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This paper realizes an underwater spiral wave sound source by using three omni-directional spherical transducers with three different phases. The pressure distribution of the sound field for a phased array is derived using the superposition theory of sound field. The generation of spiral wave field is presented, the relationship between the perform...
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The radial vibration of a radial composite tubular transducer with a large radiation range and power capacity is studied. The transducer is composed of a longitudinally polarized piezoelectric ceramic tube and a coaxial outer metal tube. Assuming that the longitudinal length is much larger than the radius, the electromechanical equivalent circuits...
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... In 2018, Lu et al. developed a Phased-Spiral source using eight longitudinal vibrating elements, which vibrated due to multiple piezoelectric ceramic hollow cylinders [26]. One year later, the same authors developed a simpler Phased-Spiral source using a group of three omnidirectional spherical transducers [27]. ...
... The developed spiral source prototype has a cylindrical shape with four quadrants, A, B, C, and D (see Figure 2) as the one developed in [23]. However, the four quadrants are not acoustically isolated, thus resulting in a transducer with four omnidirectional monopoles that can be driven by four independent signal generators simultaneously as is the case of the spiral source developed in [27], which used three independent omnidirectional acoustic sources. The spiral source's prototype was made using the STEMINC PZT-4 piezoelectric cylinder, Part Number SMC26D22H13111, shown in Figure 3a, which has two resonances: one at 43 kHz and the other at 59 kHz [28] for Mode 0 and Mode 1 of radial vibration, respectively. ...
... The absolute angle error was less than 23 • and 3 • before and after the calibration, respectively. Thus, the prototype in question, at 30 kHz, had the worst performance before the calibration compared to the maximum absolute angle errors of 4 • , 20 • , 10 • , and 21 • in [18,[25][26][27], respectively. On the other hand, it performed better after the calibration, at all tested frequencies, compared to the state-of-the-art work [25] with the maximum absolute angle error of 10 • . ...
Underwater acoustic spiral sources can generate spiral acoustic fields where the phase depends on the bearing angle. This allows estimating the bearing angle of a single hydrophone relative to a single source and implementing localization equipment, e.g., for target detection or unmanned underwater vehicle navigation, without requiring an array of hydrophones and/or projectors. A spiral acoustic source prototype made out of a single standard piezoceramic cylinder, which is able to generate both spiral and circular fields, is presented. This paper reports the prototyping process and the multi-frequency acoustic tests performed in a water tank where the spiral source was characterized in terms of the transmitting voltage response, phase, and horizontal and vertical directivity patterns. A receiving calibration method for the spiral source is proposed and showed a maximum angle error of 3° when the calibration and the operation were carried out in the same conditions and a mean angle error of up to 6° for frequencies above 25 kHz when the same conditions were not fulfilled.
... In 2018, Lu et al. developed a Phased-Spiral source using 8 longitudinal vibrating elements that vibrate due to multiple piezoelectric ceramic hollow cylinders [14]. One year later, the same authors developed a more simple Phased-Spiral source using a group of 3 omnidirectional spherical transducers [15]. Spiral acoustic sources, like other acoustic equipment, may require adjustments in order to display the desired performance. ...
... It has a cylindrical shape with four quadrants A, B, C and D (see Fig. 2) as the one developed in [11]. However, the four quadrants are not acoustically isolated, thus resulting in a transducer with four omnidirectional monopoles that can be driven by four independent signal generators simultaneously as is the case of the spiral source developed in [15] which uses 3 independent omnidirectional acoustic sources. The spiral source's prototype was made using a standard PZT-4 piezoelectric ceramic cylinder (Fig. 3a, STEMINC Part Number SMC26D22H13111) and the manufacturing process can be described in the following steps: ...
Underwater acoustic spiral sources are able to generate spiral acoustic fields where the phase depends on the bearing angle. It allows to estimate the bearing angle relatively to a receiver by subtracting the phases of a spiral and a circular wavefront, and finds application in the bearing angle estimate with a single hydrophone, e.g., for unmanned underwater vehicles localization. This paper presents a new prototype for a spiral acoustic source, which is able to generate the required wavefronts, and is composed of four monopoles in the same piezoceramic cylinder. This paper reports the prototyping and the acoustic tests performed in a water tank where the spiral source was characterized in terms o Transmitting Voltage Response, phase, and horizontal and vertical directivity patterns. A receiving calibration method for the spiral source is proposed and shows a maximum angle error of 1 degree when the calibration and the operation are carried under the same conditions and a mean angle error up to 6 degrees for frequencies above 25 kHz when the same conditions are not fulfilled.
... Several methods have been proposed to efficiently generate spiral-waves. [35][36][37] Although these methods were originally developed for underwater device navigation 36 and sonar exploration, 38 we believe they can also be used for indoor localization. Hereinafter, we refer to these methods as spiral-wave methods. ...
This paper introduces a method for indoor self-localization of a monaural microphone, which is required for various location-based services. By generating two pairs of dipole sound fields, localization is performed on each device, irrespective of the number of devices, based on orthogonal detection of observed signals and some simple operations that are feasible with limited computational resources. A method using multiple source frequencies for enhancing robustness against the effects of reflection and scattering is also proposed. The effectiveness of this method was evaluated by numerical simulations and experiments in an anechoic chamber and indoor environment, and the average errors for the azimuth and zenith angles were 4.8 and 1.9 deg, respectively, in the anechoic chamber and 21 and 11 deg, respectively, in the indoor environment.
Experiments carried out at NUWC's Seneca Lake facility in the summer of 2020 demonstrate the efficacy of underwater navigation via a single spiral wavefront (SWF) acoustic beacon. An SWF beacon is a transducer array that has the capability of generating a spiral acoustic signal whose phase varies linearly with angular aspect along with a reference signal with constant phase. An unmanned underwater vehicle (UUV) operating in Seneca Lake under various channel conditions receives a regular signal from a fixed position single SWF beacon. The UUV's aspect relative to the beacon and its radial velocity can be determined by comparing the phase of the spiral signal to that of the reference signal. The SWF navigation solutions are compared to the UUVs inertial/GPS navigation. Advances in signal processing for the spiral wavefront navigation in multipath environments are detailed. An example of multipath performance from experimental data is shown.
