NDVI and NDRE sensor


Crop Circle ACS-435 active crop canopy sensor

The Crop Circle ACS-435 active crop canopy sensor provides classic vegetative index data as well as basic reflectance information from plant canopies and soil.

Unlike passive radiometric light sensors, the Crop Circle ACS-435 is not limited by ambient lighting conditions— measurements can be made day or night due to its unique, light source technology.


Multi-Channel Spectral Measurement

The ACS-435 incorporates three optical measurement channels. The sensor simultaneously measures crop /soil reflectance at 670 nm, 730 nm and 780 nm. A unique feature of the ACS- 435 sensor, unlike any other active sensor on the market, is its ability to make height independent spectral reflectance measurements. Holland Scientific refers to these reflectance measurements as Pseudo Solar Reflectance (PSR). This means the spectral reflectance bands are scaled as percentages and will not vary with sensor height above a target. This opens the possibility of using literally dozens of vegetative indices that do not use ratio based calculations.

Easy Data collection

Using the Holland Scientific GeoSCOUT X datalogger, data can be easily and quickly recorded to a text file on an SD flash card. Additionally, by connecting a GPS receiver to the GeoSCOUT, data collected from the ACS-435 can be georeferenced and stored for later analysis in third party GIS software.

3 measurement channels: 670nm, 730nm and 780 nm

Computes height independent absolute reflectances

Make measurements day or night

Measurements not influenced by fluorescent or other AC light sources

Wide measurement range— 0.25 m to 2.0 m

Rugged IP68 packaging— dust and water resistant

Low noise performance

Fast data output rate

Light weight < 0.43kg


    • Sensor-to-Canopy Range: Typically 10 in (25 cm) to over 98 in (250 cm)
    • Field-of-View: ~40 degrees by ~10 degrees
    • Active Light Source: Modulated polychromatic LED array
    • Photodetection: Three channel silicon photodiode array
    • Optical Measurement Bands: 670nm, 730nm and 780nm
    • Sample Output Rate: Up to 10 samples per second in autosend mode
    • Operating Range: 0 to 50 ºC
    • Communication Interface: RS-485 multi-drop (bidirectional communication); RS-232 (autosend, output only)
    • RS-232 Serial Communication: 38400, no parity, 8 data bits, 1 stop bit
    • Power: 11 to 16.5V DC @ ~180 mA
    • EMC Certifications: CE
    • Enclosure: Injection molded polycarbonate
    • Environmental: IP68 for dust and water resistance
    • Weight: 0.9 lb (435 gm)
    • Sensor Mount: (2) M6 X 1 threaded holes in base of sensor spaced 1.25 in (3.18 cm)
    • Dimensions: Width 3.5 in (8.9 cm), Length 7.9 in (20.1 cm), Height 1.9 in (4.8 cm)
    • Serial/Power Connector: 12-pin Deutsch, O-ring sealed
    • Crop Circle ACS-435 Handheld System includes: Crop Circle ACS-435, GeoSCOUT X, extension pole apparatus, cables, storage case, charger and user’s guide
    • Crop Circle ACS-435 Mapping System includes: Crop Circle ACS-435, GeoSCOUT X, cables, storage case, mounting plate and user’s guide

    Specification are subject to change without notice.