Publications

This report is an analysis of the accuracy limitations of hyperbolic multilateration systems. A central result is a demonstration that the inverse of the covariance matrix for positional errors corresponds to the moment of inertia matrix of a simple mass configuration. The insight afforded by this fact is used to resolve a number of questions relating to accuracy. Specific questions addressed include the following. 1. How does accuracy depend upon the number of receivers? 2. How does accuracy depend upon the deployment of receivers? 3. What is the maximum accuracy that can be obtained from N receivers? How should the receivers be deployed to maximize accuracy? 4. How do altitude errors compare to horizontal errors in satellite based systems? In ground based systems? 5. How is accuracy impacted by dropout of any particular receiver?

Increased air traffic coupled with the proliferation of sophisticated avionics can be expected to stimulate increased demand for air traffic control (ATC) services over the next few decades. New challenges for the design of communication, surveillance, and navigation subsystems is an anticipated consequence. Since it is unlikely that significantly larger frequency bands will become available, it will be necessary to exploit more efficient multiple-access techniques. The design of a multiple-access technique for a particular application will depend on a broad range of system issues. A predetermined procedure based on general characteristics of the various techniques will have but limited value. An example of an ATC satellite surveillance system is used to illustrate some of the broad ranging systems issues that can be expected to influence the selection of the multiple access technique.