| 摘要 |
1524476 Doppler navigation device INSTITUT FRANCAISE DU PETROLE and THOMSON CSF 6 July 1976 [7 July 1975] 28084/76 Heading G1G An acoustic Doppler navigation transmitterreceiver device has at least one pair of assemblies S 1-5 , S 1-5 , each assembly comprising an array of equispaced transducers parallel to any assembly axis, the assembly axes of the or each pair being symmetrically inclined to a vertical axis with the projection of the transducer spacing on the vertical axis equal to a whole number of wavelengths of the transmitted acoustic wave, the assemblies of the or each pair being fed in phase opposition. As described the transducer assemblies consist of equispaced transducers on a frame (3), Fig. 1 (not shown) secured to a vehicle. The Doppler shifted frequencies in the direction of the subsidiary lobes B, C distort the frequency shift detected along the direction of the main frequency lobe A (arranged to be at 30 degrees to the vertical) and this distortion, Fig. 3 (not shown) is counteracted by choosing the transducer separation so that the secondary lobe B is vertical, the phase opposition of the assemblies in the or each pair resulting in destructive interference in the vertical direction. Any intensity reduction along the main lobe direction is minimized by making the projection of the separation distance D on to either assembly axis an odd number of half wavelengths of the acoustic wave. A directional compensator (not shown), used to obtain maximum extinction in the vertical direction, comprises an even number of transducers in a line equispaced by a whole number of wavelengths. Summing devices (4, 5) Fig. 7 (not shown) adds the compensator and Doppler signals.
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