Related Manuals for Delta-T Devices SunScan SS1
Summary of Contents for Delta-T Devices SunScan SS1
- Page 1 User Manual for the SunScan Canopy Analysis System type SS1-UM-3.3 Delta-T Devices Ltd Weitere Infos auf www.upgmbh.com oder vertrieb@upgmbh.com...
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Page 2: 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 Ltd. Under the law, copying includes translation into another language. Copyright © 2014 Delta-T Devices Limited SunData software and canopy theory are copyright ©... -
Page 3: Table Of Contents
Contents Notices Contents Introduction About this manual Accessory manuals To obtain manuals Overview Uses Parts and Accessories Summary Description System Connection Options Quick Start Button Actions Alternative ways of controlling SunScan. Use the Emulator Read SunScan PAR Change SunData Settings Take LAI Readings Review Data Reviewing Display Type: All data... - Page 4 Above-canopy reference requirements Direct and Diffuse components Canopy type and BF5 practicalities Canopy type and LAI estimates Canopy sampling volume Preferred light and weather conditions Planning for the sun’s position Advice on Absorption and ELADP values SunScan Measurement modes Measurement procedures in the field LAI theory Ingredients of the LAI computation method Theory versus reality...
- Page 5 Telescopic Tripod Carrying Case SunScan Probe Spares Kit type SPS1 BF5 Spares Kit type BF5-SP PAR Performance Appendices A. Logging the probe as a Linear Quantum Sensor B. Logging the Beam Fraction sensor Glossary Technical Support Terms and Conditions of sale Service and Spares Technical Support Contact Details...
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Page 6: Introduction
Introduction About this manual This shows how to use the SunScan Canopy Analyser and its accessories See also: SunScan Quick Start Guide. SunScan Technical Manual (available as a PDF file). Accessory manuals BF5 Sunshine Sensor User Manual. SunScan System Radio Link User Manual Supplement. To obtain manuals ... -
Page 7: Overview
Overview Uses Leaf Area Index In some types of canopy you can estimate leaf area index (LAI) with reasonable accuracy. For best results a BF5 sensor should also be used. PAR measurements SunScan can be used as a portable line quantum sensor for measuring levels of photo-synthetically active radiation (PAR) in plant canopies. -
Page 8: Parts And Accessories
Parts and Accessories Summary SunScan probe no radio SunData software for SDA2 Windows Mobile Ruggedised PDA running RPDA-1 Windows Mobile 5 or 6 Sunshine Sensor Radio transmitter for BF5-RL4 BF3, links to SS1-RL4 SunScan Probe + radio receiver (434 MHz) links SS1-RL4 to BF-RL4 Telescopic tripod for... -
Page 9: Description
Description 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 PDA via the RS232 link. An optional radio link is available for BF5. - Page 10 SunData software The SunData software pre-installed on your PDA is ready to control SunScan - to take readings, display and store results, and review data. It is easy to use, but a familiarity with Windows Mobile helps. SunData version 2 and later runs on a PDA, using Windows Pocket PC 2003 or Windows Mobile 5 or 6.
- Page 11 Check with us to see if this radio frequency is approved for use in your country. Note a type SS1-RL4 radio-enabled SunScan is required. Cables Cable EXT/8w-05 is provided to connect a BF5 to a SunScan. This can be extended with EXT/8w-xx cables, where xx = 5,10 or 25m. To connect either SunScan (acting as a line quantum sensor) or a BF5 to an analogue data logger use cable SP-BF/w-O5 which is 5m long.
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Page 12: System Connection Options
Possible SunScan System Combinations In Emulator mode the PDA Emulator: running SunData software probe can simulate needed!! SunScan and BF5 sensor SunScan SS1 + PDA running SunData SunScan EXT/8w-05 SunScan SS1 + BF5 + PDA running SunData SunScan Radio version: SunScan SS1-RL4... -
Page 13: Quick Start
Quick Start Button Actions Alternative ways of controlling SunScan. Figure 1 The Recon PDA with SunScan. The Recon was replaced with the Nomad PDA, which has a similar layout Principle SunData actions, such as Read and Store, are activated either by pressing the red SunScan button, or the active part of the touch sensitive screen, or by the Enter button on the PDA.... -
Page 14: Use The Emulator
Use the Emulator When first run, SunData is set to work in its Emulator mode This mode simulates having a SunScan attached (with and without an external beam fraction BFS sensor). Turn on PDA without SunScan attached. Select the SunData Program from the Start menu. This starts the program and displays the Title page showing the current settings. -
Page 15: Read Sunscan Par
Read SunScan PAR Connect SunScan to the PDA. Start SunData. Tap on File, Settings and change SunScan connection to COM1 Change the External sensor setting to None Tap on the Display page and change Display type to PAR. ... -
Page 16: Change Sundata Settings
Change SunData Settings v0.b 11/3/08 Example: Set up to measure Leaf Area Index Set PDA COM port. Specify Leaf Specify the Site Display type: select Declare if BFS Area Index and set the time LAI, PAR or All sensor connected. Constants (i.e. -
Page 17: Take Lai Readings
Take LAI Readings Start Diffuse Direct Total Average 64 diode readings per SunScan reading Taking Readings Sample BFS attached? Read Average Incident Read Average 45.1 Individual Sunscan Average of Sunscan reading readings If measuring LAI and no Beam Fraction Sensor is attached SunData ensures you measure Beam Fraction at least once First reading... - Page 18 Taking readings for estimating Leaf Area Index is simpler with an external beam fraction sensor (BFS) attached, such as the BF5 Sunshine Sensor. Note 1: If no BFS is attached, SunScan initially takes you through an extra step to measure the Beam Fraction. A typical sequence of readings is shown in the diagram below.
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Page 19: Review Data
Review Data Review Data Load file and scroll Stored data is saved to a file on the PDA. To review your readings tap File Review Data and select the data file. Tap on the scroll bars to see all the data. In the tab-formatted data file, readings do not always line up with their headings. -
Page 20: Pc Operations
PC Operations Connecting to your PC Connecting your PDA to a PC lets you transfer your data files and re- install or upgrade the SunData application on your PDA. The following guidance is specific for the Nomad 900 PDA. Other PDA’s may have different requirements and procedures. -
Page 21: Install Sundata Software
Install SunData software SunData installation software is provided on the SunScan CD. SunData is preinstalled on PDA’s supplied by Delta-T as part of a SunScan system. Even so, it is worth installing the SunData program group on your PC because: 1) It is there if you need to reinstall SunData on the PDA in the future and 2) The SunScan system manuals are also installed on the PC. -
Page 22: Configuration And Data File Handling
Configuration and data file handling SunData uses two sorts of files, data files for storing readings, and configuration files, in which you can retain the settings of different sites and experiments. Configuration files Configuration files contain all the information in the Settings tabs, that is: ... - Page 23 Use of the Default.cfg file Every time you exit SunData, using the File, Exit command, the program state is stored (in a hidden file called Default.cfg). This configuration is restored when the SunData program is next run. This means you start again exactly where you finished last time. (Perhaps a better name for it would have been MyLastConfig.cfg).
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Page 24: Data Files
Data Files A data file is automatically opened whenever you start SunData. The initial default file name is Data.txt. in My Documents. When you take readings they are appended to the data file - readings are added to the end of it, and do not overwrite it. The data is automatically saved when you switch off. -
Page 25: Displaying Data Files On Your Pc
Displaying data files on your PC As soon as you have transferred data files from the PDA to your PC you will want to analyse and print them for your records. TAB separated .TXT file format The tab separated text file format is a common format where ASCII characters are separated into fields by tabs. - Page 26 The .PRN file format This format is designed for printing out directly, rather than importing into a spreadsheet. Choose the appropriate format when you create a new data file in File, Settings, SunScan. An example printout is shown below. Created by SunData Title :Demonstration Location...
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Page 27: Menus And Screens
Menus and Screens File menu options File Exit Exits the SunData program completely (using the X in the top right corner only puts SunData into the background). Save Choose an existing settings file to Settings replace, or create a new one. You can select folders within ‘My Documents’, or on an expansion card if fitted. -
Page 28: Settings Menu Options
Settings menu options SunScan Emulator File > SunScan No external SunScan is needed. The Connection Settings software will generate random values as if a SunScan probe were connected. COM1 All the COM ports reported by your PDA are listed. Select the external serial port you have connected your SunScan to. - Page 29 Settings Display Display Values appropriate to canopy LAI (cont’d) type measurements are displayed. Values appropriate to measurements of PAR levels above and below the canopy are displayed. The display is the same as for PAR, but the 64 individual photodiode readings are also stored in the data file.
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Page 30: Utilities Menu Options
Utilities menu options Recalibrate BFS must be Utilities Calibrate Sets the individual sensors along the SunScan connected by SunScan wand to match the reading of cable the connected BFS. Restore Restores the calibration of the SunScan Factory sensors that was determined at Delta-T. Calibration Autolog SunData will operate the SunScan... - Page 31 This screen calculates the sun’s position Utilities Solar Calc (cont’d) through a day. This can be useful in planning experiments. Date Default is today, but this can be set to any date. Longitude Initially set to the current Site, but can be &...
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Page 32: What To Measure And How
What to Measure and How Experiment Design This section discusses the factors that bear on your experimental objectives. It should help you answer questions like: What equipment do I need? What readings must be taken? Will I have to wait for particular times of day or weather conditions? The type of study you propose to do will determine the time of year and duration of the experiment, and whether you are interested, for example, in monitoring growth by interception of solar radiation, or perhaps in the... - Page 33 Measuring Leaf Area Without a Beam Fraction Sensor This is the most complicated option. For an overview see Take LAI Readings on pages 17 & 18. Each LAI reading below the canopy requires a previous Incident reading and a Beam Fraction reading above the canopy. If measuring LAI without a Beam Fraction Sensor, SunData ensures you first measure Beam Fraction at least once.
- Page 34 the probe. Don't hold the shade too close to the probe - otherwise it will cut out some of the diffuse light as well. SunData looks at the readings from the photodiodes and uses the lowest value to calculate the Diffuse component of the incident light. It uses the highest photodiode values to calculate the incident Total, and uses these two values to calculate and display the Beam Fraction: The Beam Fraction reading is used to increase the accuracy of the...
- Page 35 Canopy type and LAI estimates Some types of canopy do not conform well to the assumptions about canopy structure used by the SunScan in calculating LAI. The following table will give you an initial idea of whether it is applicable to your canopy. You should read the chapter on the LAI theory for a fuller appreciation of the subject.
- Page 36 Preferred light and weather conditions These also will significantly influence your field operations. Limitation Comments Time of day Preferably within 3 hours either side of solar noon depending on the location and season, to meet the next two conditions. Solar zenith angle Measurements are easier when the sun is high.
- Page 37 Advice on Absorption and ELADP values Absorption Absorption is the percentage of incident PAR 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, e.g.
- Page 38 Setting ELADP The default setting of 1.0 (spherical leaf angle distribution) is a good starting point. If you are unable to estimate the ELADP any other way, set ELADP to 1.0. You can check how much this affects your results in the field by making several measurements in one place within a canopy using different ELADP values, and comparing the LAI values calculated.
- Page 39 Relationship between Mean Leaf Angle and ELADP Wang & Jarvis (1988) describe the relationship between ELADP and the Mean Leaf Angle, which is sometimes known from other studies. Their results are summarised by the following graph: 0.01 ELADP Typical ELADP Values (from Campbell and van Evert, 1994) Crop ELADP...
- Page 40 SunScan Measurement modes Having designed your experiment, choose which data collection option best suites your experiment, and whether you need a BF5 sensor. If used with a PDA running the SunData software, SunScan has three measurement modes: LAI, PAR or ALL. Each can be used with or without a BF5 connected.
- Page 41 LAI, PAR and All - measurement modes (Note: the values on the screens below, generated by the Emulator, are for illustration and may not be very realistic). LAI Readings With BFS Without BFS Note: LAI readings are only available in this mode.
- Page 42 Automatic logging modes Autolog mode: SunScan can be logged automatically from the PDA via the SunData Utilities, Auto log function. With Autolog you can operate SunScan automatically in any of its modes, just as if you were pushing the read, store and average buttons at regular intervals.
- Page 43 Measurement procedures in the field Check the equipment a day or two before your field experiment for routine matters such as the state of the batteries and the internal desiccant. See the Technical Reference section on page 62 for details of these. Probe handling in the field GO Button Use of the red button on the probe...
- Page 44 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.
- Page 45 Beam Fraction Sensor Handling in the Field The Beam Fraction sensor is definitely recommended for taking most types of readings, however the extra cable connection to the standard SunScan probe does add an unwelcome practical complication! Use of the BF5 radio link may be preferable See also SunScan System Radio Link User Manual Using the tripod The BF5 has a tripod mount, which will probably be the most convenient...
- Page 46 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.
- Page 47 In SunData on the PDA select Utilities, Calibrate, Recalibrate SunScan, then follow the instructions. You should not expect to have to do this very often. The photodiodes and light measurement circuits are very stable. The sources of the apparent variability mentioned above, between the probe and BF5, are ...
- Page 48 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.
- Page 49 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.
- Page 50 The relentless advance of computing power has made it possible to model the situation in ways that were not feasible in the past. By integrating the "black leaf" analysis into a computer model Wood has calculated the light levels in the canopy across the whole range of canopy and incident light parameters.
- Page 51 Derivation of Wood’s SunScan canopy analysis equations The major assumptions The canopy is an infinite, uniform, horizontal slab, with leaf elements randomly distributed in proportion to the surface area of an ellipsoid, as described by Campbell. The incident light consists of a component from a point source at a given zenith angle (the Direct beam);...
- Page 52 Note: in the following equations derived in MathCAD, different conventions are used for some symbols. Equality is represented by =, and tan (θ) is expressed tan(θ) The extinction coefficient, K, is calculated as follows: tan( ) , x 0.708 1.702 ( 1.12...
- Page 53 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.
- Page 54 Diffuse light transmission (cosine corrected sensor) Transmission fraction Leaf Angle Distribution Vertical diff ( , 0 L Vertical diff ( , 1 L Spherical diff ( 1000 L Spherical Horizontal 0.01 Horizontal 0.001 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.
- Page 55 Of the light intercepted by the leaf element, a fraction a (absorption) is totally absorbed. The remainder is re-emitted uniformly in all directions. 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.
- Page 56 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.
- Page 57 Functions used to model canopy transmission Diffuse light - cosine response sensor The transmission of diffuse light through a canopy, as measured by a cosine corrected sensor, can be modelled by the following functions: Given: A( ) x 1.38 0.15 x 0.007 B( ) x 4.32...
- Page 58 This was again calculated numerically and curves fitted to the data with similar accuracy as above. The curves fitted are: Given: P( ) x 0.4 exp( 0.1 x ( atan( 0.9 x 0.95 Q( ) x 0.255atan( ) x R( ) x exp( Q( ) x ...
- Page 59 Modelling incomplete PAR absorption and scattering Radiation models have been used for many years to calculate the effects of scattering in the canopy e.g. Norman & Jarvis (1975). Wood's model incorporates Campbell’s ellipsoidal leaf angle distribution and the effects this has on transmission of both Direct and Diffuse light. The model splits the canopy into layers of LAI 0.1, extending to a sufficient depth to absorb all of the incident light.
- Page 60 The full equation thus becomes: , x Direct f b exp g dir ( part C( ) x Diffuse exp L a A( ) x L a B( ) x L a part This looks hard to invert to get LAI from τ, but an iterative solution is fairly straightforward given the computing power, and is much simpler than the full numerical solution.
- Page 61 Scientific references Campbell G S (1986). Extinction coefficients for radiation in plant canopies using an ellipsoidal inclination angle distribution. Agric. For. Meteor., 36:317-321. Campbell G S and F K van Evert (1994) Light interception by plant canopies: efficiency and architecture. In J L Monteith, R K Scott, and M H Unsworth, Resource Capture by Crops, Nottingham University Press.
- Page 62 Technical Reference Maintenance Batteries Apart from the PDA, all the components of the SunScan system are powered by alkaline 1.5V AA cells. Do not substitute other types of cell. Checking the batteries The SunScan system requires batteries within the probe, in the PDA, in the BF5 and any BF-RL4 radio link if attached.
- Page 63 SunScan Probe SS1-RL4 The probe is powered by 4 x AA cells. These should give about 500 hrs operating time with radio usage. Replace the batteries when the level has fallen near to 5 V (or 4.7 V level for non-radio operation). BF5 radio transmitter BF5-RL4 The transmitter is powered by 4 x AA cells.
- Page 64 PDA batteries Before you start The PDA Power Boot Module is shipped detached from the unit. Before inserting it in the unit charge it for 12 hours using the AC adapter. Checking the PDA battery levels Tap System, Power to view the approximate battery power remaining in 20% increments.
- Page 65 Desiccant The SunScan probe, BF5 and BF5-RL4 transmitter module each contain desiccant packs. The desiccant packs must be refreshed from time to time to avoid the possibility of condensation within the instruments. The dryness of the desiccant pack may be indicated by a coloured panel on the instrument.
- Page 66 Checking the PAR calibration Various techniques for checking the SunScan system PAR calibration and consistency are described in Checking the probe/BF5 matching on page 46, 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.
- Page 67 Troubleshooting While running SunData SunData reports “SunScan probe not connected”. Check the cable connections. Check the condition of the batteries in the SunScan probe. SunScan or BF5 give inconsistent light readings. Make sure the desiccant condition indicators are blue. ...
- Page 68 Specifications SunScan Probe type SS1 Active area 1000 x 13 mm wide. Sensor spacing 15.6 mm Spectral response 400 - 700 nm (PAR) Measurement time 120 ms 2500 mol.m Maximum reading 0.3 mol.m Resolution Linearity better than 1% Accuracy +/- 10% 1 mV per mol.m Analogue output Serial interface...
- Page 69 Nomad PDA See Getting Started Guide for full specifications Windows Mobile 6.1 Marvel PXA320 XScale 806 MHz Memory 512 MB of non volatile Flash storage Display 480 x 640 pixel colour TFT with LED front light 15 hours continuous room temperature operation with Battery life default settings and no embedded radios Battery charging...
- Page 70 Environmental IP 65 (shower and dust proof) sealing Desiccant pack Activated clay, 60 x 130 mm Connector RS-232, 9–pin female, cable mounted Mounting 1/4 inch Whitworth tripod socket Size and weight 125 mm x 125 mm x 40 mm, 450 g ( excl. antenna) SunScan to BF5 Cable A 5 metre long (EXT/8w-5) cable is provided as standard for connecting a BF5 Sunshine Sensor to a SunScan Probe (unless using the radio link).
- Page 71 Telescopic Tripod 3-way head with quick release platform. Geared friction elevator control. Locking leg catches and brace. Dual Spike/rubber feet. Type BFT1 Max height 1.73 m Closed length 0.68 m Weight 2.5 kg Screw mount ¼inch Whitworth socket Carrying Case Moulded plastic case with O-ring seal for moisture and dust proofing, including pressure release valve.
- Page 72 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.
- Page 73 Cosine responses of probe and BF5 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.
- Page 74 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.
- Page 75 Logger requirements The probe requires a voltage supply of 7-15 V dc (unregulated), at about 30 mA current. The analogue output is enabled when the external voltage is greater than the battery voltage. Configure one channel of the logger for voltage input, with the above sensitivity.
- Page 76 Glossary Beam fraction - the fraction of the Total incident PAR in the Direct beam. Beam Fraction Sensor - The BF5 consists of an array of 7 photodiodes under a specially shaped shadow mask, used for measuring Direct and Diffuse light above the canopy. Beer’s law - a general law describing transmission through an absorbing medium.
- Page 77 canopy elements as in the same proportions as the surface of an ellipsoid. Using this model, a wide range of different canopy types can be described by a single parameter, the Ellipsoidal Leaf Angle Distribution Parameter (ELADP), which is the ratio of the horizontal to vertical axes of the ellipsoid.
- Page 78 Technical Support Terms and Conditions of sale Our Conditions of Sale (ref: COND: 06/14) set out Delta-T's legal obligations on these matters. The following paragraphs summarise Delta T's position but reference should always be made to the exact terms of our Conditions of Sale which will prevail over the following explanation.
- Page 79 Contact Details Tech Support Team Tel: +44 (0) 1638 742922 Delta-T Devices Ltd Fax: +44 (0) 1638 743155 130 Low Road, Burwell, email: tech.support@delta-t.co.uk Cambridge CB25 0EJ, U.K.
- Page 80 Index .NET ............. 21 Comms Test ........30, 31 .PRN file format ........26 Conditions of sale........78 Absorption ..........37 Configuration ........22 Accuracy ........45, 46, 68 Constants ..........28 All data ..........19 Contact Details ........79 Autolog ...........
- Page 81 Group name........... 29 Protective Case ........44 Hemispherical response ....... 76 Quick Start ..........13 Install SunData ........21 Radio Link ....10; Specifications LAD ............76 ............69 LAI ........17, 32, 33, 76 Read ..........13, 15 LAI Readings ........41 Read interval .........
- Page 82 Utils ............30 weather conditions ........ 36 Version and serial number location ..67 zenith angle ........... 36 version number ........31 Zenith angle.......... 77 Warning: PDA buttons ......13 zenith angles.......... 60 Warnings ..........2 82 Index SS1 User Manual v3.3...
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