• Title/Summary/Keyword: 주파수 변조

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A Study on the Development of Level Sensor using Frequency Modulated Continuous Wave (주파수 변조 연속파를 이용한 레벨 센서 개발에 관한 연구)

  • 박동국;한태경;박인용;윤천수
    • Proceedings of the Korean Institute of Navigation and Port Research Conference
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    • 2004.04a
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    • pp.299-303
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    • 2004
  • In this paper, it is presented a level sensor for measuring a level of the contents of cargo tank using frequency modulated continuous wave(FMCW). The frequency range is 10∼11 GHz, the radar cross section(RCS) of target is 0.8 ㎡ of metal plate. the experiment is performed in laboratory and open ground, the sweep time of the signal is 100 ms, the pyramidal horn antenna of about 20 dBi gain is used, and input power of antenna is about 5 dBm. the beat frequency according to the target moving to 40 m is measured. There is a good agreement between measured and calculated results. But the resolution of the FMCW radar is measured about 10 cm due to nonlinear of voltage controlled oscillator(VCO).

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On the Filtering of Hangul character Element with the Spatial Positioning Modulation (공간 위치 변조에 의한 한글자소의 필터링)

  • 강대수;진용옥
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.17 no.9
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    • pp.1029-1039
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    • 1992
  • This paper presents the filtering method which is processed on the frequency domain among Hangul character recognition methods. It is processed the Hangul character parrern with spatial positioning modulation and mapped the Hangul character element which have spatial position variant feature onto frequency domain, at this time, normalized spatial position and so normalized the character size in frequency domain. And it is grouped the Hangul character element according to the generating position and set the standard pattern, and used each standard character element pattern with character element filter and filtering the character pattern of Hangul character, it is derived the normalized cross correlation function and the coherence function led to the filtering results, and calculated classification threshold.

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Implementation of Real-time Stereo Frequency Demodulator Using RTL-SDR (RTL-SDR을 이용한 스테레오 주파수 변조 방송의 실시간 수신기 구현)

  • Kim, Young-Ju
    • Journal of Broadcast Engineering
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    • v.24 no.3
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    • pp.485-494
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    • 2019
  • A software-driven real-time frequency de-modulator is implemented with the aid of universal-serial-bus (USB) type software defined radio dongle. An analog stereo frequency modulation (FM) broadcast signal is down-converted to the basedband analog signal then converted to digital bit streams in the USB dongle. Computer software such as Matlab, Python, and GNU Radio manipulates the incoming bit streams with the technique of digital signal processing. Low pass filtering, band pass filtering, decimation, frequency discriminator, double sideband amplitude demodulation, phase locked loop, and deemphasis function blocks are implemented using such computer languages. Especially, GNU Radion is employed to realize the real-time demodulator.

Analysis of Input/Output Transfer Characteristic to Transmit Modulated Signals through a Dynamic Frequency Divider (동적 주파수 분할기의 변조신호 전송 조건을 위한 입출력 전달 특성 분석과 설계에 대한 연구)

  • Ryu, Sungheon;Park, Youngcheol
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.27 no.2
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    • pp.170-175
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    • 2016
  • In order to transmit baseband signals through frequency dividing devices, we studied the transfer function of the device in the term of the baseband signal distortion. From the analysis, it is shown that the magnitude of the envelope signal is related to the mixer gain and the insertion loss of the low pass filter whilst the phase is the additional function with the 1/2 of the phase delay. For the purpose of the verification of the study, we designed a dynamic frequency divider at 1,400 MHz. The operating frequency range of the device is closely related to the conversion gain of mixers and the amplitude of input signal, and becomes wide as the conversion gain of mixers increases. The designed frequency divider operates between 0.9 GHz and 3.2 GHz, for -14.5 dBm input power. The circuit shows 20 mW power dissipation at $V_{DD}=2.5V$, and the simulation result shows that an amplitude modulated signal at 1,400 MHz with the modulation index of 0.9 was successfully downconverted to 700 MHz.

A Simulation of Δ-Σ Modulators for Frequency Synthesizers of FMCW Radars (FMCW 레이더 주파수합성기용 델타-시그마 변조기의 시뮬레이션)

  • Hwang, In-Duk;Kim, Chang-Hwan
    • The Journal of the Korea institute of electronic communication sciences
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    • v.7 no.4
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    • pp.707-714
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    • 2012
  • After a single-stage, second-order, multiple-feedback ${\Delta}-{\Sigma}$ modulator and a two-stage, second-order MASH ${\Delta}-{\Sigma}$ modulator were analyzed and simulated using Simulink and Matlab and their characteristics were compared, the following result was obtained: 1) The two ${\Delta}-{\Sigma}$ modulators do not have group delay distortion. 2) The characteristics of the noise shaping are nearly identical. As a result of the noise shaping, the power spectral densities have slope of 40 dB/dec. 3) There was no spurious tone. 4) The input range of the two modulators is from -1 to +1 in common. 5) Because the output of the two-stage MASH modulator is 2-bits (4-levels), design of frequency dividers and charge pumps of PLL are more demanding.

A Study on Frequency Offset Compensation using 2-Phase Characteristic of Beacon Signal modulated by Satellite (위성 변조 비콘 신호의 2위상 특성을 이용한 주파수 오프셋 보상방법에 대한 연구)

  • Choi, Chul-Hee
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.18 no.1
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    • pp.97-103
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    • 2018
  • In satellite communication, modulated beacon signal is spreaded by gold sequence and the modulated beacon is transmitted via linear phase modulation. Due to the difference in characteristics of the satellite and the receiver on the ground, frequency offset (FO) occurs. An existing modulated beacon receiver is a method of synchronizing the frequency of a modulated beacon signal using FFT(Fast Fourier Transform), which not only increases the delay and complexity in terms of system implementation but also has a separate circuit for compensating the phase difference due to FO and phase offset from FFT points. In order to overcome this problem, this paper proposes and analyzes a scheme for compensating and demodulating the coarse FO and phase offset at one time using the 2-phase shaped characteristics of the modulated beacon signal. Also, through the simulation, the modulation index suitable for the proposed method is analyzed and the appropriate cumulative number is also analyzed.

Performance Analysis of Modulator using Direct Digital Frequency Synthesizer of Initial Clock Accumulating Method (클록 초기치 누적방식의 직접 디지털 주파수 합성기를 이용한 변조기의 성능해석)

  • 최승덕;김경태
    • Journal of the Korean Institute of Telematics and Electronics T
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    • v.35T no.3
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    • pp.128-133
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    • 1998
  • This paper is study on performance analysis of modulator using direct digital frequency synthesizer of Initial Clock Accumulating Method. It has been generally used for PLL or digital frequency synthesizing method to be synthesizd randomly chosen frequency state. In order to improve disadvantage of two methods, we constructed modulator system using DDFS of Initial Clock Accumulating Method. We also confirmed the coherence frequency hopping state and possibility of phase control. The results obtained from the experiments are as follows; First, the synthesized output frequency is proportional to the sampling frequency, according to index, K. Second, the difference of the gain between the basic frequency and the harmonic frequencies was more than 50 [dB], that is, this means facts that is reduced the harmonic frequency factor. Third, coherence frequency hopping state is confirmed by PN code sequence. Here, we confirmed the proposed method cut switching time, this verify facts that is the best characteristic of the frequency hopping. We also verified the fact that the phase varies as the adder is operated set or reset.

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A study on frequency gain control of frequency shift keying signals using the preamble error rate for underwater acoustic communications (수중 음향 통신에서 주파수 편이 변조 신호의 프리엠블 오류율을 이용한 주파수 이득 조절 연구)

  • Jeong, Hyun-Woo;Jung, Ji-Won;Kim, Wan-Jin
    • The Journal of the Acoustical Society of Korea
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    • v.41 no.2
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    • pp.218-226
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    • 2022
  • The main characteristics of the underwater acoustic channel have varying multipath and fast fading. Especially, Frequency Shift Keying (FSK) signals with multiple frequency bands caused loss of information bits allocated on the specific frequencies due to selective fading phenomenon. Therefore, this paper proposes frequency gain control algorithm based on preamble error rates. The proposed algorithm estimates optimal gain value in the range of preamble error rate with less than 10 % for specific faded frequency. By employing turbo equalized FSK signals with rate of 1/3, the experiment was conducted on a lake in Munkyeong city with distance of 300 m to 500 m. The result confirms that packets are decoded successfully by applying proposed algorithm as increasing number of iterations.

All Digital GMSK Modulator for the GSM Mobile System (GSM 무선통신 시스템을 위한 디지털 GMSK 변조기 설계 및 성능분석)

  • 김범진;한재충;홍승억
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.25 no.4A
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    • pp.502-511
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    • 2000
  • The Gaussian Minimum Shift Keying (GMSK) modulation technique belongs to the class of nonlinear modulation technique, and it is known to be bandwidth efficient. The GMSK modulation is chosen for the digital cellular phone standard by the European Telecommunications Standards Institute (ETSI). In this paper, an efficient method for implementing all digital GMSK modulator is introduced. The proposed modulator is shown to be simple to implement as well as satisfying the required spectral shape recommended by the ETSI.

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