• Title/Summary/Keyword: heterodyne system

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The Small Angle Generator Based on a Laser Angle Interferometer

  • Eom, Tae-Bong;Jeong, Don-Young;Kim, Jae-Wan
    • International Journal of Precision Engineering and Manufacturing
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    • v.8 no.3
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    • pp.20-23
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    • 2007
  • To calibrate precision autocollimators, the Korean Research Institute of Standards and Science (KRISS) has built a small angle generator using a laser interferometer. The system is based on a sine bar mechanism in which the angle is determined from the ratio of two lengths. The rotational angle is measured by the angle interferometer and the heterodyne laser interferometer detects the relative displacement of two retro-reflectors attached to the rotating arm. The distance between the two retro-reflectors of the laser angle interferometer is self-calibrated by an index table positioned on the rotating arm. The resolution of the system is 0.002 seconds, and the accuracy is better than 0.04 seconds within a measuring range of $\pm$1 degree. The small angle generator can also be used with an index table that can divide one circle into 1440 angles. The combined system can generate any angle over 360 degrees to an accuracy of 0.11 seconds.

FH/GMSK System using DDS (DDS을 이용한 FH / GMSK 시스템)

  • Kim, Cheong;Lee, Mu-Yong
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.8 no.4
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    • pp.415-425
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    • 1997
  • Although FHSS has many advantages over conventional digital radio communication system, field application has been so far hampered due to its complicated synchronization. In this paper, a new FHSS system is proposed which one FH signal modulated with GMSK and one chip delayed FH signal than former are sent from transmitter, and this is recovered by matching process at a heterodyne correlator in receiver; thus eliminates synchronization as a whole. Through analysis and experiment, we assure that there is possibility in this. The exper- imental result from 915~929 MHz bandwidth with 31 chips is investigated in the environment of AWGN.

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Numerical Analyses of Several tens of GHz Wave Signal Generation for Broadband Communication System (광대역 통신시스템을 위한 수십 GHz 신호생성을 위한 수치 해석)

  • Kim Jung-Tae
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.8 no.7
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    • pp.1581-1587
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    • 2004
  • In this paper, We have proposed an Heterodyne technique to generate millimeter-wave signal. Microwave signals in cellular broadband mobile communication networks and distributed networks can favorably be generated and distributed by optical techniques. In principle, these techniques have already been investigated for optical control of phase-array antennas, characterization of photo-detector and phase locking of millimeter-wave oscillators and now being applied to wireless communications. The generation and transmission of millimeter-wave radio signals by optical means is of interest for future pico-cell broadband mobile communication system, especially for systems operating at frequencies of 300Hz.

Adaptive Force Ripple Compensation and Precision Tracking Control of High Precision Linear Motor System (초정밀 선형 모터 시스템의 적응형 힘리플 보상과 정밀 트랙킹 제어)

  • Choi Young-Man;Gweon Dae-Gab;Lee Moon G.
    • Journal of the Korean Society for Precision Engineering
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    • v.22 no.12 s.177
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    • pp.51-60
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    • 2005
  • This paper describes a robust control scheme for high-speed and long stroke scanning motion of high precision linear motor system consisting of linear motor, air bearing guide and position measurement system using heterodyne interferometer. Nowadays, semiconductor process and inspection of wafer or LCD need high speed and long travel length for their high throughput and extremely small velocity fluctuations or tracking errors. In order to satisfy these conditions, linear motor system are widely used because they have large thrust force and do not need motion conversion mechanisms such as ball screw, rack & pinion or capstan with which the system are burdened. However linear motors have a problem called force ripple. Force ripple deteriorates the tracking performances and makes periodic position errors. So, force ripple must be compensated. To maximize the tracking performance of linear motor system, we propose the control scheme which is composed of a robust control method, Time Delay Controller (TDC) and a feedforward control method, Zero Phase Error Tracking Control (ZPETC) for accurate tracking a given trajectory and an adaptive force ripple compensation (AFC) algorithm fur estimating and compensating force ripple. The adaptive ripple compensation is continuously refined on the basis of tracking error. Computer simulation results based on modeled parameters verify the effectiveness of the proposed control scheme for high-speed, long stroke and high precision scanning motion and show that the proposed control scheme can achieve a sup error tracking performance in comparison to conventional TDC control.

Novel 10 GHz Bio-Radar System Based on Frequency Multiplier and Phase-Locked Loop (주파수 체배기와 PLL을 이용한 10 GHz 생체 신호 레이더 시스템)

  • Myoung, Seong-Sik;An, Yong-Jun;Moon, Jun-Ho;Jang, Byung-Jun;Yook, Jong-Gwan
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.21 no.2
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    • pp.208-217
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    • 2010
  • This paper presents a novel 10 GHz bio-radar system based on a frequency multiplier and phase-locked loop(PLL) for non-contact measurement of heartbeat and respiration rates. In this paper, a 2.5 GHz voltage controlled oscillator (VCO) with PLL is employed to as a frequency synthesizer, and 10 GHz continuous wave(CW) signal is generated by using frequency multiplier from 2.5 GHz signal. This paper also presents the noise characteristic of the proposed system. As a result, a better performance and economical frequency synthesizer can be achieved with the proposed bio-radar system. The experimental results shows excellent bio-signal measurement up to 100 cm without any additional digital signal processing(DSP), and the proposed system is validated.

Feasibility Study to Actively Compensate Deformations of Composite Structure in a Space Environment

  • Farinelli, Ciro;Kim, Hong-Il;Han, Jae-Hung
    • International Journal of Aeronautical and Space Sciences
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    • v.13 no.2
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    • pp.221-228
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    • 2012
  • An active compensation method for the deformation of composite structures using additional controllable metal parts is proposed, and its feasibility is experimentally investigated in a simulated space environment. Composite specimens are tested in a vacuum chamber, which is able to maintain pressure on the order of 10-3 torr and interior temperature in the range of ${\pm}30^{\circ}C$. The displacement-measuring interferometer system, which consists of a heterodyne HeNe laser and an interferometer, is used to measure the displacement of the whole structure. Meanwhile, the strain of the composite part and temperature of both parts are measured by fiber Bragg grating sensors and thermistors, respectively. The displacement of the composite structure is maintained within a tolerance of ${\pm}1{\mu}m$ by controlling the elongation of the metal part, which is bonded to the end of the composite part. Also, the possibility of fiber Bragg grating sensors as control input sensors is successfully demonstrated using a proper corrective factor based on the specimen temperature gradient data.

The Analysis of Motion Error in Scanning Type XY Stage (스캐닝 방식 XY 스테이지의 운동오차 분석)

  • 황주호;박천홍;이찬홍;김동익;김승우
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2004.10a
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    • pp.1380-1383
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    • 2004
  • The scanning type XY stage is frequently used these days as precision positioning system in equipment for semiconductor or display element. It is requested higher velocity and more precise accuracy for higher productivity and measuring performance. The position accuracy of general stage is primarily affected by the geometric errors caused by parasitic motion of stage, misalignments such as perpendicular error, and thermal expansion of structure. In the case of scanning type stage, H type frame is usually used as base stage which is driven by two actuators such as linear motor. In the point view of scanning process, the stage is used in moving motion. Therefore, dynamic variation is added as significant position error source with other parasitic motion error. Because the scanning axis is driven by two actuators with two position detectors, 2 dimensional position errors have different characteristic compared to general tacked type XY stage. In this study 2D position error of scanning stage is analyzed by 1D heterodyne interferometer calibrator, which can measure 1D linear position error, straightness error, yaw error and pitch error, and perpendicular error. The 2D position error is evaluated by diagonal measurement (ISO230-6). The yaw error and perpendicular error are compensated on the base stage of scanning axis. And, the horizontal straightness error is compensated by cross axis compensation. And, dynamic motion error in scanning motion is analyzed.

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Wireless Communication using Millimeter-Wave Envelope Detector (밀리미터파 포락선 검파기를 이용한 무선통신)

  • Lee, Won-Hui;Jang, Sung-Jin
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.17 no.6
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    • pp.79-82
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    • 2017
  • In this paper, we proposed the wireless communication system using millimeter-wave envelope detector. The sub-harmonic mixer based on schottky barrier diode was used in the transmitter. The receiver was used millimeter-wave envelope detector. The transmitter was composed of schottky diode sub-harmonic mixer, frequency tripler, and horn antenna. The receiver was composed of horn antenna, millimeter-wave envelope detector, low pass filter, base band amplifier, and limiting amplifier. At 1.485 Gbps and 300 GHz, the eye-diagram showed a very good performance as measured by the error free. Communication distance is reduced compared to the heterodyne receiver, but compact and lightweight is possible.

A Study on the Analysis of Minimum Performance and Design for Receiver System in W-CDMA Handset (W-CDMA 단말기 수신 시스템에서 요구하는 최소성능 분석 및 설계에 관한 연구)

  • Kwack, Jun-Ho;Yun, Seok-Chul;Kim, Hak-Sun
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.29 no.9A
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    • pp.1005-1012
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    • 2004
  • In this paper, we have analyzed minimum performance required for W-CDMA Handset from standard and Implemented the receiver for W -COMA Handset. We have derived the noise figure and IIP3 of receiver and determined the selectivity about adjacent channel and minimum performance for front-end stage. Before the Implementation, we have verified the performance using AOS simulator In conclusion, we have implemented the receiver for W-COMA Handset using the heterodyne architecture and performed measurement. Therefore, this paper wlll gIVe a guideline for design of the W -COMA Handset.

Implementation of Self-frequency Synchronizing Circuit using Single-sideband Up-converter and Image Rejection Mixer (단측파대 상향변환기와 이미지제거 혼합기를 이용한 자기동조회로의 구현)

  • Yeom, Seong-Hyeon;Kim, Tae-Young;Kim, Tae-Hyun;Park, Boem-June
    • Journal of the Korea Institute of Military Science and Technology
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    • v.13 no.6
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    • pp.1058-1063
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    • 2010
  • In this paper, we designed self-frequency synchronizing circuit using image rejection mixer(IRM) and single-sideband(SSB) up-converter which can effectively eliminate the image frequencies occurred in multi-channel super-heterodyne receivers and help us to match inter-channel phase. Also the self-frequency synchronizing circuit simplifies system because there need no extra devices for making intermediate frequency(IF) by creating the local signal within several nanoseconds by means of generating the same frequency of IF signal and modulating radio frequency(RF) signal. We adopt the limiting amplifier for the purpose of protecting the circuit from spurious signals which come from the front end side having wide instantaneous bandwidth characteristics and constantly injecting same level into the input local signal of IRM. The IRM we fabricated has image rejection ratio of 27dB, which is good over 7dB for foreign company's. Also, the SSB up-converter we fabricated has 1dB compression point of 18dBm, which is good over 16dB for foreign company's. And the size is compact about one-forth.