# A Vector Sensor-Based Acoustic Characterization System for Marine Renewable Energy
## 5 Conclusions  
This paper presented the performance characteristics of the NoiseSpotter, an easily deployable self-logging vector sensor array. The results of field trials were presented in a variety of environments that showed excellent data quality in each of these environments with regard to discerning controlled source transmissions and sources of opportunity. The ability to mitigate flow noise, key in energetic environments, was demonstrated in a tidal channel, with approximately 10-15-dB reduction of flow noise at 200 Hz. The in-water tests indicate that the hardware configuration is suitable for small-vessel (8 m) operations in quiescent, energetic, and deep-water environments.  
The ability of the system to estimate the location of a source of sound was demonstrated using plane-wave beamforming techniques applied to a vector sensor array. The compact size of the vector sensor array allows for beamforming array gain comparable to much larger hydrophone arrays, and location estimates of the controlled source were found to be within 2% of the source-receiver separation.  
Next steps involve further improvements in the flow noise removal ability. Further progress on the location estimation algorithm will revolve around estimating the true location of a source without any assumptions regarding source depth, while taking into account multipath reflections that can be expected with longer-range acoustic propagation.  
Conceptualization, K.R., G.C., and C.J.; methodology, K.R.; software, K.R.; validation, K.R., G.C., and F.S.; formal analysis, K.R. and G.C.; investigation, K.R., G.C., and F.S.; resources, C.J.; data curation, G.C. and K.R.; writing--original draft preparation, K.R.; writing--review and editing, K.R. and G.C.; visualization, K.R.; supervision, C.J.; project administration, G.C.; funding acquisition, K.R., G.C., and C.J. All authors have read and agreed to the published version of the manuscript.  
This material is based upon work supported by the US Department of Energy's Office of Energy Efficiency and Renewable Energy (EERE) under the Water Power Program Award Number DE-EE0007822.This presentation was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.  
The authors extend their gratitude to the Pacific Northwest National Laboratory Marine Science Laboratory (PNNL MSL) for field support. [PERSON] (Proteus Technologies LLC) and [PERSON] (Noise-Control Engineering) were invaluable for hardware design and testing. [PERSON] and [PERSON] (Georgia Tech) and [PERSON] and [PERSON] (Scripps Institution of Oceanography) provided feedback on design. The authors would like to specially thank [PERSON] and his laboratory (University of Washington) for valuable acoustic discussions and continued collaborations. The authors also thank [PERSON], [PERSON], [PERSON], and [PERSON] for help in evaluating the utility of NoiseSpotter for MRE applications.  
The authors declare no conflicts of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.