Year
1987
Abstract
The use of existing high-power radar, television or radio transmitters as non-dedicated interrogators for medium and long-range tracking or identification systems may be applicable to monitoring nuclear material during transport or storage. The basis of this type system is that some character of the transmitter signal, such as modulation or timing, may be used to selectively actuate a remote transponder to transmit a single or coded pulse so that a base station, receiving both the interrogation and response, could locate or identify the transponder. Although such a system severely constrains the designer by removing control of the interrogator frequency, coding or operating status, the costs and complexities of design, construction, licensing, and operation of a high-power transmitter are also eliminated. Illustratory systems employing commercial radio and television signals are briefly discussed, and a detailed description is provided of a long-range surveillance system using an existing search radar in a non-dedicated mode to track small boats with transponders cooperatively or covertly placed. Design procedures and range projections for this system are presented along with some preliminary results obtained with reduced transmitter power.