• Journal of Communications and Networks
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• v.18 no.1
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• pp.27-39
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• 2016

This paper derives and analyzes a novel block fast Fourier transform (FFT) based joint detection algorithm. The paper compares the performance and complexity of the novel block-FFT based joint detector to that of the Cholesky based joint detector and single user detection algorithms. The novel algorithm can operate at chip rate sampling, as well as higher sampling rates. For the performance/complexity analysis, the time division duplex (TDD) mode of a wideband code division multiplex access (WCDMA) is considered. The results indicate that the performance of the fast FFT based joint detector is comparable to that of the Cholesky based joint detector, and much superior to that of single user detection algorithms. On the other hand, the complexity of the fast FFT based joint detector is significantly lower than that of the Cholesky based joint detector and less than that of the single user detection algorithms. For the Cholesky based joint detector, the approximate Cholesky decomposition is applied. Moreover, the novel method can also be applied to any generic multiple-input-multiple-output (MIMO) system.

• The Journal of the Acoustical Society of Korea
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• v.27 no.3
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• pp.149-153
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• 2008

General underwater target detection methods adopt short-time FFT for estimate target doppler. This paper proposes the efficient target detection method, instead of conventional FFT, using approximate FFT for distributed sensor network target detection, which requires lighter computations. In the proposed method, we decrease computational rate of FFT by the quantization of received signal. For validation of the proposed method, experiment result which is applied to FFT based active sonar detector and real oceanic data is presented.

• Journal of the Institute of Convergence Signal Processing
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• v.7 no.4
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• pp.184-188
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• 2006

This paper presents DSP based narrow band satellite communication signal power detector for tracking control of mobile satellite antenna system. An analog filter based conventional power detector has poor performance due to frequency drift of carrier. Also, it is very difficult to change an analog filter bandwidth according to changed bandwidth of transmitted signal. To solve these difficulties, we proposed DSP based signal power detector, which is easy to change bandwidth of filter and to match shifted frequency of carrier. The proposed signal power detector consists of a FFT function to measure frequency drift of carrier, a programmable filter bank function to limit of received signal bandwidth and a power calculation function to measure power of filtered signal in 12-bit linear scale. Test results of implemented signal power detector, based on TMS320C5402 DSP, showed that it satisfied required functions and performances and properly operated.

• Journal of the Semiconductor & Display Technology
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• v.23 no.3
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• pp.39-45
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• 2024

The installation of arc circuit breakers is being strengthened to prevent accidents such as electric shock and fire caused by Arc. Among arcs, serial arcs are difficult to detect with general arc detectors because there is not much change in load current when an arc occurs. Therefore, in this paper, unlike the existing Arc Fault Circuit Interrupters method, arc detection hardware is implemented using the FFT algorithm. FFT is suitable for serial arc identification because it can efficiently analyze high-frequency signals generated outside of normal AC signals. This study explains ARC detection circuits and the 2048-FFT based on radix-2 and radix-4, and presents hardware implementation results using FPGA. The implemented system detects the arc up to the frequency range of 122,880 Hz. Through simulation and FPGA board testing, it was confirmed that ARC was detected.

• Proceedings of the Korea Institutes of Information Security and Cryptology Conference
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• 2001.11a
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• pp.464-468
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• 2001

In this paper, we propose a robust watermarking technique that accepts time scaling, pitch shift, add noise and a lot of lossy compression such as MP3, AAC, WMA. The technique is developed based on digital filtering. Being designed according to critical band of HAS (human auditory system), the digital filters nearly affect audio quality. Furthermore, before implementing digital filtering, wavelet transform decomposes the audio signal into several signals that is composed of specific frequencies. Designed digital filters scan the decomposed signal. The designed digital filter, band-stop filter, distorts and eliminates specific frequencies of audio signals. Watermarking detection can be accomplished by FFT (Fast Fourier Transform). Firstly, segments of audio signal are transformed by FFT. Then, the obtained amplitude spectrum by FFT is summed repeatedly. Finally the watermark detector can find filters used to watermark encoding based on eliminating frequencies. The suggested technique can embed 4bits/s in a robust manner.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.6
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• pp.580-588
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• 2009

A Missile Warning Radar is an essential sensor for active protection system to detect antitank missile in all weather environments. This paper presents the design, development, and test results of L-band pulsed Doppler radar system for main battle tank. This radar system consists of 3 LRUs, which include antenna unit, transmitter and receiver unit and radar signal & data processing unit. The developed core technologies include the patch antenna, SSPA transmitter, coherent I/Q detector, DSP based Doppler FFT filter, adaptive CFAR, SIW tracking capability, and threat decision. The design performance of the developed radar system is verified through various ground fixed and moving vehicle test.

• Proceedings of the KIEE Conference
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• 1995.11a
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• pp.74-76
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• 1995

In this paper, the results of development of arrester leakage current detector using micro computer are described. This detector is based on harmonic analysis of the leakage current by FFT. The change of leakage current is the recognized measure of deterioration. For low sensitivity to disturbance, this device used optical fiber. This will be a great benefit of detecting deterioration ZnO arrester.

• Proceedings of the KIEE Conference
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• 1995.07b
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• pp.631-633
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• 1995

In this paper, the results of development of arrester leakage current detector using micro computer are described. This detector is based on harmonic analysis of the leakage current by FFT. For low sensitivity to disturbance, this device used optical fiber. This will be a great benefit of detecting deterioration ZnO arrester.

• Journal of Advanced Navigation Technology
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• v.10 no.2
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• pp.173-180
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• 2006

An airborne radar is an essential aviation electronic system of the aircraft to perform various missions in all weather environments. This paper presents the design, development, and test results of the multi-mode pulsed Doppler radar system test model for helicopter-borne flight test. This radar system consists of 4 LRU units, which include ANTU(Antenna Unit), TRU(Tx Rx Unit), RSDU(Radar Signal & Data Processing Unit) and DISU(Display Unit). The developed technologies include the TACCAR processor, planar array antenna, TWTA transmitter, coherent I/Q detector, digital pulse compression, DSP based Doppler FFT filtering, adaptive CFAR, IMU, and tracking capability. The design performance of the developed radar system is verified through various helicopter-borne field tests including MTD (Moving Target Detector) capability for the Doppler compensation due to the moving platform motion.

• Journal of the Korean Institute of Intelligent Systems
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• v.9 no.4
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• pp.426-435
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• 1999

A high impedance fault(HIF) is one of the serious problems facing the electric utility industry today. Because of the high impedance of a downed conductor under some conditions these faults are not easily detected by over-current based protection devices and can cause fires and personal hazard. In this paper a new method for detection of HIF which uses adaptive neuro-fuzzy inference system (ANFIS) is proposed. Since arcing fault current shows different changes during high and low voltage portion of conductor voltage waveform we firstly divided one cycle of fault current into equal spanned four data windows according to the mangnitude of conductor voltage. Fast fourier transform(FFT) is applied to each data window and the frequency spectrum of current waveform are chosen asinputs of ANFIS after input selection method is preprocessed. Using staged fault and normal data ANFIS is trained to discriminate between normal and HIF status by hybrid learning algorithm. This algorithm adapted gradient descent and least square method and shows rapid convergence speed and improved convergence error. The proposed method represent good performance when applied to staged fault data and HIFLL(high impedance like load)such as arc-welder.