Patent GB-766369-A (GB)
Title: Improvements in or relating to electronic navigational aiding systems
Inventor: PLAISTOWE DONALD LEOPOLD
IPC: G01S13/00
Filed: 1954-06-14
Abstract: 766,369. Radio-navigation. MARCONI'S WIRELESS TELEGRAPH CO., Ltd. June 7, 1955 [June 14, 1954], No. 17480/54. Class 40(7) A radio-navigational aid for determining the range of an object, such as an aircraft, approaching a station along a course comprises a transmitter 1 at the station illuminating the area with continuous radio waves, a plurality of directional receiving means 5, 6, 7, 8 and 9 spaced along the course at predetermined locations and capable of receiving the transmitted waves reflected by an object in their field of view and transmitting as a response a radio signal characteristic of the particular receiving means back to a receiver 10 at the station. In order that the range to the station may be known on the craft (i.e. " object") a transmitter 17 is associated with the receiver 10 in order to retransmit the response signals to it. The station is also provided with its own display device 13. In one embodiment each of the spaced receiving means 5 to 9 consists of a directional ,lens system 23 determining the direction from which reflected waves can be received, an interrupter disc 24 driven by a motor 25 and a receiving probe 26 associated with a crystal detector 27. The detected signals are amplified at 29 and operate relay contacts 30 associated with speed regulating device 31 controlling - motor 32 which reciprocates reflector 34 in the region of the focal plane of lens 35. This lens is directed so as to -intercept part .of the energy from the transmitter 1 and reflect it back to receiver 10 modulated in accordance with the speed of movement of the reflector 34. Each of the devices 5 to 9 has a different characteristic speed of reciprocation. If desired the parts of each device shown in the upper " box " on the Figure may be physically separated from those shown in the lower " box." At receiver 10 (Fig. 3) signals from the devices 5 to 9 are directed by lens 36 to probe 37 associated with crystal detector 38. If the devices' are not linearly arranged more than one probe may be required. The detector output is amplified at 11 and fed to band-pass filters 41, 42, 43, 44 and 45 passing the signals derived from different ones of the devices. The output from each filter is coupled to a relay controlling the illumination of a' lamp. in' a particular section of the indicator 13. Each lamp is positioned behind a frosted glass panel bearing the appropriate range indication. The signal from amplifier 11 is also fed through buffer amplifier 39 to relay 18 so that when range signals are received microphone 22 is automatically disconnected from the speech communication transmitter 20 and replaced by the range tone signals derived from amplified 40. The range signals from transmitter 20 are separated at the output of the communication receiver on the aircraft and applied through filters to control. a display indicator similar to that at the station.. Modified forms of apparatus for devices 5 to 9 are described with reference to Figs. 5 and 6 (not shown). In each of these modifications the reflector 34 is reciprocated continuously and receipt of a reflected signal from transmitter. 1 causes a shutter, placed between the lens 35 and the reflector, to be opened.