Patent ID: 9557278
Date: 2017-01-31
CPC Classifications: A01C,G01N

Claim:
1. A method of counting seeds passing through a seed chute during agricultural planting operations, comprising: providing a sensor to attach to and surround the seed chute, the sensor creating a sensing plane across a diameter of the seed chute; connecting to the sensor an electronic circuit having an electromagnetic source, an interferometer, and an envelope detector; introducing an electromagnetic field in the sensor via the electromagnetic source, generating a fringing field penetrating the seed chute and creating a uniform sheet of electromagnetic field in the sensing plane; detecting a phase modulation of a signal reflected from the sensor as the electromagnetic field is perturbed by the passing seeds via the interferometer; modulating a carrier signal in response to phase variations in the sensor head reflection coefficient; providing the modulated carrier signal to an electromagnetic amplifier gain stage and then to the envelope detector; demodulating the carrier signal and providing a base band seed pulse response to an operational amplifier to remove any DC offset and providing further gain; and sampling the demodulated carrier signal with an analog to digital converter and processing the demodulated carrier signal.