• Journal of IKEEE
• /
• v.25 no.1
• /
• pp.53-63
• /
• 2021

As the types of radio equipment becomes more complex and diversified in various fields, radio interference occurs frequently. In the domestic situation where the territory is narrow, many systems are deployed in a specific highland with a good radio wave environment. Radar systems that transmit high power signals of the same band are sometimes deployed and operating at close distance. In this paper, the type of interference was classified for the actual radio wave interference phenomenon and appropriate signal interference parameters were derived. The power density of the interference signal was predicted using the analysis method and the effectiveness was verified through measurement. And, we propose a method to minimize interference by analyzing operating scenarios of interferer radar and victim radar.

• IEMEK Journal of Embedded Systems and Applications
• /
• v.17 no.1
• /
• pp.25-32
• /
• 2022

IR-UWB radar has been regarded as the most promising technology for non-contact respiration and heartbeat monitoring because of its ability of detecting slight motion even in submillimeter range. Measuring heart rate is most challenging since the chest movement by heartbeat is quite subtle and easily interfered with by a random body motion or background noise. Additionally, periodic sampling can be limited by the performance of computer that handles the radar signals. In this paper, we deploy Lomb-Scargle periodogram method that estimates heart rate even with irregularly sampled data and uneven signal amplitude. Lomb-Scargle periodogram is known as a method for finding periodicity in irregularly-sampled and noisy data set. We also implement a motion detection scheme in order to make the heart rate estimation pause when a random motion is detected. Our scheme is implemented using Novelda's X4M03 radar development kit and its corresponding drivers and Python packages. Experimental results show that the estimation with Lomb-Scargle periodogram yield more accurate heart rate than the method of measuring peak-to-peak distance.

• 전기의세계
• /
• v.29 no.9
• /
• pp.584-593
• /
• 1980

Conventional radar antenna systems are susceptible to performance degradation caused by unwanted signals received via the antenna sidelobes and/or mainlobes. Adaptive array systems offer possible solution to this interference problem by automatically steering nulls to unwanted signals providing significant system performance improvement. Another important andvantage of the adaptive array is its self-optimization capability which uses the collective incoming noise data for the nulling purposes. This paper provides a tutorial introduction to adaptive arrays as well as some new development of recent research in this area. Optimum link between the antenna theory and signal processing has been sought by illustrating the gain patterns and output signal-to-noise ratio. Signal acqusition methods are shown including a new attempt of the use of spread-spectrum techniques in conjuction with array systems.

• Journal of the Institute of Electronics Engineers of Korea SC
• /
• v.46 no.1
• /
• pp.1-9
• /
• 2009

In this paper, a 2.4 GHz doppler radar system consisting of a doppler radar sensor and a baseband module were designed to detect heart beat and respiration signal without direct skin contact. The doppler radar system emits RF signal of 2.4 GHz toward human chest, and then detects phase modulation of the reflected signal so as to investigate cardiopulmonary activities. The heartbeat and respiration signals acquired from I/Q channels of the doppler radar system are applied to the pre-processing circuit, the amplification circuit, and the offset circuit of the baseband module. The designed system was tested on mouse, rabbit and mankind, which have different range of heart rates and respiration signals, to evaluate detection accuracy of the system. ECG acquisition system and respiration transducer were used to generate the reference signal. In our experiments, a performance of detection were found to be high in the case that the subject stays still. In this paper, we confirmed that non-contact heart beat and respiration detection using the doppler radar has the possibility and limitation according to distance, cardiopulmonary activities, range of heart rates and respiration.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.30 no.6
• /
• pp.507-517
• /
• 2019

Multi-function radar(MFR) is a system that uses various functions such as detection, tracking, and classification. To operate the functions in real-time, the detection stage in MFR usually uses radar signals for short measurement time. We can utilize several conventional detectors in the MFR system to detect low radar cross section maritime targets in the sea-clutter; however, the detectors, which have been developed to be effective for radar signals measured for a longer time, may be inappropriate for MFR. In this study, we proposed a modelling technique of sea-clutter short measurement time. We combined the modeled sea-clutter signal with the maritime-target signal, which was obtained by the numerical analysis method. Using this combined model, we exploited four independent detectors and analyzed the detection performances.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.15 no.4
• /
• pp.637-642
• /
• 2020

In this study, the SLB(Sidelobe Blanking)/BLB(Blacklobe Blanking) design of the VHF band radar using the low-frequency band having a relatively larger beam width than the S-band or X-band radar. The antenna of the VHF band has a relatively large beam width, so it is reflected from the side lobe. If the reflected target signal is not processed into sidelobe, the false alarm rate of the radar increases by recognizing it from the main lobe signal. This method of SLB blocking is the elimination of the side lobe signal in the front of the array antenna using the central radiating element of the array antenna, and the blocking of side lobe signal from the antenna rear through BLB receiver block. After completed the radar implementation, The function of blocking of side lobe signals was confirmed through the system unit test by Simulated signal generator. Through this study, it will be used in the implementation of the side-lobe blocking technology of the array antenna for low-frequency band radar with large antenna size and beam width in the future.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.26 no.4A
• /
• pp.809-816
• /
• 2006

More than effectively judging the existence of reinforcing bars under multi boundary layers and void shapes in concrete, this study aims to develop the analysis algorithm of radar response on multi boundary layers in reinforced concrete and radar capable of estimation of the shape of specific voids in plain concrete. To detect or estimate reinforcing bars and void shapes in these conditions, the simulation analysis model of transmission and reflection wave of electromagnetic radar is used. This radar simulation model is carried out with reinforced or non reinforced concrete of various boundary conditions and void shapes. And, the output signals (images) of radar simulation results are calculated and represented by convolution method. As the results, it is clarified that this simulation analysis technique can be used to analyze radar response on multi boundary layers in reinforced concrete and void shapes in concrete.

• Proceedings of the IEEK Conference
• /
• 2006.06a
• /
• pp.127-128
• /
• 2006

In this paper, we propose a novel signaling method using chirp signals in UWB radio with satisfaction of FCC regulation. Chirp signals have been used in many ranging systems such as radar because of its good correlation properties. Because it is important to use broader signal bandwidth in order to get higher precision of the ranging, according to the Cramer-Rao Lower Bound, UWB radio is extremely good as the ranging systems. But, it is very difficult to apply existing chirp signals to UWB, because FCC regulates that the systems operating in UWB radio must occupy signal bandwidth more than 500MHz on the condition of stopping the frequency sweeping. So, we propose multiple chirp signals which can satisfy the regulation of FCC while maintaining chirp signal's properties. The multiple chirp signals which are composed of the sub-chirps modulated by sub-carriers can expand the signal bandwidth with the same principle of OFDM systems. The simulation results show that the BER performance of the proposed multiple chirp signals is identical to that of conventional OFDM when it is applied to data communication, and that the correlation properties of the proposed signals are almost the same with properties as those of single chirp signals whose sweeping bandwidth is the same value with the proposed one.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2012.05a
• /
• pp.568-570
• /
• 2012

The algorithm to distinguish cloud from aerosols in the measurements of Laser Radar is developed. This method use the difference of slope between return signals of cloud and aerosols. The parameters achieved from the algorithm are altitude of cloud top, cloud base, and boundary layer.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.14 no.5
• /
• pp.825-832
• /
• 2011

In this paper, we described the design and measurement results of a Front-End Receiver for S-band active phased array radar. The Front-End Receiver has input P1dB of -4dBm and IIP3 of 7dBm. The measurement results show that gain is $24{\pm}0.7dB$, noise figure are less than 2.3dB over the frequency range of $fc{\pm}0.2GHz$. The Front-End Receiver can protect the receiver path from large input signals with a maximum peak power of multi-kW and recovery time is less than 0.8us. The measurement results satisfy all specifications.