Fast and accurate positioning technique using ultrasonic phase accordance method

An innovative measurement technique for use by positioning systems using ultrasonic signals was developed. The advantage of this technique is that it can accurately identify the relative distance and orientation between devices by using an one-time ultrasonic packet. It is therefore especially useful for ubiquitous computing applications where people with mobile devices continuously change their positions in indoor environments. The technique, which is named phase accordance method, uses two or more carriers in ultrasonic communication. A special ultrasonic burst signal, called sync pattern in the header part of the communication packet gives the base point of the time measurement. The whole time difference calculation is then carried out using this base point. An experiment based on the proposed method proved that the technique attains remarkable performance, namely, errors of less than 1 min in three meter distance measurements and less than 0.5 degree errors in the zero, ten, twenty, and thirty degree measurements.