GB689781A - Improvements in or relating to radio beacons - Google Patents

Abstract

689,781. Electric selective signalling. MARCONI'S WIRELESS TELEGRAPH CO., Ltd. July 31, 1950 [Oct. 11, 1949], No. 26138/49. Class 40 (i) [Also in Group XL(c)] In a radio beacon system, the signal received at any point about the beacon comprises an initial long pulse and a train of shorter pulses, the number and timing of the shorter pulses providing on a binary scale a measure of the bearing of the point from the beacon. At the receiver, the initial long pulse charges condenser SC so ensuring that only subsequent pulses of comparable magnitude actuate the relay winding A to cause relay contacts A1 to close. Relay B is in an oscillatory condition so that when actuated its contacts 81 open and close continuously thus sampling the pulses generated by contacts A1 and passing them to a storage and measuring circuit comprising a parallel condenser-resistance circuit DC-DR1 in series with a resistance-shunted parallel-tuned circuit DOC. The pulses passed by contacts A1, B1 charge the measuring circuit to a value which then decays according to an exponential law modified by an oscillatory component due to the circuit portion DOC. At the end of the pulse train a timing relay C operates to close contacts Cl and charge condenser HC in accordance with the charge remaining in the measuring circuit. The potential across the condenser HC is measured upon a voltmeter giving a direct reading of bear ing from the beacon.