A Study of Precise Vehicle Speed Measurement Using Bluetooth and SCM Technology

By combining a non-contact photoelectric speed sensor and a single chip microcomputer (SCM) with Bluetooth technology, the authors were able to design a precise vehicle speed measurement system. Because signals collected using a comb-shaped photoelectric sensor varied greatly in amplitude and contained high and low random frequency interferences to the fundamental wave, the authors designed the circuit so it could process the signals from the sensor based on phase-locked loop (CD4046) technology. By combining SCM and Bluetooth technology, a data acquisition system was designed to gather vehicle speed data from the sensor. The authors also discuss how to use the SCM and Bluetooth module to design the hardware and software for this system. While wire layout is difficult in a situation involving vehicle speed measurement, this system makes data acquisition easier and increases measurement precision by 0.1%.