Pulse Width Modulation is a common communication protocol used in radio control of servos. A centered condition of the servo occurs with a pulse signal duration of 1500 microseconds with 1000 microseconds signaling full servo movement in one direction and 2000 microseconds full movement in the opposite direction. Different radio vendors may use slightly different numbers for center and full travel and may use slightly extended ranges beyond +- 500 µs. Note: 1000 microseconds = 1 millisecond