GB175332A - Improvements in or connected with navigational apparatus - Google Patents

Abstract

175,332. Morris, A. D. Warrington-, Cusins, A. G. T., Tucker, W. S., Paris, E. T., and Robinson, J. Oct. 7, 1920. Signalling proximity of land etc; ship's course signals; foghorn, whistle, reed, and siren signals; locating sounds. -A sound producer and director for use in navigation is adapted to transmit a note of distinctive pitch or quality for different directions. A siren, whistle, or like producer 8, Fig. 1, and a reflector 9 are mounted on a shaft 12 and rotated together by a motor 11. The pitch of the note is varied with the direction of transmission in a constant relation by a control shaft 26 geared to a cog-wheel 17 mounted' on the shaft 12. The siren is fed from a compressedair source 14 through a port 15, the hollow shaft 12 and a tube 16. An observer by noting the pitch of the note of maximum intensity can determine the bearing of the transmitting station, and by taking observations from two known stations can plot his position. In a modified transmitting apparatus an electric siren is used, the pitch of the note being varied by causing the driving-motor 11 to vary a resistance included in the current supply circuit of the siren. According to another modification a stationary spherical reflector is used, a rotating beam being produc d by moving the sound producer in a path coinciding with the acoustic focus of the reflector. The note may change continuously round the compass, or intermittently on separated compass bearings of the beam, or intermittently on continuous or separated arcs. In another method of obtaining the bearing of a transmitting station, the beam is arranged to rotate at a definite speed and when it is projected in a predetermined direction, say North, a basic reference signal is also transmitted in all or various directions. The pitch of the rotating beam may vary or remain constant. An observer may determine his bearing by noting the time interval between the basic signal and the maximum intensity of the rotating beam. A method of navigating a fairway is described in which three stations W, X, Y, each transmitting a sound beam of fixed pitch in one direction, are located on one bank, while another station Z transmitting a number of fixed beams in various directions is located on the other bank. A navigator can plot his course from point to point by noting the intersections 35, 36, 37 of beams of known pitch and bearing. The transmitted note may in all arrangements be of inaudible frequency, known detecting means being provided at the receiving stations. The Provisional Specification describes an arrangement for transmitting different pre-arranged code signals for different azimuthal arcs. This arrangement may be used on ships for preventing collision, the apparatus being arranged to transmit the letter A, say from 0‹ to 10‹ starboard, B from 10‹ to 20‹ starboard, and so on.