SunScan Canopy Analysis System User Manual SS1-UM-1.
Notices Copyright All rights reserved. Under the copyright laws, this manual may not be copied, in whole or in part, without the written consent of Delta-T Devices Limited. Under the law, copying includes translation into another language. Copyright © 1996, Delta-T Devices Limited. SunData software and canopy theory are Copyright © 1996 John Wood, Peak Design, Wensley Road, Winster, Derbyshire, U.K.
Contents Introduction .................................................................................................6 How to use the manuals ............................................................................. 6 Organisation of this manual .......................................................................... 6 The SunScan Canopy Analysis System .................................................... 6 PAR measurements............................................................................
Menus and Screens ..................................................................................30 More Psion and file handling notes.........................................................33 Navigating Psion directories and screens ...............................................33 The Workabout User Guide ........................................................................ 33 Navigating the Psion directories and screens.............................................
Maintenance and repair ............................................................................ 64 Checking the batteries ................................................................................ 64 The SunScan probe batteries ..................................................................... 64 The Workabout batteries ............................................................................ 64 Checking the desiccant ..........................................................................
Introduction How to use the manuals This manual tells you how to use your SunScan Canopy Analyser and its accessories. Some pages in the Menus and Screens section are "Quick Guides" which summarise the principal operating modes of the SunScan. They have been laminated on to durable material so that they can be taken into the field instead of the full manual. A separate Technical Manual is provided, but you will only need to refer to it in exceptional circumstances.
SunScan probe The light sensitive “wand” of the probe is 1 metre long, containing 64 photodiodes equally spaced along its length. The probe handle contains batteries and electronics for converting the photodiode outputs into digital PAR readings, which get sent to your Data Collection Terminal via the RS232 link. Beam Fraction sensor The Beam Fraction sensor (BFS) also measures PAR light levels.
Getting Started After unpacking the SunScan consignment and checking the contents against the packing list, you will want to know if everything is functioning correctly. All parts of the system are checked at our factory before despatch, so you should not anticipate trouble. If the SunScan carrying case is difficult to open, slacken the pressure release screw which is built into the carrying case moulding. If you are an experienced user, the functional checks can be done in a few minutes with no difficulty.
After some minutes of inactivity, the Workabout screen will automatically blank itself to save power. Press On/Esc once more to restore the screen display. ♦ Now connect the SunScan probe to the RS232 port at the top of the Workabout. Leave the BFS sensor disconnected. ♦ Press the yellow arrow keys to select the SunData icon.(A black background appears round the selected icon label.) ♦ Press the yellow Enter button. (Enter always accepts the selected item.
Installing the SunData s/w in your PC In this section you will be told about the SunData s/w, and what you need to do to get it running on your PC. You will then use it to establish that your PC can communicate with the SunScan probe. The SunData s/w Diskette What the s/w does The s/w is provided as three groups of programs in separate directories on the diskette. If you find a README file in the root directory of the diskette, please read it.
Running SunData The program you will run is SUNDATA.EXE (which was in the \PC directory on the diskette). This will be a quick test just to obtain the opening SunData screens on your PC. From DOS ♦ Change to the directory on your hard disk which holds the SUNDATA.EXE file. ♦ At the DOS prompt, type: SUNDATA then ↵ or Return or Enter to run it. The opening SunData screen will appear. SunData is running.
Communication checks: SunScan probe to PC For this test you will need the SunScan probe, and the SunData PC s/w running in your PC to the stage described above. ♦ Now connect the SunScan probe coiled cable to the COM port you have just specified, and press ↵ again. The CONNECT option will be activated, and the screen will change to report the connection. ♦ On the SunScan probe handle, press the red "GO" button once or twice. Further changes to the screen will occur.
Running SunData in Windows At this stage you may wish to install the SunData program so that it runs from within Windows. In Windows 3.11 The SunData diskette also contains SUNDATA.PIF and SUNDATA.ICO files for use with Windows. ♦ In Windows Program Manager, select File, New, Program Item ♦ Specify SunScan for the Description, SUNDATA.PIF for the Command Line, your program directory name for the Working Directory, and SUNDATA.ICO for the Icon File. Program Manager will then display the SunScan Icon.
SunScan Tutorial About this tutorial What you will learn This tutorial takes you step by step through the processes of setting up and taking readings with the SunScan probe, and then transferring the data files to a computer for analysis. It is divided into two parts, each of which should take about 20 to 30 minutes. For the first part you will need access to the Psion Workabout and its User Guide, or to a portable computer if you are using that instead.
Warning! If you were already in the Psion System Screen, you’ll see a message Exit System Screen? Press N, so that you stay in the System Screen. From this point you can launch SunData, the SunScan application, but first it is a good idea to familiarise yourself with the Workabout’s keyboard. The main uses of the keys are explained in the Workabout user Guide on pages 10 and 11.
Using a PC instead of the Workabout Starting the PC software Skip this section if you are using the Psion. Refer to the section in Getting Started for details on starting the PC version of the SunData software. This should bring you to the PC title screen. You will then set the probe into its emulator mode for the first part of the tutorial, as follows: ♦ Press Alt+S to drop down the Settings menu as shown.
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Setting up a measurement session Working through the menu options In normal use the SunData software calculates Leaf Area Index (LAI) based on readings from the SunScan probe and from the Beam Fraction Sensor (if fitted). These calculations also require information about the distribution of leaf angles and absorption of light by leaves within the canopy and knowledge of the solar angle calculated from the time of day and local latitude and longitude.
You will go through these different combinations later in the tutorial, and there is also a route map in the Menus and Screens section. These settings can be stored as a Configuration. Saving a number of configurations enables you to switch quickly between the different set-ups necessary at different sites, or when analysing the canopy of different crops with different characteristics. Note: The Workabout’s file structure is very similar to a standard DOS system.
Taking readings Using the Emulator mode You have now configured all the settings necessary to start taking readings, including setting SunData into emulator mode, with BFS, and setting the display to LAI At its simplest, you only need to press Enter twice to take, display and store each Leaf Area Index reading, and the values it is derived from: ♦ Press Enter once to collect and display an (emulated) reading. ♦ Press Enter again to store that reading, and return to the Next Reading screen. ....
♦ Now Set the Display to PAR (Menu, Settings, Display, Enter) The procedure for taking, displaying and storing a reading stays the same, but the reading display and the data stored change to reflect the new setting: This screen is the same if you change the Display to All, but the stored data also includes readings from all 64 individual photodiodes. Note: if you’re using a portable computer to control the SunScan, then the All setting will actually display the 64 (emulated) photodiode readings.
This time you will see the value of the PAR reading from the probe. Now is a good time to play around with the system a bit, shine a light on the probe, or take it outside and poke it into a few canopies. ♦ Press the red (GO) button to store the reading. Take a few more readings, pressing Enter or the red button, and using NOTE, so that you store a few annotated readings to your data file. You may hear occasional beeps as you take readings.
By now you may have accumulated quite a lot of readings in Data.PRN the default data file. There is no harm in this, but you may want to put further test results into new file, or maybe try out a .CSV file. If so, follow the Data Storage instructions a few pages back. Measuring Leaf Area Index without a Beam Fraction Sensor This is the most complicated of the combinations of probe and display settings.
Averages SunData can calculate and store the average of all the samples in a plot, as well as retaining each actual reading. ♦ In the Reading screen, use the ← → arrow keys to highlight the AVERAGE option and press Enter. You can then store, discard or add a note to this average. After taking an average, SunData will automatically increment the plot number. In the LAI mode SunData calculates the following averages of the samples in the plot: • The average of all the Total incident light readings.
♦ Select Format CSV: Yes in the Review dialog box or from the file itself ♦ Press Menu, Format CSV, Enter (or ∪+F) This command in fact toggles between the formatted and unformatted states, and the terminology changes accordingly. Press On/Esc to exit from any of the dialogs, or from the reviewed file itself. Note: if you’re using a portable computer to control the SunScan, the file is fitted into one screen width, and you will be able to see a bigger area of the screen.
Navigating in the File Transfer box • The Tab key (➙❘) will move you from one to the next, in sequence. Shift+Tab takes you back a step. • The area shows you other drives that can be accessed. Use the ↑↓ arrows and press ↵ to select the drive or directory you want. • "Sliders" on the side of the box give you an indication of where you are in the complete list. • ". ." takes you to the parent directory. • "." Returns you to the current directory File box.
You will immediately get a "Sending" message showing the progress of the transfer until it is completed, after which you will be returned to the SunData program. If you have no more to do, you can exit SunData with ∪+X and disconnect the RS232 comms cable. If the process is not going according to plan, and you suspect problems with the RS232 link, see the section below for help. Meanwhile, on the PC...
RS232 communication problems RS232 links between computers are notorious for giving difficulties, because there is no completely accepted international standard for them. If you are getting error messages which indicate the link is not working properly, then the difficulties may occur in a number of areas. • The physical connections (the comms cable, the computer serial ports) may be incorrect or defective. • The RS232 data parameters of the sending and receiving computers must be matched.
SunData Screens on the Workabout Note: these screens are only required if you are measuring Leaf Area Index (LAI), and you do not have a Beam Fraction sensor attached to the probe. Note: screen display and data stored will be different from this if the Menu, Settings, Display option is set to either PAR or All instead of LAI. SunScan User Manual v 1.
Menus and Screens The following table shows the menu options and settings for the Psion Workabout. Menus for SunData PC software follow a similar layout. File Data Storage Transfer Save Config’n Restore Config’n Name ≤ 8 chars. Type in name (and subdirectory) for the data file. .PRN or .CSV extensions are added automatically, depending on data type. Press Tab to display a list of files and directories on the specified Disk. These can be selected too.
Settings Titles (contd.) Site Time & Date Display Title ≤ 40 chars. Title name is stored in the data file heading, and is displayed on the Title screen. Group ≤ 40 chars. Name for a group of readings. A new name (or setting change) starts a new group. Site Name ≤ 40 chars. Name of your measurement site. Latitude -90°° to +90°° Latitude of your measurement site. Use negative numbers south of equator. Longitude -180°° to +180°° Longitude of your measurement site.
Quit 32 • Menus and Screens Exit the SunData program Document code: SS1-UM-1.
More Psion and file handling notes Navigating Psion directories and screens The Workabout User Guide At this stage you may want to learn more about operating the Workabout, so you should refer again to the Workabout User Guide in which the following subjects are well covered.
This is the Psion System screen. If you cant see the application you want, use the yellow left or right arrow keys to scroll through the range. To get to the directories press Menu, then the yellow arrow keys to select Disk, Directory, and then press Enter Warning! Do not Exit (∪ ∪+X ) from the System screen otherwise you will get this Psion Logo startup screen and lose your SunData icon.
To copy to another subdirectory, you must add that information to the filename you choose. If you only put a subdirectory name in the filename field, then the Workabout will use the original filename, but with the new subdirectory. A subdirectory name always starts and ends with “\”, for example \SUN\. If you are in any doubt about what is happening, include the complete subdirectory path and filename (but not the drive) in the filename field.
If you have other (non-data) files you want to keep, copy them to the internal drive, or to another Flashcard for temporary storage (don't forget to copy them back and delete them immediately afterwards), alternatively copy them to your PC using RCOM or SLINK, or the PsiWin program if you have it. ♦ On the Workabout, exit from SunData (if necessary) by pressing ∪+X. ♦ In the System Screen, press Menu, Disk, Format disk, Enter. Then follow the instructions and prompts carefully.
Default .cfg Every time you exit the SunData program, the program state is stored in the file Default.cfg. This configuration is restored when the SunData program is next run, which means that you start again exactly where you finished last time. Configuration files can help you if you want to alternate between different sites with different settings. Set up the appropriate titles, settings and data file information for each site you have, and save them to separate configuration files.
Displaying data files on your PC As soon as you have transferred data files from the Workabout to your PC (or have created them on a portable PC) you will want to analyse and print them for your records. The .PRN file The .PRN file format contains ASCII characters which can be read by a wide range of text reading programs, and by some spreadsheets. An example printout is shown below. Created by SunData for Workabout v0.11 Title :Demonstration Location :Burwell, Cambridge Latitude :52.2N Longitude :0.
Data file layouts and data groups If you want to get a good idea of how the data files will look, you can run the PC SunData program in the emulator mode. The general presentation of the results on screen will be similar to that in the eventual data file. The one major exception to this is in the All mode when the 64 individual photodiode readings are listed. On the PC screen they are shown as 4 rows of 16 values, whereas in the .
Measurement options Experiment design This section discusses the factors that bear on the experimental objectives you wish to achieve.
Canopy type and BFS practicalities Canopy type is the next variable to be considered. As a general guide, the abovecanopy reference measurements should be made close to, or above, the position of the SunScan probe. Tall canopies will undoubtedly exercise your ingenuity in achieving this! If you want to use the BFS for LAI readings you must be able to see the top of it to set the shade ring correctly. Canopy type Low Low High High High Options Comments BFS connected, with extension cables, if necessary.
This means that in strong sun (high Beam Fraction) the canopy volume sampled is fairly small and well defined. As the Beam Fraction decreases, the volume sampled increases, and has less well defined limits. Preferred light and weather conditions These also will significantly influence your field operations.
Advice on Absorption and ELADP values Absorption Absorption is the percentage of incident PAR that is absorbed by the leaf. Most leaves have Absorption values in the range 0.8 - 0.9, so the default value of 0.85 will usually be appropriate. Only adjust the Absorption value if you have good reason to, for example if you are working with very thick, dark leaves, or very thin transparent ones. If you set the Absorption value to 1.
Estimating ELADP in the field If the canopy shows a clear predominance of horizontal or vertical leaves, then choose a small volume of the canopy that is representative. Count the number of leaves that are at more than 45° from the vertical (i.e. mostly horizontal), and the number of leaves that are less than 45° from the vertical. If the leaves are curved, pick the angle at the widest part of the leaf.
SunScan System Measurement modes Workabout setup With your planned experiments in mind, you should now know what measurements you want to make, and what equipment you will need. The following section describes the three display functions that you may use, and gives advice on the handling of SunData configuration files. The LAI, PAR and All displays (Note that the values in the screens below were generated with the emulator for illustration purposes and may not be very realistic).
The Autolog function You can set up the SunScan system to operate automatically in any of its modes, just as if you were pushing the read, store and average buttons at regular intervals. Note: don't confuse Autolog with logging the probe as a Linear Quantum sensor, or with logging the Beam Fraction sensor as an independent sensor. These applications are dealt with in the Appendices. From Menu, Utils, Autolog, Enter you will arrive in the Automatic Logging setup screen: This is the Autolog setup screen.
Battery and memory management When leaving the SunScan probe to Autolog over a few days, the memory space on the Flashcard will determine how long it can run for, provided the Workabout Ni-Cd battery is fully charged, and the probe alkaline batteries are not near the end of their life. Approximate indications of data memory requirements are given in the earlier Data memory management section.
Levelling is most critical when you are using the probe: • for the incident radiation above the canopy, and • when then direct solar beam is strong, and • when the sun is low in the sky. Use of the tripod The probe base has a standard camera mount socket for use with the tripod. You will probably not want to use this routinely, but you could use it, for example, to mount the probe in one fixed position for taking readings in the Autolog mode during the course of a day.
Finding North, and setting the shade ring If you are taking measurements which require only the incident total radiation on the canopy, you can ignore the compass orientation of the BFS and you should set the shade ring horizontal so that it is not in use. If, however, you want the Direct and Diffuse components of the incident radiation, you must elevate the shade ring so that its shadow falls across the Diffuse sensor (the one directly in line with the shade ring pivots), covering it completely.
PAR calibrations This section describes the basis for the light calibrations used in the SunScan system, and explains when and how you might want to recalibrate the probe or restore its factory calibration. Factory light calibration The SunScan probe and Beam Fraction Sensor are calibrated to give PAR readings which match those of a standard PAR quantum sensor in typical bright daylight conditions.
You should not expect to have to do this very often. The photodiodes and light measurement circuits are very stable. The source of the apparent variability mentioned above is the not quite ideal cosine and spectral response of the sensors. Restoring the factory calibration At any time after carrying out the Recalibrate option you can restore the original factory calibration. You do not have to set up the probe or BFS in uniform light.
Environmental and moisture protection You should be aware of the different levels of protection of the components of the SunScan system to avoid putting them at risk when working outdoors. As with all field instruments you should minimise, as far as practical their exposure to high or rapidly changing temperatures. The SunScan probe and Beam Fraction Sensor Warning! The probe and BFS are designed to resist dust and water jets (IP65), but they are not hermetically sealed.
LAI theory In this section we shall explain as fully as we can how the SunScan computes its readings of leaf area index, and what the main limitations and provisos are in interpreting these for real canopies. Ingredients of the LAI computation method There are three broad areas contributing to the final result. Geometric analysis The first is the analysis of what happens to a ray of light passing through the canopy. In order to do this, we have to make some general assumptions about the canopy, i.e.
Equation fitting and inversion The results of the computer modelling, while accurate, are not suitable for use in a field instrument. It takes many minutes of processing on a fast PC to calculate light transmission for any given conditions using the model, and the Psion Workabout is not a fast computer!. The model calculates values of light transmission for a given LAI, whereas the SunScan measures light transmission.
Beer's law for canopy absorption Beer's law occurs in many situations where events happen at random. In the case of light absorption by a canopy, it applies to the absorption of incident photons or light rays. For a uniform infinite randomly distributed canopy of completely absorbing leaves, it can be shown that the relationship between the transmitted light I, a beam of incident light I0 and the Leaf Area Index L is given by: I I 0. exp( K.
The next section derives the transmission of light from a uniform overcast sky through a uniform infinite canopy of black leaves of constant LAI with an ellipsoidal leaf angle distribution. Let the sky have uniform brightness of 1 per steradian over the hemisphere. The radiance of a strip around the sky at angle θ is given by: R 2. π . sin( θ ) . dθ and the irradiance on a horizontal surface due to that strip is given by I 0 2. π . sin ( θ ) . cos ( θ ) .
Diffuse light transmission (cosine corrected sensor) Transmission fraction 1 Leaf Angle Distribution vertical τ diff ( 0 , L ) spherical τ diff ( 1 , L ) horizontal τ diff ( 1000 , L ) vertical 0.1 spherical 0.01 horizontal 0.001 0 2 4 6 L 8 10 Leaf Area Index Modelling the canopy transmission Accounting for incomplete absorption of PAR by the canopy elements, and scattering of light within the canopy is complicated.
In detail: • The canopy is divided into horizontal layers of LAI 0.1 • Direct beam absorption by each layer is calculated using Campbell's equation. In calculating the amount of absorbed light that is re-emitted, the total power in the direct beam has to be used (i.e. as measured by an integrating hemisphere or a cosine-corrected sensor perpendicular to the beam). The amount intercepted by the layer is the difference between the absolute intensity above and below the layer.
Accuracy of LAI calculations When used to predict LAI from transmitted fraction, the functions used in the SunData software are accurate to within ±10% ±0.1 over the range of LAI less than 10 and Zenith Angle less than 60° when compared to the output of the full model. The errors become larger for highly vertical leaves with a strong low sun, and users should avoid these conditions if possible.
This was again calculated numerically and curves fitted to the data with similar accuracy as above. The curves fitted are: Given: τ spher ( x , L ) exp 0.4. exp( 0.1. x ) . ( atan( 0.9. x ) P( x ) 1 Q( x ) 0.255. atan( x ) R( x ) exp( x ) Q( x ) P ( x ). L 0.95 ) 0.6 R( x ) .
The results were then analysed in terms of La, the LAI of a canopy of black leaves that would give the same transmission as a canopy of LAI L assuming incomplete absorption, all other factors being equal. L a L. ( 1 g( 1 a) ) L is the "true" LAI, La is the LAI that when used in the black leaf model, gives the same transmission as L used in the complete model. a is the leaf absorptivity in the PAR band.
Daughty, Craig S T (1990). Direct measurements of canopy structure. Remote Sensing Reviews 1990 vol 5(1) pp 45 - 60. Diffey B L (ed).(1989) Radiation Measurement in Photobiology. Academic Press. Goudriaan J (1977). Crop Micrometeorology: A Simulation Study. Centre for Agricultural Publication Documentation, Wageningen, Netherlands. Jones, Hamlyn G. (1992) Plants and Microclimate second edition. CUP. Lang A R G & Xiang Yueqin (1986).
Technical Reference section Maintenance and repair Checking the batteries The SunScan system requires batteries within the probe and in the Workabout. The Beam Fraction sensor does not require batteries because it draws its power from the probe. The SunScan probe batteries The probe is powered by 4 AA size alkaline cells mounted within the probe handle. With typical use, these batteries should last from 6 - 12 months. The probe circuit automatically "sleeps" when no readings are being taken.
Workabout battery management When you receive the Workabout, the installed battery pack may not be fully charged. Connect the Workabout to the Docking unit and Charger immediately, so that charging can proceed whilst you are learning to use the SunScan. The charger is a trickle-charger and may take 14 hours to fully recharge the battery pack. A fully charged Ni-Cd battery should easily give 2 or 3 full days use in the field.
Checking the PAR calibration Various techniques for checking the SunScan system PAR calibration and consistency are described in the Measurement Options, PAR calibration section, which you should refer to. This also includes advice on when to use the recalibrate and restore factory calibration procedures. Factory calibration method A standard PAR Quantum sensor provides the reference value of PAR that the Beam Fraction sensor and the SunScan probe are set up to.
Troubleshooting Psion Workabout There is no SunData Icon in the system screen. • From the Psion system screen, select Menu, Apps, Install, Enter, Tab, and select Sundata.app in the \SUN\ subdirectory. If this file does not exist, it must be copied from the SunScan program disk - refer to the appendix: File Transfer between Workabout and PC. The system fails to recognise a Flashcard in the A: or B: drives. • Make sure the SSD drawer is firmly closed.
“Insufficient power to write data” reported. • Recharge the Ni-Cd battery pack, or replace it with a freshly charged Ni-Cd pack or two AA Alkaline cells. When transferring files to a PC, data is transferred, but there are repeated checksum or device IO errors. • Reboot your PC and start again. See the advice on RS232 communications in the SunScan Tutorial (p28). SunScan or BFS give inconsistent light readings. • Make sure the diffusers are clean and that the desiccant condition indicators are blue.
Technical Support Distributor contact If you have a problem, please call your local distributor first. Direct Delta-T contact You can contact SunScan Technical Support at Delta-T directly on: Tel: +44 (0)1638 742922 Fax: +44 (0)1638 743155 Email: fi42@delta-t.co.uk Web site: http://www.delta-t.co.uk/users/fi42 Guarantee The SunScan system and its components are guaranteed for one year against defects in manufacture and materials.
Specifications SunScan Probe type SS1 Active area Spectral response Measurement time Maximum reading Resolution Linearity Accuracy Analogue output Serial interface Environmental Size (overall) Power 1000 x 13 mm wide. Sensor spacing 15.6 mm. 400 - 700 nm (PAR) 120 ms -2 2500 µmol.m .s-1 -2 -1 0.3 µmol.m .s better than 1% +/- 10% -2 1 mV per µmol.m .
Carrying Case type SCC1 Moulded plastic case with O-ring seal for moisture and dust proofing, including pressure release valve. Outside dimensions Weight 1.40 x 0.44 x 0.16 m approx 8 kg Telescopic Tripod type BFT1 3-way head with quick release platform. Geared friction elevator control. Locking leg catches and brace. Dual Spike/rubber feet. Max. height Closed length Weight 1.73 m 0.68 m 2.5 kg Spares Kit type SPS1 A detailed list of parts can be supplied on request.
PAR Performance The graphs below show the actual spectral and cosine response curves for the SunScan system. Spectral response The spectral response curve shows that the SunScan response is almost entirely within the PAR wavelength band of 400 nm - 700 nm. The GaAsP sensors used have an increased sensitivity towards the red end of the spectrum, but this is compensated for by the sharp cut-off at 670 nm.
Cosine responses of probe and BFS The cosine response curves show a diminishing response compared to the ideal at high zenith angles. For this reason, you should avoid taking measurements when the sun is strong and near the horizon. Most studies will be looking at the ratio of incident and transmitted light, and the graph shows the SunScan and Beam Fraction sensor are very closely matched in their cosine and spectral responses, so the small deviations from the ideal will not introduce significant errors.
Appendices A. Logging the probe as a Linear Quantum Sensor This application of the SunScan probe turns it into a simple Line Quantum sensor that can be attached to a data logger. No Data Collection Terminal is used, but you do require a data logger that can supply power to the probe when taking readings. The Delta-T DL2e and DL3000 loggers are suitable for this purpose. If you want to mount the probe on a tripod, a camera mount is provided in the base of the probe handle.
B. Logging the Beam Fraction sensor You can log the Beam Fraction sensor in a similar manner, using the (optional) special logging cable for it. Two outputs are available, corresponding to the Total incident PAR and Diffuse PAR photodiode readings. Be aware that the shade ring elevation may need readjustment after an hour or two. Also, that separately logged incident PAR readings cannot at present be merged with probe readings of transmitted PAR to give LAI estimates using the SunScan mathematical model.
C. Upgrading the SunScan system From time to time, new issues of the software programs in the SunScan system may be released and offered to existing customers. Brief notes follow for what is involved in installing them. The SunData PC s/w New versions of the PC program file SunData.exe will be provided on a floppy disk. Rename the existing file on your PC's hard disk, then copy the new file across to the same directory as was previously used. The Workabout SunData s/w New versions of the SunData.
D. File transfer between Workabout and PC Choice of different programs For the transfer of data files from the Workabout to a PC, the SunData software that resides in the Workabout and on your PC provides all you need, but it is specific for this purpose. There are other occasions however when you may want to transfer other files between the PC and the Workabout, for example to send an upgraded version of the SunData.app file to the Workabout. To do this, there are three routes.
If PsiWin has difficulty establishing the link to the Workabout at any stage, powering down PsiWin and the Workabout and physically remaking the RS232 connections before running them again may clear the problem. Don't forget to turn off the remote link in the Workabout when you have finished. SLINK and RCOM The procedure For maximum safety, to start with, close down all other applications on the PC, and run everything from the DOS prompt whilst you do this.
♦ From the Psion System Screen, press Menu, Disk, Directory, Enter. ♦ Press ← → to select the Disk Internal, (or any other Disks or drives). Note: the Workabout refers to its own drives as Internal and Disk A, B, C etc . The drives on the PC are referred to as REM::A:, REM::C: (REM = remote). If no subdirectory \SUN\ exists, then create one as follows: ♦ Select \, the root directory of the Disk Internal ♦ Press Menu, Directory, Make directory, Enter. ♦ For Dir. Name type \SUN and press Enter.
Example using RCOM On the Workabout: ♦ Exit from the SunData application on the Workabout by pressing ∪+X. ♦ In the System Screen, press Menu, Spec, Remote Link, and press Enter. Set the Remote Link to On, Baud rate to 19200, and the Port to A. ♦ Connect the RS232 port at the top right of the Workabout to the PC’s COM1 serial port using the SunScan comms cable. From the PC ♦ At the DOS prompt, in the directory holding RCOM.
E. Alternative file transfer mechanisms Sending a file to a Communication program You can send your files to a communications program such as Windows Terminal or ProComm. However, if you do this there will be no error checking during the file transfer. Connect the Workabout to an appropriate serial port on the PC using the SunScan RS232 cable or a null modem serial cable. In the communications program Set the COM port you are using to 9600 baud, No parity, 8 data bits, 1 stop bit.
F. Glossary Beam fraction - the fraction of the Total incident PAR in the Direct beam. Beam Fraction Sensor (BFS) - consists of two PAR sensors and a shade ring, used for measuring Direct and Diffuse light above the canopy. Beer’s law - a general law describing transmission through an absorbing medium. The intensity falls off exponentially with distance through the medium.
Local time - the time used in your particular time zone. It varies from GMT by an amount depending on longitude, political boundaries, and any daylight saving time. Mean Leaf Angle (also Mean Tip Angle, Mean Inclination Angle) is the average angle of all the leaf elements relative to the horizontal, weighted according to area. This can be directly related to ELADP. PAR - Photosynthetically Active Radiation is visible light of wavelength 400 nm 700 nm. It is measured in units of µmol.m-2.
Index A About ........................................................................ 31 Absorption incomplete................................................. 52, 56, 59 values .................................................................... 42 Accuracy LAI ........................................................................ 58 PAR................................................................. 48, 49 All, display................................................................ 44 Appending data..
H Hemispherical response.......................................58, 80 Hot keys ..............................................................19, 32 I Inversion....................................................................53 L LAI, display...............................................................44 LAI, theory................................................................52 Latitude .....................................................................18 Leaf absorption............................
Transfer, file ............................................................. 30 Transmitted fraction.................................................. 81 Tripod Mount...................................................... 47, 69 Troubleshooting.............................................. 8, 27, 65 Tutorial ..................................................................... 14 U Upgrades................................................................... 74 Utilities .......................................
