®

Spectral Reflectance Sensor

Low cost, weatherproof radiometer

The Spectral Reflectance Sensor (SRS) is a matchbox-sized, multiband radiometer that can be mounted on a fence post, tripod, or meteorological tower. It’s inexpensive enough to deploy multiple sensors simultaneously. And it’s rugged enough to leave in the field for an entire growing season, or longer.

Deploy for months or even years

Most spectrometers are delicate and expensive, making long-term field deployment risky. The SRS is built for long-term exposure to the elements. Encased in a durable Geloy housing with an epoxy fill, it is water tight, weatherproof, with fully sealed optics. These materials and methods have been tested over months and years on other buried and above-ground sensors. Combined, these features help minimize drift in calibration over time.

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.

Continuously monitor NDVI or PRI at the plot scale

NDVI and PRI are calculated from measurements of of electromagnetic radiation reflected from canopy surfaces. They are correlated with canopy variables such as: light use efficiency (LUE), biomass and crop yield, crop and forest phenology, canopy growth, and photosynthetic performance/CO2 uptake. SRS sensors measure incident or reflected radiation in two bands. Normalized Difference Vegetation Index (NDVI) bands are centered at 650 nm and 810 nm with 50 nm and 40 nm full width half maximum (FWHM), respectively. Photochemical Reflectance Index (PRI) bands are centered at 532 nm and 570 nm with 10 nm FWHM.

Low cost for maximum spatial coverage

By focusing on just two bands, it’s possible to make an accurate multiband radiometer for a fraction of what a full-feature spectroradiometer costs. Use the SRS-NDVI and SRS-PRI sensors to maximize spatial coverage and explore spatial and temporal variability in canopy structure and function.

Collect data and monitor remotely

The SRS is an SDI-12 digital sensor. When used with METER’s ZL6 data loggers, the SRS plugs in via stereo connector. Monitor remote sites from your office, phone, or any internet-connected device. Observe field conditions, check sensor and system function, or download data from sites that are difficult to access. METER’s database and graphing software can manage your data set and will calculate NDVI or PRI automatically. The SRS sensor is also compatible with Campbell Scientific and other SDI-12 capable data loggers.

Request a quote



California requires the following notice

⚠️ WARNING: This product may contain chemicals including ethylene glycol, lead, nickel, styrene and cadmium, which are known to the State of California to cause cancer, birth defects or other reproductive harm. For more information, go to www.P65Warnings.ca.gov

Spectral Reflectance Sensor

Specifications

NDVI wavebands

650 ± 2 and 810 ± 2 nm peak wavelengths, with 10 nm and 10 nm full width half maximum (FWHM) band widths

PRI wavebands

532 ± 2 and 570 ± 2 nm peak wavelengths, with 10 nm full width half maximum (FWHM) band widths

Foreoptics

(1) Cosine correcting Teflon diffuser, hemispherical field of view
(2) Field stop, 36° field of view

Calibration

NIST traceable calibration to known spectral irradiance (W m-2 nm-2 nm-1 sr-1)

Accuracy

10% or better for spectral irradiance and radiance values

Measurement time

~ 600 ms

Dimensions

43 x 40 x 27mm

Weight

Sensor: 47 g
Sensor with 5 m cable: 170 g

Power requirements

3.6 to 15 VDC, 4 mA (reading, 300 ms), 30µA (quiescent)

Operating temperature range

-40 to 50 °C

Cable length

5 m standard, custom cable length available upon request

Connector type

3.5 mm (stereo) plug or stripped and tinned lead wires (pigtail)

Communication

SDI-12 digital sensor

Data logger compatibility (not exclusive)

METER Em50 series, EM60 series, ZL6 series, ZSC, ProCheck, Campbell Scientific

California requires the following notice:

⚠️ WARNING: This product may contain chemicals including ethylene glycol, lead, nickel, styrene and cadmium, which are known to the State of California to cause cancer, birth defects or other reproductive harm. For more information, go to www.P65Warnings.ca.gov

Support

Have a question or problem? Our support team can help.

We manufacture, test, calibrate, and repair every instrument in house. Our scientists and technicians use the instruments every day in our product testing lab. No matter what your question is, we have someone who can help you answer it.

Email: support.environment@metergroup.com

Phone US: +1 509-332-5600
Phone Europe: +49 89 12 66 52 0

Read Knowledge Base Articles