• Title, Summary, Keyword: X-Band Frequency

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Implementation of the Past frequency Hopping Synthesizer for X-band Satellite Transportable Terminal (X-Band 휴대용 위성단말기의 고속 주파수 도약 합성기 구현)

  • 김정섭;장동운;최태환;김재환
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.27 no.2B
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    • pp.151-159
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    • 2002
  • Frequency synthesizer is an essential part for developing high speed frequency hopping radio. A high speed synthesizer using DDS driven PLL technique is designed and implemented for a X-band portable satellite terminal. It generates transmitter and receiver frequency ranging 6600∼7100MHz and 6140∼6640MHz, respectively by using 102.4MHz local oscillator, Its lock time is below 15 $\mu$sec and Its phase noise is below -754dBc at 1KHz offset Sequency.

A Study on X-band Frequency Synthesizer for Radar Transceiver (레이더 송수신기용 X 밴드 주파수 합성기에 관한 연구)

  • Park, Dong-Kook;Lee, Hyun-Soo
    • Journal of the Korean Society of Marine Engineering
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    • v.30 no.3
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    • pp.444-448
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    • 2006
  • In this paper, a frequency synthesizer for X-band FMCW radars is proposed. Some X-band FMCW radars have been used as a level sensor for tanker ship and the resolution of the level sensor may be mainly depend on linearity of frequency sweep. For a linear frequency sweep. the proposed synthesizer employs a phase-locked loop using prescalars and a high speed digital PLL chip. The measured results show that the linear frequency sweep range is from 10 GHz to 11 GHz and the output power of the synthesizer is minium 7 dBm. and the phase noise is about -80 dBc/Hz at 100 KHz offset from 11 GHz.

Automatic Detection and Analysis of Rip Currents at Haeundae Beach using X-band Marine Radar (항해용 X-band 레이다를 이용한 해운대해수욕장 이안류 자동탐지 및 특성 분석)

  • Oh, Chanyeong;Ahn, Kyungmo;Cheon, Se-Hyeon
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.31 no.6
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    • pp.485-492
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    • 2019
  • The observation system has been developed to investigate the rip currents at Haeundae beach using X-band marine radar. X-band radar system can observe shape, size, and velocity of rip currents, which is difficult to obtain through field observation by conventional device. Algorithms which automatically detect locations, shapes, and magnitudes of rip currents were developed using time averaged X-band radar sea clutter images. X-band sea clutter images are transformed through 3D FFT into 2D wave number spectrum and frequency spectrum. Rip current velocities were estimated using differences in wave-number spectra and wave frequency spectra due to Doppler shift. The algorithm was verified by drift experiments. At Haeundae beach, the radar system exactly located the rip currents and found to be sustained for 1-2 days at fixed locations.

Design, Implementation and Test of Flight Model of X-Band Transmitter for STSAT-3 (과학기술위성 3호 X-대역 송신기 비행모델 설계, 제작 및 시험)

  • Seo, Gyu-Jae;Lee, Jung-Soo;Oh, Chi-Wook;Oh, Seung-Han;Chae, Jang-Soo
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.40 no.5
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    • pp.461-466
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    • 2012
  • This paper describes the development and test result of X-band Transmitter flight model(FM) of STSAT-3 by satellite research center(SaTReC), KAIST. The communication sub-system of STSAT-3 is consist of two different frequency band channels. S-band frequency is used for Telemetry & Command, and X-band frequency is used for mission data. Payload observations data in Mass Memory Unit (MMU) is modulated by QPSK modulator in X-band Transmitter, and then QPSK modulation signal is transmitted to antenna through transfer switch. In this Paper, we described the results of modulation, low-pass filter design, power amp development, and switch test. The FM XTU is delivered Spacecraft Assembly, Integration and Test(AIT) level through the completion of functional Test and environmental(vibration, thermal vacuum) Test successfully.

Wind Retrieval from X-band SAR Image Using Numerical Ocean Scattering Model

  • Kim, Duk-Jin
    • Korean Journal of Remote Sensing
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    • v.25 no.3
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    • pp.243-253
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    • 2009
  • For the last 14 years, space-borne satellite SAR system such as RADARSAT-1, ERS-2, and ENVISAT ASAR have provided a continuous observation over the ocean. However, the data acquired from those systems were limited to C-band frequency until the advent of the first spacebome German X-band SAR system TerraSAR-X in 2007. Korea is also planning to launch the nation's first X-band SAR satellite (KOMPSAT-5) in 2010. It is timely and necessary to develop X-band models for estimating geophysical parameters from these X-band SAR systems. In this study, X-band wind retrieval model was investigated and developed based on numerical ocean scattering model (radar backscattering model and hydrodynamic interaction model). Although these models have not yet been tested and validated for broad ranges of wind conditions, the estimated wind speeds from TerraSAR-X data show generally good agreement with in-situ measurements.

Soil Moisture Measurement of Bare and Vegetated Surfaces by X-band Radars

  • Oh, Yi-Sok;Kwon, Soon-Gu;Hwang, Ji-Hwan
    • Journal of electromagnetic engineering and science
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    • v.10 no.4
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    • pp.212-218
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    • 2010
  • The radar backscatter from various earth surfaces is sensitive to the frequency of the incident wave. This study examined the radar sensitivities for surface parameters such as soil moisture content and surface roughness of both bare and vegetated surfaces at X-band. Because L-band frequencies are often used for sensing the surface parameters, the sensitivities of X-band are also compared with those of the L-band. The sensitivities of the X-band radar backscatter were examined with respect to soil moisture content and surface roughness of rough bare soil surfaces. These sensitivities were also examined using the same parameters for vegetated surfaces for various vegetation densities and incidence angles. Use of the X-band radar for soil moisture detection was as effective as L-band radar for bare soil surfaces. For vegetated surfaces, the soil moisture could be detected using an X-band radar at lower incidence angles, where the upper limit of the incidence angles was dependent on vegetation density.

The Design of a X-Band Frequency Synthesizer using the Subharmonic Injection Locking method (Subharmonic Injection Locking 방법을 이용한 X-Band 주파수 합성기 설계)

  • Kim, Ji-Hye;Yun, Sang-Won
    • Proceedings of the Korea Electromagnetic Engineering Society Conference
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    • pp.269-272
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    • 2003
  • A low phase noise frequency synthesizer at X-Band which employs the subharmonic injection locking was designed and tested. The frequency synthesizer consists of two oscillators - master and slave : A 1.75GHz master oscillator made of PLL synthesizer produces 6th harmonic at 10.5GHz, which excites the following 10.5GHz slave oscillator. The realized frequency synthesizer has a 4.5dBm of output power, and a phase noise of -108dBc/Hz at the 100kHz offset frequency.

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Design of Flexible Reconfigurable Frequency Selective Surface for X-Band Applications (유연한 구조를 갖는 X-Band 재구성 주파수 선택구조 설계)

  • Lee, In-Gon;Park, Chan-Sun;Yook, Jong-Gwan;Park, Yong-Bae;Chun, Heung-Jae;Kim, Yoon-Jae;Hong, Ic-Pyo
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.28 no.1
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    • pp.80-83
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    • 2017
  • In this paper, the X-band reconfigurable frequency selective surface having flexible geometry was proposed. The proposed RFSS is composed of patterns of cross-shaped loop with inductive stub, which can control the frequency response for C-Band and X-band by ON/OFF state of PIN diode. To minimize the parasitic effect and to obtain the high level of isolation between the unit cell of FSS and the bias circuit, we designed the grid type bias line on bottom layer through via hole. The measured transmission characteristics show good agreement with the simulation results and good stability of frequency response for different incident angles and curvatures of surface.

Design and Fabrication of a X-band Voltage Control Dielectric Resonator Oscillator with The Low Phase Noise (낮은 위상잡음을 갖는 X-band 전압제어 유전체 공진형 발진기의 설계 및 제작)

  • 박창현;최병하
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.41 no.5
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    • pp.69-76
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    • 2004
  • In this paper, a VCDRO (Voltage Control Dielectric Resonator Oscillator) with low phase noise for X-band application has been designed and fabricated. A low noise and low flicker noise MESFET and a high Q dielectric resonator were selected to obtain good phase noise Performance. Also, a varactor diode having high Q, qualify factor was used to reduce the loading effects and a big Gamma of diode was chosen for linearity of frequency over voltage tuning range. The fabricated circuits was simulated with circuit design tools, ADS to provide the optimum performances. As the measured results of fabricated oscillator, the output power was 5.8 ㏈m at center frequency 12.05㎓ and harmonic suppression -30㏈c, phase noise -114 ㏈c at 100 KHz offset frequency, respectively, and the frequency tuning range as the function of valtage applied to varactor diode was 15.2 MHz and its power variation with frequency was 0.2 ㏈. This oscillator could be available to a local oscillator in X-band.

Design and Manufacture of FMCW Radar with Multi-Frequency Bandwidths (다중 대역폭을 갖는 FMCW 레이다 송수신기 설계 및 제작)

  • Hwang, Ji-hwan;Kim, Seung Hee;Kang, Ki-mook;Kim, Duk-Jin
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.27 no.4
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    • pp.377-387
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    • 2016
  • Design of X-band frequency FMCW based imaging radar with multi-resolutions and performances of the self-manufactured radar system are presented in this study. In order to implement the multi-bandwidths, a ramp sequence of the FMCW signal is consisting of two kinds of 'saw-tooth' waveform with different bandwidth, and a receiver circuit consisting of L-band source and frequency converter circuit is used to effectively extract spectra of beat-frequency from the received signal of X-band frequency. The system setups for performance measurement of self-manufactured radar system are maximum output power of 35 dBm, sampling frequency of 1.2 MHz and sweep time of 1 ms. Then, the measured resolutions of the modulated signal having bandwidth of 500 MHz and 300 MHz in range & azimuth-direction are (0.28 m, 0.26 m) and (0.44 m, 0.27 m), respectively.