Abstract. A simple, portable, and rugged instrumentation system has been successfully developed and field demonstrated to monitor, measure, and record the harvested crop yield and selected machine field performance parameters from the typical rice combines in Malaysia. The complete system comprises of two ultrasonic sensors located at the combine header to measure the cutting width, microwave solid flow, and microwave moisture sensors at the combine clean grain auger to measure the flow rate and moisture content of the cleaned grains going into the grain tank, electromagnetic detector on the combine grain elevator drive shaft to monitor the grain elevator rotational speed, and lastly a DGPS receiver on the combine console roof to indicate the travel speed and geo-position in the field. All these measured parameters were made to display in-real time on the touch panel screen of the embedded system on-board the combine for the interest of the combine operator and also made to display in-real time on the monitor of the toughbook at the on-ground base station for the interest of the system controller. Static calibrations on the individual sensors showed excellent measurement linearity having R2 values within 0.8760 to 1.000 ranges. The wireless communication between the embedded system on-board the combine and the toughbook at the on-ground base station could be sustained to a maximum distance of 185 m apart. Site specific variability maps of crop yield, harvested grain moisture content, combine cutting width, combine traveling speed, combine field capacity, and combine field efficiency within the harvested area could be produced from the data obtained with the instrumentation system using a GIS software. Keywords: Grain harvesting, Paddy mechanization, Precision farming, Wireless data transmission, Yield monitoring.
