How It Works

The signal is converted entirely within the wheel speed sensor. The signals from 2 of the Hall sensors (1 and 3) are used to generate a difference signal. The signal frequency and the air gap between the wheel speed sensor and increment wheel are derived from this difference signal. The time lag between the signal from the middle Hall sensor and the difference signal is used to identify forwards or backwards travel. The additional information about the air gap and the direction of rotation is given by the pulse width of the current pulse. When the vehicle is stationary, a current pulse is generated approximately every 740 milliseconds, contrasting with previous wheel speed sensors. This current pulse indicates the availability of the wheel speed sensor.