Research On M-ary Position & Three-valued VMAP Technology In The Uplink Channel Of HFC

With increasingly remote sensing satellite business,the spatial resolution increases continually,all-weather requirements are also in ascension.The bigger the transmission of information is,the existing satellite data transmission puts forward the bigger challenge.At present,the bandwidth of x-band to ground stipulated by ITU is only 375MHz,and that of Ka-band to ground reaches 1.5GHz,which is difficult to meet the mass data transmission requirements of high-resolution remote sensing satellites in the future.In the case of limited bandwidth on the satellite,it is urgent to study the modulation mode with high spectral efficiency to improve the capability of satellite data transmission to the earth.In order to meet the urgent application needs of high speed satellite data transmission and spacecraft communication in the future.In this paper,the discontinuous phase EBPSK modulation and continuous phase very-minimum amplitude Phase VMAP modulation signal power spectrum characteristic carried on the thorough research and analysis,The specific work is as follows.1)Introduced the phase discontinuous EBPSK modulation mode,and four kinds of continuous phase modulation modes:CP-EBPSK,random polarity CP-EBPSK modulation,random polarity MCP-EBPSK and random polarity very small amplitude phase modulation.The power spectrum characteristics of various modulation modes were simulated and analyzed.2)The frequency spectrum efficiency and demodulation performance of EBPSK and BPSK were compared.Aiming at the requirement of EBPSK modulation applied in satellite high-speed communication,simulation analysis shows that the passband bandwidth and sidelobe attenuation of the shaping filter at the transmitting terminal have great influence on demodulation performance.The anti-jamming characteristics of EBPSK were discussed.3)The m-ary position 3-valued VMAP modulation is elaborated,its modulator block diagram is given,its theoretical power spectrum expression is deduced,the influence of modulation parameters on its power spectrum characteristics is simulated and analyzed,the"notch-frequency selection" characteristic of digital impulse filter is introduced,the demodulation method of multi-classifier based on BP neural network and support vector machine is designed,and the demodulation performance of different demodulation methods are simulated and compared.It is concluded that the multi-class demodulator based on support vector machine has the best demodulation performance.4)In order to meet the requirement of multi-position 3-value VMAP modulation applied for wire transmission in satellite cabin,LDPC information channel coding and decoding are introduced.The transmission performance of multi-position 3-value VMAP coded by LDPC in HFC up channel is simulated and analyzed.Through simulation,it can be seen that the transmission performance can be improved by constructing regular LDPC codes,and the coding gain of about 4dB can be obtained by using hard decision decoding.