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Bistatic bottom reverberation background on the estimation of underwater acoustic detection


Law. Figure 4 shows the delay = 2S ∞ _. , Shame Argentina match crab receiver azimuth / (.) Figure 4 reverberation levels change with the azimuth of the curve Fig. 4Changingofreverberationlevelwiththeazimuthangle, the reverberation level RL with the orientation curve. Given time delay, reverb all contribute to the scattering region, etc. arrive at the same ellipse. It can be seen from the curves in Figure 4 on the 0 = 180. Axial symmetry,[link widoczny dla zalogowanych], the maximum value 0 = OO. 3.3 reverberation levels change with the transceiver when the transceiver from the change from the L,[link widoczny dla zalogowanych], corresponding to the length of the ellipse axis of reaching such changes. Discussed here is the point in the propagation delay and receiving the same situation,[link widoczny dla zalogowanych], with the transceiver from reverb-level changes, this time,[link widoczny dla zalogowanych], as the distance increases, so when you reach the long axis of the ellipse will become a long, * 24 * Environmental Engineering in April 2008 the minor axis becomes shorter. Figure 5 shows the time delay t = 2s, the acceptance angle 0 = 60.璺 <5Changingofreverberationlevelwiththedistancebe-tweenthesourceandthereceivingpoint, the reverberation level transducer with the transceiver £ change the distance between the curves. Changes which range from £ 0 ~ 2500in. Since the model does not take into account the direction of scattering scattering, so the reverberation level in Figure 5, the increase mainly caused by the scattering area increases. 3.4 reverberation level at any time extend the curve of z t when the propagation delay increases, etc. will reach the oval corresponding to the increase. This discussion is received for a fixed angle of propagation delay with reverberation level, etc. arrive at different changes on the Ellipse. Figure 6 is 0 = 0. , 30. 60. 90. , 120. , 150. , Da good compliance propagation delay / s Figure 6 different single base and double-base extension 0 angle change at any time reverberation level of the curve Fig. 6Chanongofreverberationlevelwiththetransmitdelayformono-baseanddifferentbistaticanglessituation180. , The reverberation level RL simply repeating what the source to the receiver by scattering the total delay t are obtained. As can be seen from Figure 6, the increase in reverberation level decreases with time, with the solid line represents the single base curve of the reverberation time compared with bistatic reverberation level in when 0 Reverberation time than single-base level; at 0 = 90. When bistatic reverberation levels consistent with a single base; at 0 Bistatic reverberation time is less than a single base class when the situation. Different angles in Figure 4 reverberation levels also reflect the difference curve in Figure 3 with the angle of the situation. 4 Conclusion bistatic measurement of bistatic reverberation in the seabed under certain assumptions, the theoretical calculation, the calculation of bistatic bottom reverberation level formula, and based on 4 different parameters changes in the simulation, is given? Kun ring with the measurement of trace level, the acceptance angle, send and receive the distance between the transducer and the time curve. Calculated by the theoretical analysis and the following results: the case of single-base differences in the two-base measurement, the scattering contribution to the reverb with the reception area of the region and change the angle, leading to reverberation level with the receiving angle change; As the acceptance angle greater than 90. Bistatic reverberation time is smaller than a single base case level, so you can use a large acceptance angle of the double-base measurements to reduce the reverberation. On Modeling bistatic bottom reverberation has been simplified, the main consideration of the scattering area. In the actual measurement also need to consider emission beam width, the height of transmitters and receivers from the seabed, seabed scattering coefficient and other factors, the practical application of modeling to be made more precise. References [1] Hui Junying. Underwater acoustic channel [M]. Beijing: National Defence Industry Press, 1992:99. [2] Liu BS, Lei Jiayu. Water acoustics [M]. Harbin: Harbin Engineering University Press ,1993:203-207 .68-72. [3] JAMESJH. AnInitialInvestigationMethodologicaltobeUsedforHelicopter. BasedBistaticSonarinShallowWarer [R]. AD. A257865, 1992.

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