Traffic flow determining system using inductive sensing - has three inductive loops with AC generator input producing output detected when vehicle passes.

摘要

The system for determination of traffic flow values along a road lane uses three inductive sensor loops (1-3). The unit has a centre loop (1) and two ancillary loops (2,3). The loops are of the same size and are fed with currents (I1,I2,I3) respectively that have specific phase values. In particular there is a phase difference of 10 degrees between the centre loop and the other two. The centre loop current is also double that of the outer loops. A detector stage (D) is coupled to the centre loop and responds to indicate the passage of a road vehicle. ADVANTAGE - Loops occupy small area. Improved sensitivity on edges of loops.