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Campbell TDR100, Инструкция по эксплуатации

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TDR100

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Содержание TDR100

Страница 1: ...TDR100 Revision 2 10 C o p y r i g h t 2 0 0 0 2 0 1 0 C a m p b e l l S c i e n t i f i c I n c ...

Страница 2: ...rs residing in countries served by Campbell Scientific Inc directly Affiliate companies handle repairs for customers within their territories Please visit www campbellsci com to determine which Campbell Scientific company serves your country To obtain a Returned Materials Authorization RMA contact CAMPBELL SCIENTIFIC INC phone 435 753 2342 After an applications engineer determines the nature of th...

Страница 3: ... Discussion of Distances and Propagation Velocity Vp when using TDR100 4 3 2 PCTDR Help 6 4 PCTDR Software 6 4 1 General 7 4 2 PCTDR Help 7 4 3 Menu Selections 8 4 3 1 File Menu 8 4 3 2 Settings Menu 8 4 3 3 Options Menu 8 4 4 PCTDR Parameter Selection Boxes 8 4 4 1 Cable 8 4 4 2 Waveform 9 4 4 2 1 A Discussion of Start and Length Parameters 9 5 System Components Datalogger Control 11 5 1 General ...

Страница 4: ...ameter 10 Probe Offset meters 24 6 3 11 Parameter 11 Input Location 24 6 3 11 1 Reflection Waveform Values to Input Storage 24 6 3 12 Parameter 12 Multiplier 25 6 3 13 Parameter 13 Offset 25 6 3 13 1 Probe Constant for Electrical Conductivity Measurement 25 7 TDR Principles 26 8 Cable Length and Soil Electrical Conductivity Effect on Water Content Determination 28 8 1 Cable Length Effect on Water ...

Страница 5: ... is 1 0 dS m 1 29 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 30 9 1 Typical TDR100 waveform showing key features with numbers 1 2 and 3 31 9 2 PCTDR terminal emulator screen showing TDR100 algorithm parameter variables 32 9 3 Waveform and derivative values...

Страница 6: ...TDR100 Table of Contents iv ...

Страница 7: ...ntrol using the dataloggers A single TDR probe can be connected directly to the TDR100 or multiple probes connected via coaxial multiplexer units SDMX50 The TDR100 is sensitive to electrostatic discharge damage Avoid touching the inner part of the panel BNC connector or the center rod of TDR probes connected to the TDR100 Warning 1 1 TDR100 Packing List The following are included with a TDR100 1 P...

Страница 8: ...lliamps 2 2 2 SDMX50 The quiescent current demand for the SDMX50 multiplexer is less than 1 milliamp Current demand during switching is approximately 90 milliamps All multiplexers of the same level switch simultaneously see Figure 5 1 Switching takes less than 1 second 2 3 TDR100 Performance Specifications pulse generator output 250 mV into 50 ohms output impedance 50 ohms 1 time response of combi...

Страница 9: ... and the TDR100 to monitor a single TDR probe using PCTDR software A single probe is connected directly to the TDR100 and no multiplexers are used TDR100 operation with SDMX50 multiplexers is described in Section 5 4 1 Install PCTDR The following instructions assume that drive D is a CD ROM drive If the drive letter is different substitute the appropriate drive letter Put the installation disk in ...

Страница 10: ...nces and Propagation Velocity Vp when using TDR100 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 The displayed position of a waveform...

Страница 11: ...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 5 ...

Страница 12: ...A display for viewing waveforms is generally needed only for system setup and troubleshooting and the TDR100 does not have a built in display Windows software PCTDR is used with a personal computer to configure the TDR100 and multiplexers and display waveforms Conflicts between commands simultaneously issued by a datalogger and PCTDR will cause error messages in PCTDR To prevent these errors halt ...

Страница 13: ...ontrol ports 1 2 and 3 as input PortsConfig B00000111 B00000000 4 1 General PCTDR 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 PCTDR menu Settings Communications The baud rate is set during TDR100 production to 57600 4 2 PCTDR Help There are several ways to access PCTDR s help system The help file s Table of Cont...

Страница 14: ...mode of PCTDR Advanced link for downloading TDR100 operating system 4 4 PCTDR Parameter Selection Boxes 4 4 1 Cable The cable propagation velocity Vp depends on the dielectric constant of the insulating material between the coaxial cable center conductor and outer shield The value entered in this parameter selection box is the ratio of the actual propagation velocity for a selected medium to the p...

Страница 15: ...en The apparent distance is the actual distance x selected Vp actual Vp For example if the actual length of a cable having a Vp of 0 78 is 5 meters and the selected Vp is 1 0 the apparent distance to the end of the cable is 5 x 1 0 0 78 6 41 meters NOTE Length Beginning at distance Start the length of the display window and apparent length depicted by the number of data Points selected For water c...

Страница 16: ...gh 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 Recommended Waveform Length value m 0 10 to 0 20 3 0 21 to 0 30 4 0 31 to 0 40 5 0 41 to 0 6 6 0 61 to 0 75 7 0 76 to 1 00 9 Use the recommended values listed in Table 1 or us...

Страница 17: ...trol 5 1 General Datalogger FIGURE 5 1 TDR System Components 5 2 Datalogger Campbell Scientific CR800 CR850 CR1000 and CR3000 dataloggers use Instruction TDR100 to control the TDR100 measurement sequence and store the resulting data PC400 or LoggerNet version 3 0 or higher are used to create and send the CRBasic Program to the datalogger Campbell Scientific CR10X and CR23X dataloggers use Instruct...

Страница 18: ...xial multiplexer The same multiplexer circuit is packaged as the SDMX50 the SDMX50LP or the SDMX50SP The SDMX50 is designed to minimize signal attenuation and all channels have equal transmission line lengths Spark gaps provide protection from voltage surge damage Figure 5 2 describes typical signal attenuation from the common to one output channel for frequency range important for TDR measurement...

Страница 19: ...the switched 12 volts is turned on at the beginning of the datalogger program table that contains the TDR measurement instructions and it is turned off at the end of the table CRBasic Instruction SW12 can be used to switch 12 volt power on the CR800 CR850 CR1000 or CR3000 datalogger See CR1000 programming example in the program example section of this manual CR10X and CR23X datalogger Instruction ...

Страница 20: ...d to connect C2 or SDM C2 of the datalogger to C2 of the other system components The last wire is used to connect C3 or SDM C3 of the datalogger to C3 of the other system components If PCTDR is being used to control multiplexers the control lines connect 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 s...

Страница 21: ... SDMX50 Muxs TDR100 2 MSD LSD Level 3 SDMX50 Muxs TDR100 3 MSD LSD 0 00 0 0 1 0 2 0 3 1 01 1 0 2 0 3 1 0 2 02 2 0 3 1 0 1 1 3 03 3 1 0 1 1 1 2 4 10 4 1 1 1 2 1 3 5 11 5 1 2 1 3 2 0 6 12 6 1 3 2 0 2 1 7 13 7 2 0 2 1 2 2 8 20 8 2 1 2 2 2 3 9 21 9 2 2 2 3 3 0 10 22 A 2 3 3 0 3 1 11 23 B 3 0 3 1 3 2 12 30 C 3 1 3 2 3 3 13 31 D 3 2 3 3 not available 14 32 E 3 3 not available not available 15 33 F not a...

Страница 22: ...e insulation for the individual wires of the SDM cable affects the frequency response and reliability PVC insulation has more attenuation than polypropylene or polyurethane and should not be used for SDM communication except when total SDM cable length is less than 250 feet 5 7 ENCTDR100 Many TDR system applications require installation of equipment at field sites The ENCTDR100 is a weather proof ...

Страница 23: ...DC OR AC RMS POSITIVE TO EITHER TERMINAL NEGATIVE TO OTHER POWER TO DATALOGGER OR 12V PERIPHERALS Not intended to be used as wiring guide ENCTDR100 shown with PS12 power supply CR10X datalogger TDR100 and SDMX50SP coaxial multiplexer 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 ...

Страница 24: ...ve 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 Datalogger Instructions for TDR Measurements 6 1 CR800 CR850 CR1000 or CR3000 Datalogger Instruction TDR100 The TDR100 instruction is used to measure one or more time doma...

Страница 25: ...tivity in S m 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 enter...

Страница 26: ...specifies the length in meters of the probe rods that are exposed to the medium being measured The value of this parameter only has an affect when Option 0 La L is used for the measurement ProbeOffset The ProbeOffset is an apparent length value used to correct for the portion of the probe rods that may be encapsulated in epoxy and not surrounded by soil or other medium being measured This value is...

Страница 27: ... value Offset 13 FP Offset value added to La L and stored in input location specified in parameter 11 Set to 0 when parameter 2 is 1 or 2 6 3 Discussion of TDR Instruction Parameters Instruction 119 6 3 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 i...

Страница 28: ... number of input locations is twice the number of points Instruction 119 parameter 6 plus 9 for the header information 6 3 2 4 Enter 3 Measure Bulk Electrical Conductivity The electrical conductivity routine in the datalogger returns the value 1 1 1 Zc ρ ρ which must be multiplied by the probe constant Kp to get an electrical conductivity value Kp is entered in Instruction 119 parameter 12 See Sec...

Страница 29: ...rised 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 The displayed position of a waveform is apparent distance The value chosen for Vp does not affect water content or el...

Страница 30: ...l 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 However this is not the same physical position as the beginning of the probe s exposure to the soil being measured Therefore a correction must be made for the distance which the signal travels inside the probe block This offset is de...

Страница 31: ...ue added to the value stored in input location specified in parameter 11 Set to 0 when parameter 2 is 1 or 2 6 3 13 1 Probe Constant for Electrical Conductivity Measurement The section TDR Principles presents the equation used for soil bulk electrical conductivity For convenience it is repeated here σ ρ ρ K Zc 1 p 1 A portion of the datalogger algorithm evaluates the reflected waveform to determin...

Страница 32: ...truction 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 7 TDR Principles The travel time for a pulsed electromagnetic signal along a waveguide is dep...

Страница 33: ...ntent In general as the water content increases the travel time of the applied pulse increases The reflected waveform of the probe can be used to identify the impedance transitions 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 s...

Страница 34: ...th increases the rise time and the amplitude of the reflection are affected The slopes and extrema used by the datalogger algorithm to analyze the waveform are shifted by the cable losses resulting in error For the data shown in Figure 8 1 the water content measurement using the 66 meter cable was in error by about 1 5 volumetric water content when electrical conductivity is low However in saline ...

Страница 35: ... at the probe will be attenuated when ionic conduction occurs in the soil solution This inherent attenuation is used in TDR measurements to determine soil electrical conductivity as described by equation 5 The presence of ions in the soil solution provides a path for electrical conduction between TDR probe rods The attenuation of the signal can affect the accuracy and resolution of water content m...

Страница 36: ...justment 9 1 Introduction This section presents a general description of the algorithms in the TDR100 for electrical conductivity and water content measurement 9 2 Algorithm for Calculation of TDR Probe Rod Apparent Length 9 2 1 Algorithm Description Equation 2 of Section 7 shows the relationship between apparent dielectric constant Ka and apparent TDR probe rod length La The equation is repeated ...

Страница 37: ... 50 100 150 200 250 0 3 0 2 0 1 0 0 1 waveform data point reflection coefficient rho 1 3 FIGURE 9 1 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 Beginning at the first data point the algorithm searches for a value ne...

Страница 38: ...mmand descriptions Press Enter for prompt Electrical conductivity parameters SEC1 xx Set EC Parameter 1 SEC2 xx xx Set EC Parameter 2 SEC3 xx xx Set EC Parameter 3 SEC4 xx xx Set EC Parameter 4 GECP Get EC Parameters Apparent length parameters SMO1 0 xx Set Apparent Length Threshold GMOP Get Apparent Length Parameters SSU Save Changes to EEPROM FIGURE 9 2 PCTDR terminal emulator screen showing TDR...

Страница 39: ... point 4 Calculate a threshold value using threshold a maximum derivative b mean from step 3 c standard deviation from step 3 The default values for a b and c are 0 1 and 2 respectively 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 calculate...

Страница 40: ... flexibility when conditions of noise or large amount of signal attenuation are present threshold a maximum derivative b mean from step 3 c standard deviation from step 3 840 860 880 900 920 940 960 980 1000 0 0 1 0 2 0 3 0 4 0 5 waveform waveform derivative waveform and derivative near probe data point reflection coefficient max_deriv indexmax_derivative values used for applied signal FIGURE 9 3 ...

Страница 41: ...be Waveforms Equipment Wiring CR1000 TDR100 SDMX50 SW12 12 V 12 V G G G C1 C1 C1 C2 C2 C2 C3 C3 C3 Sensor Wiring TDR100 SDMX50 TDR Probe Coax Common Channel_1 Probe 1 Channel_2 Probe 2 Channel_3 Probe 3 Channel_4 Probe 4 Channel_5 Probe 5 Channel_6 Probe 6 Channel_7 Probe 7 Channel_8 Probe 8 Note TDR probe cable length must be determined using PCTDR 35 ...

Страница 42: ...e 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 HourDataTable i e TDR100VWCMeasurements 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 Capture TDR...

Страница 43: ...R100 LaL 5 0 0 5001 4 1 0 251 7 0 5 0 0 3 0 085 1 0 TDR100 LaL 6 0 0 6001 4 1 0 251 10 5 5 0 0 3 0 085 1 0 TDR100 LaL 7 0 0 7001 4 1 0 251 11 5 5 0 0 3 0 085 1 0 TDR100 LaL 8 0 0 8001 4 1 0 251 9 5 5 0 0 3 0 085 1 0 For I 1 to 8 LaL2 I LaL I 2 Apparent Dielectric Constant K La L 2 Next I Topp Conversion from Dielectric Constant to Volumetric Water Content VWC For I 1 to 8 ToppVWC I a0 a1 LaL2 I a2...

Страница 44: ...51 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 2 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 ...

Страница 45: ...o the TDR100 and convert to water content 4 TDR100 Measurement P119 1 0 SDM Address 2 0 La L 3 0000 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 0 085 Probe Offset meters 11 3 Loc WC_1 12 1138 Mult Multiplier for Liedu Calibration 13 0 1758 Offset Offset for Liedu Calibration Turn off the switched...

Страница 46: ...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 The array id time analog measurements volumetric water content are output to Final Storage once a minute CR10X Program Name T100EX 2 Table 1 Program 01 60 Execution Interval seconds The following P91 instru...

Страница 47: ...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 0 Offset Square La L to convert to dielectric constant 6 Z X Y P36 1 3 X Loc LaL_CH3 2 3 Y Loc LaL_C...

Страница 48: ... units Siemens meter 13 0 0 Offset Get the raw waveform for the CS610 probe on Channel 3 When creating this program in Edlog the user must reserve 259 input locations for data storage How In Edlog click on Edit select Input Labels In the Input Location Editor click on Edit select Insert Block and identify 259 input storage location for the captured waveform Note 9 parameter elements 250 waveform d...

Страница 49: ...Year Day Hour Minute midnight 2400 Output the Battery_Voltage DataLogger Temperature WaterContent and Electrical Conductivity 14 Sample P70 1 1 Reps 2 1 Loc Bat_Volt 15 Sample P70 1 1 Reps 2 2 Loc DL_Temp 16 Sample P70 1 1 Reps 2 4 Loc WC_CH3 17 Sample P70 1 1 Reps 2 5 Loc EC_CH3 Output the WaveForm data point 1 to WaveForm data point 259 18 Sample P70 1 259 Reps 2 11 Loc WF_1 Table 2 Program 02 0...

Страница 50: ...DMX50 return La L When creating the program with Edlog the user must manually allocate the 8 input locations i e LaL_1 through LaL_8 For Edlog s help on how to do this right mouse click the La L parameter select help then click on manually inserting input locations in Edlog 2 TDR100 Measurement P119 1 00 SDM Address 2 0 La L 3 1008 MMMP Mux Probe Selection 4 4 Waveform Averaging 5 1 Vp 6 250 Point...

Страница 51: ... WC_1 2 0 1 F 3 11 Z Loc WC_1 Apply Topp s 3rd order polynomial 7 Polynomial P55 1 1 Reps 2 11 X Loc WC_1 3 11 F X Loc WC_1 4 0 053 C0 5 292 C1 6 0 055 C2 7 0 0043 C3 8 0 0 C4 9 0 0 C5 8 End P95 End of the Loop Measure the datalogger power supply voltage 9 Batt Voltage P10 1 19 Loc Bat_Volt Set the Output Flag to output data each time measurements are made 10 Do P86 1 10 Set Output Flag High Flag ...

Страница 52: ...re made every 60 minutes Twenty nine CS605 or CS610 probes are connected to 4 SDMX50 multiplexers Figure 10 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 The array id time average of the analog measurements and the volumetric water conten...

Страница 53: ...port 5 high to switch ON Switched 12V power from the datalogger to power the TDR100 4 Do P86 1 45 Set Port 5 High Measure the 6 CS610 probes connected to the Level 1 SDMX50 Channels 3 to 8 and convert to water content 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...

Страница 54: ... 1 00 SDM Address 2 0 La L 3 2107 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 25 Loc WC_2101 12 1138 Mult 13 0 1758 Offset 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 apparent...

Страница 55: ...5 End of Instructions to execute once an hour The following instructions only send data to Final Storage once an hour when the Output flag is set Output a time stamp year day and hour minute 13 Real Time P77 1 1220 Year Day Hour Minute midnight 2400 Output the averages of the 5 minute measurements of Battery Voltage and Datalogger temperature 14 Average P71 1 2 Reps 2 1 Loc Bat_Volt Output the 29 ...

Страница 56: ... Outputs This allows the user to manually set the ports high 5V or low 0V in order to check the port operation with a volt meter Ports and flags can be set with the Keyboard Display 6 Mode Datalogger Manual Section 1 3 or from the Connect Screen of PC208W or LoggerNet 1 Set Port s P20 1 7777 C8 C5 output output output output 2 7777 C4 C1 output output output output To test wiring and multiplexer o...

Страница 57: ... media 387 396 Topp G C J L Davis A P Annan 1980 Electromagnetic determination of soil water content measurements in coaxial transmission lines Water Resources Research v 16 No 3 574 582 Ledieu J P De Ridder P De Clerck and S Dautrebande 1986 A method of measuring soil moisture by time domain reflectometry J Hydrol 88 319 328 Giese K and R Tiemann 1975 Determination of the complex permittivity fro...

Страница 58: ...TDR100 52 ...

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Страница 60: ...da Corp CSC 11564 149th Street NW Edmonton Alberta T5M 1W7 CANADA www campbellsci ca dataloggers campbellsci ca Campbell Scientific Centro Caribe S A CSCC 300 N Cementerio Edificio Breller Santo Domingo Heredia 40305 COSTA RICA www campbellsci cc info campbellsci cc Campbell Scientific Ltd CSL Campbell Park 80 Hathern Road Shepshed Loughborough LE12 9GX UNITED KINGDOM www campbellsci co uk sales c...

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