• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.1C
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• pp.130-137
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• 2010

An uplink indoor positioning system is proposed in the present work, where the acoustic signals are solely used for positioning. The underlying acoustic signals include whistle, finger snap, and hands-clapping. In the proposed method, positioning is achieved by finding the time-difference-of-arrivals using several self-generating sounds. To evaluate the feasibility of the signals and their positioning accuracies, the database of 100 persons about self-generating acoustic signals is built up. The results show that the hands-clapping sound is the most suitable for acoustic-based indoor positioning.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.1
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• pp.199-205
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• 2015

Indoor positioning technology has been developed very actively for the smart phone handheld by most users. Especially, many TDOA positioning systems using acoustic signal have been studied, and it estimates the smart phone position by measuring the distance between the smart phone speaker and the microphones which is installed to receive the acoustic signal from the smart phone, and by calculating the hyperbolic equations. But there are always errors for the distance measurements, and furthermore the microphone installation error produces huge position estimation error. In this paper, the position estimation error due to the position error of acoustic sensor in the 3 dimensional TDOA positioning system, is analyzed by PDOP simulation and experiment.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.2
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• pp.191-197
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• 2017

According to the ubiquitous usage of smartphone, so many smartphone applications have been developed, and especially data communications and position measurement technologies without additional equipments have been developed using acoustic signal. But there is a limitation to select the frequency of the acoustic signal due to the smartphone hardware, and there is non-linearity in the electronic circuits in a sound generation devices, the audible sound generated from the speaker is not avoidable. And it causes critical difficulty to the commercial system deployment. In this paper, a simulation technique to calculate the power of the audible acoustic signal by human is applied to several types of acoustic signals to evaluate the loudness. These could be referred when the acoustic communications or positioning systems are designed, for the purposed of inaudible sounding to human.

• Journal of the Korean Institute of Navigation
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• v.17 no.1
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• pp.99-105
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• 1993

Underwater acoustic positioning systems have been extensively used not only in surface position fixing but also in underwater position fixing. Recently, these systems have been applied in the field of installation and underwater inspection offshore platforms etc. But in these systems are included the fixing errors as results of a signal with noise and irregular motion of vessel by ocean waves. In this paper to improve the accuracy of the position fixing a Kalman filter is applied to the short baseline(SBL) acoustic positioning system. The optimal position obtained by the Kalman filter is compared with the raw position and it is confirmed that the former is more accurate than the latter.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.29 no.2
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• pp.109-116
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• 1993

Underwater acoustic positioning systems have been extensively used not only in surface position fixing but also in underwater position fixing. Recently, these systems have been applied in the field of installation and underwater inspection of offshore platforms etc. But in these systems are included the fixing errors as results of a signal with additive noise and irregular motion of vessel by ocean waves. To improve the accuracy of the position fixing a Kalman filter is applied to the supershort baseline (SSBL) acoustic positioning system with beacon mode in noise conditions. The position data obtained by the Kalman filter is compared with raw position data and it is confirmed in the simulation that the former is more accurate than the latter. And an indicator monitoring the filtering effect is described while ship's moving.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.16 no.6
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• pp.191-196
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• 2016

A development on the indoor positioning technologies and services has been proceeded very actively. Among the several positioning technologies, the TDOA(Time Difference of Arrival) technology using acoustic signal has the best positioning performance. Because so many people use their own smartphones, the location of the smartphone is important, and the TDOA technology should be employed to use the acoustic signal for the positioning. For the digital signal processing with the acoustic signal, the signal should be sampled, and as the sampling rate increases, the positioning accuracy could be improved instead of processing time burden. In this paper, the position estimation error according to the sampling rate is analyzed, and the appropriate sampling rate for the positioning system is proposed.

• International Journal of Ocean System Engineering
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• v.3 no.1
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• pp.44-48
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• 2013

This paper describes the design and implementation of a practical underwater positioning system, which is applicable for shallow water depth conditions. In this paper, two strategies are used to enhance the navigation performance. First, a low-cost acoustic-ranging-based precise navigation solution for shallow water is designed. Then, the outlier rejection algorithm is introduced by designing a velocity gate. The acoustic-ranging-based navigation is implemented by modifying the long base line solution. To enhance the tracking precision, the outlier rejection algorithm is introduced. The performance of the developed approach is evaluated using experiments. The results demonstrate that precise shallow water depth navigation can be implemented using the suggested approaches.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.10
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• pp.907-911
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• 2007

This paper dealt with the frequency spectrum analysis of acoustic signal produced by partial discharge (PD) in insulation oil and the positioning of PD occurrence to apply in diagnosis of oil insulated transformers. Three types of electrode system ; the needle-plane, the plane-plane, and the wire-wire structure were assembled to simulate partial discharges in oil insulated transformers. A low-noise amplifier and a decoupling circuit were designed to detect acoustic signal with high sensitivity The frequency spectrum of the acoustic signal were 50 kHz ${\sim}$ 260 kHz in the needle-plane, 50 kHz ${\sim}$ 250 kHz in the plane-plane, and 45 kHz${\sim}$195 kHz in the wire-wire electrode system. Their peak frequencies were 145 kHz, 130 kHz and 114 kHz, respectively The position of PD occurrence was calculated by the time difference of arrival (TOA) using three acoustic emission (AE) sensors, and we could find the position within the error of 1 % in the experimental apparatus.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.2C
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• pp.119-125
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• 2011

Start This paper analyzes the propagation characteristics of acoustic signals in indoor environments, which is applicable to indoor positioning system. Indoor stereo sound system is generally valid within $25m^2$. So it is not possible to apply prevalent sound propagation characteristic to indoor positioning system because the prevalent acoustic signals propagation characteristic is defined under free space condition. Therefore, in this paper, we present the propagation characteristics of acoustic signals in indoor environments considering the free space propagation characteristic as well as room characteristic such as humidity, temperature, absorption of atmosphere and so on. To verify the designed propagation model of indoor acoustic signals, this paper presents the propagation characteristics of decreasing sinusoidal signals whose frequencies ate from 1kHz to 20kHz in anechoic room. In addition, this paper also presents the propagation characteristics of decreasing sinusoidal signals which have multiple frequencies.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.2
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• pp.151-156
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• 2015

As the proliferation of smart phone, almost every user has one's own smart phone, and the user could get the global position and location based services using GPS system outdoors. But indoor positioning system using GPS does not work, and it could not detect global position using TDOA local positioning system. In this paper, a new indoor global positioning system for smart phone employing GPS receiver and electronic compass device is proposed with the TDOA local positioning system using acoustic signal, and the performance and the experimental result are described.