Abstract:
The present invention relates to an apparatus and a method of transmitting and receiving based on a DVB-S2 standard which is operational in an environment of a low signal-to-noise ratio. The present invention comprises: a transmitter of the DVB-S2 standard base; a mapping unit to determine a bit mapping based on at least one among the area to be applied and the state of transmission channel; and a physical layer frame iteration unit repeating a physical layer frame where a physical layer header is inserted as a spreading factor.
Abstract:
입력된 통신방송 융합(triple play) IP 데이터를 인터넷 및 TV 데이터와 음성(VoIP) 데이터로 나누어, 긴 지연시간을 허용하는 인터넷 및 TV 데이터는 기존의 DVB-S2 규격으로 부호화하고, 짧은 지연시간만을 허용하는 음성 데이터는 DVB-RCS +M 규격 기반의 4K 모드로 부호화한다. 부호화된 데이터는 각각 직교 변조되고, 직교 변조된 음성 데이터는 확산 계수(spreading factor)에 따라 직접수열 기반으로 대역 확산된다. 대역 확산된 신호는 SCPC(FDMA: frequency division multiple access) 형태로 각 사용자별로 할당된 주파수와 중첩되도록 다중화된다.
Abstract:
PURPOSE: A frame synchronization apparatus in a satellite communication system and method thereof are provided to calculate a correlation between an input signal for synchronizing a frame at a reception end of a satellite communication system and a signal sequence of the reception end without using a multiplier factor. CONSTITUTION: A correlation unit(110) acquires a correlation value between the unique word of a receiver and a symbol data string of a frame received from a transmission end of a satellite communication system. A comparison unit(130) compares the correlation values and the pre-established threshold values. A determination unit(150) determines whether the frame is synchronized according to a comparison result of the comparison unit.
Abstract:
PURPOSE: A method for demodulating signals in a return link of a satellite system and a demodulating apparatus thereof and a method for modulating signals in the return link and a modulating apparatus thereof are provided to check a symbol of a burst signal in a reception terminal by modulating the burst signal in a transmission terminal of a return link in a satellite system. CONSTITUTION: The symbol timing of burst, which is received through a return link of a satellite system, is estimated. The estimated symbol timing of the received burst is synchronized by reference symbol timing(110). An Oerder & Myer algorithm of a non data-aided method is used to estimate a symbol timing error. A location of timing synchronous burst is synchronized to a reference burst location(150) by using a preamble symbol and a postamble symbol of the timing synchronous burst synchronized by symbol timing(130). A carrier wave of the location synchronous burst is recovered by using a pilot symbol of the location synchronous burst synchronized to the reference burst location.
Abstract:
위성 방송 프레임 신호를 복조하는 방법이 개시된다. 본 발명에 따른 DVB-S2(Digital Video Broadcasting - via Satellite, Second Generation) 규격의 위성 방송 프레임 신호를 복조하는 복조기의 복조 방법은, 심볼 타이밍을 동기화하는 단계; 심볼 타이밍 동기 후 프레임을 동기화하는 단계; 프레임 동기화 후 반송파를 복원하는 단계; 및 반송파 복원 완료 후 모드코드(MODCOD) 정보를 복호하여 프레임 구성 정보를 획득하는 단계;를 포함한다. 이에 의해 고속 복조 및 복조 데이터의 신뢰성이 확보된다.
Abstract:
PURPOSE: A method and an apparatus for transmitting/receiving data by using a satellite channel are provided to use low cost analog device in a terminal by providing excellent transmission performance under a weak communication environment. CONSTITUTION: When receiving bit data, the encoding unit performs channel encoding through an e-BCH(extend BCH) code. An interleaver(103) interleaves the encoded data through the encoding unit. A modulation unit(105) modulates interleaved data through a CPM(Continuous Phase Modulation) method which use 4 symbols, and a transmission unit(107) transmits the modulated data to a primary center.
Abstract:
PURPOSE: A correlation apparatus for the strong synchronous acquisition and method uses the distance value about the receiving symbol. The frequency error can be over gotten. CONSTITUTION: The receiving symbol phase difference calculation unit(201) obtains the receiving symbol phase difference between the delay receiving symbol delaying the receiving symbol and the receiving symbol. The correlation symbol phase difference calculation unit(203) obtains the correlation symbol phase difference between the lag correlation symbol delaying the correlation symbol and the correlation symbol. The gradation correlator(205) uses the receiving symbol phase difference and correlation symbol phase difference.
Abstract:
An apparatus and a method for selecting a correlation mode based on a frequency error of a carrier are provided to obtain initial synchronization by selecting the correlation mode according to the corresponding region after calculating a frequency error boundary point between correlation modes. Non-detection probability values are calculated according to a frequency offset normalized in each correlation method(201). A point meeting graphs of non-detection probability values is determined to a frequency error boundary point(202). A correlation mode is selected based on the determined frequency error boundary point(203).