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SunScan

1. SunScan Canopy Analysis System type ss1 e Measures incident and transmitted PAR in plant canopies e Direct display of Leaf Area Index LAI e Unique Sunshine Sensor type BF3 for measuring Direct and Diffuse components of incident light e Usable in all weather conditions e Portable weatherproof and battery powered p ie SunScan Probe SunScan uses field measurements of PAR in crop canopies to provide valuable information about LAI and biomass production Vast areas can be sampled quickly Introduction The SunScan system offers convenient and flexible tools for measuring and analysing incident and transmitted Photosynthetically Active Radiation PAR in crop canopies It provides vital information about the penetration of PAR into crops and is essential in work such as comparative crop studies for separating out the effects of cultivar and treatment It is particularly well suited to low regular canopies as found in many agricultural crops SunScan users don t have to wait for special weather conditions it can be used in most light conditions The probe has an array of 64 PAR sensors embedded in a 1m long probe and is connected via an RS 232 cable to a PC or handheld Data Collection Terminal type DCT2 When a reading is taken all sensors are scanned and the measurements transmitted to the Terminal or PC The average light level along the probe is calculated and all of the individual sensor readings are av
2. DCT2 specify mains type 230V AC 50Hz UK or EURO or 120V AC 60Hz Removable flashcard type RFC2 for DCT2 spare 1Mb data storage card holds typically an additional 8000 single readings PsiWin software type PSW2 PC based software links Data Collection Terminal DCT2 to Windows PCs providing convenient file and data transfer PsiWin is strongly recommended for communications between the DCT2 and your PC PsiWin can be purchased from Delta T or can be downloaded from the Psion website Extension cables for BF3 with connectors 10m cable type BFXL10 25m cable type BFXL25 50m cable type BFXL50 Logger cable type BFDL5 for BF3 Sunshine Sensor 3 channels Cable terminates in bare wires For use with data logger not with SunScan Probe Logger cable type SSDL10 for SunScan probe enables SunScan to be used as a Linear Quantum Sensor when connected to a data logger not for use with DCT2 or PC For spares recalibration and consumables please enquire Carrying Case type SCC1 for SunScan Probe and accessories Input Voltage Range 5 15V DC powered from SunScan Size amp Weight 120 mm x 122 mm x 95 mm 556g Data Collection Terminal type DCT2 Screen keypad 10 lines x 40 characters full alohanumeric sensor readings Environmental IP54 0 90 RH non condensing 20 to Seer 60 C Resists 1m drop onto concrete Power 2xAAalkaline cells or NiCd option 15 000 readings with internal memory Calibration The SunScan Probe SS1
3. ailable if required for detailed PAR mapping An operating button on the Probe handle enables successive readings to be taken quickly and simply on demand Alternatively unattended logging can be conducted under program control from the Terminal or PC Readings are in units of PAR quantum flux umol m s eo a 7 ck E d i q Fe e iy E 3 i F l in E z e B i E n ll i j b J a g T pa A F J T ond Jaa i le alll p d E j os f te TA H T Y ty a td a p E al i AME o SunScan Probe and Data Collection Terminal with SunShine Sensor mounted on tripod SunScan System Choices SunScan is modular and expandable This means researchers can specify a system that suits their own performance requirements and budget System type SunScan Recommended Plus System type SS1 R3 BF3 This is the complete package of SunScan items including SunScan Probe SunData Software Data Collection Terminal Sunshine Sensor type BF3 tripod and carrying case SunScan Standard System type SS1 STND2 The Standard System comprises The SunScan Probe SunData Software and the Data Collection Terminal Entry System type SS1 ENTRY The Entry System includes the SunScan Probe and the SunData Software only SunData software modelling Features and Advantages The Recommended Plus System provides a powerful canopy analysis tool It can calculate instant estimates of LAI measure PAR interception using spot read
4. and Sunshine Sensor are calibrated under a standard light source against an accurate PAR quantum sensor traceable to national standards The spectral and cosine responses of the sensors approximate to the ideal response graphs available on request but fall off at the extremes of the range Under most normal daylight conditions errors due to the deviation are small but it is possible for example under artificial light to find larger errors in the absolute values measured However because the SunShine Sensor and SS1 Probe are closely matched and the calculations are based on ratios of incident and transmitted light in practice this is not a problem The SS1 Probe can be recalibrated by the user if necessary using the BF3 SunShine Sensor Individual calibration values for each photodiode are stored in non volatile memory within the Probe Delta T Devices Ltd 128 Low Road Burwell Cambridge CB5 0EJ UK Tel 44 1638 742922 Fax 44 1638 743155 E mail sales delta t co uk Web www delta t co uk SSI DS 4 5 Sep 2002
5. ings or with unattended logging and measure sunflecks A major advantage for field use is that the BF3 Sunshine Sensor needs minimal adjustment during use see opposite page The Standard System is able to make the full range of SunScan measurements including LAI However as the SunScan Probe has to be used as its own above canopy reference it can only be used in steady light conditions blue sky or evenly overcast The lowest cost version of SunScan The Entry System runs on the user s portable PC instead of the Data Collection Terminal it has all the functionality of the Standard System but see Use With a Portable PC opposite for comments on the use of PCs in the field An advanced model of light transmission through a uniform canopy has been developed and is used in the analysis software This model builds on work by Campbell 1985 and Norman and Jarvis 1975 and takes account of the following factors e Direct amp Diffuse incident light e Solar zenith angle e Canopy Leaf Area Index e Canopy Leaf Angle Distribution e Leaf PAR absorption e Transmitted fraction Solar zenith angle is calculated from the actual time latitude and longitude Estimates of canopy Leaf Angle Distribution and Leaf Absorption are made by the user All other variables necessary to calculate LAI are measured directly Because the relative contributions of Direct and Diffuse incident light are physically measured at the same time as the transmit
6. ments Collected data can be transferred to a PC The optional PsiWin software provides convenient file transfer and data management for Windows based PCs Unattended Logging with DCT2 The SunData software can automatically take readings from the SunScan Probe and averages at user defined intervals from 1 second to 24 hours This might for example be used to obtain diurnal readings at a particular location of canopy light interception Data Collection Terminal type DCT2 Use with a Portable PC The SunData Software can be run on a portable PC but in practice an extra person is usually required to hold the PC In addition most portables have a shorter battery life and are less rugged than the Data Collection Terminal Use with a Data Logger The SunScan Probe can be connected directly toa data logger for use as a Linear Quantum Sensor When powered by the logger it outputs a voltage proportional to the average PAR incident on the probe Cables for connecting the SunScan probe to a logger can be supplied SunScan Specifications SunScan Probe type SS1 Ordering Information SunScan systems All systems are based on main components listed below SunScan Recommended Plus System type S S1 R3 BF3 ebee al tesponse picid Goal a SunScan Probe SunData Software Data Collection Terminal 120 ms Sunshine Sensor type BF3 with cable type BFXL10 Tripod and Maximum reading 2500 umol m s Carrying Case T SunScan Standard S
7. s requires no specific polar alignment or routine attention and works at any latitude levelling is the only adjustment required Other Applications The BF3 can also be used with a data logger for long term monitoring of Direct and Diffuse light and to record sunshine duration For these purposes the output units can be preset to energy W m or illuminance klux instead of PAR units Further information is available on request 1 Patent numbers EP 1012633 US 6417500 Delta T can also supply HemiView a system for obtaining and processing hemispherical images of plant canopies If your research involves high irregular canopies such as forests please request a HemiView data sheet Data analysis and storage Data Collection Terminal type DCT2 The DCT2 is a robust lightweight handheld computer the Psion Workabout which collects and analyses readings from the SunScan Probe In the field raw readings and derived functions such as LAI can be displayed reviewed and stored by the SunData Software groups of readings can be averaged if required The Terminal s full alphanumeric keypad makes annotation easy Readings are stored in the internal 2Mb internal memory which holds about 15000 readings reduced with some data formats or if lengthy notes are entered Optional 1Mb flashcards provide removable data storage or can hold copies of different Application set ups making it easier to switch between different experi
8. ted PAR readings can be made in a wider range of daylight conditions than has been possible with previous instruments We advise against taking measurements when the sun is strong and near the horizon when large errors may occur The assumptions and calculations made in the SunData software are fully explained in the user manual along with practical advice on how to use the system effectively Sunshine Sensor type BF3 for above canopy reference SunScan s unique feature is an optional reference sensor integrated into the design to measure simultaneously the Direct and Diffuse light above the canopy The Sunshine Sensor type BF3 provides these above canopy reference measurements quickly and conveniently The BF3 uses an array of photodiodes and a unique shading pattern to calculate whether the sun is shining and to measure the Direct and Diffuse components of solar radiation This completely avoids the need for troublesome shade ring adjustments required with conventional Diffuse light sensors The special shading pattern of the dome is matched to the layout of photodiodes in such a way that at least one photodiode always sees an unobstructed solar disc and at least one is always in full shadow The BF3 provides two cosine corrected analogue outputs corresponding to the Diffuse and Total components and a digital output of sunshine presence The outputs are compatible with most data loggers The sensor uses no moving part
9. ystem type SS1 STD2 SunScan Probe SunData Software and Data Collection Terminal Linearity better than 1 SunScan Entry System type SS1 ENTRY SunScan Probe plus SunData Software requires a portable PC for readout and data Analogue output 1 mV per umol m s collection Serial interface RS232 9 pin female D connector Main components Protected to IP65 0 60 C working temp SunScan Probe type SS1 including alkaline batteries and user Size overall mm 1300 1 x 100 w x 130 h manual SunData Software type SDA1 4 x AA Alkaline cells lifetime up to 1 year Sunshine Sensor type BF3 Data Collection Terminal type DCT2 Psion Workabout including Output Sensitivity 1 mV per umol m s cosine Total amp Diffuse PAR corrected alkaline batteries comms cable and leather case Accuracy Total 12 amp Diffuse 15 PAR 10 umol m s Sunshine Sensor type BF3 including user manual NB requires cable type BFXL10 for use with SunScan Probe or type BFDL 05 for use with data logger see below Temperature range 20 to 50 C with alkaline batteries Range PAR 0 2500 umol m s Total amp Diffuse Spectral Response PAR 400 700 nm Telescopic Tripod type SS TD for mounting BF3 4 x 1 5V AA alkaline batteries lifetime gt 1 year typical Active area 1000 x 13 mm wide Sensor spacing 15 6 mm Optional Items NiCd battery pack type DCT BAT for DCT2 Terminal Mains NiCd Charger type PSBC1 with docking unit for

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