A blind spot detector system adapted to the exterior of a vehicle comprising
at
least one infrared light emitting diode (LED), an infrared photodetector and demodulator,
and a microcontroller. The output power of the infrared transmitter is linearly
modulated, enabling the blind spot detector to determine the proximity of the detected
object. Furthermore, the transmitter output is frequency modulated to screen out
random infrared radiation that might adversely affect the operation of the infrared
photodetector. The system is calibrated to the position of the attached vehicle
by linearly increasing the output power of the transmitter until the rear quadrant
of the vehicle is detected when the transmitter is outputting power at a pre-determined
calibration level. During normal operation, an object detected while the transmitted
power is greater than a predetermined lower threshold and less than the calibration
level will activate a LED indicator on the system housing.
