Patent ID: 7027822

Claim:
A method of determining absolute positions of a plurality of nodes in a network, the plurality of nodes including first, second and third nodes, the method comprising: determining relative distances between the first, second, and third nodes; calculating a first range from a first distant ranging source to the first node; calculating a second range from a second distant ranging source to the second node; calculating a third range from a third distant ranging source to the third node; determining an absolute location of the first node using a combination of the first range, the second range, and the third range, and the relative distances between the first, second, and third nodes, wherein the step of determining relative distances comprises: transmitting, from the first node, a first signal that is unique to the first node; receiving the first signal at the second and third nodes; retransmitting the first signal from the second and third nodes; transmitting, from the second and third nodes to the first node, a second signal that represents an observed time necessary for the first signal to be transmitted from the first node to the second and third nodes; receiving the retransmitted first signal and the second signal at the first node; calculating distances between the first node and the second and third nodes, respectively, using one-half of a time necessary for the first signal to be transmitted from and retransmitted to the first node; and calculating time biases between the first node and the second and third nodes, respectively, by subtracting, from the observed time, one-half of the time necessary for the first signal to be transmitted from and retransmitted to the first node.