Proposed Power-Equalized EDFA Modules Using Fiber Bragg Gratings with Various Reflectivities

We proposed and experimentally demonstrated two power-equalized erbium-doped fiber amplifier (EDFA) modules using fiber Bragg gratings (FBGs) with various reflectivities for individual channels. The transmission type power-equalized EDFA module is low-cost for its simple design, while the reflection type power-equalized EDFA module can suppress most of the amplified spontaneous emission noise. Both consist of a bidirectional EDFA, a set of FBG chains with suitable reflectivities, and an optical isolator/optical circulator. They can find potential applications in wavelength division multiplexing lightwave transmission systems.     

一种基于空时分组编码的MIMO-SC/FDE系统的接收空间分集方案

该文提出了一种基于空时分组编码的多输入多输出频域均衡单载波分组传输(MIMO-SC/FDE)系统的空间分集接收方案,通过在Huang(2004)提出的分集结构中引入使用空时分组编码的发射分集,弥补了因减少DFT块数目而造成的性能损失,同时在接收端进一步减少了IDFT块的数目;通过适当设计空时分组编码,还可以进一步提高数据传输速率。该文详细推导了使用空时分组编码后的处理过程,并对使用空时编码后的MIMO-SC/FDE系统和相应的MIMO-OFDM系统性能进行了仿真比较。仿真结果表明,MIMO-SC/FDE系统的性能从总体上优于MIMO-OFDM系统。     

Closed-form error rates of STBC systems and its performance analysis

The closed-form solutions for error rates of Space-Time Block Code （STBC） Multiple Phase Shift Keying （MPSK） systems are derived in this paper. With characteristic function based method and the partial integration based respectively, the exact expressions of error rates are obtained for （2,1） STBC with and without channel estimation error. Simulations show that the practical error rates accord with the theoretical ones, so closed-form error rates are accurate references for STBC performance evaluation. For the error of pilot assisted channel estimation, the performance of a （2,1） STBC system is deteriorated about 3dB.     

高功率速调管发射机的防护设计

雷达装备的防护设计直接与系统设计、电讯设计、结构设计、工艺设计、计划与生产管理等相关联,是一门复杂的涉及多专业的系统工程。针对海洋大气环境的具体特点,详细阐述了高功率速调管发射机的环境适应性防护设计方法,从电讯设计、结构设计、工艺设计等方面给出了具体而有效的防护设计措施,具有广阔的应用和参考价值。     

A low EVM zero-IF RF transmitter for cognitive radio application

A zero-IF transmitter for Cognitive Radio (CR) application is presented. To effectively reduce the interference between Power Amplifier (PA) and Voltage Controlled Oscillator (VCO), two VCOs are adopted, one is 450 MHz and the other is from 1148 MHz to 1252 MHz with an 8 MHz step, so the frequency of them are different from the operational frequency of PA. The Local Oscillator (LO) of the modulator generated by mixing the signals of the two VCOs has a low phase noise of −82 dBc/Hz with an offset of 1 kHz. The measurement result of the transmitter shows that the Adjacent Channel Power Ratio (ACPR) is less than −47.5 dBc at 27 dBm output, and the Error Vector Magnitude (EVM) is less than 1.7%.     

集成两路射频SiP发射器的设计和研究

随着移动通信和其它电子应用领域的不断进步,系统集成需求日益紧迫。除了可以应对系统性能、功能、成本和小型化的更高要求,系统级封装(SiP)在降低开发成本、实施灵活设计、缩短开发周期,和集成异质芯片上也有突出优势。这篇文章介绍了一个可用于手机基站系统的双通路发射系统SiP模块的开发。我们用计算模拟方法辅助优化设计,并成功制造和验证了SiP模块。SiP为内嵌电磁干扰屏蔽罩的12mmx12mmx1.9mm的多层栅格阵列封装(LGA)。各种射频信号性能均通过测试,包括严格的隔离度要求。电磁屏蔽测试和计算模拟结果高度吻合。最后,文章介绍了一种高效的计算模拟方法,极大地缩短了计算模拟的时间,并对未来射频SiP开发将提供有力帮助。     

用于智能变送器的DAC

描述智能变送器及其对高分辨率，低功率D/A转换器的需求。     

脉压体制下的雷达发射机上变频器

本文根据脉冲压缩技术对雷达发射机的辐相特性要求,分析了传统上变频器方案的缺点,提出利用锁相环方案解决信号的幅相失真、保证雷达对目标的检测性能的方案。     

一种实用的基于导频的空时编码OFDM系统信道估计方法

该文研究了在多径衰落信道情况下的基于导频的空时编码OFDM系统的信道估计方法,包括基于DFT的LS,LMMSE算法,提出了一种实用的估计方法,该方法通过优化设计的导频符号避免了复杂的矩阵求逆计算,大大降低了LS,LMMSE算法的复杂度和运算量,在性能上接近理想信道信息情况下的性能。