GB625917A - Improvements in or relating to navigation devices - Google Patents

Abstract

625,917. Radio navigation. SPERRY GYROSCOPE CO., Inc. Oct. 7, 1946, No. 29834. Convention date, Aug. 7, 1943. [Class 40 (vii)] In order to enable a craft to follow an asymptotic approach to the equi-signal courseline defined by an overlapping-beam radio beacon, the receiver carried by the craft comprises an indicator responsive to both the displacement of the craft from the course-line and to the rate of change thereof, so that by maintaining the indicator at a zero indication the desired approach will be made. The beacon may radiate signals of either the complementary or simultaneous kind and may be used to define a course in either the horizontal or vertical plane. Fig. 3 illustrates a system wherein the two lobes are modulated at different audio-frequencies. The audio-frequencies are separated at the receiver, which is similar to that described in Specification 550,660 as far as the audio-frequency stage, and applied to respective transformers 12 and 13. The signals at tappings 17 and 18, whose difference is a measure of the displacement of the craft from the course, are applied to the grids of rectifying valves 19 and 21. These signals are also separately rectified by double-diode 24 and applied through differentiating condensers to the grids of valves 22 and 23 which have common cathode circuits with valves 19 and 21 respectively. The outputs from these cathode circuits are applied differentially to the meter M which consequently records a signal compounded from signals proportional to the displacement and its rate of change. The sharpness of the asymptotic approach may be controlled by adjusting the potentiometer 27 to adjust the relative amplitudes of the displacement and rate of change signals. In an alternative circuit, Fig. 4, the outputs of the transformers 12 and 13 are rectified at 33 and 34 and applied by resistors 39 and 41 respectively and condensers 42 and 43 respectively to grids of valves 38. The couplings via the resistors provide a component proportional to the displacement and those via the condensers provide a component proportional to its rate of change, so that the signal applied to the meter M is a composite signal, as before. The sharpness of the approach path may be varied by varying the resistors 39 and 41 and by switching in or out additional condensers 47 and 48.