Patent GB-581081-A (GB)
Title: Improvements in or relating to phase compensator for groups of microphones or transmitters, particularly for submarine transmission
IPC: G10K11/34
Filed: 1940-07-18
Abstract: 581,081. Subaqueous signalling. SOC. FRANCAISE RADIO-ELECTRIQUE. July 18, 1940, No. 11873. Convention date, July 18, 1939. [Class 118 (ii)] The invention relates to phase compensators used in, apparatus for the directive transmission or reception of sonic or supersonic waves, particularly for submarine use, comprising a group of transmitters or receivers M1-M6. In a known form of compensator, each of the members M1-M6 of the group is electrically connected to the corresponding member B1- B6 of a geometrically similar group of contact brushes engaging a contact device which is rotatable relatively to 'the brushes about a point O and consists of an assemblage of narrow relatively-insulated strips connected to successive intermediate points on a delay network line L formed of a number of similar elements equal to that of the strips. When the relative orientation of the group of brushes and the contact strips is adjusted to correspond with the direction of the sonic waves, owing to the geometrical similarity of the groups M1-M6 and B1-B6, the number of elements in the delay network introduced between the brushes will correspond to the times taken by a sonic wave to travel between the corresponding elements M1-M6. Thus, in reception, the electrical delays compensate the phase differences in the sonic waves on arrival at the members M1-M6, and in transmission they introduce the necessary phase differences to give the desired directivity. According to the invention, the brushes of .the compensator are adjustable so that they may be grouped to correspond to any desired arrangement of the members M1-M6, and they may also be adjustable in correspondence with different speeds of the sonic waves produced by variation of the transmitting medium, for example by different degrees of salinity of sea water. As shown in Fig. 4, the contact strips of Fig. 2 are replaced by a rotatable contact body formed by an assemblage of insulated blades turned to form a surface of revolution about the axis XY. The brushes, of which two only are shown, are carried by arms arranged radially and pivoted on a ring concentric with the axis XY. To adjust the compensator for a given grouping, each brush arm is individually adjusted 'along the ring so as to lie in the desired radial plane, and its angle of inclination is then adjusted so that the brush contacts with the desired point on the curved surface of the contact blades. To adjust the device for a change in the speed of the sonic waves, the brushes are collectively adjusted all by the same angular amount, for which purpose the brush arms are formed with toothed sectors E<2> engaging worms E<1> simultaneously operated by gears E<3> meshing with a central gear E<4>. The transmission line is contained in a casing B rotatable with the contact body. The direction of transmission. or reception is indicated by a dial G. The method.of determining the correct curvature in radial section of the contact body is explained; to avoid the necessity of providing brushes movable axially of their supporting arms the correct curve may be replaced by a circular arc..