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Download Optical-Sensors. Wavelength nm Visible Light Near Infrared 4505506507508509501050 0.250.50 % Reflectance

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  • Optical-Sensors

  • Irradiance Sensing Strategies

  • Red Reflectance:r = Rred / Ired Reflectance is primarilya function of targetReflectance Sensing Strategies

  • Normalized Difference Vegetative Index (NDVI)

  • Reflectance NDVI

  • Natural LightingLight source is free.Much of the effect of spectral shift can be corrected by measuring incident and reflected. light and calculating reflectance.Spectral shifts occur as sun angle changes.Cloud cover affects intensity.Moisture and dust cause differences in refraction and absorbence across the spectra.Cant be operated at night. AdvantagesLimitations

  • OSU Reflectance Sensor

  • Artificial Lighting Patchen high frequency pulsed narrow spectra lightingBroad spectra lighting with filters Constant or Pulsed

  • Artificial LightingRemoves the effect of changing background illumination.Can be operated 24 hours/day.Can produce an absolutely calibrated signal.Choice of spectral bands are limited when pulsed solid state lighting sources (LEDs or lasers) are used.Broadband lighting requires high power .Cost of the sensor/lighting systems are higher than those using natural lighting.

  • Patchen WeedseekerOptical Sensor

  • Patchen Sensing Technique

  • Patchen Sensing Technique

  • Patchen Sensor NDVI Calibrationy = 0.7711x - 1.06180.40.50.60.70.80.911.92.12.32.52.7Patchen DET_OUT Voltage (x/6420)OSU NDVIGood calibration to NDVI after filtering

  • Temperature driftunacceptable for absolute measurementsPatchen Temperature Calibration

    Sheet1

    Calibration of Patchen Units to NDVI w/ Temperature equation, NDVI conversion @ 100 degrees F, and offset value for sensors

    11/13/98

    T=70

    y=c*v-d

    @ 100 (F)

    y = 0.8237v - 1.2497

    y = 0.7083v - 0.9025

    y = 0.686v - 0.7799

    y = 0.7009v - 0.9054

    y = 0.7711v - 1.0618

    y=c*v-d

    cdy=NDVI

    33850.82371.2497v=DET_OUT

    33860.70830.9025T=temp (F)

    33870.6860.7799x=Laptop output

    33880.70090.9054v=x/6420

    34930.77111.0618

    Standard Temp = 100 degrees F

    x=a+b/T^2z=a+b/100^2)

    abz

    338512741.12062800842290408.13322511338512970.1614413309

    338611846.84355218622754242.45402546338612122.2677975887

    338711365.59622485113117182.72750549338711677.3144976016

    338811213.45119235233246873.35048842338811538.1385274011

    349311588.46512647782579739.38931502349311846.4390654093

    Calibration Equation

    y=c*x*(z/a+b/T^2)/6420-d

    3385-0.823557197

    3386-0.5376507826

    3387-0.4277860414

    3388-0.5455343525

    3493-0.6517025635

    Offset Change

    d

    33851.2497

    33860.9425

    33870.8099

    33880.8954

    34931.0518

    Calibration Equation w/ Offset

    y=c*x*(z/a+b/T^2)/6420-d

    3385-0.823557197

    3386-0.5781507826

    3387-0.4577860414

    3388-0.5355343525

    3493-0.6417025635

    NDVI Chart

    0.79033640192.4332096392.4332096392.4332096392.433209639

    0.81148748942.47820353062.47820353062.47820353062.4782035306

    0.8895306132.58262201452.58262201452.58262201452.5826220145

    0.8907368242.60003367852.60003367852.60003367852.6000336785

    0.90457642122.59139148492.59139148492.59139148492.5913914849

    0.82819987492.51667185882.51667185882.51667185882.5166718588

    0.85811608192.55896818652.55896818652.55896818652.5589681865

    0.91446173192.62876752342.62876752342.62876752342.6287675234

    0.91290650452.61939001112.61939001112.61939001112.6193900111

    0.87819376532.60814419232.60814419232.60814419232.6081441923

    0.83225330672.47457541962.47457541962.47457541962.4745754196

    0.70324127292.36929104132.36929104132.36929104132.3692910413

    0.75098989312.425032662.425032662.425032662.42503266

    0.70930007312.38017707822.38017707822.38017707822.3801770782

    0.68218873022.35677821322.35677821322.35677821322.3567782132

    0.71950360552.40305685362.40305685362.40305685362.4030568536

    0.75057317782.44919197822.44919197822.44919197822.4491919782

    0.81801644812.47967643732.47967643732.47967643732.4796764373

    0.82397829972.50370166762.50370166762.50370166762.5037016676

    2.41963074950.81175040572.41963074952.41963074952.4196307495

    2.5442920310.88844271312.5442920312.5442920312.544292031

    2.40962811530.77442942122.40962811532.40962811532.4096281153

    2.54795619750.90035697772.54795619752.54795619752.5479561975

    2.54360072690.90020567092.54360072692.54360072692.5436007269

    2.41365052390.79709789972.41365052392.41365052392.4136505239

    2.56402688970.90784693382.56402688972.56402688972.5640268897

    2.49099980530.89633556942.49099980532.49099980532.4909998053

    2.49385221960.8708321132.49385221962.49385221962.4938522196

    2.32902220880.75018512332.32902220882.32902220882.3290222088

    2.34344287010.73345083342.34344287012.34344287012.3434428701

    2.36452617830.71645868222.36452617832.36452617832.3645261783

    2.30184456470.67484100852.30184456472.30184456472.3018445647

    2.35106885810.69368226292.35106885812.35106885812.3510688581

    2.34593599552.34593599550.82056783122.34593599552.3459359955

    2.34380062312.34380062310.7894649722.34380062312.3438006231

    2.45975077882.45975077880.89678282332.45975077882.4597507788

    2.43828660442.43828660440.91138679622.43828660442.4382866044

    2.33566506182.33566506180.81291775582.33566506182.3356650618

    2.36045393862.36045393860.83806583862.36045393862.3604539386

    2.4503351272.4503351270.90468252222.4503351272.450335127

    2.45505314282.45505314280.9073323352.45505314282.4550531428

    2.45477024922.45477024920.90626123892.45477024922.4547702492

    2.38408989762.38408989760.86442681472.38408989762.3840898976

    2.21817907752.21817907750.6935728382.21817907752.2181790775

    2.2267584852.2267584850.72545154542.2267584852.226758485

    2.15992636652.15992636650.66463738182.15992636652.1599263665

    2.19811821172.19811821170.6828273832.19811821172.1981182117

    2.22558182152.22558182150.6922874342.22558182152.2255818215

    2.37935163552.37935163550.85606191352.37935163552.3793516355

    2.41334557192.41334557190.89030628972.41334557192.4133455719

    2.31933474022.31933474020.805227122.31933474022.3193347402

    2.39189026232.39189026230.87616300582.39189026232.3918902623

    2.32079690482.32079690480.82144060262.32079690482.3207969048

    2.44837704752.44837704752.44837704750.81459023012.4483770475

    2.49315099872.49315099872.49315099870.82096471282.4931509987

    2.56034569392.56034569392.56034569390.89281178032.5603456939

    2.5526802022.5526802022.5526802020.89445048662.552680202

    2.4622108942.4622108942.4622108940.78932412222.462210894

    2.55356795172.55356795172.55356795170.88950738912.5535679517

    2.58533391742.58533391742.58533391740.9087452452.5853339174

    2.51450105522.51450105522.51450105520.86655154142.5145010552

    2.5305295952.5305295952.5305295950.83913916742.530529595

    2.34035683942.34035683942.34035683940.70869010012.3403568394

    2.34322429912.34322429912.34322429910.6999045122.3432242991

    2.30124152462.30124152462.30124152460.68618957112.3012415246

    2.35230050322.35230050322.35230050320.71799019012.3523005032

    2.41093457942.41093457942.41093457942.41093457940.8217007487

    2.39770534152.39770534152.39770534152.39770534150.7910871495

    2.54055371322.54055371322.54055371322.54055371320.890749855

    2.53892523362.53892523362.53892523362.53892523360.9019156774

    2.52153049942.52153049942.52153049942.52153049940.8967357582

    2.43118134122.43118134122.43118134122.43118134120.8247694026

    2.43229491172.43229491172.43229491172.43229491170.8451029368

    2.55803360712.55803360712.55803360712.55803360710.9082051795

    2.46695655942.46695655942.46695655942.46695655940.8612724392

    2.53911164712.53911164712.53911164712.53911164710.8466791575

    2.44563360472.44563360472.44563360472.44563360470.8231890329

    2.30513481582.30513481582.30513481582.30513481580.7114162889

    2.31215455732.31215455732.31215455732.31215455730.7044728379

    2.27389622952.27389622952.27389622952.27389622950.6626855894

    2.29003115262.29003115262.29003115262.29003115260.6856740524

    2.3664920232.3664920232.3664920232.3664920230.7296755255

    2.32327744182.32327744182.32327744182.32327744180.7039565209

    2.52090744652.52090744652.52090744652.52090744650.8636071326

    2.44854620982.44854620982.44854620982.44854620980.8268410251

    2.4484131622.4484131622.4484131622.4484131620.8316365182

    0.70240593152.47843595382.47843595382.47843595382.4784359538

    0.67275034222.38750973522.38750973522.38750973522.3875097352

    0.74506058162.47505102592.47505102592.47505102592.4750510259

    0.73114450232.36126004262.36126004262.36126004262.3612600426

    0.67777706752.3330080632.3330080632.3330080632.333008063

    0.57017293532.22923453492.22923453492.22923453492.2292345349

    0.69766166182.34182242992.34182242992.34182242992.3418224299

    0.46077878012.06924649532.06924649532.06924649532.0692464953

    0.77708768232.42060794862.42060794862.42060794862.4206079486

    0.75300609372.41954828662.41954828662.41954828662.4195482866

    0.7067941032.42193827882.42193827882.42193827882.4219382788

    2.24291764020.6992441592.24291764022.24291764022.2429176402

    2.29873929130.74311341072.29873929132.29873929132.2987392913

    2.13619270140.5803432892.13619270142.13619270142.1361927014

    2.21376746060.67746845612.21376746062.21376746062.2137674606

    2.2653904130.72236093952.2653904132.2653904132.265390413

    2.07156455520.52349323322.07156455522.07156455522.0715645552

    2.26479750780.71983042922.26479750782.26479750782.2647975078

    2.27135372420.71640585932.27135372422.

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