INSTRUCTION MANUAL TDR100 Revision: 9/05 C o p y r i g h t ( c ) 2 0 0 0 - 2 0 0 5 C a m p b e l l S c i e n t i f i c , I n c .
Warranty and Assistance The TDR100 is warranted by CAMPBELL SCIENTIFIC, INC. to be free from defects in materials and workmanship under normal use and service for twelve (12) months from date of shipment unless specified otherwise. Batteries have no warranty. CAMPBELL SCIENTIFIC, INC.'s obligation under this warranty is limited to repairing or replacing (at CAMPBELL SCIENTIFIC, INC.'s option) defective products.
TDR100 Table of Contents PDF viewers note: These page numbers refer to the printed version of this document. Use the Adobe Acrobat® bookmarks tab for links to specific sections. 1. Introduction..................................................................1 1.1 TDR100 Packing List ...............................................................................1 1.2 ENCTDR100 Packing List .......................................................................1 2. System Specifications....................
TDR100 Table of Contents 5.8 Soil Probes ............................................................................................. 17 5.8.1 Determining Probe Constant, Kp, using PCTDR.......................... 18 6. Datalogger Instructions for TDR Measurements ....18 6.1 CR10X and CR23X Datalogger Instruction 119 ................................... 18 6.2 Discussion of TDR Instruction Parameters (Instruction 119)................ 19 6.2.1 Parameter 1: SDM address .......................................
TDR100 Table of Contents 8-1 Waveforms collected in a sandy loam using CS610 probe with RG8 connecting cable. Volumetric water content is 24% and bulk electrical conductivity is 0.3 dS m-1 ............................28 8-2 Waveforms collected in a sandy loam using CS610 probe with RG8 connecting cable. Volumetric water content values are 10, 16, 18, 21 and 25%. Solution electrical conductivity is 1.0 dS m-1...................................................................
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TDR100 1. Introduction This document presents operating instructions for the TDR100 and associated equipment and discusses time domain reflectometry (TDR) principles. Section 3 (Getting Started with TDR100 using PCTDR) describes a simple start-up configuration to quickly and easily display TDR probe waveforms using PCTDR. The TDR100 can be controlled either by a computer using Windows software PCTDR or by using Instruction 119 with a CR10X or CR23X datalogger.
TDR100 2. System Specifications 2.1 General See the CR10X, CR23X, or CR1000 datalogger manuals for datalogger specifications. 2.2 Power Consumption 2.2.1 TDR100 • The current demand for the TDR100 during measurement is 270 milliamps. • When the TDR100 is controlled by a datalogger, a 35 second timer puts the device in sleep mode requiring about 20 milliamps. After 35 seconds in sleep mode, a timer puts the TDR100 in standby mode requiring about 2 milliamps.
TDR100 waveform averaging 1 to 128 electrostatic discharge protection internal clamping power supply unregulated 12 volt (9.6 V to 16 V), 300 milliamps maximum temperature range -40°C to 55°C dimensions 210mm x 110mm x 55 mm weight 700 g 2.4. Electromagnetic Compatibility The TDR100 is Œ compliant with performance criteria available upon request. RF emissions are below EN55022 limit.
TDR100 1 is the default setting and can be changed in PCTDR menu Settings/Communications. The baud rate is factory set to 57600. 3. Connect 12 volt power to TDR100 12 volt power to the TDR100 is connected using terminals +12V and GROUND on the panel 5-terminal connector. An external power supply or the 12V terminals of a datalogger can be used for power. The C1, C2 and C3 terminals are for SDM (synchronous device for measurement communication protocol) communications.
TDR100 FIGURE 3-1. Waveform of a CS610 in water. Changing the Waveform Start value to 5.7 m and the Waveform Length to 5 m gives the waveform displayed in Figure 3-2.
TDR100 FIGURE 3-2. Waveform of CS610 in water after changing Start and Length parameters to display relevant portion of reflected signal. 3.2 PCTDR Help Information on PCTDR is available from the HELP menu or by pressing F1. Using F1 gives specific help associated with the position of the cursor or active screen. See Section 4.2 for PCTDR HELP details. 4.
TDR100 Note for use of PCTDR when TDR100 is connected to CR23X or CR1000 datalogger When the TDR100 is connected to a CR23X or CR1000 datalogger using control ports 1-3 for SDM control and SDMX50 multiplexers are also connected, an instruction must be used in the datalogger program to properly configure the control ports. If this is not done, PCTDR will not control the multiplexers.
TDR100 4.3 Menu Selections 4.3.1 File Menu Save Configuration/Load Configuration - save and reload configuration of user-selectable parameters. Saves configuration as .wfd file. Save ASCII Waveform - save displayed waveform as .dat file. Save Mux Setup/Load Mux Setup - save and reload multiplexer setup. Saves as .mux file. Print Graph - send displayed graph to default printer Exit - quit PCTDR 4.3.
TDR100 4.4.2 Waveform 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. Averaging is accomplished by collecting n values at a given distance before collecting values at the next distance increment where n is the value entered in Average.
TDR100 FIGURE 4-1. PCTDR waveform for CS610 in water. The algorithm will use the length of the waveform set by the Waveform Length. After finding the probe beginning, the algorithm searches over the remaining waveform for the end of the probe. The length must be large enough to display a short distance past the end of the probe under the wettest expected conditions. TABLE 4-1. Recommended Waveform Length values for range of TDR probe rod lengths assuming soil porosity of 0.60. Probe rod length (m) 0.
TDR100 Lw = L ⋅ (θv − max + 0176 . ) 0114 . +2 with L the actual probe rod length, and, θv-max the maximum expected volumetric water content. Two m is added for the .5 m before the probe and some distance after the probe end. For example, using a CS610 with 0.3 m probe rod length in a soil with a porosity of 0.6 gives an estimated apparent probe length of 4.04 m. Setting the Waveform Length to 4 m is recommended. 5. System Components: Datalogger Control 5.1 General CR10X, CR23X, or CR1000 FIGURE 5-1.
TDR100 LoggerNet (version 3.0 or higher) are used to create and send the CRBasic Program to the CR1000 datalogger. 5.3 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. The TDR100 communicates with the datalogger using SDM protocol or with a computer using PCTDR and serial communications. 5.
TDR100 5.4.1 Grounding The TDR system should be installed with a single ground point. A good earth ground should be established close to the datalogger/TDR100. A copper clad grounding rod comes with the model CM6 or CM10 tripod. The UTGND kit provides hardware needed for grounding rod use. The dataloggers, TDR100 and SDMX50SP multiplexer have grounding lugs. These lugs should be tied together with short pieces of grounding wire no smaller than 12 AWG.
TDR100 TABLE 5-1.
TDR100 5.6.1 Mounting Equipment in ENCTDR100 The ENCTDR100 is a 16” x 18” weathertight enclosure that is modified for use with a Campbell Scientific TDR system. The ENCTDR100 comes with the following parts: 1. 2. 3. 4. 5. 6. Enclosure Supply Kit; desiccant packs, humidity indicator, cable ties, putty and mounting hardware. ENCTDR100 Enclosure Ground Wire Kit. TDR100/SDMX50 Coaxial Interconnect Cable. TDR100/SDMX50 and TDR100/Datalogger SDM 5-Conductor Cable. Enclosure ENC 16/18 with two 1.
TDR100 from voltage surge damage. Figure 5-3 describes typical signal attenuation from the common to one output channel for frequency range important for TDR measurements. 0 SDMX50 attenuation (dBm) 0.2 0.4 0.6 0.8 1 1.2 1.4 100 1 . 10 3 Frequency (MHz) FIGURE 5-3. SDMX50 signal attenuation. Each of the eight ports can be connected to a probe or another multiplexer (see Figure 5-1). The multiplexers use synchronous communications and require address coordination with the datalogger. See Section 5.
TDR100 FIGURE 5-4. Location of Address Jumpers on SDMX50 5.8 Soil Probes The TDR probes are the sensors of the TDR measurement system and are inserted into the medium to be measured. The probes are a wave guide extension on the end of coaxial cable. Reflections of the applied signal along the waveguide will occur where there are impedance changes.
TDR100 5.8.1 Determining Probe Constant, Kp, using PCTDR Section 6.2.6 presents the principles for TDR measurements of soil electrical conductivity. The result of the measurement must be multiplied by the probe constant (Kp) to give bulk electrical conductivity in S/m (Siemens/meter). The Kp value can be measured using PCTDR. The method requires submersion of the TDR probe rods in de-ionized water of known temperature. See PCTDR HELP for simple instructions. 6.
TDR100 6.2 Discussion of TDR Instruction Parameters (Instruction 119) 6.2.1 Parameter 1: SDM Address The SDM address of the TDR100 is set by selecting hexadecimal values with the thumbwheel switch on the TDR100 front panel. Instruction 119 requires a 2 digit integer that is the base 4 value of the TDR100 address. See Table 5-1 6.2.2 Parameter 2: Output Option 6.2.2.1 Enter 0: Measure La/L In the section on TDR Principles, the equation Ka = La L is presented.
TDR100 Section 7 for discussion of the electrical conductivity measurement method and Section 6.2.13.1 for discussion of Kp.. 6.2.3 Parameter 3: Multiplexer and Probe Selection Addressing scheme: ABCn Where: A -- Level 1 multiplexer channel B -- Level 2 multiplexer channel C -- Level 3 multiplexer channel n -- the number of consecutive probes; addressing starts with the channel specified for the highest level multiplexer. Note: enter a 0 when a level is not used.
TDR100 6.2.5 Parameter 5: Relative Propagation Velocity Relative propagation velocity is the ratio of actual propagation velocity for a transmission line to the propagation velocity in air. A TDR system is typically comprised of components with different signal propagation properties. The Vp for a particular component depends on transmission line characteristics such as the dielectric constant of inter-conductor insulating material. Setting Vp = 1.0 and using apparent distances simplifies system setup.
TDR100 6.2.10 Parameter 10: Probe Offset (meters) Most TDR probes have a block of epoxy or other material which holds the rods rigidly spaced and houses an impedance matching transformer (balun) if used. The algorithm in the TDR100 uses changes in the reflection coefficient to identify end points of the probe. The transition from the coaxial cable to the TDR probe occurs inside the probe block and causes an increase in the reflection coefficient if the probe impedance is greater than the cable impedance.
TDR100 6.2.12 Parameter 12: Multiplier Multiplication factor applied to the value stored in the input location specified in parameter 11. Set to 1 when parameter 2 is 1 or 2. The multiplier can be used for the probe constant value when measuring electrical conductivity. 6.2.13 Parameter 13: Offset Offset value added to the value stored in input location specified in parameter 11. Set to 0 when parameter 2 is 1 or 2. 6.2.13.
TDR100 Entering these constants as the multiplier when using Instruction 119 for electrical conductivity measurement will give units of Siemens/meter. For example, when using a CS600 the value 3.16 can be entered into parameter 12 of Instruction 119 and the electrical conductivity value in Siemens per meter will be written to the input location specified in parameter 11. 6.
TDR100 Mux/ProbeSelect: The Mux/Probe Select parameter is used to define the setup of any multiplexers and attached probes in the system. The addressing scheme used is ABCR, where A = level 1 multiplexer channel, B = level 2 multiplexer channel, C = level 3 multiplexer channel, and R = the number of consecutive probes to be read, starting with the channel specified by the ABC value (maximum of 8). 0 is entered for any level not used.
TDR100 parameter only has an affect when Option 0, La/L, is used for the measurement. Mult, Offset: The Mult and Offset parameters are each a constant, variable, array, or expression by which to scale the results of the measurement. 7. TDR Principles The travel time for a pulsed electromagnetic signal along a waveguide is dependent on the velocity of the signal and the length of the waveguide. The velocity is dependent on the dielectric constant of the material surrounding the waveguide.
TDR100 caused by the probe beginning and end. This information is then analyzed to determine soil water content. While the velocity of the applied pulse along a waveguide is dependent on the dielectric constant of the material surrounding the waveguide, the amplitude of the reflected voltage is dependent on electrical conduction of the applied signal between probe rods. The presence of free ions in the soil solution will result in attenuation of the applied signal.
TDR100 16 meter cable 26 meter cable 45 meter cable 66 meter cable FIGURE 8-1. Waveforms collected in a sandy loam using CS610 probe with RG8 connecting cable. Volumetric water content is 24% and bulk electrical conductivity is 0.3 dS m-1. In general, water content is overestimated with increasing cable length. A calibration of volumetric water content with apparent dielectric constant for a given cable length can improve accuracy.
TDR100 water content = 9.5% water content = 25% FIGURE 8-2. Waveforms collected in a sandy loam using CS610 probe with RG8 connecting cable. Volumetric water content values are 10, 16, 18, 21 and 25%. Solution electrical conductivity is 1.0 dS m-1. water content = 18% water content = 37% FIGURE 8-3. Waveforms collected in a sandy loam using CS610 probe with RG8 connecting cable. Volumetric water content values are 10, 18, 26, 30 and 37%. Solution electrical conductivity is 10.2 dS m-1.
TDR100 9. Programming Examples 9.1 CR10X/CR23X Program Examples Example 1, Measure and Record; Analog Measurements and Volumetric Water Content A CS605 or CS610 probe is connected directly to the TDR100. A cable length of 6.25 meters was determined using PCTDR. The La/L value is converted to volumetric water content using the Ledieu , etal linear calibration function. The program is executed once a minute.
TDR100 ;Turn off the switched 12V to power off the TDR100: 5: Do (P86) 1: 55 Set Port 5 Low ;Set the Output Flag to output data every 5 minutes: 6: If time is (P92) 1: 0 Minutes (Seconds --) into a 2: 5 Interval (same units as above) 3: 10 Set Output Flag High (Flag 0) ;Output a time stamp; year, day, and hour/minute: 7: Real Time (P77) 1: 1220 Year,Day,Hour/Minute (midnight = 2400) ;Output the minimum Battery Voltage: 8: Minimum (P74) 1: 1 Reps 2: 0 Value Only 3: 1 Loc [ Bat_Volt ] ;Output the average D
TDR100 Example 2, Measure and Record; Analog Measurements, Volumetric Water Content, Electrical Conductivity, and Capture a Waveform A CS605 or CS610 probe is connected to Channel #3 of a Level #1 SDMX50 Multiplexer. A cable length of 9.5 meters was determined using PCTDR. The La/L value is converted to volumetric water content using the Topp’s calibration (Section 7). The program is executed every one minute while Flag 1 is High. The user can set Flag 1 high or low to control when data are stored.
TDR100 ;Measure the CS610 probe connected to Channel 3 of the level 1 SDMX50 and return La/L. 5: TDR100 Measurement (P119) 1: 0 SDM Address 2: 0 La/L 3: 3001 MMMP Mux & Probe Selection 4: 4 Waveform Averaging 5: 1 Vp 6: 250 Points 7: 9.5 Cable Length (meters) 8: 5 Window Length (meters) 9: .3 Probe Length (meters) 10: .085 Probe Offset (meters) 11: 3 Loc [ LaL_CH3 ] 12: 1.0 Mult 13: 0.
TDR100 ;Measure Electrical Conductivity on the same CS610 TDR probe connected to Channel 3. 9: TDR100 Measurement (P119) 1: 0 SDM Address 2: 3 Electrical Conductivity 3: 3001 MMMP Mux & Probe Selection 4: 4 Waveform Averaging 5: 1 Vp 6: 250 Points 7: 9.5 Cable Length (meters) 8: 5 Window Length (meters) 9: .3 Probe Length (meters) 10: .085 Probe Offset (meters) 11: 5 Loc [ EC_CH3 ] 12: 7.4 Mult 13: 0.0 Offset ;Get the raw waveform for the CS610 probe on Channel 3.
TDR100 ;Output the Battery_Voltage, DataLogger Temperature, WaterContent, ;and Electrical Conductivity. 14: Sample (P70) 1: 4 Reps 2: 1 Loc [ Bat_Volt ] ;Output the WaveForm data point 1 to WaveForm data point 259: 15: Sample (P70) 1: 259 Reps 2: 11 Loc [ WF_1 ] *Table 2 Program 02: 0.
TDR100 Example 3, Measure and Record; Volumetric Water Content and Analog Measurements Eight CS605 or CS610 probes are connected to Channel #1 through #8 of a Level #1 SDMX50 multiplexer. A cable length value of 10 meters was determined using PCTDR. The La/L value is converted to volumetric water content using the Topp calibration. The program is executed every two minutes. The array id, time, volumetric water content and analog measurements are output to Final Storage every two minutes.
TDR100 4: Beginning of Loop (P87) 1: 0 Delay 2: 8 Loop Count ;Square La/L to convert to dielectric constant: ;Note: The user must manually allocate 8 input locations "WC_1" through WC_8". 5: Z=X*Y (P36) 1: 1 2: 1 3: 11 -- X Loc [ LaL_1 -- Y Loc [ LaL_1 -- Z Loc [ WC_1 ] ] ] ;Multiply the dielectric constant by 0.1 to prepare for the 3rd order polynomial ;with the appropriately scaled coefficients for Topp's calibration: 6: Z=X*F (P37) 1: 11 2: 0.
TDR100 ;Output the 8 water content measurements and battery voltage: 12: Sample (P70) 1: 9 Reps 2: 11 Loc [ WC_1 ] *Table 2 Program 02: 0.
TDR100 Example 4, Measure and Record; Analog Measurements and Volumetric Water Content In this example analog measurements are made every 5 minutes and TDR100 measurements are made every 60 minutes. Twenty-nine CS605 or CS610 probes are connected to 4 SDMX50 multiplexers (Figure 9-1). The cable length values were determined using PCTDR. The La/L value is converted to volumetric water content using the linear calibration function of Ledieu, etal. (1986). The program is executed every 5 minutes.
TDR100 5: TDR100 Measurement (P119) 1: 00 SDM Address 2: 0 La/L 3: 3006 MMMP Mux & Probe Selection 4: 4 Waveform Averaging 5: 1 Vp 6: 250 Points 7: 5.75 Cable Length (meters) 8: 5 Window Length (meters) 9: .3 Probe Length (meters) 10: .085 Probe Offset (meters) 11: 11 Loc [ WC_3001 ] 12: 1138 Mult 13: -0.1758 Offset ;Switch the level 1 SDMX50 to Channel 1 and measure the 8 probes on the Level 2 ;multiplexer that is connected to channel 1 of the level 1 mux (apparent cable length to ;probe 9.
TDR100 ;Switch the level 1 SDMX50 to Channel 2, the level 2 SDMX50s to Channel 8 and ;measure the 8 probes (channels 1 through 8) on the Level 3 SDMX50 ;(aparent cable length to probe 10 meters): 8: TDR100 Measurement (P119) 1: 00 SDM Address 2: 0 La/L 3: 2818 MMMP Mux & Probe Selection 4: 4 Waveform Averaging 5: 1 Vp 6: 250 Points 7: 25.0 Cable Length (meters) 8: 5 Window Length (meters) 9: .3 Probe Length (meters) 10: .085 Probe Offset (meters) 11: 32 Loc [ WC_2811 ] 12: 1138 Mult 13: -0.
TDR100 ;Output the 29 TDR water content measurements: 15: Sample (P70) 1: 29 Reps 2: 11 Loc [ WC_3001 ] *Table 2 Program 02: 0.0000 Execution Interval (seconds) *Table 3 Subroutines End Program FIGURE 9-1. Twenty-nine CS605 or CS610 probes connected to 4ea SDMX50 multiplexers.
TDR100 Example 5, Trouble Shooting Program for SDMX50 Multiplexer, Datalogger Control Ports, and Analog Measurements The following program can be used to test the operation of the SDMX50 Multiplexer and the datalogger control ports. ;{CR10X} ;Program Name: Example 5 *Table 1 Program 01: 5 Execution Interval (seconds) ;The Following Instruction 20 configures all 8 Control Ports as Outputs.
TDR100 9.
TDR100 Public Flag(2) public WavePT(260) public MuxChan Dim I 'Declare Constants -----------------------------------------------'Topp Equation Dielectric Constants const a0= -0.053 const a1= 0.0292 const a2= -0.00055 const a3= 0.0000043 I const high = true const low = false 'Define Data Tables ---------------------------------------------DataTable (Dat15min,1,-1) '15-minute Data Table (i.e.
TDR100 If TimeIntoInterval(0,24,Hr) then flag(2)=high ' If Flag(1)=High Then '************************************* SW12 (1) 'Turn on 12V Power to TDR100 & SDMX50 'Note: Wire TDR100 & SDMX50 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. TDR100 (LaL(1),0,0,1001,4,1.0,251,9.5,5.0,0.3,0.085,1,0) TDR100 (LaL(2),0,0,2001,4,1.0,251,9.0,5.0,0.3,0.
TDR100 TDR100 (WavePT(),0,1,6001,4,1.0,251,9.5,5.0,0.3,0.085,1,0) CallTable TDR_Wave() ' MuxChan=7001 TDR100 (WavePT(),0,1,7001,4,1.0,251,9.5,5.0,0.3,0.085,1,0) CallTable TDR_Wave() ' MuxChan=8001 TDR100 (WavePT(),0,1,8001,4,1.0,251,9.5,5.0,0.3,0.085,1,0) CallTable TDR_Wave() ' 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 10.
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