Dectra: A long-range radio-navigation aid

The paper first outlines the operational requirement for a navigational aid covering the air routes on an ocean crossing such as the North Atlantic. After a short reference to the Decca phase comparison technique, the tracking and ranging functions of the Dectra system are described with special reference to the time-sharing technique on which the tracking pattern is based. Details are given of the transmitting stations which are common to the Dectra and Decca services, and of the associated airborne receiving and display equipment. A note is included on the prediction of the accuracy and performance of the system. Details of flight trials are summarized in an Appendix.