多带通UWB信号光子学产生方法

基于多个不同权重与时延的doublet脉冲叠加,提出一种新的多带通超宽带（ MB-UWB）信号光学产生与传输的方法。射频（ RF）信号对光载波进行强度调制后,电高斯脉冲对光信号进行相位调制并利用标准单模光纤（ SMF）进行传输。 SMF实现相位调制-强度调制（ PM-IM）转换,产生doublet脉冲；实现多个doublet信号的时延差,产生叠加的UWB信号。通过调节RF信号源的频率可以实现UWB信号中心频率和带宽的改变；通过调节RF信号源的幅度可以实现边带抑制比的改变。仿真实现了边带抑制比大于25dB,中心频率5~8GHz,带宽2.9~3.8GHz的UWB的信号产生。

基于多层感知器的3型多带通FIR滤波器设计

利用多层感知器神经网络设计了3型多带通FIR滤波器,其基本思想是该神经网络利用总误差的能量函数,使能量函数递减,然后根据给定的幅频响应以及通带和阻带误差设计滤波器。提供了有效的训练方法,克服了传统方法的主要缺陷,改进了滤波器的设计。该方法设计滤波器收敛速度很快,适用于高阶系统。仿真结果表明该方法设计的3型FIR线性相位多带通滤波器的性能接近于理想滤波器。

长跑训练的跑步机故障信号特征提取方法

长跑运动员训练用的跑步机发生故障,会导致使用者受伤,甚至出现生命危险,为此提出长跑训练的跑步机故障信号特征提取方法。分析体育训练跑步机的结构,利用小波包准确分解跑步机信号的高频段信息,分析脉冲信号时间间隔变化和相位变化,提取时域特征得到正常脉冲以及故障脉冲信号间差异。通过小波包分解对应输出信号,重构某尺度内所有频带系数,即可构成全新的时间序列,实现提取故障信号特征。实验证明:所提方法能够有效区分正常信号与故障信号,提取的故障信号脉冲波动非常明显。

Enhanced multiple access schemes for future broadband satellite communications

A new structure of next generation integrated communication system was proposed, which is composed of space segment based on satellites and terrestrial segment. Moreover, the characteristics of enhanced multiple access schemes based on orthogonal frequency division multiplexing (OFDM) technique were analyzed for satellite links. However, OFDM is a doubtful candidate as its higher peak-to-average power ratio (PAPR) that causes the distortion of high power amplifier (HPA). Furthermore, different schemes were evaluated and compared in terms of the HPA nonlinearity and the link level performance in detail. And the pilot-aided channel estimation and equalization techniques were also considered for analyzing the problem. Simulation results show that the bit error rate (BER) and block error rate (BLER) performance of orthogonal frequency division multiple access (OFDMA) outperforms that of single carrier-frequency division multiple access (SC-FDMA) for the satellite links in the proposed structure, though discrete Fourier transform-spread OFDM DFT-S OFDM has low PAPR, especially the BER performance of OFDMA is 3.6 dB larger than that of SC-FDMA at the target BER.

A compact dual-band bandpass filter based on porous silicon dual-microcavity of one-dimensional photonic crystal

We propose a compact dual-band bandpass filter(BPF)based on one-dimensional porous silicon(PS)photonic crystal by electrochemical etching.By inserting three periods of high and low reflective index layers in the center of porous silicon microcavity(PSM),two sharp resonant peaks appear in the high reflectivity stop band on both sides of the resonance wavelength.Through simulation and experiment,the physical mechanisms of the two resonance peaks and the resonance wavelength are also studied.It is found that the resonance wavelength can be tuned only by adjusting the effective optical thickness(EOT)of each PS layer,in which different resonance wavelengths have different widths between the two sharp resonance peaks.Besides,the analysis indicates that oxidization makes the blue shift become larger for high wavelength than that for low wavelength.Such a fabricated BPF based on PS dual-microcavity is easy to be fabricated and low cost,which benefits the application of integrated optical devices.

MULTISTAGE FILTERS FOR IDENTIFICATION OF EUKARYOTIC PROTEIN CODING REGIONS

A class of multistage filters, namely, real narrowband bandpass filter （RNBPF） has been previously used for identification of protein coding regions. This filter passes the frequency component at 2π/3 along with its conjugate. This conjugate frequency compo- nent may degrade the identification accuracy. To improve the identification accuracy, two types of multistage filters are proposed in this paper. A complex narrowband bandpass filter （CNBPF） is proposed for suppressing the conjugate frequency component which, in turn, reduces the background noise present in the deoxyribonucleic acid （DNA） spec- trum and improves identification accuracy. By cascading RNBPF with moving average filter （RNBPFMA）, another type of multistage filter is proposed. As moving average filter smooth out the rapid variations in the DNA spectrum, RNBPFMA improves the identification accuracy. The computational complexity of RNBPFMA is less than that of CNBPF. The RNBPF and proposed multistage filters are compared with previously reported short-time discrete Fourier transform （ST-DFT） method in terms of compu- tational complexity. It is found that multistage filters reduce the computational load to a greater extent compared to ST-DFT method. The identification accuracy of the proposed CNBPF and RNBPFMA methods is compared with existing anti-notch filter and RNBPF methods. The results show that proposed methods outperform existing methods in terms of identification accuracy for benchmark data sets.