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NDVI / PRI Sensor
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NDVI / PRI Sensor

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Continuously monitor NDVI or PRI

At METER, we think you should spend less time on complexity and more time doing what matters. Apogee NDVI and PRI sensors are easy-to-use. And the best part? They’re pre-configured for use with the ZENTRA system, so you’re instantly up and running.

Low cost—low maintenance

By focusing on just two relevant bands, it’s possible to make an accurate multiband radiometer for a fraction of what a full-spectrum spectroradiometer costs. Apogee NDVI/PRI sensors are multiband radiometers that combine an ultra-rugged form with sophisticated cloud data delivery for an unbeatable price-to-performance ratio. They're inexpensive enough to deploy multiple sensors simultaneously, so you can maximize spatial coverage and explore spatial and temporal variability in canopy structure and function.

Deploy for months or even years

Most spectrometers are delicate and expensive, making long-term field deployment risky. Apogee NDVI and PRI sensors are built for long-term exposure to the elements. Encased in a durable housing with an epoxy fill, they are watertight, weatherproof, and have fully sealed optics. Mount them on a fence post, tripod, or a meteorological tower. They’re rugged enough to leave in the field for an entire growing season or longer. 

Field ready and radiometrically calibrated

Each sensor is radiometrically calibrated to a NIST-traceable standard. Readings are output in units of radiant flux density. Calibration information is stored on board the sensor, so you never have to worry about keeping track of calibration coefficients.

Collect data and monitor remotely

To simplify your workflow, Apogee NDVI and PRI sensors are plug-and-play with ZL6 data loggers, which means automatic sensor recognition and zero programming. ZENTRA Cloud lets you monitor remote sites in near-real time from any internet-connected device. Observe field conditions, check and configure sensor and system function, or download data from the comfort of your home or office.

Work less. Measure more.

Apogee NDVI/PRI sensors are part of a complete system of affordable, easy-to-use sensors, loggers, and software that require little maintenance and put near-real-time data at your fingertips, so you can publish more and work less.

Specifications 

PRI SENSOR SPECIFICATIONS  
Calibration factor (reciprocal of sensitivity) Custom for each sensor and stored in firmware

NOTE: The calibration factor (reciprocal of sensitivity) and output range are all approximations and variable from sensor to sensor
Calibration uncertainty ± 5 %
Output range SDI-12

NOTE: The calibration factor (reciprocal of sensitivity) and output range are all approximations and variable from sensor to sensor
Power supply 5.5 to 24 V DC
Wavelength ranges Green detector = 532 nm with 10 nm FWHM*
Yellow detector = 570 nm with 10 nm FWHM*

*FWHM = full-width half-maximum
Measurement range 2x full sunlight
Measurement repeatability Less than 1 %
Long-term drift Less than 2 % per year
Response time Less than 0.6 s
Field of view S2-421-SS (upward-looking): 180°
S2-422-SS (downward-looking): 35°
Directional (cosine) response ± 2 % at 45°, ± 5 % at 75° zenith angle
Temperature response Less than 0.1 % per C
Housing Anodized aluminum body with acrylic diffuser
IP rating IP68
Operating environment -40 to 70 C; 0 to 100 % relative humidity
Dimensions S2-421-SS (upward-looking): 30.5 mm diameter, 37 mm height
S2-422-SS (downward-looking): 23.5 mm diameter, 43 mm height
Mass (with 5 m of cable) S2-421-SS (upward-looking): 140 g
S2-422-SS (downward-looking): 110 g
Cable 5 m of shielded, twisted-pair wire; TPR jacket (high water resistance, high UV stability, flexibility in cold conditions); pigtail lead wires; stainless steel (316), ZL6 stereo plug termination
NDVI SENSOR SPECIFICATIONS  
Power supply 5.5 to 24 V DC
Calibration factor (reciprocal of sensitivity) Custom for each sensor and stored in firmware
Calibration uncertainty ± 5 %
Output range SDI-12
Wavelength ranges Red detector = 650 nm ± 5 nm with 65 nm FWHM
NIR detector = 810 nm ± 5 nm with 65 nm FWHM
Measurement range 2x full sunlight
Measurement repeatability Less than 1 %
Long-term drift Less than 2 % per year
Response time Less than 0.6 s
Field of view 180°
Directional (cosine) response ± 2 % at 45°; ± 5 % at 75° zenith angle
Temperature response Less than 0.1 % per C
Housing Anodized aluminum body with acrylic window
IP rating IP68
Operating environment -40 to 70 C; 0 to 100 % relative humidity
Dimensions 30.5 mm diameter, 34.5 mm height
Mass (with 5 m of cable) 140 g
Cable 5 m of shielded, twisted-pair wire with TPR jacket and stainless steel connector
Warranty 4 years against defects in materials and workmanship
Data logger compatibility (not exclusive) METER EM60 series, ZL6 series, ZSC, ProCheck, Campbell Scientific

Downloads

Apogee NDVI sensor manual Manual PDF, 0.9MB
Apogee PRI Sensor Manual Manual PDF, 1.5MB
Using Apogee NDVI and PRI Sensors with ZENTRA System Manual PDF, 1.1MB
Meter Legacy SRS Spectral Reflectance Sensor Manual Manual PDF, 1.699MB
METER Legacy SRS Quick Start Quickstart Guide PDF, 0.46MB
Meter Legacy Spectral Reflectance Sensor (SRS)(NVDI) Integrator Guide Quickstart Guide PDF, 0.643MB
Meter Legacy Spectral Reflectance Sensor (SRS)(PRI) Integrator Guide Quickstart Guide PDF, 0.643MB
METER Legacy SRS NDVI Calculator Calculator/Converter XLSX, 0MB
Anemometer Mast Assembly Instructions Manual PDF, 0.527MB

FAQ's

Can I check downward facing NDVI/PRI sensors output using a white panel test?

Yes, you could check downward facing sensor response in the field on a sunny day using a white panel. Ideally, a Spectralon panel should be used. The SRS field stop calibration check should be done with the field stop sensors pointing down at an angle toward a white Teflon panel or Spectralon panel, so that the field of view is totally encompassed by the white panel. Then, with the hemispherical sensors pointing up to collect irradiance data at the same location and time (with no obstructions in the field of view), radiance values * pi (3.14) should be approximately equal to irradiance values.

 

Radiance = Irradiance/pi

Irradiance = Radiance * pi

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