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Appendix B. Example Programs

B-6

B.5.2 Cycle Shutter/Wiper for Each Measurement CR1000

Program

The following CRBasic program will:

•

Open the shutter if closed, then make a measurement

•

Make a measurement if open, then close

Shutter/wiper cycles will be cut by 50%. This will reduce wear and power
consumption 50% but still leave the optics shuttered 50% of the time.

CRBasic Example B-6. Cycle Shutter/Wiper for Each Measurement CR1000 Program

'CR1000 Series Datalogger
'OBS501 cycle shutter each measurement

'Declare Public Variables

Public

OBS501(4)

Public

obsDatOpen(4),obsDatClose(4)

Public

Open

'Declare Other Variables

Alias

OBS501(1) = turb_bs

Alias

OBS501(2) = turb_ss

Alias

OBS501(3) = tempC_OBS501

Alias

OBS501(4) = wet_dry

Alias

obsDatOpen(1) = Open_counts

'Full movement of slider is about 20,000 counts. If it jams this # will be smaller

Alias

obsDatOpen(2) = Open_Max_mA_cnts

'Number of times the shutter stops while opening because of max current

Alias

obsDatOpen(3) = Open_slip

'Open timeout count. If the threads are stripped the slide will not move and this count will increase

Alias

obsDatOpen(4) = Open_mA

'mA current of the motor

Alias

obsDatClose(1) = Close_counts

'Full movement of slider is about 20,000 counts. If it jams this # will be smaller

Alias

obsDatClose(2) = Close_Max_mA_cnts

'Number of times the shutter stops while opening because of max current

Alias

obsDatClose(3) = Close_slip

'Open timeout count. If the threads are stripped the slide will not move and this count will increase

Alias

obsDatClose(4) = Close_mA

'mA current of the motor

Units

turb_bs = fbu

Units

turb_ss = fnu

Units

tempC_OBS501 = degC

Units

wet_dry = YesNo

'Define Data Tables

DataTable

(Test,1,1000)

DataInterval

(0,5,Min,10)

Sample

(1,turb_bs,FP2)

Sample

(1,turb_ss,FP2)

EndTable

'Main Program

BeginProg

Scan

(60,Sec,0,0)

'If open make measurement and close. If closed, open then make measurement.

If Open = 1 Then

'If open the make measurement, then close

SDI12Recorder

(OBS501(),1,0,"M4!",1,0)

'Measure without moving the wiper

SDI12Recorder

(obsDatClose(),1,0,"M7!",1,0)

'Close wiper

Open = 0

Else

'if closed

SDI12Recorder

(obsDatOpen(),1,0,"M3!",1,0)

'Open wiper

Delay

(0,11,Sec)

SDI12Recorder

(OBS501(),1,0,"M4!",1,0)

'Measure without moving the wiper

Open = 1

EndIf

'Call Output Tables

CallTable

Test

NextScan

EndProg

Содержание OBS501

Страница 1: ...OPERATOR S MANUAL OBS501 Smart Turbidity Meter with ClearSensor Technology Revision 1 16 C o p y r i g h t 2 0 0 8 2 0 1 6 C a m p b e l l S c i e n t i f i c I n c ...

Страница 2: ......

Страница 3: ...ducts to CSI CSI will return such Products by surface carrier prepaid within the continental United States of America To all other locations CSI will return such Products best way CIP port of entry per Incoterms 2010 This warranty shall not apply to any Products which have been subjected to modification misuse neglect improper service accidents of nature or shipping damage This warranty is in lieu...

Страница 4: ...ng container Campbell Scientific s shipping address is CAMPBELL SCIENTIFIC INC RMA _____ 815 West 1800 North Logan Utah 84321 1784 For all returns the customer must fill out a Statement of Product Cleanliness and Decontamination form and comply with the requirements specified in it The form is available from our website at www campbellsci com repair A completed form must be either emailed to repai...

Страница 5: ...e beginning work Wear a hardhat and eye protection and take other appropriate safety precautions while working on or around tripods and towers Do not climb tripods or towers at any time and prohibit climbing by other persons Take reasonable precautions to secure tripod and tower sites from trespassers Use only manufacturer recommended parts materials and tools Utility and Electrical You can be kil...

Страница 6: ......

Страница 7: ...7 1 Default Settings 8 7 2 Device Configuration Utility 8 7 2 1 Terminal Tab 9 7 2 2 Setting Editor Tab 11 7 2 3 Downloading a New Operating System 11 7 3 Datalogger RTU Connection 12 7 3 1 SDI 12 Wiring 13 7 3 2 RS 232 Wiring 13 7 3 3 Analog 0 to 5 Volt Wiring 14 7 4 Programming 14 7 4 1 SDI 12 15 7 4 2 RS 232 15 7 4 3 Analog 15 7 5 Mounting Suggestions 15 7 5 1 Mounting Example 16 8 Operation 18...

Страница 8: ...ogram B 4 B 5 Examples for High Sediment Loads B 5 B 5 1 Normally Open CR1000 Example B 5 B 5 2 Cycle Shutter Wiper for Each Measurement CR1000 Program B 6 C Sleeve Installation C 1 D SDI 12 Sensor Support D 1 D 1 SDI 12 Command Basics D 1 D 1 1 Address Query Command D 1 D 1 2 Change Address Command aAb D 1 D 1 3 Start Measurement Commands aM D 2 D 1 4 Aborting a Measurement Command D 2 D 1 5 Send...

Страница 9: ... OBS beam orientation in suspender tub right 29 8 6 Remove the screw 31 8 7 Insert screwdriver and rotate clockwise 31 8 8 Shutter disassembled 32 8 9 Shutter components 32 D 1 CR200 X example of using the SDI 12 transparent mode to change the SDI 12 address from 0 to 1 D 3 D 2 CR1000 example of using the SDI 12 transparent mode to change the SDI 12 address from 3 to 1 Sensor is connected to contr...

Страница 10: ... Response Set D 1 CRBasic Examples B 1 CR6 SDI 12 Program B 1 B 2 CR1000 SDI 12 Program B 2 B 3 CR1000 RS 232 Program B 3 B 4 CR1000 Analog Program B 4 B 5 Normally Open CR1000 Example B 5 B 6 Cycle Shutter Wiper for Each Measurement CR1000 Program B 6 ...

Страница 11: ...mpbellsci com old manuals or contact a Campbell Scientific application engineer for assistance 2 Precautions READ AND UNDERSTAND the Safety section at the front of this manual The OBS501 needs to be sent in after two years or 70 000 cycles for drive shaft seal replacement See aM9 command in TABLE 8 2 SDI 12 and RS 232 Measurement Commands p 21 The sensor may be damaged if it is encased in ice Dama...

Страница 12: ...g damage and if found report the damage to the carrier in accordance with policy The contents of the package should also be inspected and a claim filed if any shipping related damage is discovered When opening the package care should be taken not to damage or cut the cable jacket If there is any question about damage having been caused to the cable jacket a thorough inspection is prudent The model...

Страница 13: ...ing terminals Short Cut is available as a download on www campbellsci com and the ResourceDVD It is included in installations of LoggerNet PC200W PC400 or RTDAQ The following procedure shows using Short Cut to program the OBS501 1 Open Short Cut and select New Program 2 Select Datalogger Model and Scan Interval default of 5 seconds is OK for most applications Click Next ...

Страница 14: ...changed by clicking the Temperature or Measure Sensor box and selecting a different option Typically the default SDI 12 address of 0 is used 4 After selecting the sensor click Wiring Diagram to see how the sensor is to be wired to the datalogger The wiring diagram can be printed now or after more sensors are added 5 Select any other sensors you have then finish the remaining Short Cut steps to com...

Страница 15: ... Assess the effect of land use management on water quality Monitor waterside construction mining and dredging operations Characterization of wastewater and energy production effluents Tracking water well completion including development and use 5 2 Backscatter and Sidescatter Sensors The heart of the OBS501 sensor is a near infrared NIR laser and two photodiodes for detecting the intensity of ligh...

Страница 16: ...s sand grains or packed sediment from getting wedged between the shutter and the sensor body The OBS501 also uses a flushing action that moves the sediment down and out of the cavity behind the shutter The OBS501 can sense if the shutter s motor is working harder than normal If it is the shutter moves slightly back and forth to dislodge sand grains before fully opening or closing Users who are par...

Страница 17: ...sumption Quiescent Current 200 μA Measurement Communication Current 40 mA Shutter Motor Active Current 120 mA Maximum Peak Current 200 mA for 50 ms when shutter motor starts Cycle Time Open measure close 25 s Measurement Time 2 s Outputs SDI 12 version 1 3 1200 bps RS 232 9600 bps 8 data bits 1 stop bit no parity no flow control Analog 0 to 5 V Submersion Depth 100 m 328 ft Diameter 4 76 cm 1 875 ...

Страница 18: ...ice Configuration Utility Device Configuration Utility DevConfig is used to change settings set up the analog sensor enter RS 232 commands and update the operating system Use the OBS501 test cable to connect the OBS501 to a computer running DevConfig The red wire is connected to a 12 Vdc power supply and the black to ground The datalogger power supply is a good choice to use for the power supply D...

Страница 19: ...n be used to verify the setup of the OBS501 Select the Terminal tab Click in the Terminal window and select the Enter key several times This will wake up the RS 232 mode of the sensor Once successfully connected you will see an OBS 500 prompt FIGURE 7 2 shows DevConfig after pressing l one to identify the OBS501 By default the OBS501 is in the SDI 12 mode for communication Once in the RS 232 mode ...

Страница 20: ... RS 232 Terminal Commands Terminal Commands Values Returned 1 Identify Serial Number SDI 12 address etc 2 Open Wiper Command to open wiper started please wait Wiper now open average current was xxx mA 3 Close Wiper Command to close wiper started please wait Wiper now closed average current was xxx mA H or h Help menu ...

Страница 21: ...ings Editor screen There are three settings that can be changed SDI 12 address measurement mode and sidescatter ratio top Select the desired values and press the Apply button The SDI 12 address is not used while in analog mode 7 2 3 Downloading a New Operating System DevConfig is used to download a new operating system to the OBS501 Select the Send OS tab and follow the directions on the screen NO...

Страница 22: ...SDI 12 Wiring p 13 TABLE 7 4 RS 232 Wiring p 13 and TABLE 7 5 Analog 0 5 Volt Wiring p 14 provide wiring for connecting the OBS500CBL L Field Cable to a Campbell Scientific datalogger Wiring to dataloggers or RTUs manufactured by other companies is similar Campbell Scientific recommends powering down the system before wiring the OBS501 The shield wire plays an important role in noise emissions and...

Страница 23: ...versal channels can be used for SDI 12 for example C1 C3 7 3 2 RS 232 Wiring The CR800 series CR1000 and CR3000 dataloggers support serial communications with dedicated UART hardware on their control ports They use two control ports configured as a single communications COMn port The CR6 uses two control ports or two universal channels configured as a single communication port TABLE 7 4 RS 232 Wir...

Страница 24: ...close the shutter Note that measurements can be differential or single ended Differential measurements are recommended The output is scaled as 1 mV per TU For example 100 mV 100 TU 4000 mV 4000 TU 7 4 Programming Short Cut is the best source for up to date datalogger programming code Programming code is needed when Creating a program for a new datalogger installation Adding sensors to an existing ...

Страница 25: ...lOut instruction sends strings over the Tx COM port and the SerialIn instruction receives strings from the Rx COM port Refer to Appendix B 3 CR1000 RS 232 Program p B 3 for an example of using these CRBasic instructions More information about using the RS 232 protocol is provided in Section 8 5 2 RS 232 p 23 7 4 3 Analog The PortSet instruction is used to open the shutter Either the VoltDiff recom...

Страница 26: ...C pipe is a convenient way to provide structure and protection for deployments The OBS501 will fit inside a 2 in schedule 40 PVC pipe The most convenient means for mounting the unit to a frame or wire is to use large high strength nylon cable ties 7 6 mm 0 3 in width or stainless steel hose clamps First cover the area s to be clamped with tape or 2 mm 1 16 in neoprene sheet Clamp the unit to the m...

Страница 27: ...OBS501 Smart Turbidity Meter with ClearSensor Technology 17 FIGURE 7 6 Apply tape to protect sensor FIGURE 7 7 Secure with hose clamps do not overtighten ...

Страница 28: ...ption by suspended matter Operationally a TU value is interpolated from neighboring light scattering measurements made on calibration standards such as Formazin StablCal or styrene divinylbenzene SDVB beads Turbidity is caused by suspended and dissolved matter such as sediment plankton bacteria viruses and organic and inorganic dyes In general as the concentration of suspended matter in water incr...

Страница 29: ... to the OBS501 Optical Backscatter FBU Formazin Backscatter Unit Sidescatter FNU Formazin Nephelometric Unit Ratio Back and Sidescatter FNRU Formazin Nephelometric Ratio Unit The document U S Geological Survey Implements New Turbidity Data Reporting Procedures details the units http water usgs gov owq turbidity TurbidityInfoSheet pdf 8 2 Vertical Cavity Surface Emitting Laser Diode OBS501 sensors ...

Страница 30: ...00CBL L Connector Pin Out MCIL 8 MP MCBH 8 FS Contact Number Electrical Function Wire Color 1 Power Ground Black 2 SDI 12 RS 232 TX Analog SS BS Control White 3 Power 9 6 to 15 V Red 4 Analog Signal Green 5 RS 232 RX Shutter Open Blue 6 NC 7 Analog Ground Brown 8 NC No Connection Clear Braid 8 4 Measurements The OBS501 design combines the sensor analog measurement and signal processing within a si...

Страница 31: ...is shipped from the factory to output turbidity in TU and temperature in degrees Celsius The analog output supports backscatter and or sidescatter according to the status of a control line 8 5 Communication Modes 8 5 1 SDI 12 The OBS501 uses an SDI 12 compatible hardware interface and supports a subset of the SDI 12 commands The most commonly used command is the aM command issued by the datalogger...

Страница 32: ...open timeout count open current mA total open close count aM4 aC4 Measure Send Data obs TU ss TU temperature ºC wet dry 0 dry 1 wet aC5 Burst Data Measure 100 Times Send Data bs median bs mean bs standard deviation bs minimum bs maximum ss median ss mean ss standard deviation ss minimum ss maximum aM6 aC6 Measure Send Data obs TU ss TU ratio TU temperature ºC raw obs V raw ss V open current mA clo...

Страница 33: ... between the probe and the datalogger digitally there are no offset errors incurred with increasing cable length as seen with analog sensors However with increasing cable length there is still a point when the digital communications will break down resulting in either no response or excessive SDI 12 retries and incorrect data due to noise problems In these circumstances use the aMC command to do a...

Страница 34: ...onse of an OBS501 sensor to SDVB turbidity over the range from 0 to 4 000 TU is shown in FIGURE 8 2 As shown on the inset the response function is contained within region A the linear region of the universal response curve However there is residual nonlinearity that is removed by calibration and by computation of a TU value with a 2nd order polynomial This section explains how to do a turbidity ca...

Страница 35: ...nge Evaporation causes this ratio to increase and dust bacteria growth and dirty glassware can also cause it to increase Therefore take the following precautions 1 Always use clean glassware and calibration containers 2 Don t leave standards on the bench in open containers or leave the standard bottles uncapped Perform the calibration as quickly as possible and return the AMCO solutions to their b...

Страница 36: ...k PE polyethylene calibration cups Procedure 1 Swab sensor with an alcohol soaked towel to sterilize it Position the OBS sensor in a large black tub of fresh tap water as shown in FIGURE 8 3 and record a 10 s average of the low range output Record the average output on the calibration log sheet FIGURE 8 3 Position of OBS501 in clean tap water in big black tub 2 Pour the first SDVB standard into th...

Страница 37: ...ediment concentration is calculated in a spread sheet or database after the data is retrieved to a computer 8 6 2 1 Dry Sediment Calibration Dry sediment calibration is a calibration performed with sediment that has been dried crushed and turned to powder This is the easiest calibration to do because the amount of sediment can be determined accurately with an electronic balance and the volume of w...

Страница 38: ... are not altered from their natural form in the river see Lewis 1996 It is also the most tedious expensive and time consuming method It can take several years of water sampling with concurrent OBS measurements to record the full range of SSC values on a large river 8 6 2 4 Performing a Dry Sediment Calibration Materials and equipment OBS501 with test cable dry disaggregated sediment from the locat...

Страница 39: ...d about 10 cc of water from the suspender tub to the teacup and mix the water and sediment into a smooth slurry with the teaspoon 4 Add the sediment slurry to the tub and rinse the teacup and spoon with tub water to get all the material into the suspender 5 Turn the suspender on and let it run for 10 minutes or until the OBS signal stabilizes 6 Take averages of signals with the computer or datalog...

Страница 40: ... aM7 closes the wiper 2 Clean the shutter assembly The frequency that the shutter should be cleaned depends on the sediment load and can vary from weeks to months step 3 can help you determine the required frequency for cleaning Two levels of cleaning should be done a flush the wiper as it opens and closes with a stream of clean water or b remove the wiper from the OBS501 by removing one screw and...

Страница 41: ...4 Engage the end of the drive shaft and then rotate clockwise until the shutter is free FIGURE 8 7 and FIGURE 8 8 Keep track of all of the components FIGURE 8 9 5 Reassemble by reversing the steps FIGURE 8 6 Remove the screw FIGURE 8 7 Insert screwdriver and rotate clockwise CAUTION Remove 4 40 flat head screw Copper plate Drive shaft access port ...

Страница 42: ...low to dissolve The OBS501 should be sent in for service seal shaft and nut replacement after 2 years or 70 000 cycles of the shutter whichever occurs first The sensor has a cycle count and a moisture alarm in the data string SDI 12 and RS 232 only If the seals are not replaced the sensor will eventually leak and potentially be destroyed It is recommended that the cycles and moisture alarm be reco...

Страница 43: ...ck the power Red is V and Black is Ground and signal White is SDI 12 Data lines to ensure proper connection to the datalogger Check the datalogger program to ensure that the same port the SDI 12 data line is connected to is specified in the measurement instruction The following three tests are used to diagnose malfunctions of an OBS501 1 The Finger Wave Test is used to determine if an OBS sensor i...

Страница 44: ...nsert plug Sensor broken Visually inspect for cracks return OBS501 to manufacturer if cracks are found Electronic failure Unit draws less than 11 mA or more than 40 mA Return OBS501 to manufacturer Fails shake test Sensor leaked Return OBS501 to manufacturer Fails calibration check Aging of light source causes it to become dimmer with time Recalibrate see Section 8 6 Calibration p 24 11 References...

Страница 45: ... program and exit Short Cut Make note of the file name used when saving the Short Cut program 2 Open CRBasic Editor 3 Click File Open Assuming the default paths were used when Short Cut was installed navigate to C CampbellSci SCWin folder The file of interest has the CR6 CR2 CR1 CR8 CR3 or CR5 extension Select the file and click Open 4 Immediately save the file in a folder different from C Campbel...

Страница 46: ...Appendix A Importing Short Cut Code Into CRBasic Editor A 2 This character instructs the datalogger compiler to ignore the line when compiling ...

Страница 47: ...e Table1 True 1 DataInterval 0 60 Min 10 Sample 1 Turb_BS FP2 Sample 1 Turb_SS FP2 Sample 1 Temp_C FP2 Sample 1 WD_OBS FP2 EndTable DataTable Table2 True 1 DataInterval 0 1440 Min 10 Minimum 1 BattV FP2 False False EndTable Main Program BeginProg Main Scan Scan 5 Sec 1 0 Default Datalogger Battery Voltage measurement BattV Battery BattV Default Wiring Panel Temperature measurement PTemp_C PanelTem...

Страница 48: ...I 4 Declare Other Variables Alias SDI 1 OBS Alias SDI 2 SS Alias SDI 3 Temp Alias SDI 4 WetDry Define Data Tables DataTable Test 1 1000 DataInterval 0 15 Min 10 Sample 1 OBS FP2 Sample 1 SS FP2 Sample 1 Temp FP2 Sample 1 WetDry FP2 EndTable Main Program BeginProg Scan 30 Sec 0 0 SDI12Recorder SDI 1 0 M 1 0 0 Call Output Tables CallTable Test NextScan EndProg ...

Страница 49: ...SerialOpen Com1 9600 0 0 150 Scan 30 Sec 0 0 OutString2 CHR 13 a series of carriage returns will put OBS501 into RS 232 mode OutString 0M CHR 13 address and then use commands M to M8 Send String over communication port C1 COM1 TX SerialOut Com1 OutString2 OBS_500 15 100 put OBS501 into RS232 mode delay 1 1 Sec SerialOut Com1 OutString 0 1000 send command Receive String over communication port C1 C...

Страница 50: ...its obs NTU Units ss NTU DataTable OBS501_analog 1 1 DataInterval 0 3 min 10 Minimum 1 batt_volt FP2 0 False Sample 1 PTemp FP2 Sample 1 obs FP2 Sample 1 ss FP2 EndTable Main Program BeginProg Scan 30 sec 3 0 PanelTemp PTemp 250 Battery batt_volt PortSet 1 1 blue wire drive high to open shutter PortSet 2 0 white wire selects obs 0 or ss 1 Delay 0 9500 msec 6 secs shutter open 3 5 secs VoltDiff obs...

Страница 51: ...ipped the slide will not move and this count will increase Alias obsDatOpen 4 Open_mA mA current of the motor Alias obsDatClose 1 Close_counts Full movement of slider is about 20 000 counts If it jams this will be smaller Alias obsDatClose 2 Close_Max_mA_cnts Number of times the shutter stops while opening because of max current Alias obsDatClose 3 Close_slip Open timeout count If the threads are ...

Страница 52: ...the slide will not move and this count will increase Alias obsDatOpen 4 Open_mA mA current of the motor Alias obsDatClose 1 Close_counts Full movement of slider is about 20 000 counts If it jams this will be smaller Alias obsDatClose 2 Close_Max_mA_cnts Number of times the shutter stops while opening because of max current Alias obsDatClose 3 Close_slip Open timeout count If the threads are stripp...

Страница 53: ...used to install the plastic pn 31570 or OBS501 Copper Sleeve pn 31569 The installation of the older OBS500 Copper Sleeve pn 27803 is slightly different refer to an older manual at www campbellsci com old manuals for more information 1 Ensure that the 4 40 x SS Slot Head Screw is fully tightened into the OBS501 2 Slide the copper shown or plastic sleeve over the OBS501 and line up the hole in the s...

Страница 54: ......

Страница 55: ... commands supported by the OBS501 are listed in TABLE D 1 TABLE D 1 OBS501 SDI 12 Command and Response Set Name Command Response Acknowledge Active a a CR LF Send Identification aI allccccccccmmmmmmvvvxxx xx CR LF Change Address aAb b CR LF Address Query a CR LF Start Measurement aM atttnn CR LF Send Data aDv a values CR LF Start Verification aV atttn D 1 1 Address Query Command Command requests t...

Страница 56: ...rent mode can be activated Transparent mode is entered while the PC is in telecommunications with the datalogger through a terminal emulator program It is easily accessed through Campbell Scientific datalogger support software but is also accessible with terminal emulator programs such as Windows HyperTerminal Datalogger keyboards and displays cannot be used The terminal emulator is accessed by na...

Страница 57: ...CR200 X example of using the SDI 12 transparent mode to change the SDI 12 address from 0 to 1 D 2 2 CR1000 Datalogger Example 1 Connect an OBS501 to the CR1000 see TABLE 7 3 2 In the LoggerNet Connect screen navigate to the Datalogger menu and select Terminal Emulator The terminal emulator window will open In the Select Device menu located in the lower left hand side of the window select the CR100...

Страница 58: ... a is the current address from the above step and b is the new address see FIGURE D 2 The OBS501 will change its address and the datalogger will respond with the new address To exit SDI 12 transparent mode select the Close Terminal button FIGURE D 2 CR1000 example of using the SDI 12 transparent mode to change the SDI 12 address from 3 to 1 Sensor is connected to control port 1 ...

Страница 59: ...surface water streams estuaries and ocean With size shape and color remaining constant particle area normal to a light beam will determine the intensity of light scattered by a volume of suspended matter Results of tests with sediment shown in FIGURE E 1 indicate a wide range of sensitivity is associated with fine mud and coarse sand about two orders of magnitude The significance of these results ...

Страница 60: ...e time There are no simple remedies for this problem One solution is to take many water samples and analyze them in the laboratory however this is not always practical during storms when the errors are likely to be largest Do not rely solely on turbidity sensors to monitor suspended sediment particles when particle size or composition is expected to change with time at a monitoring site E 3 Partic...

Страница 61: ...ong the path connecting the emitter the particle and the detector that backscatter decreases exponentially with increasing sediment concentration For mud this occurs at concentrations greater than about 5 000 mg l FIGURE E 4 shows a calibration in which sediment concentrations exceeding 6 000 mg l cause the output signal to decrease It is recommended not to exceed the specified turbidity or suspen...

Страница 62: ...color blind tests have shown that whiteness color and IR reflectivity are correlated Calcite which is highly reflective and white in color will produce a much stronger turbidity signal on a mass concentration basis than magnetite which is black and IR absorbing Sensitivity to colored silt particles varies from a low of about one for dark sediment to a high of about ten for light gray sediment see ...

Страница 63: ...t least a factor of ten to produce significant errors E 7 Bubbles and Plankton Although bubbles efficiently scatter light monitoring in most natural environments shows that OBS signals are not strongly affected by bubbles The sidescatter measurement may be more affected Bubbles and quartz particles backscatter nearly the same amount of light to within a factor of approximately four but most of the...

Страница 64: ...sensitive by factors of four to six to mineral particles than particulate organic matter and interference from these materials can therefore be ignored most of the time One notable exception is where biological productivity is high and sediment production from rivers and re suspension is low In such an environment OBS signals can come predominately from plankton ...

Страница 65: ......

Страница 66: ...Rua Apinagés nbr 2018 Perdizes CEP 01258 00 São Paulo SP BRASIL www campbellsci com br vendas campbellsci com br Campbell Scientific Canada Corp 14532 131 Avenue NW Edmonton AB T5L 4X4 CANADA www campbellsci ca dataloggers campbellsci ca Campbell Scientific Centro Caribe S A 300 N Cementerio Edificio Breller Santo Domingo Heredia 40305 COSTA RICA www campbellsci cc info campbellsci cc Campbell Sci...

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