卫星电视上行站信号自动监测系统

每个卫星电视上行站都必须对卫星转发器上的电视信号进行监测,才能及时发现卫星电视上行信号的异常变化,准确处理异常突发干扰。为实现自动、连续、实时监测,就需要建立卫星电视上行站射频信号自动监测系统。文章详细介绍了一个自动监测系统的设计及实现。     

MULTICARRIER DS—CDMA WITH ADAPTIVE MODULATION AND POWER ALLOCATION

Adaptive modulation and power allocation is introduced into the multicarrier DSCDMA system to improve the system performance and bandwidth efficiency.First,the system design appropriate for adaptive modulation and power allocation is given,then the algorithm of adaptive modulation and power allocation is applied.Simulation results demonstrate great performance improvement compared with the fixed modulated one.     

小波变换分离太阳射电频谱图中的纤维结构

太阳射电爆发纤维精细结构是太阳射电爆发活动中一类重要的观测现象,利用二维小波变换对纤维精细结构动态频谱图进行处理,分离频谱图中的纤维结构。首先对原始频谱图实行多层小波变换,由低频分量重构原始图像,就可得到爆发的背景信息,令原始频谱图减去背景并经过阈值处理后,便可将原始频谱图中的纤维结构很好地分离出来。     

SAW软扩频调制解调器的研究

报道了一种直接序列软扩频调制解调器的SAW实现方案，并给出了相应的实验结果。该方案对提高系统抗干扰能力、频宽利用等方面均具有与其他技术不同的特点。同时，该技术方案为进一步研究DS-OFDM打下了基础。     

Inner derivations and norm equality

We characterize when the norm of the sum of two bounded operators on a Hilbert space is equal to the sum of their norms.

     

氢化丁苯共聚物结构的核磁共振波谱表征Ⅱ.微观结构的定量计算

在氢化丁苯共聚物¹³C-NMR谱脂肪碳部分谱带归属的基础上,根据各谱带的主要来源,推导出六个二单元浓度的计算公式。计算出二单元、一单元的相对含量,各结构单元的数均序列长度、嵌段含量和其它结构参数。加氢前后的¹H-和¹³C-NMR谱的组成计算结果基本一致。初步探讨了作为粘度指数改进剂的氢化丁苯共聚物微观结构与性能的关系,为合成提供了依据。     

应用于生物医学的光声光谱技术的改进和实验研究

改进的光声光谱归一化技术，避免了普通的分光法归一化光声光谱技术中分束镜以及锁相放大器动态范围的影响和限制，实现宽光谱范围内准确的光谱测量。氙灯光源功率起伏用修正项修正，误差在5％以内，实现各次实验数据的可比性。     

Mass Power Spectrum in a Universe Dominated by the Chaplygin Gas

The mass power spectrum for a Universe dominated by the Chaplygin gas is evaluated numerically from scales of the order of the Hubble horizon to 100 Mpc. The results are compared with a pure baryonic Universe and a cosmological constant model. In all three cases, the spectrum increases with k, the wavenumber of the perturbations. The slope of the spectrum is higher for the baryonic model and smaller for the cosmological constant model, the Chaplygin gas interpolating these two models. The results are analyzed in terms of the sound velocity of the Chaplygin gas and the moment the Universe begins to accelerate.     

The Lamb-dip spectrum of methylcyanide: Precise rotational transition frequencies and improved ground-state rotational parameters

Methylcyanide, CH₃CN, is an important interstellar species, and therefore the accurate knowledge of precise rest frequencies for rotational transitions as well as ground-state rotational and hyperfine constants is needed. In this work the hyperfine structure of the millimeter- and submillimeter-wave spectra of CH₃CN has been further investigated. In addition, accurate THz measurements have been carried out for the first time. Consequently, the present investigation allowed us to provide the most accurate ground state rotational and hyperfine parameters known at the moment for CH₃C¹⁴N. To resolve the hyperfine structure of the rotational transitions observed, the Lamb-dip technique has been exploited. Both frequency-modulated and video-type detections have been employed.     

一种有效的优化的多载波通信系统的功率分配算法

本文提出一种关于DMT系统传输纯数据流业务的最佳的功率分配算法，该算法使用了一种有效的表格查手工艺工和拉格朗日乘法器对分搜索办法，能够较快的收敛到最佳的功率点。同时，易于用硬件和软件实现。