Electronics and Telecommunications Research Institute

Joon-Gyu Ryu

Deock-Gil Oh

Ho-Jin Lee

Dae-Ig Chang

Hoon Jeong

Ho-Kyom Kim

Minsu Shin

Il-Han Kim

A phase locked loop includes: a loop filter; a voltage controlled oscillating unit configured to output a frequency varying according to an output voltage of the loop filter; a frequency down-converting unit configured to down-convert an output frequency of the voltage controlled oscillating unit according to a band of the output frequency of the voltage controlled oscillating unit; and a frequency divider configured to divide a frequency down-converted by the frequency down-converting unit. The output frequency of the voltage controlled oscillating unit varies according to the output voltage of the loop filter and a control signal compensating the frequency down-converted by the frequency down-converting unit.

Phase locked loop and satellite communication terminal using the same

Provided are a forward link rain attenuation compensating apparatus using an adaptive transmission scheme in an interactive satellite communication system and a method thereof. The apparatus separates the mobile stations into clear-sky mobile stations and mobile stations in the state of rain attenuation and makes the clear-sky mobile stations receive data having a high data transmission efficiency at a high-speed while making the rain attenuation mobile stations receive the data continuously although the data transmit rate is low by making each of the two kinds of mobile stations receive data frames of a different transmission method, and provides a method therefor. The apparatus includes: a resource manager, a transmitting data format converter, a forward modulator, a backward demodulator, a receiving data format converter.

Apparatus and method for compensating forward link rain attenuation based on adaptive transmission scheme for interactive satellite transmission system

Provided are an apparatus and method for robust Binary Phase Shift Keying/Quadrature Phase Shift Keying (BPSK/QPSK) blind modulation classification. The apparatus includes first and second likelihood value calculators for calculating a likelihood value of a received baseband signal each for of BPSK and QPSK modulation modes. A maximum setting unit derives a maximum value of the likelihood values or ilikelihood ratios calculated by the first and second likelihood value calculators. A flag is set for the maximum value to '1' and a flag for the remaining value is set to '0'. First and second flag combining units combine the flags for the modulation modes. A modulation mode flag setting unit selects a maximum value from the flags combined by the first and second flag combining units.

Apparatus and method for robust BPSK/QPSK blind modulation classification against errors in satellite control system

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Daejon, South Korea

Joon-Gyu Ryu