .
resentative of the difference function between re?ections
4,135,397 1/1979 Krake .
under shorted and open conditions and/or of the slope of the
4,254,214 6/1988 Bramanti et al. .
4,281,285 7/1981 Bastida . diode open re?ection.
(List continued on neXt page.) 12 Claims, 13 Drawing Sheets
55
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RF DISPLAY
550mm | SECTION
6,104,200
Page 2
US. PATENT DOCUMENTS Malicki, MA. and Skierucha, W.M., A Manually Controlled
TDR Soil Moisture Meter Operating With 300ps Rise—Time
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Measurement of Soil and Plant Water Status, vol. 1—Soils,
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4,782,313 11/1988 Brant, Jr. . Nadler, A., Dasberg, S. and Lapid, 1., Time Domain Re?ec
4,786,857 11/1988 Mohr, et al. .
tometry Measurements of Water Content and Electrical
4,807,471 2/1989 Courane et al. .
Conductivity of Layered Soil Columns, Soil Science Society
4,918,375 4/1990 Malicki et al. .
ofAmerica Journal, vol. 55, pp. 938—943 (Jul.—Aug., 1991).
4,949,076 8/1990 Wann.
Rhoades, J.D., Raats, P.A.C. and Prather, R.J., Effects of
5,136,249 8/1992 White 618.1. .......................... .. 324/643
5,376,888 12/1994 Hook 618.1. 324/643 Liquid—phase Electrical Conductivity, Water Content, and
Surface Conductivity on Bulk Soil Electrical Conductivity,
5,726,578 3/1998 Hook 618.1. ........................... .. 324/643
Soil Science Society of America Journal, vol. 40, pp.
OTHER PUBLICATIONS 651—655 (1976). (No Month).
Rhoades, J .D. and van Schilfgaarde, J ., An Eledtrical Con
Anon., Circuit Description, Tektronix 1502 TDR Instrument ductivity Probe for Determining Soil Salinity, Soil Science
Operators and Maintenance Manual, Sect. 3, pp. 3—1—3—6 Society of America Journal, vol. 40, pp. 647—651 (1976).
and Pulser/Sampler Drg. (rev.) (Jan., 1986). (No Month).
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Multiplexing Soil Moisture Measurement by Time—Domain tion of Time Domain Re?ectometry for Water Content
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Baker, J.M. and lascano, R.J., The Spatial Sensitivity of (Oct., 1990).
Time—Domain Re?ectometry, Soil Science, vol. 147, No. 5, Topp, G.C., The Application of Time—Domain Re?ectom
pp. 378—384 (May, 1989). etry (TDR) To Soil Water Content Measurement, Proceed
ings of International Conference on Measurement of Soil
Dalton, F.N., Herkelrath, W.N., RaWlins, DS and Rhoades,
and Plant Water Status, vol. 1—Soilsm 00, 85—93, Academic
J .D., Time—Domain Re?ectometry: Simultaneous Measure
Press, Inc. (1987). (No Month).
ment of Soil Water Content and Electrical Conductivity With
Topp, G.c., Davis, J.L. and Annan, A.P., Electromagnetic
a Single Probe, Science, vol. 224, pp. 989—990 (1984), (No
Month). Determination of Soil Water Content: Measurements in
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Dalton, F.N. and van Genuchten, M.Th., The Time—Domain
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Re?ectometry Method For Measuring Soil Water Content
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And Salinity Geoderma, vol. 38, pp. 237—250 (1986), (No
Determination of Soil Water Content Using TDR:II, Evalu
Month).
ation of Installation and Con?guration of Parallel Transmis
Dasberg, S. and Dalton, F.N., Time Domain Re?ectometry sion Lines, Soil Science Society of America Journal, vol. 46,
Field Measurements of Soil Water Content and Electrical pp. 672—678 (1982). (No Month).
Conductivity, Soil Science Society of America, vol. 49, pp. Topp, GO and Davis, J.L., Time—Domain Re?ectometry
293—297 (1995). (TDR) and Its Application to Irrigation Scheduling,
Dasberg, S. and Hopmans, J.W., Time Domain Re?ectom Advances in Irrigation, vol. 3, pp. 107—127, Academic Press,
etry Calibration for Uniformly and Nonuniformly Wetted Inc. (1985). (No Month).
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America Journal, vol. 56, pp. 1341—1345 (1992). Content using Time—domain Re?ectrometry (TDR): A Field
Fellner—Feldegg, H., The Measurement of Dielectrics in the Evaluation, Soil Science Society of America Journal, vol.
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Multiple Re?ection and Attenuation of Time Domain
Remote Diode Shorting Improves Measurement of Soil
Re?ectometry Pulses: Theoretical Considerations for Appli
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ment of Solute Travel Times Using Time Domain Re?ec Measurement Using Time Domain Re?ectometry, Water
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(1986). (No Month). (1987). (No Month).

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