• Title/Summary/Keyword: FM radar

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The Characteristics of Contiguous Pulse Trains of Stepped FM Signals with binary Phase Coding (2진위상 부호화 연속 펄스 계단 FM 신호의 특성)

  • 윤태환;박송배
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.15 no.6
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    • pp.79-86
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    • 1978
  • The characteristics of contiguous pulse trains of stopped FM signals with binary phase coding, to be used as radar signals, were investigated. For this purpose, the general expressions for the spectra and the ambiguity functions of this class of signals were first obtained; these expressions were then compute6 and plotted by the use of computer for various coding scheme. The results show that alternate phase coding provides the best time resolution and the corresponding ambiguity functon has a configuration of "be6 of spikes" in the whole time-velocity plane.ity plane.

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Millimeter-wave Fast-sweep FM Reflectometry Applied to Plasma Density Profile Measurements

  • Kang, Wook-Kim
    • Journal of electromagnetic engineering and science
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    • v.1 no.1
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    • pp.18-23
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    • 2001
  • A fast-sweep broadband FM reflectometer system has been successfully developed and operacted at the DIII-D tokamak, producing reliable density Profiles with excellent spatial (1 $\leq$ cm) and temporal resolution (~100 $\mu$ s). The system uses a solid-state microwave oscillator and an active quadrupler, covering full Q-band frequencies (33~50 GHz) and providing relatively high output power (20~60 mW). The system hardware allows fu11band frequency sweep in 10 $\mu$ s, but due to digitization rate limit on DIII-D, sweep time was limited to 75~100 $\mu$ s. Fast frequency sweep has helped to reduce density fluctuation effects on the reflectometer phase measurements, thus improving reliability for individual sweeps. The fast-sweep system with high spatial and temporal resolution has allowed to measure fast-changing edge density profiles during plasma ELMS and L-H transitions, thus enabling fast-time sca1e physics studies.

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A Study on Barker Code of Radar Pulse Compression Technique (레이더 펄스 압축 기술의 Barker Code에 관한 연구)

  • Kim, Min-Soo;Koo, Ryung-Seo;Rhee, Young-Chul
    • The Journal of the Korea institute of electronic communication sciences
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    • v.8 no.4
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    • pp.541-547
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    • 2013
  • Range resolution is important performance parameter to distinguish a target accurately. The destination of modern radar systems, to overcome the limitations of existing analog radar systems, is to improve the range resolution of the distance with low transmission power. For that reason, the research on pulse compression techniques is briskly studying. In the Receiver, modulation system of transmitted signal which has used in pulse compression technique is divided PM and FM to distinguish a target. In this paper, We analysed and designed the pulse compression signal processing module using the Baker Code which is the one of PM method's.

Design and Development of TRM for NEXTSat-2 X-band Synthetic Aperture Radar (차세대소형위성2호 X대역 합성 개구 레이더용 송·수신 모듈의 설계 및 개발)

  • Jeeheung Kim;Dong Guk Kim;Ilyoung Jang
    • Journal of Advanced Navigation Technology
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    • v.28 no.2
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    • pp.193-200
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    • 2024
  • This paper describes the design and development of a transmit receiver module(TRM) for mounting on X-band SAR of the NEXTSat-2. The TRM generates the chirp signal with required bandwidth through the DDS in X-band and performs frequency conversion, combination for the signal to transmit and be received and frequency synthesis. Tx path of the TRM produces signals of total 28 bandwidths up to 96.8 MHz and has output signal level of more than + 9.37 dBm. Rx path of the TRM has minimum noise figure of 15.7 dB. The measurement results show that required requirements are satisfied. The TRM is installed on the NEXTSat-2 flight model(FM), launched by KSLV-II(Nuri) on May 23, 2023 and currently operational.

Design and Implementation of True Random Noise Radar System

  • Min, Woo-Ki;Kim, Cheol-Hoo;Lukin, Constantin A.;Kim, Jeong-Phill
    • Journal of electromagnetic engineering and science
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    • v.9 no.3
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    • pp.130-140
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    • 2009
  • The design theory and experimental results of a true random noise radar system are presented in this paper. Target range information can be extracted precisely by correlation processing between the delayed reference and the signal received from a target, and the velocity information by the Doppler processing with successive correlation data. A K-band noise radar system was designed using random FM noise signal, and the characteristics of the fabricated system were examined with laboratory and outdoor experiments. A C-band random FM noise signal was generated by applying a low-frequency white Gaussian noise source to VCO(Voltage Controlled Oscillator), and a K-band Tx noise signal with 100 MHz bandwidth was obtained by using a following frequency multiplier. Two modified wave-guide horn arrays were designed and fabricated, and used for the Tx and Rx antennas. The required amount of Tx/Rx isolation was attained by using a coupling cancellation circuit as well as keeping them apart with predetermined spacing. A double down-conversion scheme was used in the Rx and reference channels, respectively, for easy post processing such as correlation and Doppler processing. The implemented noise radar performance was examined with a moving bicycle and a very high-speed target with a velocity of 150 m/s. The results extracted by the Matlab simulation using the logging data were found to be in a reasonable agreement with the expected results.

Correlation Algorithm for High-Precision Measurement in FM-CW Radar Level Meters (FM-CW 레이더 거리계의 비트 신호 스펙트럼 상관성을 이용한 고정밀 측정 알고리듬)

  • Kim, Jeong-Mok;Lim, Zong-Soo;Chun, Joong-Chang;Kim, Tae-Soo;Shim, Jae-Ryun;Park, Wee-Sang
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.38 no.4
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    • pp.38-44
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    • 2001
  • In this paper, for the microwave level meter based on the FM-CW radar, we analyze the spectrum correlation of beat signals and propose a measurement algorithm using the theory. For industrial applications, level meters must have high precision, which requires a good linearity of VCO. But, in practice, it is very complicated or very expensive to make VCO linear enough to be acceptable in the industrial field. We propose a measurement algorithm using the fact that there exists a peak in the spectrum correlation of beat signals when range difference is sufficiently small. This makes it possible to determine the range difference in a precise manner even using a practical VCO. We present some experimental results to show the validity of this algorithm.

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The Low Probability of Intercept RADAR Waveform Based on Random Phase and Code Rate Transition for Doppler Tolerance Improvement (도플러 특성 개선을 위한 랜덤 위상 및 부호율 천이 기반 저피탐 레이다 파형)

  • Lee, Ki-Woong;Lee, Woo-Kyung
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.26 no.11
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    • pp.999-1011
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    • 2015
  • In modern electronic warfare, RADAR is under constant threat of ECM(Electronic Counter Measures) signals from nearby jammers. The conventional linear frequency modulated(Linear-FM) waveform is easy to be intercepted to estimate its signal parameters due to its periodical phase transition. Recently, APCN(Advanced Pulse Compression Noise) waveform using random amplitude and phase transition was proposed for LPI(Low probability of Intercept). But random phase code signals such as APCN waveform tend to be sensitive to Doppler frequency shift and result in performance degradation during moving target detection. In this paper, random phase and code rate transition based radar waveform(RPCR) is proposed for Doppler tolerance improvement. Time frequency analysis is carried out through ambiguity analysis to validate the improved Doppler tolerance of RPCR waveform. As a means to measure the vulnerability of the proposed RPCR waveform against LPI, WHT(Wigner-Hough Transform) is adopted to analyze and estimate signal parameters for ECCM(Electronic Counter Counter Measures) application.

Wideband Chirp Signal Generation for W-Band SAR (W-대역 영상레이다를 위한 광대역 Chirp 신호 발생장치)

  • Lee, Myung-Whan;Jung, Jin Mi;Lee, Jun Sub;Singh, Ashisg Kumar;Kim, Yong Hoon
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.29 no.2
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    • pp.138-141
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    • 2018
  • In this paper, we describe the designed digital waveform of a linear frequency-modulated (FM) chirp signal using field-programmable gate arrays (FPGAs) for image radar, and this signal is modulated with an I-Q modulator, and multiplied by 24 frequency multipliers to obtain a 94-GHz W-band wideband chirp generator. The developed chirp generator is an FM signal with a 94-GHz carrier frequency and a 960-MHz bandwidth, and the flatness is less than 1.0 dB at intermediate frequency (IF) (3.9 GHz), 2.0 dB in the W-band, and it has a 0.3-W output power in the W-band.

Simple Method for Improving the Frequency Sweep Linearity of FMCW Collision Warning Radar (차량 충돌방지용 FMCW 레이더의 주파수 Sweep 선형성 개선을 위한 간단한 기법)

  • Hyun, Eu-Gin;Oh, Woo-Jin;Lee, Jong-Hun
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.21 no.10
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    • pp.1109-1115
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    • 2010
  • FMCW(Frequency Modulation Continuous Wave) Radar can detect the distance and the velocity of forward obstacles using linearly modulated FM signal. For better performance, the RF of radar should be operated with wideband frequency linearity on 300 MHz bandwidth at 77 GHz carrier frequency. In this paper, we propose a simple method for improving frequency linearity of FMCW radar implemented with VCO. The proposed method shows that the Voltage-Frequency relation of VCO could be measured by using the modified Tx waveform of FMCW radar. Then the measured nonlinearity could be compensated using LUT(Look-up Table) with easy. It is noted that the proposed can be adopted in existing system without extra circuit.

A Study on the Performance Improvement in Sidelobe Suppression for Pulse Compression of LFM Signal (LFM 신호의 펄스압축에 대한 부엽억제 성능향상 기법연구)

  • Shin, Jeong-Hoon
    • Journal of the Korea Institute of Military Science and Technology
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    • v.9 no.3
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    • pp.95-100
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    • 2006
  • The pulse compression technique using Linear FM signal is commonly used for improving the performance of both the detection range and range resolution in radar system. In general, the compressed LFM waveform has relatively large sidelobe level which may prevent a target from being detected when strong jammer or clutter signal is near the target signal. In this paper, we propose a new weighting method which uses the square-root weight to suppress the sidelobe level. Typical applications are missile seekers and tracking radar systems where target tracking range is available prior to the signal processing. By computer simulation, we show that the performance of the proposed method is better than that of the conventional weighting methods in terms of sidelobe suppression.