GB396715A - Improvements in or relating to correcting devices for soundlocating appliances - Google Patents

Abstract

396,715. Locating sounds. LEKARSKO TECHNICKY PRUMYSL AKC. SPOL. and HARLAS, J., 80, Kralovska Tr, Kralin, Prague. Feb. 6, 1932, No. 3621. Convention date, Feb. 7, 1931. [Class 118 (ii).] A correcting device for use with soundlocating apparatus comprises a lamp controlled to project the path of a sound source, corrected for temperature and wind-velocity errors, into the interior of a spherical surface coated with a layer of light-sensitive material. A device is also described whereby the path so recorded may be corrected, by extrapolation, for the speed of the sound source. The apparatus may be connected directly to a sound-locating device or may have results obtained from such a device transmitted to it by known means. An arm 1 is moved about an axis b, to take up the apparent altitude angle of the sound source. An arm 3 is connected to a slidable sleeve on the arm 1 and has pivoted to it a link 4 the length of which is proportional to the velocity of sound at the normal temperature. The lower end of the link 4 is attached by a universal joint to a block slidable along an arm 2 pivoted at z. The block is adjusted along the arm 2 a distance corresponding to the wind velocity w and, another member 5 is adjusted along the arm in the opposite direction a distance kw, where k is a known constant. The member 5 is connected through a parallel linkage to a point l<1>a on a link which is pivoted to the arm 3. This link carries a lamp at the point l<1>a the beam from which is projected on to a light-sensitive spherical surface S rotated about the centre point b to follow the apparent azimuthal movements of the sound source. The air temperature is taken into consideration by manually adjusting the distances w and kw in accordance with formulµ given in the Specification. The point l<1>a may be situated some distance above the central plane of the hemisphere. In order to correct for the speed of the sound source, the device shown in Fig. 7 is employed. An arm 11 is pivoted to rotate about a diameter of the spherical surface S and carries two sliders 13, 16 bearing indicating marks. The sliders are maintained by a screw 12 at an adjustable distance e apart, e being proportional to the known or estimated sound-source speed. The slider 16 is connected by a link 14 to an arm 15 secured to the arm 11. The slider 13 is caused to follow the path recorded on the spherical surface, the slider 16 then indicating the path as corrected for the speed of the source.