A new surface acoustic Wave differential quadraphase shift key（SAW DQPSK） spread spectrum （SS） signal matched filter based on the fusion of SS and differential modulation is reported. The design of multi-phase cod...A new surface acoustic Wave differential quadraphase shift key（SAW DQPSK） spread spectrum （SS） signal matched filter based on the fusion of SS and differential modulation is reported. The design of multi-phase coded SAW matched filter is proposed rather than another design of SAW DQPSK filter, which can cut in a half of the delay time of SAW DQPSK matched filter and SAW fixed delay line（FDL） used for differential demodulation. This breakthrough is made the system largely reduce a size and process much easily. This method can also be feasible in other SAW MPSK matched filter design especially when the modulation phase number is larger than 4. The design example and its experimental results are given.展开更多
In this paper , the angular spread of the SAW beam diffracted by Bragg grating , denoted by δθ1 ,is analysed based on the equations of the deflection angle and the deflection effciency . A parameter δθB is defined...In this paper , the angular spread of the SAW beam diffracted by Bragg grating , denoted by δθ1 ,is analysed based on the equations of the deflection angle and the deflection effciency . A parameter δθB is defined to refer to ' Bragg angular spectrum width ' of the grating . The importance of this parameter in distinguishing the angular spread range of the deflected beam for different regimes is discussed as well. It is show from the analysis that if the spread angle of the incident beam labelled with δθinc is larger than the ' Bragg witdth of the angular spectrum ' of the grating , the spread angle δθ1 of the deflected beam will equal to δθB ; but if the angular divergence of the incident beam is less than δθB , then δθ1 =δθinc.Experimentally , four kinds of samples with different configurations are investigated by optical method , two of which operate in the regime of δθinc<<δθB and the others correspond to the case in the regime of δθinc >>δθB . The widths of the angular spread of the incident beam and the deflected beam are estimated by measuring the widths of their own acousto - optical diffraction points . It is demonstrated that the experimental results agree with the theoretical results approximately .展开更多
基金National High Technology Research and Development Programof China(2002AA325040)
文摘A new surface acoustic Wave differential quadraphase shift key（SAW DQPSK） spread spectrum （SS） signal matched filter based on the fusion of SS and differential modulation is reported. The design of multi-phase coded SAW matched filter is proposed rather than another design of SAW DQPSK filter, which can cut in a half of the delay time of SAW DQPSK matched filter and SAW fixed delay line（FDL） used for differential demodulation. This breakthrough is made the system largely reduce a size and process much easily. This method can also be feasible in other SAW MPSK matched filter design especially when the modulation phase number is larger than 4. The design example and its experimental results are given.
文摘扩频技术是一种新型的通信体制,是通信领域和控制领域中的一个重要的发展方向.在扩展频谱通信系统中,常用SAW抽头延迟线来实现扩频序列的捕捉,利用SAW抽头延迟线可以生成被扩频序列调制的中频BPSK信号.由于SAW器件具有频率选择性及较高的插入损耗,使得它的输入必须为高脉冲且脉冲的频谱宽度能覆盖SAW抽头延迟线的中心频率.笔者采用CPLD和雪崩三极管电路产生了适合要求的脉冲.实验中测得脉冲电压15～25 V,脉冲宽度<7 ns.
文摘In this paper , the angular spread of the SAW beam diffracted by Bragg grating , denoted by δθ1 ,is analysed based on the equations of the deflection angle and the deflection effciency . A parameter δθB is defined to refer to ' Bragg angular spectrum width ' of the grating . The importance of this parameter in distinguishing the angular spread range of the deflected beam for different regimes is discussed as well. It is show from the analysis that if the spread angle of the incident beam labelled with δθinc is larger than the ' Bragg witdth of the angular spectrum ' of the grating , the spread angle δθ1 of the deflected beam will equal to δθB ; but if the angular divergence of the incident beam is less than δθB , then δθ1 =δθinc.Experimentally , four kinds of samples with different configurations are investigated by optical method , two of which operate in the regime of δθinc<<δθB and the others correspond to the case in the regime of δθinc >>δθB . The widths of the angular spread of the incident beam and the deflected beam are estimated by measuring the widths of their own acousto - optical diffraction points . It is demonstrated that the experimental results agree with the theoretical results approximately .
