Campbell TDR100 Instruction Manual
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Campbell TDR100 Instruction Manual

Reflectometer
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TDR100
Revision: 5/15
C o p y r i g h t
©
2 0 0 0 - 2 0 1 5
C a m p b e l l
S c i e n t i f i c ,
I n c .

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Summary of Contents for Campbell TDR100

  • Page 1 TDR100 Revision: 5/15 C o p y r i g h t © 2 0 0 0 - 2 0 1 5 C a m p b e l l S c i e n t i f i c ,...

  • Page 3: Limited Warranty

    Limited Warranty “Products manufactured by CSI are warranted by CSI to be free from defects in materials and workmanship under normal use and service for twelve months from the date of shipment unless otherwise specified in the corresponding product manual. (Product manuals are available for review online at www.campbellsci.com.) Products not manufactured by CSI, but that are resold by CSI, are warranted only to the limits extended by the original manufacturer.
  • Page 4 SCIENTIFIC, INC., phone (435) 227-9000. After an application engineer determines the nature of the problem, an RMA number will be issued. Please write this number clearly on the outside of the shipping container. Campbell Scientific’s shipping address is: CAMPBELL SCIENTIFIC, INC.
  • Page 5 • Periodically (at least yearly) check electrical ground connections. WHILE EVERY ATTEMPT IS MADE TO EMBODY THE HIGHEST DEGREE OF SAFETY IN ALL CAMPBELL SCIENTIFIC PRODUCTS, THE CUSTOMER ASSUMES ALL RISK FROM ANY INJURY RESULTING FROM IMPROPER INSTALLATION, USE, OR MAINTENANCE OF TRIPODS, TOWERS, OR ATTACHMENTS TO TRIPODS AND TOWERS SUCH AS SENSORS, CROSSARMS, ENCLOSURES, ANTENNAS, ETC.

  • Page 7: Table Of Contents

    TDR100 Packing List ................2 SDM8X50 Packing List ............... 2 ENCTDR100 Packing List ..............2 4. Quickstart ..............2 Getting Started with TDR100 using PC-TDR ........2 Discussion of Distances and Propagation Velocity (V ) when using TDR100 .................. 3 More Information .................
  • Page 8 ....5 7-1. PC-TDR waveform for CS610 in water..........11 7-2. TDR system components ..............12 7-3. Terminal strip adapters for connections to battery ......13 7-4. ENCTDR100 with SDM8X50, PS150, TDR100, and CR1000 ..16...
  • Page 9 18, 26, 30 and 37%. Solution electrical conductivity is 10.2 –1 dS m ..................... 23 8-4. Typical TDR100 waveform showing key features with numbers 1, 2 and 3.................... 24 8-5. PC-TDR terminal emulator screen showing TDR100 algorithm parameter variables................. 25 8-6.
  • Page 10 Table of Contents...

  • Page 11: Introduction

    Upon receipt of the equipment, inspect the packaging and contents for damage. File damage claims with the shipping company. • Check the contents of the shipment (see Section 3.1, TDR100 Packing List , Section 3.2, SDM8X50 Packing List , and Section 3.3, (p.

  • Page 12: Tdr100 Packing List

    Getting Started with TDR100 using PC-TDR This section lists steps for a simple connection between a computer and the TDR100 to monitor a single TDR probe using PC-TDR software. A single probe is connected directly to the TDR100, and no multiplexers are used.

  • Page 13: Discussion Of Distances And Propagation Velocity

    RS-232 connector on the TDR100 The RS-232 connector on the TDR100 is used for communication between a serial communication port of a computer and the TDR100. A 9- conductor cable is supplied with the TDR100. Serial communication port 1 is the default setting and can be changed in PC-TDR menu Settings/Communications.

  • Page 14: Waveform Of A Cs610 In Water

    1.0, the apparent distance to the end of the cable is 5 x (1.0/0.78) = 6.41 m. Typical cable V ’s range from 0.67 to 0.9. Campbell Scientific TDR probes use RG-58 with a V of 0.80, RG-8 with a V of 0.84, and...

  • Page 15: More Information

    , for PC-TDR HELP details. (p. 9) Overview The TDR100 has a single BNC connector for communication with an attached coaxial cable. To measure multiple sensors the TDR100 requires one or more SDM8X50 or SDMX50 multiplexers. The SDM8X50 is a 50 ohm, coaxial, 8:1 multiplexer.

  • Page 16: System Specifications

    TDR system that includes a compatible datalogger, TDR100, SDMX50 series or SDM8X50 multiplexers, 12 V power supply, weatherproof enclosure, and solar panel is recommended. A single TDR probe can be connected directly to the TDR100 or multiple probes connected via coaxial multiplexer units (SDMX50 series and SDM8X50).

  • Page 17: Electromagnetic Compatibility

    TDR100 Electromagnetic Compatibility The TDR100 is Πcompliant with performance criteria available upon request. RF emissions are below EN55022 limit. The TDR100 meets EN61326 requirements for protection against electrostatic discharge and surge except for electrostatic discharge on the center conductor of the panel BNC connector.

  • Page 18: Electrical

    PC-TDR requires a connection from a COM port of the computer to the RS- 232 port of the TDR100. Choice of COM port and baud rate is made in PC- TDR menu Settings/Communications. The baud rate is set during TDR100 production to 57600.

  • Page 19: Pc-Tdr Help

    Multiplexer – configure multiplexer switching Calibration Function – select calibration functions for volumetric water content and bulk electrical conductivity Units – select meters or feet 7.1.2.3 Options Menu Terminal Emulator – line command mode of PC-TDR Advanced – link for downloading TDR100 operating system...

  • Page 20: Pc-Tdr Parameter Selection Boxes

    Average – sets the number of measurements averaged at a given distance from the TDR100. A value of 4 is recommended. Higher values can be used when noise is present. Averaging is useful when noise from power sources or when noise of random nature is superimposed on the reflection waveform.

  • Page 21: A Discussion Of Start And Length Parameters

    7.1.3.3 A Discussion of Start and Length Parameters Only the waveform reflection near the probe is used for water content determination. The reflections for most of the cable between the TDR100 and the TDR probe are not used for TDR100 measurements. The apparent probe length algorithm begins analysis of the probe waveform at the distance set by Waveform Start.

  • Page 22: System Components: Datalogger Control

    TDR100 TABLE 7-1. Recommended Waveform Length Values for Range of TDR Probe Rod Lengths Assuming Soil Porosity of 0.60 Recommended Waveform Probe Rod Length (m) Length Value (m) 0.10 to 0.20 0.21 to 0.30 0.31 to 0.40 0.41 to 0.6 0.61 to 0.75...

  • Page 23: Datalogger

    CRBasic program to the datalogger. 7.2.3 TDR100 The TDR100 contains the pulse generator for the signal applied to a TDR probe. The TDR100 also digitizes the reflection and applies numerical algorithms for measuring volumetric water content or electrical conductivity.

  • Page 24: Grounding

    C1, C2, and C3 of TDR100 and multiplexer(s). The SDM address of the TDR100 is set using the thumbwheel switch on the TDR100 front panel. The address selected on the TDR100 must match the...

  • Page 25: Sdm Cable And Cable Length Considerations

    There are a maximum of three multiplexer levels (see FIGURE A-2). The level 1 multiplexer has an address value equal to the TDR100 address plus 1. Level 2 multiplexers have an address value equal to the TDR100 address plus 2 and the level 3 multiplexers have an address value equal to the TDR100 address plus 3.

  • Page 26: Soil Probes

    Both volumetric water content and electrical conductivity can be measured using fixed spacing 2-rod designs and 3-rod designs. Campbell Scientific manufactures 3-rod TDR probes with rod lengths ranging from 0.075 m to 0.3 m.

  • Page 27: Determining Probe Constant, K , Using Pc-Tdr

    Edlog dataloggers are provided at www.campbellsci.com/old-manuals. 7.3.1 TDR100() CRBasic Instruction The TDR100 instruction is used to measure one or more time domain reflectivity (TDR) probes attached to a TDR100 device. Syntax TDR100 ( Dest, SDMAddress, Option, Mux/ProbeSelect, WaveAvg, Vp, Points,...
  • Page 28 (maximum of 8). 0 is entered for any level not used. WaveAvg: The WaveAvg parameter is used to define the number of waveform reflections averaged by the TDR100 to give a single result. A waveform averaging value of 4 provides good signal-to-noise ratio under typical applications.

  • Page 29: Operation

    This value is supplied by Campbell Scientific for the probes we manufacture. The value of this parameter only has an affect when Option 0, La/L, is used for the measurement.
  • Page 30 − 01138 01758 The TDR100 generates a very fast rise time pulse that is sent to the connecting cable and probe. Reflections over a specified length of transmission line are sampled and digitized. Discontinuities in cable impedance will cause changes in the amplitude of the reflected signal.

  • Page 31: Cable Length And Soil Electrical Conductivity Effect On Water Content Determination

    TDR probe. The pulse generated by the TDR100 and its reflections are subject to distortion during travel between the TDR100 and the TDR probe. The cable connecting the probe to the reflectometer has a characteristic impedance resulting in both resistive and reactive losses.

  • Page 32: Soil Electrical Conductivity Effect On Water Content Measurement

    RG8. Careful probe design ensures correct probe impedance giving robust reflections. All TDR probes offered by Campbell Scientific are designed to optimize accuracy when longer cable lengths are used.

  • Page 33: Algorithm Description And Parameter Adjustment

    TDR measurements are taken. Algorithm Description and Parameter Adjustment This section presents a general description of the algorithms in the TDR100 for electrical conductivity and water content measurement. 8.3.1 Algorithm for Calculation of TDR Probe Rod Apparent Length Equation [2] of Section 8.1, TDR Principles...

  • Page 34: Algorithm Parameter Adjustment For Special Conditions

    FIGURE 8-4) and the width of the waveform window as defined by PC-TDR or datalogger instruction parameters. waveform data point FIGURE 8-4. Typical TDR100 waveform showing key features with numbers 1, 2 and 3. The algorithm to calculate apparent length uses both the waveform values and the first derivative of the waveform to identify the beginning and end of the probe.

  • Page 35: Algorithm For Calculation Of Bulk Electrical Conductivity

    TDR100 to calculate bulk electrical conductivity. The electrical conductivity calculation uses waveform values for the region immediately before the TDR probe and values from about 200 meters from the TDR100. The value at the location before the probe is used to calculate the applied signal and the 200 meter values are used for the reflected signal.

  • Page 36: Algorithm Parameter Adjustment For Special Conditions

    5. With the point of the maximum first derivative as the right hand point, define a window of 10 waveform values. Incrementally move this window toward the TDR100 until all values are less than the threshold calculated in step 4.

  • Page 37: References

    TDR100 waveform and derivative near probe index max_derivative max_deriv 1000 data point waveform waveform derivative values used for applied signal FIGURE 8-6. Waveform and derivative values near TDR probe and locations of index for point of maximum derivative and maximum derivative value.
  • Page 38 TDR100 Rhoades, J.D., P.A.C. Raats, and R.J. Prather. 1976. Effects of liquid-phase electrical conductivity, water content and surface conductivity on bulk soil electrical conductivity. Soil Sci. Soc. Am. J. 40:651-655.

  • Page 39: Sdmx50-Series Multiplexers

    A.1 General Prior to the SDM8X50, the SDMX50 series multiplexers were used with the TDR100 to measure multiple sensors. The SDMX50SP was identical to the SDM8X50 in form, fit, and function. The SDMX50 came with the multiplexer mounted in a 10” x 12” enclosure, similar to the SDM8X50-E. The SDMX50LP included the backplate and multiplexer found in the SDMX50 but shipped without an enclosure.

  • Page 40: Electrical

    Appendix A. SDMX50-Series Multiplexers SDMX50SP Multiplexer Weight: 590 g When the 50 Ohm circuit board (1.3 lb) multiplexer will Coaxial encased in metal be housed in the Multiplexer Multiplexer housing and a same enclosure Housing with Strain separate strain as the datalogger Dimensions with Relief Bracket relief bracket.

  • Page 41: Sdm Communication

    Edlog addresses and jumper positions is provided in the 2/10 version of the TDR100 manual available at www.campbellsci.com/old-manuals. It is recommended to use a TDR100 address of 0, level 1 SDMX50 address of 01, level 2 SDMX50 address of 02, and level 3 SDMX50 address of 03.
  • Page 42 Appendix A. SDMX50-Series Multiplexers FIGURE A-2. Location of address jumpers on SDMX50...

  • Page 43: Cr1000 Program Example

    Appendix B. Example Program B.1 CR1000 Program Example This CR1000 program measures and records analog measurements and volumetric water content. It also captures the TDR probe waveforms. Equipment Wiring CR1000 TDR100 SDM8X50 SW12 +12 V 12 V Sensor Wiring TDR100...
  • Page 44 'Define Data Tables ---------------------------------------------- DataTable (Dat15min,1,-1) '15-minute Data Table (i.e. Analog Measurements) DataInterval (0,15,Min,10) Minimum (1,batt_volt,IEEE4,0,False) Average (1,Panel_temp,IEEE4,0) EndTable DataTable (Data_TDR,1,-1) '2-Hour Data Table (i.e. TDR100 VWC Measurements) DataInterval (0,120,Min,10) Minimum (1,batt_volt,IEEE4,0,False) Average (1,Panel_temp,IEEE4,0) Sample (8,LaL(),IEEE4) sample (8,LedieuVWC(),FP2) sample (8,ToppVWC(),FP2) EndTable DataTable (TDR_Wave,1,240) 'Data Table (i.e.
  • Page 45 '************************************* SW12 (1) 'Turn on 12V Power to TDR100 & SDMX50 'Note: Wire TDR100 & SDM8X50 12V power leads to CR1000 SW12 Terminal Delay (1,2,Sec) 'pause 2 sec to allow power supply voltage to settle 'Measure La/L on SDMX50 channel #1 thru channel#8 & convert to VWC using Topp Eq.

  • Page 46: Example Program

    Appendix B. Example Program Flag(2)=0 'reset state of Flag 2 SW12 (0 ) 'Switched 12V Low endif 'EndIf ******************************** PortsConfig (&B00000111,&B00000000) 'configure SDM ports C1,C2,C3 as inputs NextScan EndProg...
  • Page 48 • info@campbellsci.com.cn • info@campbellsci.de www.campbellsci.com www.campbellsci.de Campbell Scientific do Brasil Ltda. (CSB) Campbell Scientific Spain, S. L. (CSL Spain) Rua Apinagés, nbr. 2018 ─ Perdizes Avda. Pompeu Fabra 7-9, local 1 CEP: 01258-00 ─ São Paulo ─ SP 08024 Barcelona...

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