Decagon Devices AccuPAR LP-80 Operator's Manual
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Decagon Devices AccuPAR LP-80 Operator's Manual

Par/lai ceptometer
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AccuPAR PAR/LAI
Ceptometer
LP-80
Operator's Manual
Decagon Devices, Inc.
Version: December 13, 2013 — 08:29:36

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  • Page 1 AccuPAR PAR/LAI Ceptometer LP-80 Operator’s Manual Decagon Devices, Inc. Version: December 13, 2013 — 08:29:36...
  • Page 2 AccuPAR LP-80 Decagon Devices, Inc. 2365 NE Hopkins Court Pullman WA 99163 Phone: 509-332-5600 Fax: 509-332-5158 Website: www.decagon.com Email: support@decagon.com or sales@decagon.com Trademarks AccuPAR and Ceptometer are registered trademarks of Decagon Devices, Inc. c 2006-2013...

  • Page 3: Table Of Contents

    1.4 Seller’s Liability ..... . 2 About the LP-80 2.1 AccuPAR LP-80 Instrument Specifications ..2.2 Overview of the LP-80 ....
  • Page 4 CONTENTS AccuPAR LP-80 8 Config Menu 8.1 Calibration ......31 8.1.1 Location ..... . 32 8.1.2...

  • Page 5: Introduction

    Decagon has Cus- tomer Service Representatives available to speak with you Monday through Friday, between 7am and 5pm Pacific time. Note: If you purchased your AccuPAR LP-80 through a distribu- tor, please contact them for assistance. Email: support@decagon.com or sales@decagon.com...

  • Page 6: Warranty

    1 INTRODUCTION AccuPAR LP-80 instructions before operating the LP-80 to ensure that the instrument performs to its full potential. Warranty The AccuPAR has a one year warranty on parts and labor. Your warranty is automatically validated upon receipt of the instrument.

  • Page 7: About The

    700 nm waveband. The AccuPAR displays PAR in units of micro- mols per meter squared per second (µmol m ). The instrument is capable of hand-held or unattended measurement. AccuPAR LP-80 Instrument Specifications Operating Environment: 0 to 50 C (32 122 F) 0 to 100% relative humidity Probe Length: 86.5 cm...

  • Page 8: Overview Of The

    2 ABOUT THE LP-80 AccuPAR LP-80 Keypad: 7-Key menu-driven Clock: 24-hour 1 minute per month Interface Cable: RS-232 cable Power: Four AAA Alkaline cells. External PAR Sensor Connector: Locking 5-pin sealed circular con- nector Overview of the LP-80 Decagon designed the menu-driven LP-80 interface for ease of use.
  • Page 9 AccuPAR LP-80 2 ABOUT THE LP-80 Figure 1: Product Features Figure 2: LP-80 Keypad...

  • Page 10: Turning On The Instrument

    2 ABOUT THE LP-80 AccuPAR LP-80 The LP-80 keypad is a 7-key panel, designed for ease of use and intuitive navigability through the operating system. Here is a brief description of the key functions, refer to Figure 2 for Keypad de- scriptions.
  • Page 11 AccuPAR LP-80 2 ABOUT THE LP-80 Figure 3: PAR Data Return Screenshot At any time, you can cycle between the four menus by pressing the MENU key. The menus are indicated by the tabs on the top of the screen, with the active menu in the foreground. If the battery is low, a low battery indicator will appear to the right of the menu tabs.

  • Page 12: Definitions

    3 DEFINITIONS AccuPAR LP-80 Definitions The AccuPAR LP-80 uses several variables to calculate Leaf Area Index, and displays values for these variables on the screen as mea- surements are taken. This chapter will discuss these variables and their definitions. If you are not familiar with them, we recommend that you review this chapter before proceeding with measurements.
  • Page 13 AccuPAR LP-80 3 DEFINITIONS LAI(L) LAI (Leaf Area Index) is defined as the area of leaves per unit area of soil surface. It is a valuable measurement in helping to assess canopy density and biomass. The AccuPAR calculates LAI based on...
  • Page 14 3 DEFINITIONS AccuPAR LP-80 Fractional beam radiation is the ratio of direct beam radiation com- ing from the sun to radiation coming from all ambient sources like the atmosphere or reflected from other surfaces. A fractional beam radi- ation value is necessary for calculation of LAI using PAR data. The...
  • Page 15 AccuPAR LP-80 3 DEFINITIONS Table 1: Typical χ Values Crop χ Crop χ Ryegrass 0.67 to 2.47 Rape 1.92 to 2.13 Maize 0.76 to 2.52 Cucumber 2.17 0.80 to 1.27 Tobacco 1.29 to 2.22 Wheat 0.96 Potato 1.70 to 2.47 Barley 1.20...

  • Page 16: Par/Lai Menu

    4 PAR/LAI MENU AccuPAR LP-80 PAR/LAI Menu The first menu option is the PAR/LAI sampling menu, which is used for measurements with the AccuPAR. The default screen is similar to the PAR screen. This PAR screen indicates that the current real-time PAR level is 2 µmols/m...
  • Page 17 AccuPAR LP-80 4 PAR/LAI MENU LP-80 updates and displays the current calculated Tau (τ ), LAI value, beam fraction (F ), leaf distribution parameter (χ) and zenith angle (z) values are updated and displayed at the bottom of the screen with each subsequent below canopy PAR measurement. If the external sensor is attached and you press an up or down arrow, the LP-80 records both above and below canopy readings.

  • Page 18: Saving And Annotating Readings

    4 PAR/LAI MENU AccuPAR LP-80 Saving and Annotating Readings To save a reading once you are done taking above and below PAR data, press ENTER. The Save Method screen appears. You have three options at the Save Method screen. 1. Select “Save” and press ENTER to save your information.

  • Page 19: Log Menu

    AccuPAR LP-80 5 LOG MENU Log Menu When you advance to the LOG menu, the Log screen appears. The Log menu allows you to put the instrument in an unattended PAR data logging mode. In this mode, the AccuPAR will automat- ically measure and store PAR data at an interval that you specify.
  • Page 20 5 LOG MENU AccuPAR LP-80 Note: You can move from this menu to other menus while the logging mode is activated. While activated, the LP-80 continues to log data whether or not the AccuPAR display is on or if you are in a different menu.

  • Page 21: Data Menu

    AccuPAR LP-80 6 DATA MENU Data Menu The Data menu allows you to view, download, and erase the data that you store with your AccuPAR. When you advance to this menu, the Data screen appears. You can view summary records and their relevant data, download the data to your computer terminal for analysis, or erase the data memory from the Data screen.

  • Page 22: Download

    6 DATA MENU AccuPAR LP-80 Download The download option allows you to download stored data to your computer via the RS-232 cable that came with your system. You can download the data using the LP-80 Utility (free software in- cluded with your system), Windows Hyperterminal or any similar terminal software.
  • Page 23 AccuPAR LP-80 6 DATA MENU 4. In the Communication Properties Dialog box, select these: 9600 bits per second, 8 data bits, no parity, 1 stop bit, and no flow control.(Figure: 4) Figure 4: Communication Properties Dialog Box 5. Once the terminal window opens, click on the File menu and select Properties.

  • Page 24: Description Of Outputs

    6 DATA MENU AccuPAR LP-80 and select “Capture Text > Stop.” Before closing Hypertermi- nal, save the session with a name you will be able to recognize. The next time you need to download, you will just need to open the Hyperterminal folder and select the name you saved.
  • Page 25 AccuPAR LP-80 6 DATA MENU External Sensor (0.00): PAR reading from the External Sensor RID (1759): The Record ID is a unique identifier for each record. RID store sequentially in memory and can be used for keeping track of downloaded data.

  • Page 26: Erase

    6 DATA MENU AccuPAR LP-80 RawRID and the RID of the summary record is also associated with the summary record. Latitude (47): Latitude location in degrees. Longitude ( 117): Longitude location in degrees. Annotation (SAMPLE3): The annotation is a string used to iden- tify a record in a user readable format.

  • Page 27: Utility Software

    AccuPAR LP-80 7 LP-80 UTILITY SOFTWARE LP-80 Utility Software The AccuPar LP-80 comes with the LP-80 Utility software which allows you to download stored data to your computer via the RS-232 cable that came with your system. Downloading Data Follow steps 1 through 9 to download data.

  • Page 28: Data Organization

    7 LP-80 UTILITY SOFTWARE AccuPAR LP-80 Note: The Excel format includes column headers by default. These are titles at the top of each column. These can be disabled by using the Preferences Menu. Tab Delimited Text (.txt): Saves the file in tab delimited for- mat, where all values are separated with tabs.

  • Page 29: Erasing Data

    AccuPAR LP-80 7 LP-80 UTILITY SOFTWARE 10. Zenith Angle–The zenith angle is the angle the sun makes with respect to the zenith (point in sky directly overhead). 11. Latitude–Latitude location in degrees. 12. Longitude–Longitude location in degrees. 13. Segment 1-8 PAR–Individual PAR readings from each of the 8 segments.

  • Page 30: Setting The Date And Time

    7 LP-80 UTILITY SOFTWARE AccuPAR LP-80 Setting the Date and Time You can use the LP-80 Utility to easily set your device date and time. Make sure you properly connect the LP-80 to your computer. Then choose “Set LP-80 Date/Time” from the Actions menu. (If you encounter an error message after click the Download button, please see Troubleshooting.) By default, the LP-80 Utility automatically...

  • Page 31: The Preferences Menu

    AccuPAR LP-80 7 LP-80 UTILITY SOFTWARE Current date and time as set in your LP-80 You can also update the time on this screen. The Preferences Menu Use the Preferences Menu to modify aspects of the Utility that relate to downloading and organizing data. The Preferences menu consists of three tabs: the Data File, Communications, and Application tabs.

  • Page 32: Communications Tab

    7 LP-80 UTILITY SOFTWARE AccuPAR LP-80 Communications Tab Command Retries: If you are having trouble communicating with your LP-80, then set the program to automatically re-send com- mands to the LP-80, up to ten times. Maximum Baud Rate: Baud rate is the number of bits per sec- ond transferred between a device and your computer.

  • Page 33: Software And Firmware Updates

    AccuPAR LP-80 7 LP-80 UTILITY SOFTWARE Automatic Internet Version Check: If you selected this box, the program will automatically check for updates as soon as it starts (only if you are connected to the Internet). Automatic Clock Synchronization: Keeps the LP-80 clock syn- chronized to the time on your computer.

  • Page 34: Config Menu

    8 CONFIG MENU AccuPAR LP-80 Config Menu The Config menu is where you configure and set most of the param- eters that affect the functionality of your AccuPAR. When you scroll to this menu, the Config screen appears with numerous options.

  • Page 35: Calibration

    AccuPAR LP-80 8 CONFIG MENU Calibration The LP-80 has a calibrated external PAR sensor that it uses for making simultaneous above and below canopy PAR measurements. The LP-80 also uses this sensor to calibrate the AccuPAR probe, ensuring that the PAR response between the external sensor and the probe are the same.

  • Page 36: Location

    8 CONFIG MENU AccuPAR LP-80 Press ENTER again to complete the calibration. 8.1.1 Location You will need to set the correct longitude and latitude for your loca- tion to make accurate LAI calculations. This is due to the fact that zenith angle calculation is based not only on the time and date, but the longitude and latitude of the site.

  • Page 37: Date And Time

    AccuPAR LP-80 8 CONFIG MENU 8.1.2 Date and Time Set your current time and date in this menu. The instrument uses the time and date provided here to calculate its zenith angle and F values, so make sure it is accurate. Use the up and down arrow keys to change the values of each item, and use the ENTER key to move to the next item.
  • Page 38 8 CONFIG MENU AccuPAR LP-80 nal sensors drift over time and periodically need recalibration. We recommend that you have your external sensor recalibrated. If you use it heavily each year, we suggest this be done on a yearly basis. If you only make periodic measurements, one recalibration every two to three years should be adequate.
  • Page 39 AccuPAR LP-80 8 CONFIG MENU Power Filter Artificial lighting uses AC electrical power and can add a signifi- cant amount of noise to the AccuPAP LP80 sensor measurements. We designed the power filter setting to eliminate the electrical noise that comes from the AC powered light source. You should set the value of the Power Noise Filter to match the frequency of the power where you live.
  • Page 40 8 CONFIG MENU AccuPAR LP-80 The About menu provides you with the serial number, firmware ver- sion number, and copyright info.

  • Page 41: Par And Lai Theory

    AccuPAR LP-80 9 PAR AND LAI THEORY PAR and LAI Theory The AccuPAR is useful for a number of applications, including the measurement of average and intercepted PAR. The LP-80 calculates LAI and other attributes of the canopy structure with these mea- surements.
  • Page 42 9 PAR AND LAI THEORY AccuPAR LP-80 transmitted through the canopy and absorbed or reflected at the soil surface, or reflected by the canopy. In principle, only PAR absorbed by the canopy is useful in producing dry matter, so f should be the fractional absorption.
  • Page 43 AccuPAR LP-80 9 PAR AND LAI THEORY for fractional interception are those from which you calculate t, r, and . If S is the PAR reading from an upward-facing AccuPAR above the plant canopy, R is the reflected PAR above the plant canopy (in- verted AccuPAR above the crop), T is the upward-facing AccuPAR below the plant canopy, and U is the reflected PAR from the soil...

  • Page 44: Using Par To Determine Leaf Area Index

    9 PAR AND LAI THEORY AccuPAR LP-80 see the current τ value displayed in the lower left corner of the screen. With each subsequent below-canopy measurement, the τ value will be updated. After you have taken sufficient measurements, use the displayed τ...
  • Page 45 AccuPAR LP-80 9 PAR AND LAI THEORY model suggested by Goudriaan (1988). Equation 11 gives the frac- tion of transmitted PAR, τ (ratio of PAR measured below the canopy to PAR above the canopy), below a canopy of LAI, L, as τ...

  • Page 46: Applications And Examples

    9 PAR AND LAI THEORY AccuPAR LP-80 Applications and Examples This section describes the method of manually collecting PAR data for the determination of LAI in a barley and pea canopy. This ex- ample has been included to show how the AccuPAR automatically calculates LAI in the field.
  • Page 47 AccuPAR LP-80 9 PAR AND LAI THEORY fleck fraction, which is the beam transmission coefficient, τ (Θ), for the canopy. The parameter, Θ, is the zenith angle (angle measured from the vertical) of the probe or solar beam. τ usually varies with zenith angle.
  • Page 48 9 PAR AND LAI THEORY AccuPAR LP-80 Figure 6: Extinction Coefficient vs. Zenith Angle Figure 1 shows the extinction coefficient plotted as a function of zenith angle for various values of x. There are two important things to note. First, at a zenith angle of about 57 , the extinction coeffi- cient is near unity for all canopies.

  • Page 49: Correction Of Par For Sun Angle

    AccuPAR LP-80 9 PAR AND LAI THEORY L = 2(A + B) (19) An approximate value for χ is χ = exp( B/0.4L). Example: Readings were obtained as follows: Table 2: Sample Readings Θ-deg Θ-rad τ -cosΘ lnτ 0.61 0.21 1.28...
  • Page 50 9 PAR AND LAI THEORY AccuPAR LP-80 τ (Θ ) = τ (Θ (22) We can calculate p from equation 17: (χ + (tanΘ (23) (χ + (tanΘ If Θ = 0, (χ (24) (χ + (tanΘ If χ is not known, assume χ = 1. Example: From the measurements in the previous example, find the canopy cover.

  • Page 51: Lai Measurements & Non-Random Distribution

    AccuPAR LP-80 9 PAR AND LAI THEORY Table 3: Values of u and v for equation 26 χ 0.69 0.73 0.75 0.82 0.81 0.89 0.90 0.95 0.96 0.98 0.99 0.99 Combining equations 16 and 25 gives: τ = τ (Θ)
  • Page 52 9 PAR AND LAI THEORY AccuPAR LP-80 for canopies which never close, as in desert vegetation. The degree of error in measurement is a result of the canopy deviation of the canopy from this random dispersion assumption. Past studies use LAI to relate both actual biomass area and the interception of PAR by a plant canopy.

  • Page 53: Zenith Angle And Equation Of Time

    AccuPAR LP-80 9 PAR AND LAI THEORY lows the recommendation of Lang and Yueqin (1986) for minimizing clumping effects. You can also measure only at certain times of day or at positions within the canopy that directly minimize clumping effects.
  • Page 54 9 PAR AND LAI THEORY AccuPAR LP-80 per hour, so the 0.2618 factor converts hours to radians. Time, t, is in hours (local solar time), ranging from 0 to 24. Latitude of a given site is easily found in an atlas or using a GPS system. Users in the Southern hemisphere should enter latitude as a negative number.
  • Page 55 AccuPAR LP-80 9 PAR AND LAI THEORY June 30 is J = 181. Pullman latitude is 46.77 , or 0.816 radians, and longitude is 117.2 . The standard meridian for Pullman is 120 . The local meridian is 2.8 east of the standard meridian, so LC = 2.8/15 = 0.19 hours.
  • Page 56 9 PAR AND LAI THEORY AccuPAR LP-80 Table 4 – Continued from previous page Date Day of Year D in Radians ET Hour Aug 18 0.233 0.065 Aug 28 0.174 0.022 Sep 7 0.111 0.031 Sep 17 0.045 0.089 Sep 27 0.023...

  • Page 57: Measurement Tips

    AccuPAR LP-80 10 MEASUREMENT TIPS Measurement Tips 10.1 Above Canopy (External) Sensor The AccuPAR is supplied with an external PAR sensor which con- nects to the port on the right side of the AccuPAR. The external sensor allows you to take simultaneous above and below canopy PAR readings without having to move the instrument above and below the canopy you are measuring.

  • Page 58: Clumping In Canopies

    10 MEASUREMENT TIPS AccuPAR LP-80 10.3 Clumping in Canopies When evaluating discontinuous canopies or canopies with definite clumping, the AccuPAR can be configured such that its active sam- pling area is reduced, or you can download the data collected by the AccuPAR probe segments.
  • Page 59 AccuPAR LP-80 10 MEASUREMENT TIPS Figure 10: Scenario 1: The two ends of the AccuPAR probe are in the middle of each row, getting a good representative sample of the entire area below and between rows. Figure 11: Scenario 2: The base of the probe is in the center of the row, while the end is in the center of the open space between rows.

  • Page 60: Care And Maintenance

    11 CARE AND MAINTENANCE AccuPAR LP-80 Care and Maintenance 11.1 Batteries The AccuPAR uses four standard 1.5 V AAA alkaline batteries. These batteries are easily obtained and should last for at least two years before they have discharged. If a battery icon appears in the upper right corner of the screen (to the left of the time) or a low battery message is displayed, you will need to change your batteries.

  • Page 61: Recalibration

    AccuPAR LP-80 11 CARE AND MAINTENANCE 11.3 Recalibration The AccuPAR calibrates its sensors against the external sensor sup- plied with the instrument. Therefore, provided your external sensor calibration is good, you simply recalibrate the AccuPAR in the Con- fig menu (see chapter 9) as often as you wish. However, as is the case with all electronic components, shifts in the external sensor sen- sitivity will occur over time.

  • Page 62: Troubleshooting

    12 TROUBLESHOOTING AccuPAR LP-80 Troubleshooting The AccuPAR LP-80 is a high performance, low maintenance in- strument, designed to have few problems if used with care. Unfortu- nately, sometimes even the best operators using the best instruments encounter technical difficulties. Below is quick reference guide that will direct you to detailed solutions of some problems that may oc- cur.
  • Page 63 AccuPAR LP-80 12 TROUBLESHOOTING SOLUTION: Make sure that the batteries are inserted correctly, and/or if they have enough power to activate the machine. 2. PROBLEM: The display is difficult to see. SOLUTION: Turn off the LP-80 and then turn it on again. If this does not fix the problem, the LP-80 features a built-in screen for changing screen contrast.
  • Page 64 12 TROUBLESHOOTING AccuPAR LP-80 Check your zenith angle (Z). If Z is greater than 90 degrees, the time or latitude/longitude are most likely set incorrectly. Return to the set date/time menu and double check that: 1. Time is set in 24 hour format.
  • Page 65 AccuPAR LP-80 12 TROUBLESHOOTING SOLUTION: After changing the batteries or loading new firmware onto an in- strument, this message may appear. Navigate to the configuration menu and verify that the date and time are set properly. 7. PROBLEM: Message on screen displays the following:...
  • Page 66 12 TROUBLESHOOTING AccuPAR LP-80 SOLUTION: The instrument cannot download new firmware updates. To down- load new firmware to the LP-80, or to stop this message from dis- playing, the instrument must be serviced by Decagon. 9. PROBLEM: Message on screen displays the following: SOLUTION: This screen means that your firmware was not loaded properly, and...
  • Page 67 AccuPAR LP-80 12 TROUBLESHOOTING 10. PROBLEM: Message on screen displays the following: Figure 12: May also say “reading” SOLUTION: Anytime a reading or logging mode is activated (indicated by a busy icon in the upper left hand corner of the PAR or Log menu), config- uration settings are locked to prevent inconsistent data from being saved.
  • Page 68 12 TROUBLESHOOTING AccuPAR LP-80 on the PAR screen, a message similar to this will appear in the Log menu. Press ENTER to stop the currently running mode or press MENU to proceed to the next menu without changing the mode.
  • Page 69 AccuPAR LP-80 12 TROUBLESHOOTING data. To make this message go away, save a summary record on the PAR or Log menu by pressing ENTER. 14. PROBLEM: Message on screen displays the following: SOLUTION: If you are trying to change a country or city location and you have custom configured the longitude, latitude or UTC offset, this mes-...
  • Page 70 12 TROUBLESHOOTING AccuPAR LP-80 A noisy serial connection can disrupt the connection between the Utility and the LP80. If this error happens regularly, you can try setting your baud rate lower or increasing the number of times a command is sent to the LP80. Choose the “Communications” tab in...

  • Page 71: Support And Repair

    Shipping Directions The following steps will help to ensure the safe shipping and pro- cessing of your AccuPAR LP-80. 1. Ship your LP-80 in its original cardboard box with suspension packaging. If this is not possible, use a box that has at least four inches of space between your instrument and each wall of the box.

  • Page 72: Repair Costs

    13 SUPPORT AND REPAIR AccuPAR LP-80 6. Tape the box in both directions for added support. 7. Include the RMA number in the attention line on the shipping label. Ship to: Decagon Devices Inc. ATTN: RMA (insert your RMA #)

  • Page 73: Further Readings

    AccuPAR LP-80 14 FURTHER READINGS Further Readings The following is a list of references that offer more detail concerning plant canopy characteristics and research. Anderson, M.C., (1971). Radiation and crop structure. Plant Photo- synthetic Production, Manual of Methods (eds. A. Sestak, J. Catsky and P.G.
  • Page 74 14 FURTHER READINGS AccuPAR LP-80 Cohen, S., Striem, M.J., Bruner, M., and I. Klein. Grapevine Leaf Area Index Evaluation by Gap Fraction Inversion. Proceedings of the 3rd Intl. Symposium on Irrigation Hort. Crops, Ferreira and Jones (eds.) Acta Horticulturae. 537, ISHS 2000 pp. 87-91.
  • Page 75 AccuPAR LP-80 14 FURTHER READINGS Biomass and Bioenergy. 17:95-112. Kiniry, J.R., J.A. Landivar, M. Witt, T.J. Gerik, J. Cavero, and L.J. Wade, Radiation-use efficiency response to vapor pressure deficit for maize and sorghum. European Journal of Agronomy Oct. 1995. Kiniry, J.R. and D.P. Knievel., Response of Maize Seed Number to Solar Radiation Intercepted Soon after Anthesis.
  • Page 76 14 FURTHER READINGS AccuPAR LP-80 Lang, A.R.G., Xiang Yueqin and J.M. Norman, (1985). Crop struc- ture and the penetration of direct sunlight. Agric. For. Meteorol., 35: 83-101. Lemur, R., (1973). A method for simulating the direct solar ra- diation regime in sunflower, Jerusalem artichoke, corn and soybean canopies using actual stand structure data.
  • Page 77 AccuPAR LP-80 14 FURTHER READINGS 63:743-748. Norman, J. M. and J.M. Welles., (1983). Radiative transfer in an array of canopies. Agron. J., 75:481-488. Norman, J. M., S.G. Perry, A.B. Fraser, and W. Mach., (1979). Re- mote sensing of canopy structure. Proc. 14th Conf. Agric. For.

  • Page 78: Declaration Of Conformity

    2003 This is to certify that the AccuPAR model LP-80, manufactured by Decagon Devices, Inc., a corporation based in Pullman, Washington, USA meets or exceeds the standards for CE compliance as per the Council Directives noted above. All instruments are built at the factory at Decagon and pertinent testing documentation is freely available for verification.

  • Page 79: External Sensor Information

    AccuPAR LP-80 16 APPENDIX A Appendix A 16.1 External Sensor Information The external quantum sensor provided with the AccuPAR model LP- 80 is the Apogee SQ110. It is calibrated to provide an output of 5 µmol m per mV. This sensor offers good accuracy, however you should be aware of potential sources of error.
  • Page 80 16 APPENDIX A AccuPAR LP-80 The output of all radiation sensors tends to drift over time as the detector ages. The long term shift of the sensor is less than 3% per year. We recommend returning the sensor for recalibration at least...
  • Page 81 Index About Menu, 35 Dry Matter Production, 37 Accessories, 4 Email, 1, 67 Batteries, 56 Erase Data, 22 Replacing, 56 Error Type, 56 in Readings, 38 Beam Fraction, 9 Measurement, 38, 40 Biomass External Sensor, 9 Calibration Constant, 33 Production, 48 Specifications, 75 Calibration, 31, 57 Extinction Coefficient, 42...
  • Page 82 INDEX AccuPAR LP-80 Maintenance, 56 X (Leaf Distribution Parameter, Measurement Taking PAR and LAI Sam- X (Leaf Distribution Parameter), ples, 12 10, 41 Overcast Sky Conditions, 42 Zenith Angle, 41 Defined, 9 Equation, 49 and Dry Matter Production, Example Calculation, 50 Setting Location of, 32 Definition, 37...

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