re long distance ir detection jvannes vms macc wisc edu writes i designed and built hardware in that would output a logic level from a tone detector upon detecting a microwatt led feet away used a motorola mrd biased linearly in a dc feedback loop to servo out variations in sunlight and hz from lights used no lenses allen sullivan i would be interested in knowing more about the sensing hardware what did you use for the detector could you detect the angle of location or did the system simply respond to the presence of the transmitter in the sensors field of view phototransistor x x ne with kohm limiter feedback to base to control operating point i expect this really hurts noise figure any comments from phototransistor experts we intended to use this atop a stepper motor to provide headings to the beacons the plan was to have or beacons of different frequencies in each room and tell the what frequency to phase lock to we did not do so one challenge was that the available stepper had degree steps knowing the headings to each beacon we would have used the surveyor technique of resection to determine robot location no i ain t going to explain resection over the net given hindsight i would digitize the amplified output of the self nulling phototransistor circuit and correlate in phase quadrature square waves at the several expected frequencies to extract amplitude of each beacon by doing this at the numerous steps even with degree steps with knowledge of the angular response of the phototransistor you should be able to rather more accurately determine the heading to each beacon allen sullivan
