| 摘要 |
482,102. Directive wireless signalling. STANDARD TELEPHONES & CABLES, Ltd. July 30, 1937, No. 21187. Convention date, Oct. 1, 1936. [Class 40 (v)] In an overlapping-beam system for indicating a predetermined route, the usual continuous note which marks the correct path is deliberately broken-up or varied, so as to give a more positive or distinctive indication to the pilot. For instance the normally unbroken note XY, Fig. 3, which indicates the median line is periodically interrupted by periods a, a' either of silence or of different modulation notes. As shown in Fig. 5, for instance, a raised portion b on a cam c periodically opencircuits and so silences the modulator Mod. Alternatively a similar arrangement of control cams is used periodically to distort the normal field of one of the radiators from the shape D1, Fig. 7, to the shape D<1>1. This swings the median line from position x to x<1>, and so gives an occasional port or starboard signal even when the craft is flying straight, partly to show that the transmitter is still in action, and partly to "break up " the monotony of the usual continuous note. |
