Integrity of range measurements

A system comprising:

• a plurality of nodes in a network;
• wherein each respective node in the network includes at least one range sensor operative to obtain range measurements between the respective node and other nodes in the network;
• wherein each respective node includes a processor operatively coupled to the at least one range sensor, the processor operative to perform a method of assuring integrity of range measurements and position solutions for the nodes, the method comprising:
• performing a snapshot integrity test for one or more range measurement statistics, at a single epoch, for the nodes in the network, wherein the snapshot integrity test comprises:
• obtaining a current configuration of the nodes in the network;
• computing singular values of a Gram matrix, G, using all nodes N and singular values of Gram matrices, Gi, using N−1 sub-node combinations, where i is a missing node;
• performing a singular value consistency check of the one or more range measurement statistics using the Gram matrices from all nodes and N−1 sub-node combinations against a user selected threshold;
• and
• identifying and excluding any of the range measurement statistics with instantaneous errors that cause the singular values to exceed the user selected threshold;
• and
• performing a sequential integrity test using the one or more range measurement statistics, to assure the integrity of relative positions of the nodes in the network, wherein the sequential integrity test comprises:
• formulating main node sets and sub-node sets using a solution separation technique for one or more combinations of in-view nodes, wherein the main node sets include one or more combinations of node triangle geometries, and the sub-node sets are one or more combinations of N−1 in-view nodes that maintain the same main node triangle geometries;
• implementing a set of filters for each of the main node sets and sub-node sets;
• performing a consistency check of the one or more range measurement statistics using one or more discriminators and decision thresholds;
• detecting and excluding any of the range measurement statistics with both instantaneous and time-correlated errors;
• and
• computing a protection level for relative positions computed from the main node and sub-node sets;
• wherein each node in the network is considered individually as an anchor node for the node triangle geometries.