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Anti-drone sensors, effectors, and systems –a concise overview

Zmysłowski D., Skokowski P., Kelner J. M.

TransNav : International Journal on Marine Navigation and Safety of Sea Transportation

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2023

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Vol. 17 No. 2

455--461

EN

The dynamic development of microelectronics and wireless communication at the turn of the 20th and 21st centuries contributed to the increase in the availability and popularity of all kinds of unmanned platforms, air, land, surface, and underwater. In the case of unmanned aerial vehicles (UAVs), also popularly known as drones, the significant (crucial) advantages are high freedom of motion (i.e., the ability to move in three planes) and the possibility of using it practically anywhere (as opposed to water platforms). These factors influenced the dynamic development of this market sector and the high availability of various models and equipment. UAVs are being used in many sectors and services, both for civil and military purposes. Widespread availability, low cost, and ease of use also favor the possibility of using civilian UAVs for criminal, smuggling, terrorist, or military purposes. Recent armed conflicts, e.g., in Nagorno-Karabakh or Ukraine, and the situation on the eastern Polish-Belarusian border clearly show this. All countries recognize the potential and threat posed by the development of unmanned platforms. Therefore, for several years, special attention has been paid to analyses and research in sensors, effectors, and anti-drone systems. It is worth emphasizing that some effectors (e.g., jammers or spoofers) may significantly affect the navigation process of neighboring objects that use global navigation satellite systems (GNSSs). On the other hand, the use of anti-drone systems is important, especially in the context of protecting institutions and facilities of companies, state administration (i.a., embassies, consulates), army, strategic importance objects (e.g., related to energy, chemical industry), or protection of mass events. In this paper, we present an overview of solutions available on the market and development directions in the field of anti-drone technology.

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Acquisition Module for a Wireless Acoustic Sensor Network Suitable for Argentinian Urban Environments

Caccia Matias, Sacerdoti Eduardo, Lombera Esteban

Journal of Ecological Engineering

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2022

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Vol. 23, nr 12

89--98

EN

Urban noise is a main component in the deterioration of life quality for people in urban areas. This problem mainly affects those who periodically travel through high traffic areas. The first step in reducing environmental noise is to characterize the urban setting with acoustic metrology for its diagnosis and control. This document exposes the design, construction and characterization of a wireless urban noise measurement module. The device works as a low-cost node with the capacity to be replicated for the deployment of a network of wireless acoustic sensors that allows the elaboration of dynamic urban noise maps. Each module consists of an electrical autonomy system, a single board computer and a MEMS microphone. The project also includes the design of a web portal to display measurement results in real time. The low-cost system was calibrated and compared with a class 1 sound level meter used to measure urban noise in the Autonomous City of Buenos Aires (CABA). Global differences of less than 1 dB were obtained. Urban noise was measured near the National University of Tres de Febrero following guidelines of ISO 1996-2 standard. The performance obtained in the evaluation instance and the results of the comparison were satisfactory.

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Microphone Based Acoustic Vector Sensor for Direction Finding with Bias Removal

Wajid Mohd, Kumar Arun, Bahl Rajendar

Archives of Acoustics

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2022

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Vol. 47, No. 2

151--167

EN

The acoustic vector sensor (AVS) is used to measure the acoustic intensity, which gives the direction-of-arrival (DOA) of an acoustic source. However, while estimating the DOA from the measured acoustic intensity the finite microphone separation (d) in a practical AVS causes angular bias. Also, in the presence of noise there exists a trade off between the bias (strictly increasing function of d) and variance (strictly decreasing function of d) of the DOA estimate. In this paper, we propose a novel method for mitigating the angular bias caused due to finite microphone separation in an AVS. We have reduced the variance by increasing the microphone separation and then removed the bias with the proposed bias model. Our approach employs the finite element method (FEM) and curves fitting to model the angular bias in terms of microphone separations and frequency of a narrowband signal. Further, the bias correction algorithm based on the intensity spectrum has been proposed to improve the DOA estimation accuracy of a broadband signal. Simulation results demonstrate that the proposed bias correction scheme significantly reduces the angular bias and improves the root mean square angular error (RMSAE) in the presence of noise. Experiments have been performed in an acoustic full anechoic room to corroborate the effect of microphone separation on DOA estimation and the efficacy of the bias correction method.