Young-Wan Kim

A new active phased array antenna for mobile direct broadcasting satellite reception

This paper represents a new active phase array antenna for a Ku-band mobile service that will be possible with satellite broadcasting. The main idea for the antenna is to use minimum active array elements with cost-effective one-dimensional subarrays with an inclined pencil beam structure for a 34 dBi gain. For this antenna, we also used the squint beam tracking algorithm. This tracking gives a different way to the traditional monopulse tracking method in tracking capability. The electronic scanning angle of the beam peak in this antenna is over /spl plusmn/12/spl deg/ wide only with 20 phase shifter elements for its scan ranges. This antenna with the attractive hybrid-tracking concept has about 142 times less array elements than antennas with a two-dimensional array.

Improvement of microstrip open loop resonator filter using aperture

Apertures has been employed on the ground plane in the open loop resonator filter. The bandwidth has been widen maximally 40% and the passband ripple has been flatten compared with the conventional open loop resonator filter. The coupling spacing between loops has been widened to easily implement filter.

Performance analysis of channel impairment in high data rate satellite communication service

This paper presents a performance analysis for channel impairments that affect the service quality of a high data rate satellite communication system. Based on the modeling of group delay and nonlinear characteristics that severely affect the service quality, the system performances are analyzed for various data rate services via the Ka-band satellite channel. As the transmission data rate is increased, the degradations due to these channel impairments increase. The linear component of the group delay and the AM-AM component of the nonlinear characteristics severely affect the system performance.

Phase Noise Allocation For Digital Satellite Broadcasting System

This paper presents the phase noise allocation for the digital satellite broadcasting system adopting the QPSK coherent demodulation scheme. The phase noise requirement for the local oscillator of the Korean digital DBS system is 23.7 dB (0.2 dB impairment). To meet this requirement, the local oscillator SNR of the receiver terminal should be 24.12 dB, and 34.12 dB for the transmitter terminal. These phase noise characteristics are applicable to the design of the digital satellite broadcasting system as requirements of the system phase noise.

Circuit design and performance analysis of carrier recovery loop for digital DBS system in the presence of phase noise

The theoretical analysis of a digital satellite broadcasting system in the presence of phase noise is performed. An effective technique to design the carrier recovery circuit is also presented based on the analyzed loop parameters, such as degradation loss due to phase noise, average time to cycle slip, and carrier signal acquisition time. It is possible to design a system providing the optimal service and satisfying service requirements for a digital satellite broadcasting system. In this paper, the carrier recovery loop that provides optimal performance in the presence of phase noise exhibits the parameters of 0.707 for damping factor and 40 kHz for noise bandwidth. The designed phase-locked loop indicates a performance of 0.26 dB for impairment due to phase noise at 10/sup -3/ BER, 3.88/spl times/10/sup 6/ hours for average time to cycle slip, and 34 msec for carrier signal acquisition time. The carrier acquisition time of the designed carrier recovery circuit is in accordance with the analyzed result.

On the blind decision of modulation type in impaired AWGN channel environment

We propose a new modulation classification method that utilizes likelihood function of received signal in an impaired AWGN (Additive White Gaussian Noise) channel environment. The proposed method utilizes the likelihood under the assumption that each modulated signal is sent, but the direct use of the ML (Maximum Likelihood) method is not considered for high computational complexity and weakness to channel impairment such as phase offsets and frequency offsets. The proposed method has lower computational complexity than does the ML method. Moreover, the proposed method is robust to the channel impairment such as phase offsets and frequency offsets. The correct classification probabilities of the proposed method and the ML method are given for an AWGN channel with phase offsets and frequency offsets, which are simulated with extensive Monte-Carlo simulation. As shown in simulation results, a more accurate classification performance both in phase offset environment and in frequency offset environment can be achieved with the low computational complexity of the proposed method. Log-Likelihood Ratio) test, this method is the approximation at a low SNR and it is hard to get a threshold value for general QAM modulation. In this paper, we propose a low complexity digital modu- lation classification method based on the likelihood function of the received signal in an AWGN (Additive White Gaussian Noise) channel environment with phase offsets and frequency offsets. The proposed method is similar to the ML method (2), (3) in the sense that it utilizes the likelihood function of the received signal, but it has lower computational complexity than the ML method and it is less sensitive to phase offsets and frequency offsets than the ML method. This paper is organized as follows. In Section II, we give the signal model used in this paper. This section also gives a previous modulation classification method with this signal model. Section III provides the new modulation classification method based on the ML method. In Section IV, we give some numerical simulation results and discussion to verify the performance of the proposed method. Section V concludes the paper.

Design and implementation of mobile satellite modulator based on MF-CDMA

In this paper a mobile satellite modulator based on MF-CDMA is designed and fabricated. The mobile satellite modulator can support maximally 384 kbit/s. To support maximum transmission rate of 384 kbit/s we need 3 frequency bands. The baseband I/Q quadrature modulation and Mux is implemented in the digital block. The output of the digital part is a low IF signal, 20/spl plusmn/4.35 MHz. And then the analog block converts this low IF signal to 950/spl sim/1450 MHz by the double conversion method. The mobile satellite modulator includes a 5-bit digital attenuator, RF switch and BPF. We implemented both digital part and analog part in one PCI card. We measured the mobile satellite modulators spurious rejection at about >55dBc and the output signal flatness is <5dB at 950/spl sim/1450 MHz. And the modulator shows good IMD3, -61 dBc.