GPS positioning method under condition of only three acquired satellites

To measure a position by GPS, observing more than three satellites is needed. If there are not obstacles near a receiver, more than three satellites are generally observed and the position is located. However, in an urban canyon or forest, more than three satellites can not be frequently acquired because of buildings and trees. Then we suggest a new algorithm for positioning using only three satellites. When only three satellites are observed, data for positioning is not enough. Therefore we use consecutive data and measure a position. Other methods using only three satellites usually need past data of receiver such as the position or data other than received data from satellites. However our method needs not other data and has only to fix a receiver for a few seconds. In this paper, we showed the effectiveness of our method using a dual frequency receiver and received data from satellites whose elevation angles are high.