• Journal of Institute of Control, Robotics and Systems
• /
• v.16 no.8
• /
• pp.751-755
• /
• 2010

In this paper, we proposed an omnidirectional ranging system that is able to obtain $360^{\circ}$ all directional distances effectively based on structured light image. The omnidirectional ranging system consists of laser structured light source and a catadioptric omnidirectional camera with a curved mirror. The proposed integro-differential structured light image processing algorithm makes the ranging system robust against environmental illumination condition. The omnidirectional ranging system is useful for map-building and self-localization of a mobile robot.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.30 no.12C
• /
• pp.1125-1132
• /
• 2005

Ultra-wideband (UWB) ranging poses a set of time delay estimation problems for designers. The possibility of a large error can be a challenging problem for accurate ranging and positioning. An approximate analysis of large error performance of UWB ranging in multipath and multiuser environments is posed. Both analytical and experimental approaches are taken to evaluate the large error variance in a correlation-based serial search scenario.

• ETRI Journal
• /
• v.33 no.6
• /
• pp.841-848
• /
• 2011

A signal-to-noise ratio (SNR) enhancement algorithm using multiple chirp symbols with clock drift is proposed for accurate ranging. Improvement of the ranging performance can be achieved by using the multiple chirp symbols according to Cramer-Rao lower bound; however, distortion caused by clock drift is inevitable practically. The distortion induced by the clock drift is approximated as a linear phase term, caused by carrier frequency offset, sampling time offset, and symbol time offset. SNR of the averaged chirp symbol obtained from the proposed algorithm based on the phase derotation and the symbol averaging is enhanced. Hence, the ranging performance is improved. The mathematical analysis of the SNR enhancement agrees with the simulations.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.34 no.2A
• /
• pp.164-169
• /
• 2009

This paper presents a fast and accurate ranging algorithm for the WiBro system. The proposed algorithm detects a received ranging code and estimates its propagation delay using the correlation characteristics of the PRBS (Pseudo Random Binary Sequence) and the circular shift property of the discrete Fourier transform operator. The proposed ranging algorithm was applied to array antenna systems to show how it could improve the ranging performance of an array antenna system compared to a conventional base station system, which uses only a single antenna.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.14 no.3
• /
• pp.587-594
• /
• 2010

In this paper, we propose an asynchronous IR-UWB ranging system based on the two-way ranging protocol. The periodic pulse sequence is used to measure a distance between two devices. At the receiver, a received signal is first transformed into a frequency-domain signal using an analog correlator bank and digital signal processing is followed in the frequency-domain. This make it possible for the system to use an ADC with a conversion speed of pulse rate. The proposed algorithm at the receiver side includes a peak detection procedure using mutipath channel compensation and matched filtering, and retransmits a pulse sequence synchronized with the detected peak. The validity of the proposed algorithm is verified from simulation results where the CM1 channel is assumed.

• Proceedings of the IEEK Conference
• /
• 2000.06a
• /
• pp.248-251
• /
• 2000

The ATM-PON is regarded as an effective access network because the system transmits the various user's information through the passive optical splitter in a single platform. The ranging technology is to place all ONUs at the same distance virtually in order to form ATM-PON based on the Time Division Multiplexing (TDM). In This paper, We show the steps about ranging protocol based on ITU-T G.983.1 and ranging procedure modeling. Also, We implement the simulator that considers various environments to verify the time specifications of G.983.1. By using the simulator, We find out the wasted bandwidth which influences active ONUs during the ranging procedure.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.19 no.6
• /
• pp.762-768
• /
• 2016

In this paper, a method for generating ranging signal to reduce the effects of interference and overcome intentional jamming is proposed in slow frequency hopping(SFH) communication system. A terminal uses ranging signal for initial Up-link synchronization in the frequency hopping communication systems using multi-terminal. However, ranging signal generated by unsynchronized terminal acts as an interference signal to another terminal. Therefore, we propose the design of the ranging signal with PN sequence in order to minimize the affection to the other terminal and simulated its performance. From the simulated result, we confirm synchronization performance.

• Journal of fish pathology
• /
• v.32 no.2
• /
• pp.123-127
• /
• 2019

In this study, white spots appearing in carapace of imported white leg shrimp Litopenaeus vannamei were observed by macroscopic and microscopic examination. White spots due to white spot disease showed two types, white spots with a regular circular shape ranging from 0.4 mm to 1.7 mm and white spots with an irregular shape ranging from 0.05 mm to 2 mm. White spots due to other causes showed four types that appeared as crystalized materials in range of 100 ㎛ around the tegumental gland, as polygonal inorganic deposits ranging from 58 ㎛ to 188 ㎛, as Linear inorganic deposits ranging from 0.8 mm to 9 mm, as brownish spots ranging from 0.1 mm to 0.4 mm, and brownish spots containing melanin ranging from 0.1 mm to 2 mm. As a result, white spots occurred in imported white leg shrimp Litopenaeus vannamei were divide two type, due to white spot disease or other causes, for quarantine works.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.13 no.10
• /
• pp.4971-4987
• /
• 2019

Node localization is the basic task of underwater wireless sensor networks (UWSNs). Most of the existing underwater localization methods rely on ranging accuracy. Due to the special environment conditions in the ocean, beacon nodes are difficult to deploy accurately. The narrow bandwidth and high delay of the underwater acoustic communication channel lead to large errors. In order to reduce the ranging error and improve the positioning accuracy, we propose a localization algorithm based on ranging correction and inertial coordination. The algorithm can be divided into two parts, Range Correction based Localization algorithm (RCL) and Inertial Coordination based Localization algorithm (ICL). RCL uses the geometric relationship between the node positions to correct the ranging error and obtain the exact node position. However, when the unknown node deviates from the deployment area with the movement of the water flow, it cannot communicate with enough beacon nodes in a certain period of time. In this case, the node uses ICL algorithm to combine position data with motion information of neighbor nodes to update its position. The simulation results show that the proposed algorithm greatly improves the positioning accuracy of unknown nodes compared with the existing localization methods.

• The Journal of the Acoustical Society of Korea
• /
• v.20 no.2
• /
• pp.52-57
• /
• 2001

The passive ranging estimation techniques using a focused beamformer have been studied under the water. It is well known that the passive ranging estimation method using a focused beamformer is excellently evaluated. Among these, the passive ranging sonar is known to have a good performance under low signal-to-noise. ratio. However, its performance is degraded in multi-source environments. In this paper, we proposed the technique using dual focused beamformers to estimate the range. And when the sampling frequency is low, it is very difficult to steer the focused beam to the desired direction, as a result of this, the low performance occurs because of a distorted beam pattern. In this paper, we study the effect of sampling rate on passive ranging by using focused beamformer. And we verified the performance of the proposed method via computer simulation.