NDVI and NDRE sensor


Crop Circle ACS-430 active crop canopy sensor

The Crop Circle ACS-430 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-430 is not limited by ambient lighting conditions— measurements can be made day or night due to its unique, light source technology.

For on-the-go applications, the Crop Circle ACS-430 sensor can be mounted to virtually any type of vehicle to remotely sense and/or map plant or crop canopy biomass while driving through a field. The compact size and low weight design allows Crop Circle to be easily adapted to pole-mounted and handheld applications. Information produced by the sensor can be utilized to quantify the impact of nutrients, water, disease or other growing conditions on plants or crops.

Crop Circle ACS-430

Multi-Channel Spectral Measurement

The ACS-430 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- 430 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-430 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

Crop Circle ACS-430


  • Sensor-to-Canopy Range: Typically 10 in (25 cm) to >72 in (183 cm)
    Field-of-View: ~30 degrees by ~14 degrees
    Active Light Source: Modulated polychromatic LED array
    Photodetection: Three channel silicon photodiode array with spectral range of 320 nm to 1100 nm
    Optical Measurement Bands: 670 nm, 730nm and 775nm

  • Sample Output Rate: Programmable for 1 sample per second to 20 samples per second; Factory default 10 samples per second
    Operating Range: 0 to 50 oC
    Communication Interface: RS-485 multidrop (bidirectional communication); RS-232 (autosend, output only)
    RS-232 Serial Communication: 76800, no parity, 8 data bits,1 stop bit
    Power: 9 to 17V DC @ ~350 mA
    EMC Certifications: C-Tick, CE

  • Enclosure: Injection molded polycarbonate
    Environmental: IP68 for dust and water resistance
    Weight: 0.94 lb. (430 gm)
    Sensor Mount: (2) 1⁄4 – 20 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: Four pin male Eurofast type, O-ring sealed

  • Crop Circle ACS-430 Handheld. System includes: Crop Circle ACS-430, GeoSCOUT X, FieldPAK PS-12 power supply, extension pole apparatus, cables, storage case, charger and user’s guide

    Crop Circle ACS-430 Mapping System. System includes: Crop Circle ACS-430, GeoSCOUT X, cables, storage case, mounting plate and user’s guide