• Journal of Sensor Science and Technology
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• v.24 no.4
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• pp.232-238
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• 2015

In this paper, we introduce a passive transponder in which an LED is used for both a light transmitter and a receiver, and a solar cell is used for supplying power to the all devices in the transponder. The LED in the transponder operates as a photodetector in the receiving mode, and acts as a light source in the transmitting mode. The current responsivity of the LED detector was measured to be in the order of $10^{-4}A/W$, and the receiving bandwidth with a load resistance of $10k{\Omega}$ was about 10 to 30 kHz. Using the LED for an optical transceiver in a VLID transponder, the detection range was about 70 cm when the transponder was illuminated by the visible light from a $3{\times}3$ LED array in a reader.

• Proceedings of the IEEK Conference
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• 2001.06a
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• pp.305-308
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• 2001

In this paper, we realized a transceiver system for short distance communication with a commercial RF module working in ISM band and a microprocessor. Also we measured system performance by transmitting baseband data in a building and then we compared the demodulated 긴ta bits with stored data bits in a PC connected with demodulator. The RF module in the experiments works oかy in the bandwidth, 424MHz - 429MHz. with FM mode. The signal level degrades as the distance between transmitter and receiver increases we measured the signal level and bit error in the building of engineering college of our university. we present the measured data with various locations in the building. and the data may be used in design short distance network in a building.

• Proceedings of the IEEK Conference
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• 2000.06e
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• pp.187-190
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• 2000

We presents the construction of radio frequency pad area array package modules which operate at radio frequency of 224MHz, and proposes the structure of RF module packages to improve its electrical characteristics. The module of RF PAA package was constructed in the configuration of three dimensional stacked package and reduced size. RF PAA packages showed the optimized and improved gain of 2dB by partitioning the RF transceiver with 3 dimensional stacked PAA packages.

• JSTS:Journal of Semiconductor Technology and Science
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• v.15 no.2
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• pp.194-201
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• 2015

A frequency modulated ultra-wideband (FM-UWB) transmitter with a high-robust relaxation oscillator for subcarrier generation and a dual-path Ring VCO for RF FM is proposed, featuring low power and low complexity. A prototype 3.65-4.25 GHz FM-UWB transceiver employing the presented transmitter is fabricated in $0.18{\mu}m$ CMOS for short-range wireless data transmission. Experimental results show a bit error rate (BER) of $10^{-6}$ at a data rate of 12.5 kb/s with a communication distance of 60 cm is achieved and the power dissipation of 4.3 mW for the proposed transmitter is observed from a 1.8 V supply.

• Proceedings of the Korea Contents Association Conference
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• 2005.11a
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• pp.596-600
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• 2005

In High-speed Portable Internet system to improve performance of whole system, adaptive modulation and coding technology is used, this technology changes modulation and encoding techniques depending on wireless channel environment. Modulation technology that is used in High-speed Portable Internet system is BPSK, QPSK, 16QAMs and 64QAMs. If terminal is distant from base station transceiver system, BPSK or QPSK technology Is used and 16QAMs or 64QAM technology is used if is near in the base station transceiver system. In this paper, number of sub-channel in each modulation technology minimized total transmitting number of PDU is analyzed for efficient radio resources usage. For this, simulation is conducted and the results are presented at High-speed Portable Internet system environments.

• Journal of Satellite, Information and Communications
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• v.8 no.1
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• pp.71-76
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• 2013

In this paper, a transceiver of VLC (Visible Light Communication) using LED white lighting has been implemented. The transmitted waveforms of LED and PD (Photo Diode) of the received signal are analyze to restore VLC data. Audio signal was successfully transmitted to demonstrate possibility and potential of optical wireless communication systems. Various modulation formats are considered to evaluate and compare performance in diverse channel conditions.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.2
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• pp.787-806
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• 2016

Traditional radio-based gesture recognition approaches usually require the target to carry a device (e.g., an EMG sensor or an accelerometer sensor). However, such requirement cannot be satisfied in many applications. For example, in smart home, users want to control the light on/off by some specific hand gesture, without finding and pressing the button especially in dark area. They will not carry any device in this scenario. To overcome this drawback, in this paper, we propose three algorithms able to recognize the target gesture (mainly the human hand gesture) without carrying any device, based on just Radio Signal Strength Indicator (RSSI). Our platform utilizes only 6 telosB sensor nodes with a very easy deployment. Experiment results show that the successful recognition radio can reach around 80% in our system.

• Journal of electromagnetic engineering and science
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• v.2 no.2
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• pp.105-111
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• 2002

New high-performance Ka-band waveguide-to-microstrip transitions for millimeter-wave transceiver applications have been developed and characterized. These transitions are probe-type, but the dielectric material completely covers the whole waveguide aperture, thus providing moisture-barrier and robustness in the probe section. The new probe transitions are also designed to be less sensitive to fabrication tolerances. Further performance enhancements have been obtained by placing vias around the waveguide aperture. Also, the resonance phenomena associated with waveguide wall-penetration have been identified. The developed probe transitions provide insertion loss less than 0.4 dB over entire Ka-band frequencies, but can be optimized for narrowband applications with insertion loss less than 0.2 dB.

• The Journal of the Acoustical Society of Korea
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• v.24 no.3E
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• pp.109-114
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• 2005

In this paper, we present a phase coherent all-digital transceiver for underwater acoustic communication, which allows the system to reduce complexity and increase robustness in time variant underwater environments. It is designed in the digital domain except for transducers and amplifiers and implemented by using a multiple digital signal processors (DSPs) system. For phase coherent reception, conventional systems employed phase-locked loop (PLL) and delay-locked loop (DLL) for synchronization, but this paper suggests a frame synchronization scheme based on the quadrature receiver structure without using phase information. We show experimental results in the underwater anechoic basin at MOERI. The results show that the adaptive equalizer compensates frame synchronization error and the correction capability is dependent on the length of equalizer.

• ETRI Journal
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• v.19 no.3
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• pp.116-140
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• 1997

The base station transceiver subsystem (BTS) of the CDMA Mobile System is interfaced to mobile stations over the air and to the wired network through a packet switched interconnection network. The potential benefits of CDMA technology are achieved when the transmitter and the receiver are properly designed and implemented. The physical layer of the interface at the base station is implemented with the CDMA ASICs and control circuits in channel card of the BTS. We present the design perspectives and structural illustration of the BTS. Base station modem ASICs and their control to implement the CDMA receiver, Baseband and RF signal processing blocks, and BTS controller are described. Elaborate power control is essential to ensure the high capacity which is one of advantages of the CDMA technology. The closed loop reverse link power control and the forward link power control operated in the BTS are described.