• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.10 no.7
• /
• pp.1104-1110
• /
• 1999

When a FM-CW radar is used to measure the target distance, the nonlinearity relationship between the VCO control voltage and the output frequency makes an adverse effect on the measurement accuracy. Recently, many nonlinearity correction schemes using signal processing techniques and dedicated hardwares have been studied. This paper presents a signal processing technique to compensate for the VCO nonlinearity using a reference signal. To demonstrate the validity of the presented technique, several experiments were conducted and the results show reduction of the distortion in the range profile and the resolution improvement.

• Journal of Broadcast Engineering
• /
• v.5 no.2
• /
• pp.211-219
• /
• 2000

The IBAC DAB system was interfered by existing FM broadcasting signal as was used guardband within existing FM broadcasting. The FM interference signals are very important parameter in performance evaluation of IBAC DAB system. We got the characteristic of FM PSD in according to instantaneous change and average characteristic of FM broadcasting signal in according to characteristic of FM channel. In this paper, based on proposed IBAC DAB system, we analyze effects of FM interference for occupied bandwidth and performance of IBAC DAB modeling various FM interference signals with sum of sinusoid function using C language, suggest FM interference ratio that can maintain performance. We was know that IBAC DAB system have a great performance variation in according to average characteristic of FM PSD by simulation results, also, FM interference ration that can maintain performance of system is 10dB.

• Journal of Broadcast Engineering
• /
• v.18 no.6
• /
• pp.823-834
• /
• 2013

In this paper, we propose a detection method for Digital Radio Mondiale (DRM) Plus suitable for hybrid mode broadcasting which services both DRM Plus and analog FM within the same frequency band. The guard-interval correlation method of Orthogonal Frequency Division Multiplexing (OFDM) is good for DRM Plus signal detection, but the possibility for false alarm increases when FM signal is received. The proposed method includes a reference block in the guard-interval correlation which increases the identification rate of weak DRM Plus signals and decreases the possibility of false alarm when analog FM is received. The performance of the proposed method is verified through simulations.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.65 no.2
• /
• pp.329-334
• /
• 2016

In this paper, we demonstrate a Non-Foster matching method for an electrically small antenna to improve the signal-to-noise ratio (SNR) of communication link. For the experiment, we used a general FM antenna whose resonance frequency is about 52-57 MHz and a floating type Linvill negative impedance converter(NIC)-based circuit as a Non-Foster matching element. By implementing the Non-Foster circuit to cover FM band, we can achieve a wide bandwidth matching covers 40-200 MHz. Our measurement shows 3-7 dB improvement of SNR for the same bandwidth though there are several spikes which means no improvement of SNR in the band.

• Journal of the Korean Institute of Navigation
• /
• v.19 no.2
• /
• pp.115-120
• /
• 1995

Recently, the ship automation technology(SAT) has received great attention for the efficient management of the ship with minimum human efforts. Among the SAT, a distance measuring system, the key element is the signal processing unit for the interpretion of the received signal from the remote sensing of the oil tank. In this paper, the tank monitoring system using FM-CW is described for the oil tank level guage measurement with an emphsis of signal processing unit.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.28 no.10
• /
• pp.769-778
• /
• 2017

In this paper, a self-interference signal cancellation(SIC) circult for In-band Full-Duplex has been developed and tested in RF/analog region. By use of this SIC circuit, a FM two-way radio has been developed working at FRS(Family Radio Service) band. The two-way radio device is transmitting the FM modulated signal and demodulating the wanted FM signal at the same time. A circulator is used to enable a single antenna to transmit and receive simuultaenously. The receiver circuit needs to cancel out the self-interference signal due to the transmit signal. A vector modulator(VM) is used to control the phase and magnitude of the esitmated signal. And in-phase and quadrature correlators are used to figure out the optimal coefficients of the VM to remove the self-interference signal according to the change of channel environment. In this work, SA58646 has been used as the FM transceiver, and the system is tested with a frequency of 465 MHz and a bandwidth of 12.5 kHz FM signal. The output power is 17.2 dBm at the antenna port, and the self intererence signal level is measured -49.2 dBm at the receiver end. Therefore the SIC level is measured by 66.4 dB.

• IEIE Transactions on Smart Processing and Computing
• /
• v.3 no.6
• /
• pp.372-381
• /
• 2014

This study examined a radar signal active cancelation technique, which is a theoretical way of achieving stealth by employing a baseband process that involves sampling the incoming hostile radar signal, analyzing its characteristics, and generating countermeasure signals to cancel out the linear-FM signal of the hostile radar signal reflected from the airborne target. To successfully perform an active cancelation, the effects of errors in the countermeasure signal were first analyzed. To generate the countermeasure signal that requires very fast and accurate processing, the down-sampling technique with the suboptimal maximum likelihood estimation (sMLE) scheme was proposed to improve the speed of the estimation process while preserving the estimation accuracy. The simulation results showed that the proposed down-sampling technique using a 2048 FFT size yields substantial power reduction despite its small FFT size and exhibits similar performance to the sMLE scheme using the 32768 FFT size.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.35 no.11A
• /
• pp.1059-1065
• /
• 2010

Recently, analog broadcasting are being converted into digital radio broadcasts, Among the various ways that HD Radio is a candidate for the U.S. approach, Digital Radio will transmit a digital signal to existing analog FM/AM. It provides clear sound quality, traffic information, weather information and various value-added services. In addition, the converted digital radio will be able to meet demand to growing demand for analog FM. In this paper, Digital FM Radio system in the same frequency band using electric field strength of the received digital radio broadcasting interference effects were analyzed. And Digital FM Radio Receiver interference effects were analyzed by interference signal power and signal power. Results were confirmed by applying equation at minimum field strength and SNR.

• Korean Journal of Environment and Ecology
• /
• v.23 no.6
• /
• pp.553-563
• /
• 2009

This study was conducted to analyze the changes in the echolocation of Pipistrellus abramus according to environmental characteristics. The survey was conducted in the day-roosting site of P. abramus located in Gyeongju City (North Gyeongsang Province) from April to August, 2009. The environmental characteristics during the research were classified in six categories: the emergence time after sunset moving time from day roost to feeding areas; rice fields; forest edges; open spaces; and residential areas. Analysis results showed that there are differences in environmental characteristics and also differences between the moving time to the habitat and the moving time to capture preys. At the emergence time from day roost, Pipistrellus abramus used a FM signal with a short pulse-duration. In open spaces, however, they used a CF signal with a long pulse-duration. In different environmental situations, they used both FM and CF signals, although the types of pulse which they used were different. Except pulse-duration, there were significant differences in pulse-interval, peak-frequency, starting-frequency and ending-frequency between the movement among habitats and the movement to capture preys. Except the emergence time from day-roost, they showed a narrow band FM signal and a long pulse-duration that are suitable to search for insects by sensing echoes of insects when they moved among their habitats. When they were out to capture their preys, they showed a broad band FM signal and a short pulse-duration which enabled them to widely search and accurately locate their preys.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.10 no.10
• /
• pp.1183-1188
• /
• 2015

The FM-QCSK(: Frequency Modulated Quadrature Chaos Shift Keying) system is one of the most efficient systems in chaotic literature. One of the problems in this system is that half the bit duration is used for sending a chaotic reference signal which leads to increase the energy losses and reduces the data rate. In this paper, a novel scheme to enhance the performance of FM-QCSK system has been proposed. With the proposed scheme, FM-QCSK would be able to operate at higher data rates with reduced BER(: Bit Error Rate) and energy consumption. The basic modification introduced by the proposed scheme is the use one reference chaotic signal to transmit multi information signals in both in-phase and quadrature-phase channels. The results showed that the proposed scheme have achieved more than 3 dB gains in SNR for AWGN channels respectively at $BER=10^{-3}$ over the conventional one. The results also showed that the optimum number information signals can be send per reference signal is 8.