GB580482A - Improvements in direction finding systems utilising electromagnetic waves - Google Patents

Abstract

580,482. Wireless direction finding systems. BRITISH THOMSON-HOUSTON CO., Ltd., and MACKENZIE, T. H. April 3, 1942, No. 4508. [Class 40 (v)] [Also in Group XXXVIII] In a direction-finding system in which a directional aerial is oriented towards a target and its orientation is transmitted by electrical variations through a link circuit to an indicator, means other than those causing these variations are provided for producing at least one " error voltage " corresponding in sign and magnitude to an error in the orientation of the aerial, and for introducing this error or correction voltage into the link circuit, so that the indicator more accurately indicates the bearing of the target rather than the orientation of the aerial system. The Figures show a direction-finding system in which a directional transmitting aerial 1 and an aerial 2 for receiving reflected waves arc adjustable in altitude and azimuth, the latter adjustment being transmitted by a device 4 and link circuit 5 to a remote indicator 6. The altitude adjustment may be similarly transmitted to another indicator. The receiving aerial 2 is rotated, so producing, when it is not accurately directed towards the reflecting object, a fluctuating voltage which, by way of a receiver 9, filter 10, amplifier 11 and a rotary switch 7 charges condensers 8 in pairs to voltages representing the directional errors respectively in altitude and azimuth. The indicating device 6 consists of a cathode-ray tube to the deflecting plates of which potentials corresponding to the angular positions of the aerial system are applied by transformers 14, only one of which is shown. The input to these transformers may be obtained by means such as that described in Specification 580,483. The " error voltages " are introduced into the link circuit by connecting the appropriate pair of the condensers 8 through a resistance network 15 to the corresponding pair of deflecting plates, thus correcting the indications produced by the potentials derived from the transformer 14. Specification 500,648, [Group XXXVIII], also is referred to.