The application and design of medium-precision ranging equipment

With the introduction of centimetre radar warning equipment, particularly for use in small vessels, a requirement arose for a ranging attachment capable of providing range data of sufficient accuracy for use with the simple fire-control system in small craft and also for providing tactical range information. The electronic ranging system developed to meet the above requirement was the first example of naval medium-precision ranging equipment and is known as Ranging Outfit R.T.A. A modified version of the above equipment known as Ranging Outfit R.T.C., having greater accuracy at very short ranges, was subsequently developed to provide radar control for two mortar-type anti-submarine weapons fitted in escort vessels. The extensive use of the Plan Position Indicator (P.P.I.) as the standard display with radar warning equipment marked the next stage in the development of medium-precision ranging equipment. New ranging units (in some cases built-in to the P.P.I. display itself) were introduced to meet the requirements of specific applications such as torpedo-control, navigation, shore-bombardment, etc. The limitations of the P.P.I. display from the point of view of range measurement led to the development of a new type of display with which medium-precision ranging equipment could be used with advantage. Ranging Outfit R.T.B. is an example of the combination of this new display, known as a sector display, and R.T.A. A typical modern display and ranging equipment of the type used with long range air- and surface-warning sets is described to illustrate the trend of technique in medium-precision equipment.