Evaluating Temporal Variation in Active-Light Plant Sensors

Spectral sensing in agriculture has developed a significant body of research over the past several years as a non-destructive method for evaluating crop and soil characteristics.  Multi-band spectral sensors are commercially available for agricultural applications.  These sensors have been evaluated for use in many of the dominant American row crops including: wheat, soybeans, rice, corn, and cotton.  Active-light plant sensors, those that use a modulated light source to remove ambient light interference and dependence, have come to the forefront of this research.  Using this type of sensor, data can be collected irrespective of time of day or weather conditions.  Temporal variation in sensor data was evaluated for multiple active light sensors at the University of Tennessee.  The output for a spectral sensor, set to transmit data ten times a second, was logged for a period of twenty minutes.  The sensor was statically mounted over each of three uniform pieces of colored fabric.  Each test was conducted in both total darkness as well as outdoors under partly cloudy skies.  The intensity of incoming radiation was logged once a second during each of the outdoor tests.  Results will be discussed for each sensor tested.