GB380466A - Improvements in or relating to wireless direction-finding systems - Google Patents

Abstract

380,466. Directive wireless signalling. LEVY, L., 5, Rue du Cirque, Paris. June 15, 1931, No. 17380. Convention date, June 13, 1930. [Class 40 (v).] In a wireless direction-finding system of the rotating beacon type the azimuth is defined by the comparison of the intensities of two mutually perpendicular beams of waves modulated at different frequencies, which frequencies vary continuously with a different law of variation for each beam. The arrangement for producing one of these beams is shown in the Figure and comprises an aerial system 1 .. 8 consisting of two horizontal aerials 5, 6 and 7, 8 as described .in Specifications 233,346 and 251,638, [both in Class 40 (v), Wireless signalling &c.]. These are connected to the fixed goniometer coils 13, 14 respectively, fed from a rotating coil 15 connected to the transmitter 23 which receives radio frequency from a source 22 and audio frequency for modulation from a source 21 whose frequency is cyclically varied by a variometer 19, 20 mounted on the goniometer shaft. To produce the second rotating beam with different audio frequency characteristics, another rotating goniometer coil is mounted perpendicular to coil 15 and supplied with radio frequency currents from the same source but modulated by a second variable audio frequency source. Each direction is thus characterized by a given pair of audio frequencies heard at the same intensity at the receiver. The acoustic frequency circuits at the receiver may be tuned by variable condensers having the same law of variation as a function of the angle of rotation as the audio frequency circuits at the transmitter which may also be varied by condensers instead of variometers The receiver may comprise tuned reeds or a pair of milliammeters whose pointers are arranged to cross on a fixed line, Fig. 2 (not shown), when the receiver is on the desired route. When laying out an aerial route utilizing beacons according to the invention, similar projectors of limited range are placed at each bend of the route and emitting, towards the zenith, successively, the two acoustic pairs corresponding to the portions of the route on either side of the bend. The Specification as open to inspection under Sect. 91 (3) (a) comprises also systems in which is emitted a single rotating beam of light or wireless radiation some characteristic of which varies with the direction of emission. In the case of light, the colour, the polarization, the frequency of interruption, the intensity or the frequency of variation of the polarization of the beam may be varied. Thus, for example, a lamp may be arranged in a glass cage coloured with different coloured bands in different azimuths. It also comprises a system of defining a route r, Fig. 2 (Cancelled), the route being the locus of points defined by the intersection of beams of predetermined acoustic frequencies from transmitters R. This subjectmatter does not appear in the Specification as accepted.