Tracer decoder¿a receiver for radio navigation relay systems

Tracer is a retransmission system for radio navigation aids which uses a voice frequency communications channel to enable objects to be located and tracked remotely. Its applications are to marine surveying, monitoring of seamarks and automatic vehicle location. The paper describes a unit which accepts the signal transmitted over a link from a Tracer converter and extracts and displays the mobile´s position. Its novel features are its ability to indicate position after only one complete sequence of the navigation transmissions, permitting rapid multiplexing of many mobiles, and a frequency correction arrangement which allows the unit to process signals having frequency errors which would normally be unacceptable in high precision systems. Both these techniques are finding applications in radio navigation receiving equipment.