# Smart Ocean: A New Fast Deconvolved Beamforming Algorithm for Multibeam Sonar
## 3 Experimental Results
### Real Data Experiment
#### 3.3.2 Experimental Data Results of Kongsberg M3 Multibeam Sonar  
The experimental data used in this section were measured by Kongsberg M3 multibeam sonar. The frequency of the acoustic wave was 500 kHz, and the pulse width was 20 us. The experimental environment was 25 m long, 15 m wide, and 10 m deep for the full acoustic pool. The sonar and installation method used in the experiment are shown in Figure 10.  
Two Small Ball Targets Experiment  
As shown in Figure 11, as the two balls used in the experiment, the two balls in the were placed in a position 3 meters ahead of the horizontal sonar front. The geometric center was about 30 cm apart, and the 2D acoustic image is shown in Figure 11. Figure 12a is the image output from the sonar display and control software. As shown, the two ball targets show only one target in the software, and they cannot be separated. Figure 12c shows the 2D acoustic images obtained by CBF utilizing the raw  
Figure 10: The Kongsberg M3 multibeam sonar and installation method for the experiment. Figure 9: The experimental data processing results of a multibeam sounding system, (**a**) 2D acoustic image obtained utilizing CBF, (**b**) the enlarged result of the middle and upper part of (**a**), (**c**) 2D acoustic image obtained utilizing deconvolved beamforming, (**d**) the enlarged result of the middle and upper part of (**c**), (**e**) CBF beam power (solid line) and deconvolved beam power (dashed line) for t = 0.0933 s, (**f**) the echo strength (normalized) so that the sinusoidal value (sin \(\theta\)) of the beam angle is \(-\)0.906 and varies along with time, and the solid line is obtained by CBF and the dashed line is obtained by deconvolved beamforming. data. Figure 12d is the enlarged area where the two targets exist in Figure 12c, and the two targets cannot be separated--it looks likes one target. Figure 12e shows the 2D acoustic images obtained by the deconvolved beamforming utilizing the raw data. Figure 12f is the enlarged area where the two targets exist in Figure 12e, and the two targets are completely separated. Next, we put the CBF beam power (solid line) and deconvolved beam power (dashed line) into a figure at the distance where the targets exist. To show the same dynamic range, all the beam plots were normalized with a peak set at 0 dB. As shown in Figure 12b, the CBF beam power had only a very fat main lobe, and there was only one target in the corresponding 2D acoustic image. Nevertheless, deconvolved beamforming had two narrow main lobes, and there were two targets in the corresponding 2D acoustic image. This indicates that the bearing resolution of deconvolved beamforming was better than that of CBF, and it also had a higher bearing resolution than the beamforming algorithm utilized in Kongsberg M3 multibeam sonar. It is obvious that the side lobe of the deconvolved beam power was about 7 dB lower. Accordingly, the arc bright side lobe in the 2D acoustic image of CBF vanished in the 2D acoustic image of deconvolved beamforming. This conclusion is consistent with the simulation experiment and theoretical analysis. Figure 11: The two balls used in the experiment. Figure 12: _Cont._  
Imaging Experiment of Pool Wall  
As shown in Figure 13, the sonar transducer launch sector was kept horizontal, and the 2D acoustic image is obtained. Figure 13a is the 2D acoustic image output from the display control software, and there are many bright arcs formed by the side lobe leakage besides the wide bright line formed by the pool wall profile. Figure 13c is the 2D acoustic image obtained from CBF utilizing raw data. As shown, it is the same as the output image of the display control software, that is, the profile formed by the pool wall was wide, and the side lobe leakage was serious.