在数字通信中,载波恢复电路是非常重要的电路环节,而其中的平方环变换以其电路的简单受到了广泛的使用。为了进一步简化该电路结构,提出了一种改进的平方环电路,这种改进的平方环省去了2分频电路,同时在文章中作者进一步改进了这个电路...在数字通信中,载波恢复电路是非常重要的电路环节,而其中的平方环变换以其电路的简单受到了广泛的使用。为了进一步简化该电路结构,提出了一种改进的平方环电路,这种改进的平方环省去了2分频电路,同时在文章中作者进一步改进了这个电路,将其中的多个乘法器用CORDIC算法来实现,该算法仅使用移位运算与加法器,便于流水线结构实现,降低了电路的复杂特性。最后,将该改进的电路联合ISE14.7和Modelsim10.1a进行仿真,恢复出了输入信噪比分别为6 d B和80 d B下的载波信号,验证了该电路的可行性。展开更多
载波时延整周模糊解算是目前连线干涉测量(connected elements interferometry,CEI)中的瓶颈问题。针对扩频信号、数传信号等常见的航天器信号类型,提出了基于宽带信号相关处理的连线干涉测量方案。该方案首先通过对宽带信号进行相关处...载波时延整周模糊解算是目前连线干涉测量(connected elements interferometry,CEI)中的瓶颈问题。针对扩频信号、数传信号等常见的航天器信号类型,提出了基于宽带信号相关处理的连线干涉测量方案。该方案首先通过对宽带信号进行相关处理得到群时延信息;然后再进行载波提取得到载波差分相位信息;最后以群时延进行载波时延整周模糊解算,实现CEI测量。理论分析和仿真结果表明了所提方案的正确性,并对嫦娥二号宽带数据进行处理,得到了载波时延估计,精度较群时延提高了24dB。展开更多
The development of photovoltaic devices, solar cells, plays a key role in renewable energy sources. Semiconductor colloidal quantum dots （CQDs）, including lead chacolgenide CQDs that have tunable electronic bandgaps...The development of photovoltaic devices, solar cells, plays a key role in renewable energy sources. Semiconductor colloidal quantum dots （CQDs）, including lead chacolgenide CQDs that have tunable electronic bandgaps from infrared to visible, serve as good candidates to harvest the broad spectrum of sunlight. CQDs can be processed from solution, allowing them to be deposited in a roll-to-roll printing process compatible with low-cost fabrication of large area solar panels. Enhanced multiexciton generation process in CQD, compared with bulk semiconductors, enables the potential of exceeding Shockley-Queisser limit in CQD photovoltaics. For these advantages, CQDs photovoltaics attract great attention in academics, and extensive research works accelerate the development of CQD based solar cells. The record efficiency of CQD solar cells increased from 5.1% in 2011 to 9.9% in 2015. The improvement relies on optimized material processing, device architecture and various efforts to improve carrier collection efficiency. In this review, we have summarized the progress of CQD photovoltaics in year 2012 and after. Here we focused on the theoretical and experimental works that improve the understanding of the device physics in CQD solar cells, which may guide the development of CQD photovoltaics within the research community.展开更多
文摘在数字通信中,载波恢复电路是非常重要的电路环节,而其中的平方环变换以其电路的简单受到了广泛的使用。为了进一步简化该电路结构,提出了一种改进的平方环电路,这种改进的平方环省去了2分频电路,同时在文章中作者进一步改进了这个电路,将其中的多个乘法器用CORDIC算法来实现,该算法仅使用移位运算与加法器,便于流水线结构实现,降低了电路的复杂特性。最后,将该改进的电路联合ISE14.7和Modelsim10.1a进行仿真,恢复出了输入信噪比分别为6 d B和80 d B下的载波信号,验证了该电路的可行性。
文摘载波时延整周模糊解算是目前连线干涉测量(connected elements interferometry,CEI)中的瓶颈问题。针对扩频信号、数传信号等常见的航天器信号类型,提出了基于宽带信号相关处理的连线干涉测量方案。该方案首先通过对宽带信号进行相关处理得到群时延信息;然后再进行载波提取得到载波差分相位信息;最后以群时延进行载波时延整周模糊解算,实现CEI测量。理论分析和仿真结果表明了所提方案的正确性,并对嫦娥二号宽带数据进行处理,得到了载波时延估计,精度较群时延提高了24dB。
文摘The development of photovoltaic devices, solar cells, plays a key role in renewable energy sources. Semiconductor colloidal quantum dots （CQDs）, including lead chacolgenide CQDs that have tunable electronic bandgaps from infrared to visible, serve as good candidates to harvest the broad spectrum of sunlight. CQDs can be processed from solution, allowing them to be deposited in a roll-to-roll printing process compatible with low-cost fabrication of large area solar panels. Enhanced multiexciton generation process in CQD, compared with bulk semiconductors, enables the potential of exceeding Shockley-Queisser limit in CQD photovoltaics. For these advantages, CQDs photovoltaics attract great attention in academics, and extensive research works accelerate the development of CQD based solar cells. The record efficiency of CQD solar cells increased from 5.1% in 2011 to 9.9% in 2015. The improvement relies on optimized material processing, device architecture and various efforts to improve carrier collection efficiency. In this review, we have summarized the progress of CQD photovoltaics in year 2012 and after. Here we focused on the theoretical and experimental works that improve the understanding of the device physics in CQD solar cells, which may guide the development of CQD photovoltaics within the research community.
