• Title/Summary/Keyword: Chirp Signal

Search Result 144, Processing Time 0.018 seconds

A Study on a 3-Dimensional Positioning System over Indoor Wireless Environments (실내 무선 환경에서 3차원 위치 추적 시스템에 관한 연구)

  • Kang, Byeong-Gwon;Choi, Sung-Ja;Kim, Gui-Jung;Park, Yong-Seo
    • Journal of Digital Convergence
    • /
    • v.12 no.11
    • /
    • pp.273-279
    • /
    • 2014
  • In this paper, we propose a novel algorithm for three dimensional positioning system and implement a system over indoor wireless channel. A commercial modules are used for mobile and fixed nodes which are product of German company Nanotron Co. This module adopts chirp spread spreading scheme as modulation method to improve the ranging resolution and the module satisfies the IEEE standard 802.15.4a. The distance computation is based on received signal strength(RSS) levels and trilateration method. A testbed was set up to measure and compare the positioning estimation error of the proposed algorithm. The experiments results showed that the accuracy of location estimation was sufficiently good as much as 1m distance error in a wireless environment in an office building.

Range Design of Pulse Repetition Frequency for Removal of SAR Residual Image (영상레이더 잔상 제거를 위한 펄스 반복 주파수의 범위 설계)

  • Kim, Kyeong-Rok;Heo, Min-Wook;Kim, Tu-Hwan;Ryu, Sang-Burm;Lee, Sang-Gyu;Lee, Hyeon-Cheol;Kim, Jae-Hyun
    • The Journal of Korean Institute of Communications and Information Sciences
    • /
    • v.41 no.11
    • /
    • pp.1653-1660
    • /
    • 2016
  • The synthetic aperture rardar (SAR) is an active sensor using microwaves. It transmits a microwave signal, called a chirp pulse, and receives the reflected signal in a moving platform such as satellite and unmanned aerial vehicle. Since this sensor uses microwaves that can penetrate the atmosphere, SAR generates the images regardless of light and weather conditions. However SAR operates on the moving platform, the Doppler shift and the side-looking observation method should be considered. In addtion, a residual image or ghost image can be occurred according to selection of the pulse repetition frequency (PRF). In this paper, a range design of the PRF for the L-band spaceborne SAR system is studied for prevention of SAR image distortion. And the system is studied for prevention of SAR image distortion. And the system parameter and the PRF are calibrated iteratively according to the proposed system design procedure and design constraints. The MATLAB based on SAR system simulator has been developed to verify the validity of calculated PRF. The developed simulator assumes that SAR sensor is operated by the PRF calculated from the design. The results of the simulator show that the targets in image has a valid peak to side-lobe ratio (PSLR) so that the PRF can be used for the spaceborne SAR sensor.

A Study on the Technology Development of User-based Home Automation Service (사용자 위치기반 홈오토메이션 서비스 기술 개발에 관한 연구)

  • Lee, Jung-Gi;Lee, Yeong-Seok
    • Journal of the Korea Academia-Industrial cooperation Society
    • /
    • v.18 no.3
    • /
    • pp.327-332
    • /
    • 2017
  • As Internet of Things (IoT) technology advances, there is a growing demand for location-based services (LBSs) to identify users' mobility and identity. The initial LBS system was mainly used to measure position information by measuring the phase of a signal transmitted from a global positioning system (GPS) satellite or by measuring distance to a satellite by tracking the code of a carrier signal. However, the use of GPS satellites is ineffective, because it is difficult to receive satellite signals indoors. Therefore, research on wireless communications systems like ultra-wide band (UWB), radio frequency identification (RFID), and ZigBee are being actively pursued for location recognition technology that can be utilized in an indoor environment. In this paper, we propose an LBS system that includes the 2.45GHz band for chirp spread spectrum (CSS), and the 3.1-10.6GHz band and the 250-750MHz bands for UWB using the IEEE 802.15.4a standard for low power-based location recognition. As a result, we confirmed that the 2.45GHz Industrial, Scientific and Medical (ISM) band RF transceiver and the ranging function can be realized in the hardware and has 0dBm output power.

A study of ubiquitous-RTLS system for worker safety (작업자 안전관리를 위한 유비쿼터스-실시간 위치추적시스템 연구)

  • Kim, Young-Baig
    • The Journal of Korean Institute of Communications and Information Sciences
    • /
    • v.37 no.1C
    • /
    • pp.1-7
    • /
    • 2012
  • At the industrial work site, the manufacturing process is being automated to improve work efficiency. However, it is often difficult to automate the entire manufacturing process, and there are spaces in which workers there are constantly exposed to danger. To protect such workers from the danger, this paper studied a worker safety management system for the industrial work site which uses a location recognition system and which is based on the Ubiquitous-Wireless Sensor Network (U-WSN). Using wireless signals, the distance between two devices can be measured and the location of a worker can be calculated using triangularization in 3-D. But at the industrial work sites where there are a lot of steel and structures, errors occur due to signal reflection and multi-path, etc., which makes it difficult to get the accurate location. To address this problem the following was done: first, a circular polarization patch antenna appropriate to the work site was used to reduce the degree of error that may occur from the antenna emission pattern and the particular Line of Sight (LOS); second, a 3-D localization technique and a filtering algorithm were used to improve the accuracy of location determination. The developed system was tested by using it on a wharf crane to validate its accuracy and effectiveness. The proposed location recognition system is expected to contribute greatly in ensuring the safety of workers at industrial work sites.