Fuente: Wipo "precision farming" An apparatus (26) for measuring the flow of a particulate or clumpy material such as cotton (24) includes a transmitter array (28) and a receiver array (30) spaced on opposite sides of a flow path of a chute (18) through which the cotton (24) travels. The transmitter array (28) is pulsed at a particular rate and the receiver array (30) sampled synchronously with the pulsing of transmitter array (28). Controller (32) determines how many of the receivers in array (30) were blocked from receiving signal from corresponding transmitter array (28) by impeding clumps of cotton (24). From this, a digital signal is produced and the controller (32) can calculate an instantaneous volume of cotton (24) in accordance with the algorithm F=KS where F is the volume, S is the digital signal and K is a calibration constant.