Abstract :
A study of the relative performance factors of conventional radio ground beacons provides the necessary evidence for the postulation of an `ideal¿ direction-defining beacon, and this, in turn, permits the identification of the limitations of practical systems. Theory confirms that signal-amplitude-comparison and phasecomparison systems are equivalent, but practical considerations lead to the conclusion that a specific performance is likely to be achieved with greater simplicity by the `Doppler¿ version of the `phase¿ system. Suggestions are made for new-generation beacons which code direction in terms of frequency, a parameter which is more easily defined and measured with accuracy than any other
