APPARATUS FOR NATURAL HAND WRITING INPUT DEVICE USING ADAPTIVE SIGNAL ALGORITHM

摘要

At the location information input apparatus using ultrasound, an adaptive algorithm can be used to prevent phase error like a phase shift or a phase jump which is generated by the distant change between the ultrasonic transmitter and the ultrasonic receiver. The received analog signal is converted to the digital signal with different threshold level at the comparator by the distance between the transmitter and the receiver, or the amplification ratio of the received ultrasound signal is changed with adaptive ratio by the distance between the ultrasonic transmitter and the ultrasonic receiver. This adaptive algorithm can prevent phase error with simple signal processing and can be simply applied to the ultrasound based position calculation system.