Time-Synchronized Ranging System

This paper describes a time-ordered precision ranging system, identified as time synchronized ranging system (TSRS). The TSRS is a cooperative ranging system serving up to 1024 users within an operational community. Synchronization of time, relative to a designated controller, is established and maintained to less than 7 ns. Slant range measurements between users and controller are provided with a measurement accuracy of 21 ft, one sigma for ranges up to 100 nmi. The synchronization and range-measurement process also provides a high speed, real time, two-way data link between members of the community including relay capabilities where required. Automatic unit identification is provided by means of user time slot assignments. Design features of interest include ultra-high-speed digital logic, digital filtering (Kalman) of time-error measurements with optimal correction of both frequency and phase of a 100-MHz precision source. The TSRS has been tested both in surface communities and surface-air communities and is currently under test by the U. S. Navy.