In direct sequence spread spectrum communication both for satelliteto-ground and inter-satellite links, the system constrains due to radio frequency spectral occupation, channel data throughput and link performances i...In direct sequence spread spectrum communication both for satelliteto-ground and inter-satellite links, the system constrains due to radio frequency spectral occupation, channel data throughput and link performances in terms of data channel coding which might result in a signal structure where the symbol duration is shorter than the pseudo code period. This can generate some difficulties in the DSSS signal acquisition due to the polarity inversion caused by the data modulation. To eliminate the influence due to polarity inversion, this paper proposes a novel acquisition algorithm based on the simultaneous search of the code phase, data phase and Doppler frequency. In the proposed algorithm the data phase is predicted and the correlation period for the coherent integration can be set equal to the symbol duration. Then non-coherent accumulation over different symbol is implemented in order to enhance the acquisition algorithm sensitivity; the interval of non-coherent accumulation is the least common multiple between the symbol duration and the pseudo code period. The algorithm proposed can largely minimize the SNR loss caused by data polarity inversion and enhance acquisition performance without a noticeable increase in hardware complexity. Theoretical analysis, simulation and measured results verify the validity of the algorithm.展开更多
Energy transfer and electron transfer are both fundamental mechanisms enabling numerous functional materials and applications.While most materials systems employ either energy transfer or electron transfer,the combine...Energy transfer and electron transfer are both fundamental mechanisms enabling numerous functional materials and applications.While most materials systems employ either energy transfer or electron transfer,the combined effect of energy and electron transfer processes in a single donor/acceptor system remains largely unexplored.Herein,we demonstrated the energy transfer followed by electron transfer(ETET)process in a molecular dyad TPE-NBD.Due to energy transfer,the fluorescence of TPE-NBD was greatly enhanced in non-polar solvents.In contrast,polar solvents activated subsequent electron transfer and markedly quenched the emission of TPE-NBD.Consequently,ETET endows TPE-NBD with significant polarity sensitivities.We expect that employing ETET could generate many functional materials with unprecedented properties,i.e.,for single laser powered multicolor fluorescence imaging and sensing.展开更多
基金the support of the National High Technology Research and Development Program of China (863) (Grant No. 2012AA1406)
文摘In direct sequence spread spectrum communication both for satelliteto-ground and inter-satellite links, the system constrains due to radio frequency spectral occupation, channel data throughput and link performances in terms of data channel coding which might result in a signal structure where the symbol duration is shorter than the pseudo code period. This can generate some difficulties in the DSSS signal acquisition due to the polarity inversion caused by the data modulation. To eliminate the influence due to polarity inversion, this paper proposes a novel acquisition algorithm based on the simultaneous search of the code phase, data phase and Doppler frequency. In the proposed algorithm the data phase is predicted and the correlation period for the coherent integration can be set equal to the symbol duration. Then non-coherent accumulation over different symbol is implemented in order to enhance the acquisition algorithm sensitivity; the interval of non-coherent accumulation is the least common multiple between the symbol duration and the pseudo code period. The algorithm proposed can largely minimize the SNR loss caused by data polarity inversion and enhance acquisition performance without a noticeable increase in hardware complexity. Theoretical analysis, simulation and measured results verify the validity of the algorithm.
基金supported by Singapore University of Technology and Design(No.T1SRCI17126)A*STAR under its Advanced Manufacturing and Engineering Program(No.A2083c0051)+1 种基金the National Natural Science Foundation of China(Nos.21878286,21908216)Dalian Institute of Chemical Physics(Nos.DMTO201603,TMSR201601)。
文摘Energy transfer and electron transfer are both fundamental mechanisms enabling numerous functional materials and applications.While most materials systems employ either energy transfer or electron transfer,the combined effect of energy and electron transfer processes in a single donor/acceptor system remains largely unexplored.Herein,we demonstrated the energy transfer followed by electron transfer(ETET)process in a molecular dyad TPE-NBD.Due to energy transfer,the fluorescence of TPE-NBD was greatly enhanced in non-polar solvents.In contrast,polar solvents activated subsequent electron transfer and markedly quenched the emission of TPE-NBD.Consequently,ETET endows TPE-NBD with significant polarity sensitivities.We expect that employing ETET could generate many functional materials with unprecedented properties,i.e.,for single laser powered multicolor fluorescence imaging and sensing.
