• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.11
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• pp.1323-1326
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• 2012

In military applications, many radar systems are simultaneously operated at a close range. In particular, the frequency allocation must be executed for operating the homogeneous radar systems at the same time. As many radar systems are simultaneously operated with overlapping frequency bands, interference between systems inevitably occurs. Because interference can degrade radar performance, suppression of interference is a critical issue in radar systems. In this letter, we analyze the interference between two FMCW radars. In addition, time synchronization method between radars using mutual interference is proposed. Experiments are carried out to validate the proposed method. The results demonstrate that the proposed method is suitable for real radar systems.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.11 no.4
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• pp.70-79
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• 2012

A design guide to type-3 PLLs for FMCW radars is provided. To do that, the cross-over frequencies of the open-loop transfer functions were normalized to 1 Hz and closed-loop properties were compared through simulations using Pspice. As a result, several guides to design type-3 PLLs were provided: 1) secure 45 degrees of phase margin, 2) locate two zeroes at an identical frequency, and 3) poles may be added to raise order of the PLL at higher frequencies than the cross-over frequency of the open-loop transfer function about ten times.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.7
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• pp.848-851
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• 2012

As many radar systems are simultaneously operated with overlapping frequency bands, interference between systems inevitably occurs. Because interference can degrade radar performance, suppression of interference is a critical issue in radar systems. In this letter, a new interference detection and suppression method using a short-time Fourier transform and an adaptive notch filter is proposed. An experiment is carried out to validate the proposed method and the results demonstrate that the proposed method is suitable for application in real FMCW radars.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.30 no.2
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• pp.169-172
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• 2019

Frequency-modulated continuous wave(FMCW) radars with array antennas are widely used because of their light weight and relatively high resolution. A usual approach for the joint range and angle estimation of a target using an array FMCW radar is to create a range-angle matrix with the deramped received signal, and subsequently apply two-dimensional(2D) frequency estimation methods such as 2D fast Fourier transform on the range-angle matrix. However, such frequency estimation approaches cause bias errors since the frequencies in the range-angle matrix are not independent. Therefore, we propose a new maximum likelihood-based algorithm for joint range and angle estimation of targets using array FMCW radar, and demonstrate that the proposed algorithm achieves the Cram?r-Rao bounds, both for range as well as angle estimation.

• IEMEK Journal of Embedded Systems and Applications
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• v.17 no.3
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• pp.139-148
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• 2022

In this paper, we implement a distributed FMCW MIMO radar system to obtain Micro Doppler signatures of target motions. In addition, we also develop federated learning based motion recognition algorithm based on the Micro-Doppler radar signature collected by the implemented FMCW MIMO radar system. Through the experiment, we have verified that the proposed federated learning based algorithm can improve the motion recognition accuracy up to 90%.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.7
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• pp.31-39
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• 2014

Recently, as Intelligent Transportation System (ITS) and self-driving system become influential in the ground transportation system, automotive radar systems have been actively studied among the various radar systems to implement the vehicle collision detection system and distance measurement system between vehicles. Most of the automotive radars are Frequency Modulated Continuous Wave (FMCW) radar type which can calculate distance and velocity of target by estimating the frequency difference between the transmitted signal and received signal. Therefore, accurate frequency estimation is very important in the FMCW radar system. For this reason, to improve the measurement accuracy of the FMCW radar, Reverse Directional FRI (RD-FRI) Super-Resolution technique which has high frequency estimation accuracy is applied to the FMCW radar system. The feasibility of the proposed technique is evaluated with simulation results and compared with FFT and conventional Super-Resolution techniques. The simulation results show that the proposed technique estimates the frequency with high accuracy and the distance with centimeter accuracy.

• Journal of Advanced Marine Engineering and Technology
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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.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.30 no.1
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• pp.88-94
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• 2019

A leakage canceller and adaptive algorithm for FMCW Radar is presented. Because a strong leakage signal causes various problems in the transceiver and digital processor, specific FMCW radars are in need of a leakage canceller. The leakage canceller has an adaptive structure and the algorithm calculates the prediction vector and learns the adaptive coefficient simultaneously. The proposed algorithm an improvement of 10 dB in the cancellation performance.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.10 no.4
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• pp.86-92
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• 2011

ITS(Intelligent Transport System) has been researched actively to guarantee the smooth traffic and the safety of the vehicle. In recent, as the sensor for the measurement of distance between vehicles, the FMCW radar system in millimeter wave band has been interested in ITS. Actually, 47, 60, 77, 94 and 139 GHz have been assigned for the vehicle radar frequencies in Europe and Japan. However, the performances of the FMCW radar are deteriorated due to the interferences from the surrounding radars and mobile devices. In this paper, in order to model and simulate the performance of FMCW radar under the exterior interference, we propose a new performance parameter, RER(Radius Error Rate), which contains the information of the range error due to the interferences, and show the effectiveness of the proposed parameter.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.45 no.6
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• pp.35-41
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• 2008

The most important requirement for the automotive radars is the simultaneous target range and velocity measurement under environment of multi-target, clutters, multi-path, and so on. If the many vehicles with 77GHz FMCW(Frequency Modulation Continuous Wave) radar system are in the near area we should consider the interference signals occurred by other radar systems because these signals reduce exact detection of range and velocity. In this paper, we propose the interference cancellation method, which each vehicle radar transmits chirp trains with the different frequency sweep shapes. The proposed method is applied into the various applications such as an intelligent vehicle, Robot, and UGV(Unmanned Ground Vehicle).