Sensors: Rotary Encoders
The above diagram demonstrates two signals in a quadrature relationship as the
signals from the two lines of the rotary encoders are. Note that Phase A leads Phase B by 90 degrees when looking from left to right. Looking from right to
left the opposite is true. This is directly analogous to the change in
signal relationship when the rotary encoder is turned the opposite direction.
This filter circuit helps to stabilize the output of the shaft encoder and
reduces noise by introducing pull-up resistors and low pass filters with cut-off frequency of ~ 1.6kHz on each of the two output pins.