ekS - Instytut Agrofizyki im. Bohdana DobrzaÅskiego PAN w Lublinie ...

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D-LOG/mpts is a moisture/pressure/temperature/salinity datalogger for field application that is able to switch between up to120 probes type of FP/mts (or FP/m). The above-mentioned TDR-based devices are worldwide patented and produced in the Institute of Agrophysics, Polish Ac. of Sciences in Lublin. 12.1. FOM/mts - Field Operated Meter for determination of moisture, temperature and salinity of soils Fig. 57. Portable TDR meter, FOM/mts, for the measurement of soil water content using TDR technique as well as soil apparent electrical conductivity and temperature FOM/mts (Fig. 57) is a TDR (Time-Domain Reflectometry) based, portable, battery operated, microprocessor-controlled device designed for in situ field measurements of soil water content, temperature and salinity (bulk electrical conductivity) from the same probe. It is designated for periodic measurements at random and/or fixed locations where water content, salinity and temperature distribution is to be determined by readings taken at various levels of the soil profile. It utilizes the FP/mts-type probe. FOM/mts is equipped with a 256 by 64 dot matrix graphic LCD to display data and TDR trace simultaneously. The TDR trace is a voltage-versus-time record of the voltage pulse round-trip along the probe. It is helpful to check the probe status during (break, short) and after its installation (excessive attenuation of the pulse). FOM/mts provides a Mineral/Organic option switch for soils originated from mineral or organic parent 121
material, thus no user calibration is needed to read the soil water content directly. Also FOM/mts-RS equipped with the RS232C serial port is offered. This makes it possible to operate the meter under control of any IBM compatible PC. • Features:of FOM/mts • Pulse: sin -like needle pulse having 200 ps rise-time : • Range of readings: − volumetric water content: 0 ÷ 100 % − temperature: -20 ÷ +50 °C − electrical conductivity: 0.000 ÷ 1 S/m • Accuracy: − water content absolute error: displayed water content ±2 % − temperature absolute error: ±0.8 °C or less if read from − individually calibrated probe el. conductivity relative error: ±10 % for 0 ÷ 1 S/m or less if read from individually calibrated probe • Resolution of readings: • volumetric water content: 0.1 % • temperature: 0.1 °C • el. conductivity: 0.001 S/m • Time of test: less than 20 s • Display: 256 x 64 dot matrix LCD • Ambient temperature: 0 ÷ +50 °C • Dimensions: 26 x18 x 13 cm • Weight: 3.75 kg with battery • Capacity: 150 readings in continuous mode • Supply unit: 12 V, 2200 mAh maintenance-free lead-acid rechargeable battery • Battery charger: automatic, overcharge-safe, wall charger • Maintenance: The meter is not user serviceable. No special maintenance means are required. If the apparatus is to be stored, recharge the battery each three - four months. Temperature of storage: -10 ÷ +50°C. 12.2. New prototype version of FOM/mts soil water content, salinity and temperature measurements The device presented in Fig. 58 is the new generation of TDR soil water content, salinity and temperature meter constructed in the Institute of Agrophysics. 122
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TDR METHOD FOR THE MEASUREMENT OF W
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PREFACE The importance of water for
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CONTENTS 1. Status of water as an s
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12.2. New prototype version of FOM/
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that stimulate the phenomena and pr
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The solution to the problem of elec
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3. ELECTRICAL MEASUREMENTS METHODS
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v = c 1 2L = = ( θ ) n ∆t ε (2)
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The TDR probe consists of two waveg
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ε a =1 and φ=0.5 the Eq. (10) has
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The experiment description is given
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Results obtained with the discussed
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Notice that at C s = 0, ie when dis
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water orientation polarization [s],
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Fig. 8. Frequency dispersion of the
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The measurements were performed in
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5. EVALUATION OF DIELECTRIC MIXING
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ε α = ∑V α iε i (29) i where
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where SAND and CLAY are percents of
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Below the transition value, the soi
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To verify the observations concerni
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6. TEMPERATURE EFFECT ON SOIL DIELE
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chamber and the freezer, only one w
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The user interface on the main comp
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soil sample volumetric water conten
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close vicinity of the analyzed obje
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process of measurement is non-destr
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dielectric permittivity change caus
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The values of the refractive index
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The relative, ∆n/∆T, and absolu
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Fig. 25. The temperature effect on
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The temperature effect of TDR soil
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The purpose of the above discussion
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( ,25 + T )( 45 + T ) 49 9 f rel =
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8. THE ACCURACY OF SOIL WATER CONTE
Page 72 and 73: gravimetric method and the soil ref
Page 74 and 75: where: a 0 ÷ a 6 are coefficients
Page 76 and 77: values of p F calculated for the re
Page 78 and 79: eason of this is the fact that wate
Page 80 and 81: 9 ∆θ = 0,2 ⋅10 ⋅ ∆t = 0.00
Page 82 and 83: values of θ rel for lower values o
Page 84 and 85: 9. COMPARISON OF OPEN-ENDED COAX AN
Page 86 and 87: ε" = EC ε d " + (82) 2π fε wher
Page 88 and 89: dielectric permittivity, the dielec
Page 90 and 91: The applied lumped capacitance mode
Page 92 and 93: stainless steel wires soldered to t
Page 94 and 95: ε’ Open Coax and ε b-TDR , exce
Page 96 and 97: − − The difference of the imagi
Page 98 and 99: Integrated Circuit) recently introd
Page 100 and 101: 10.2. Electromechanical microwave s
Page 102 and 103: RF1. Two PIN diodes in series in ea
Page 104 and 105: The significant aspect of the proto
Page 106 and 107: visible for lower values of soil el
Page 108 and 109: In the TDR method the signal propag
Page 110 and 111: description of functional and techn
Page 112 and 113: MASTER modules are wireless transce
Page 114 and 115: time the Real Time Clock module wak
Page 116 and 117: ase station distinguishes A SLAVE d
Page 118 and 119: sensor, format the data received fr
Page 120 and 121: 12. SOIL WATER STATUS MONITORING DE
Page 124 and 125: For compatibility reasons it uses t
Page 126 and 127: D-LOG/mts (Fig. 59) is a TDR (Time-
Page 128 and 129: 12.4. FP/m, FP/mts - Field Probe fo
Page 130 and 131: inside of a separate polyethylene b
Page 132 and 133: differential water capacity and the
Page 134 and 135: − maximum number of LP/p probes t
Page 136 and 137: 12.7. LP/t - Laboratory Probe for s
Page 138 and 139: From the collected data set, after
Page 140 and 141: 25. de Loor G.P.: Dielectric proper
Page 142 and 143: TDR. Symposium on Time Domain Refle
Page 144 and 145: 100. Whalley W.R.: Considerations o
Page 146 and 147: Fig. 14. Fig. 15. Fig. 16. Fig. 17.
Page 148 and 149: Fig. 38. The three-rod TDR probe -
Page 150 and 151: Fig. 67. A set of LP/ms and LP/p LO
Page 152: Table 17. An example of the executa
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