摘要:
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.
摘要:
Provided are a method and apparatus for measuring a time delay in an envelope elimination and restoration (EER) transmitter. A method of measuring a time delay in an EER transmitter includes receiving a modulated sinusoidal signal and distributing the modulated sinusoidal signal to be transmitted through transmission lines separated from each other, extracting an amplitude modulation signal and a phase modulation signal from the modulated sinusoidal signal, and detecting envelops of the amplitude and phase modulation signals and determining a difference in time between the amplitude and phase modulation signals. In the EER transmitter, to measure a time delay between input and output signals, time delays of paths of amplitude and phase modulation signals of the input signal are compared, thereby determining a difference in time between the amplitude and phase modulation signals.
摘要:
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.
摘要:
Provided is a frequency error estimating method of a communication system. The method includes receiving a frame, and calculating a frequency error from a SOF field of the received frame.
摘要:
Provided are a 3-port orthogonal mode transducer, and a receiver and receiving method using the same. The 3-port orthogonal mode transducer includes: a transmission port having a rectangular shape elongated in a horizontal direction and configured to transmit a Ka-band (30 GHz) vertical polarization signal; a first reception port having a rectangular shape inclined at about +45 degrees at a location being at about +45 degrees with respect to the transmission port and configured to receive a K-band (20 GHz) vertical or horizontal polarization signal phased-delayed about +45 degrees; and a second reception port having a rectangular shape inclined at about −45 degrees at a location being at about −45 degrees with respect to the transmission port and configured to receive a K-band (20 GHz) vertical or horizontal polarization signal phase-delayed about −45 degrees.
摘要:
Provided are an adaptive coding modulation (ACM)-based simulcast transmission and reception apparatus and method. The apparatus includes a transmitter configured to analyze whether or not it is raining in a region where a receiver is present on the basis of channel state information (CSI) provided by the receiver, encode and/or modulate an image signal according to the analysis result, and provide the encoded and/or modulated image signal through a single band or multiple bands. On the basis of a result of analyzing whether or not it is raining in a region where a receiver is present, it is possible to effectively prevent signal attenuation caused by rain by providing image signals having different resolutions through multiple bands when the region is in a rainfall state.
摘要:
Provided are an apparatus and method for robust Binary Phase Shift Keying/Quadrature Phase Shift Keying (BPSK/QPSK) blind modulation classification against errors in a satellite communication system. 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, respectively, a maximum setting unit for deriving a maximum value of the likelihood values or ith likelihood ratios calculated by the first and second likelihood value calculators and setting a flag for the maximum value to “1” and a flag for the remaining value to “0”, first and second flag combining units for combining the flags for the modulation modes, respectively, a modulation mode flag setting unit for selecting a maximum value from the flags combined by the first and second flag combining units, and a modulation classification mode deciding unit.
摘要:
A center district network synchronization acquisition apparatus and method capable of accommodating both a GPS mode based terminal and an NCR mode based terminal. The center district network synchronization acquisition apparatus for a satellite communication system according to an exemplary embodiment includes: a timing generating unit configured to generate an interrupt signal by being synchronized with a PPS (pulse per second) signal received from a reference clock generation module, an NCR counter configured to extract a corresponding NCR (network clock reference) value at a timing indicated by the interrupt signal, and a packet generating unit configured to generate an MPEG2-TS packet including the NCR value extracted according to the interrupt signal. Therefore, this apparatus can accommodate both a GPS mode based terminal and an NCR mode based terminal. As a result, the satellite communication system can operate regardless of the network synchronization mode performed by the terminal.
摘要:
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.
摘要:
Provided are an adaptive coding modulation (ACM)-based simulcast transmission and reception apparatus and method. The apparatus includes a transmitter configured to analyze whether or not it is raining in a region where a receiver is present on the basis of channel state information (CSI) provided by the receiver, encode and/or modulate an image signal according to the analysis result, and provide the encoded and/or modulated image signal through a single band or multiple bands. On the basis of a result of analyzing whether or not it is raining in a region where a receiver is present, it is possible to effectively prevent signal attenuation caused by rain by providing image signals having different resolutions through multiple bands when the region is in a rainfall state.